MALNUTRITION: PROTEIN-ENERGY MALNUTRITION

MALNUTRITION: PROTEIN-ENERGY MALNUTRITION. Protein-energy malnutrition (PEM) may be present at any time during the life cycle, but it is more common in the extreme ages, that is, during infancy/childhood and in the elderly. The present review will be restricted mostly to the condition present during infancy and childhood.

Protein-energy malnutrition is a syndrome characterized by its progressive onset and a series of symptoms and signs that encompass a continuum, ranging from clinically undetected manifestations to the full-blown clinical picture of marasmus or kwashiorkor. A syndrome is defined in clinical practice as a set of symptoms and signs that may be caused by different etiologies.

In the case of PEM, the earliest symptoms include subtle changes in the mood of the child, which may be described by the mother as saying that the child is not as playful as he/she used to be. Further changes include a loss of appetite and a loss of interest in the surroundings, which lead to decreased social interaction with peers or siblings and adults (parents or other caregivers). When PEM becomes more severe, there are adverse effects on the child's cognitive and behavioral development, evident in both the short and the long term.

In relation to signs, the earliest clinical sign of PEM is the lack of adequate weight gain. Also common in the early stages are mild episodes of common acute infectious diseases, such as acute diarrhea or acute respiratory infections. As the condition advances, the child will show signs of body wasting, progressing to an extreme thinness. If the syndrome becomes chronic, there are small or no increases in length. When the condition becomes more severe, the child may show the clinical pictures of marasmus or kwashiorkor, which will be defined later in this article.

The etiology of protein-energy malnutrition as a syndrome may be classified as primary or secondary. Although in practice most cases of PEM are caused by a combination of both, the concept may be useful for targeting interventions. Primary PEM refers to a deficit of available food. This, in turn, may be because of biological conditions, such as maternal malnutrition prior to or during pregnancy and lactation, or to social conditions, such as poverty; to a limited or selective unavailability of food; to war; to ecological disasters leading to famine, or, more often, as a result of profound social inequalities, either at the individual level (discrimination, refugees, prisoners) or at the community or country level. The largest prevalences of protein-energy malnutrition are found in socioeconomically deprived areas of the world, as will be reviewed further on in this article. Secondary causes of PEM include several conditions that impair food intake, absorption, or utilization, or that increase energy and/or protein requirements or losses. Secondary causes of PEM may be biological or social conditions.

Biological conditions may interfere with food intake, such as congenital anomalies (for example, harelip); with absorption, such as any of several malabsorption syndromes (for example, tropical sprue); or with utilization, such as inherited metabolic diseases (for example, phenylketonuria). Biological conditions that increase the need for energy include all infectious diseases accompanied by fever, and other diseases that increase catabolism, such as tuberculosis, or that are accompanied by an increased nutrient loss, such as intestinal parasitism.

On the other hand, social causes that affect food intake, whether it be in quantity or quality (protein-energy or micronutrient content), include several conditions associated with poverty, such as ignorance, inadequate weaning practices, child abuse, alcoholism or other drug addictions, and others.

Different conceptual frameworks for the study of malnutrition have been proposed and adopted throughout the years; one of the most widely accepted ones was developed during the WHO/UNICEF Joint Nutrition Programme in Iringe, Tanzania (B. Jonsson et al., 1993) (UNICEF 1990), from where it has been extended to many parts of the world. An appealing feature of this conceptual framework is that it may be adapted to describe causes of the major nutritional deficiencies present in the world, including vitamin A, iron, and iodine deficiency.

Clinical Picture of Marasmus and Kwashiorkor

Marasmus is characterized by a chronic and severe restriction of both energy and protein to the body. Marasmus is more frequently found at a younger age than kwashiorkor, usually in children under one year of age. A marasmic child presents severe wasting, with a very low weight-for-age and reduced length-for-age, often below -3 standard deviation of the reference population values. The clinical history of a marasmic child may reveal poverty or famine affecting the family; inadequate child-rearing practices, like starvation wrongly prescribed as part of the management of diarrhea; an early stopping of breast-feeding; over-dilution of formula; a history of repeated and/or chronic infections, such as diarrhea or tuberculosis; or some physical condition that affected the child's growth and development, such as prematurity, mental defects, or a malabsorption syndrome. The mother or caregiver will often report that the child is hungry. On a first appreciation, the child may be interested in the environment, with an active cry and reaching for food if offered, or else he/she may be depressed to the point of coma. The typical clinical picture is that of a striking loss of subcutaneous fat and muscle wasting, observed as markedly thin limbs, an evident rib cage, sunken cheeks and eyes that give the child a "monkey-like" or gaunt appearance, a prominent abdomen (although with no evidence of an enlarged liver), and a relatively big head. The hair is often thin and dry, and comes off easily. However, skin rashes or dermatosis are not usually present. Common micronutrient deficiencies include vitamins A and D, zinc, and iron, although anemia is less common in marasmus than in kwashiorkor.

The clinical picture of kwashiorkor is not as striking in appearance, as this syndrome often affects slightly older children, i.e., between one and three years of age. The clinical onset of kwashiorkor usually takes place in a shorter period of time as compared to marasmus, and is characterized by a relative, though severe, limitation in protein intake, with a lesser involvement of energy deficit. A child affected with kwashiorkor is often apathetic to external stimuli, is irritable, and gives the impression of misery, rejecting or crying when cared for. The most salient clinical characteristic of this syndrome is the presence of edema, which may mask the evidence of body weight loss and reduced length in relation to age. It is also common to find skin lesions that range from a flaky, pink dermatosis with skin dryness and depigmentation to deep ulcerations. Also common are petechiae and ecchymoses, as well as clinical signs of anemia. The hair presents discoloration with bands of dark and light hair (described by clinicians as the "flag sign"). An enlarged, fatty liver is also characteristic of kwashiorkor, palpable as a soft mass under the right rib cage. Co-occurring micronutrient deficiencies are common, so clinical signs of deficiencies of specific vitamins, including A, B, C, D, iron, or others, also may be present.

Classification of Protein-Energy Malnutrition

The clinical signs of severe PEM are so impressive that, for several years, they drew the attention of pediatricians and other physicians interested in furthering the understanding of the clinical syndromes and their treatment. Therefore, the study of PEM was long confined to the hospital setting. Actually, the first classification of PEM came from Mexican observers, who ranked the severity of malnutrition based on the risk of death for children with a clinical diagnosis of PEM. This group, led by Gomez, proposed that children with a weight-for-age deficit greater than 40 percent in relation to a reference population were in the greatest risk of dying, and thus labeled them as having third-degree malnutrition. Further, children with 25–40 percent weight-for-age deficit were labeled as having second degree malnutrition, and children with 10–25 percent weight-for-age deficit were classified as having first degree malnutrition (Gómez-Santos, 1946).

This classification had a high predictive value for the risk of death, and therefore had important implications for clinical practice. It was further abused, however, when its use was extended to the classification of malnutrition at a population level. In other words, children with no evidence of clinical malnutrition who have low weight-for-age should not be classified as malnourished; doing so may not only misdiagnose an individual, but may over-estimate the prevalence of malnutrition in a population. Also, the Gomez classification has been criticized because a single measure of a child's weight referred to age gives no idea about the nutritional history of the child. That is, an underweight child may be growing according to his/her normal growth channel, may be recovering from a recent episode of weight loss ("catch-up growth"), or may be deteriorating in relation to the recent past.

In order to overcome these caveats, Waterlow proposed combining weight-for-height, as an indicator of an acute episode of malnutrition, with height-for-age, as an indicator of chronic nutritional deficits that would be reflected in growth stunting (Waterlow, 1972).

Although these classifications have been used for several years, they have two important disadvantages that often are overlooked. To illustrate the first disadvantage, it is important to highlight the concept of Z-scores as a means of describing an individual child's anthropometric indicators in a normal distribution. The normal distribution of a reference population has been published by the World Health Organization (WHO) and is most often accepted worldwide as the standard for comparison. Eighty percent of the median weight-for-age might be above or below -2 Z-scores, depending on the child's age. The second disadvantage is that, to approximate a fixed point in the normal distribution, say, -2 Z-score, different percents of median have to be used depending on the anthropometric index used—for example, 90 percent for low height-for-age, or 80 percent of low weight-for-height.

In consequence, the World Health Organization Expert Committee on Physical Status has recommended the use of Z-scores to express weight-for-age, weight-for-height, or height-for-age relative to values reported in a reference population (WHO Expert Committee on Physical Status, 1995). The use of this system has several advantages; i.e., when applied at a population level, it allows the mean and standard deviation to be calculated for a group of Z-scores, and it allows the use of fixed cut-off points (i.e., -1, -2, or -3 Z-scores) to classify mild, moderate, or severe deficits for any anthropometric indicator. Although the use of Z-scores may be difficult to grasp for those who have been accustomed to classifying nutritional deficits based on the percent of median, the advantages of Z-scores outweigh their disadvantages.

Global Prevalence of Protein-Energy Malnutrition

The most recent estimates about the distribution of PEM at a worldwide level were compiled by the World Health Organization (WHO) Programme of Nutrition, available in its Global Database on Child Growth and Malnutrition (de Onis and Blössner, 1997). This database covered 95 percent of the total population of children under 5 years of age who lived in 103 developing nations in 1995, as was reported in nationally representative surveys available at the time. According to these data, an estimated 206.2 million children, who represent 38 percent of all children under 5 years old, were stunted (low height-forage); 167.3 million children (31 percent) were underweight (low weight-for-age), and 48.8 million children (9 percent) were wasted (low weight-for-height). PEM is most often found in the poor regions known as the "developing world." The largest number of affected children were found in Asia, where 41 percent of all under 5 years old were stunted, 35 percent were underweight, and 10.3 percent were wasted. Africa had 38.6 percent stunted, 28.4 percent underweight, and 8 percent wasted children of all those under 5 years old; Latin America and the Caribbean showed 17.9 percent stunted, 9.5 percent underweight, and 3 percent wasted children of all those under 5 years old. The proportion of children under 5 years of age affected in Oceania was 31.4 percent, 22.8 percent, and 5 percent, respectively, but the total number of children living in this region is much lower, so in reality, these percentages translate into many fewer children affected than in the other regions.

Since the mid-1980s, the Administrative Committee on Coordination/Sub-Committee on Nutrition (ACC/ SCN) of the United Nations periodically has examined the trends of malnutrition in the world's children. In its Third Report on the World Nutrition Situation (ACC/ SCN, 1997), this Committee (from data from 61 countries) estimated the trends in stunting with two or more nationally representative surveys. In the period from 1980 to 1995, stunting declined globally at a rate of 0.54 percentage points per year. Sub-Saharan Africa had an increase of 0.130 percentage points per year in the average prevalence of stunting; the remaining regions of the world showed statistically significant decreases that ranged from -0.26 in Middle-America and the Caribbean to -0.90 in Southeast Asia (Table 1).

The same Committee was able to use data from 95 countries that had data from at least one national survey to estimate the prevalence of undernutrition; underweight and stunting showed a consistent 11.5 percentage point difference. The higher prevalence was for the underweight classification. During the 1980–1995 period studied, only sub-Saharan Africa had an increase in the prevalences of both stunting and underweight; all the other regions showed decreasing trends in these two indicators (Table 1).

Acute and Long-Term Consequences of Protein-Energy Malnutrition

PEM results from a relative deficiency of protein (essential amino acids and/or total nitrogen) and energy substrates (carbohydrates, fats, or proteins). However, these deficiencies are almost always accompanied by micronutrient (minerals and vitamins) deficits. Manifestations of PEM differ depending on the duration, the severity, and the combination of these deficiencies. In the early stages,

there are functional impairments, which are later followed by biochemical and physical damage.

The identification, understanding, and treatment of the full-blown clinical syndromes characteristic of severe PEM began in the mid-1930s with the description of kwashiorkor (Williams, 1933). On the other hand, the identification and understanding of the functional manifestations of malnutrition have only come about during the last three decades of the twentieth century, with the launching of two large-scale, community-based research projects: the first one, known as the INCAP Longitudinal Study, was based in Guatemala (Habicht and Martorell, 1992). The second took place simultaneously in three countries—Egypt, Kenya, and Mexico—and was known as the CRSP study (Calloway, Murphy, et al., 1988).

Functional consequences of protein-energy malnutrition. As described earlier, the functional consequences of PEM were recognized and studied only relatively recently (Allen, 1993). Among the most well documented functional consequences of PEM are growth impairment, a reduced immune response, and a disruption in cognitive ability.

Growth impairment. Growth failure because of PEM usually starts to manifest very early in life. Information from the INCAP longitudinal study, as well as from the CRSP studies, coincides in showing that growth stunting begins at about 3 to 4 months of age and is complete before 18 months (Allen, 1995). A further contribution from the INCAP study was provided by a long-term follow-up of the same populations that showed not only that growth stunting present during infancy carried on until adolescence, but also that length at 3 years of age was a strong predictor of adolescent size (Martorell, Schroeder, et al., 1995). It also seems as if stunting in early life is correlated significantly with reduced physical performance (Haas, Martinez, et al., 1995) and reduced psychomotor and mental performance, both during late childhood (Mendez and Adair, 1999) and even until adolescence (Grantham-McGregor, 1995; Pollit, Gorman, et al., 1995).

Two more relevant issues related to growth failure are that there is a window of opportunity for intervention from the ages of 3 to 6 months, when response to the intervention may be greatest (Lutter, Mora, et al., 1990), and that most of the growth deficit found at later ages accumulated during the first months of life (Rivera, Cortes, et al., 1998).

Immune response. It has been recognized that malnutrition is the most common cause of immunodeficiency worldwide (Chandra, 1991). Actually, malnutrition and infection interact in a vicious cycle: the presence of one more easily leads to the development of the other (Scrimshaw, Taylor, et al., 1968). There are several mechanisms involved in this relationship. PEM impairs cell-mediated immunity, phagocitic function, and the complement system. It also diminishes immunoglobulin (IgA, IgM, and IgG) concentrations, and cytokine production (Chandra, 1991). Micronutrient deficiencies associated with PEM also adversely effect the immune response. For example, iron plays an important role in several metabolic functions, including both the host and invasive bacteria. Several microorganisms that infect the human body only achieve their full infectious activity in the presence of iron. Such is the case of bacteria that cause diarrheal disease, such as Escherichia coli, Yersinia septica, Salmonella sp., and Vibrio cholerae; and others responsible for lower respiratory infections, such as Mycobacterium tuberculosis, Klebsiella pneumoniae, Pseudomona aeruginosa, and Listeria monocytogenes. These microorganisms actively seek iron in their host during infection, uptaking it from destroyed red cells (erythrocytes) and body stores (liver). On the other hand, the host tries to make iron less available to invasive microorganisms, sequestering it through different mechanisms—referred to as nutritional immunity—that include the binding of iron to transferrin and lactoferrin, and the increase in ferritin saturation in the liver (Kochan, 1976). Other micronutrients that play active roles in modulating immunity include zinc, selenium, copper, vitamins A, C, E, B _6, and folic acid (Nezu and Nakahara, 1994).

Conversely, infectious diseases lead to malnutrition by several mechanisms that often interact with each other. Almost every malnourished child will sooner or later present with diarrhea. Many of the interactions between malnutrition and infection are understood because of studies of diarrheal disease (Chen, 1983); hence the illustration of the mechanisms by which these two morbid conditions interact is particularly useful. One of the first symptoms of diarrheal disease is anorexia, as a result of vomiting and abdominal discomfort. Also, fever, dehydration, and electrolyte imbalances contribute to it (Martorell, Yarbrough, et al., 1980). Anorexia leads to a restricted intake, which is often reinforced by erroneous caregiver practices. In part, it is culturally engrained in different societies to withhold food from a diarrheaaffected child (Bentley, 1988), and it is also quite common to find physicians who still think that it is necessary to "put the bowel to rest" during the acute stage of the illness (Brown and MacLean, 1984). The deleterious effect of decreased food intake is worsened by increased catabolic losses of nitrogen that occur as a result of increased metabolic rates and structural damage to the intestine (Powanda, 1977). Another consequence of intestinal damage is the transient loss of absorptive surface and absorptive function as a result of villous atrophy (Davidson and Barnes, 1979). This condition leads to a decreased absorption of macronutrients (fat and carbohydrates) and micronutrients (particularly fat-soluble vitamins). The presence of unabsorbed carbohydrates in the intestinal lumen increases the osmolarity of the intestinal content, thus causing an hyperosmolar diarrhea (Wapnir, 1982). It also subjects these substrates to bacterial fermentation, which produces gas and intestinal bloating, worsening gastrointestinal symptoms. Catabolic losses also are increased by the presence of fever. In cases of parasitic infestations, the child's nutritional status is impaired by blood losses that are secondary to colitis or direct intestinal mucosal damage (common in cases of roundworm [Ascaris lulmbricoides], hookworm [Ancylostoma duodenale and Necator americanus], or whipworm [Trichuris trichiura]). Parasitic infestations also are associated with respiratory symptoms (particularly in case of Ascaris infestations) and anorexia (Lunn and Northrop-Clewes, 1993).

Disrupted cognition. PEM can disrupt cognition in several ways. Following the lessons learned from the effect of PEM on the body during infections, the classic explanation was that malnutrition caused physical damage to the brain, particularly during sensitive periods of development, namely, during the first two years of life, when about 80 percent of the brain's growth is achieved (Guilarte, 1993; Levitsky and Strupp, 1995). At present, however, it is clear that there are several other mechanisms, aside from organic damage, by which malnutrition can impair intellectual development. There is also evidence that at least part of this damage may be reversible, even in the presence of structural damage to the brain (Levitsky and Strupp, 1995).

Malnutrition may affect brain growth and development, which will be reflected in cognitive disabilities, motor impairment, or lower intelligent quotient (IQ), by means of micronutrient deficiencies such as vitamin B₆ or iron, both of which are vital for normal brain function (Guilarte, 1993; Pollitt, 1997). Malnutrition also may affect these functions because of energy deficiency, which limits activity and social interaction with peers and caregivers. This mechanism was explored first in the early 1970s by Levitsky and coworkers in a rat model. They showed that energy-deprived rats scored lower on such tests as maze running—a proxy for mental ability—because they were so feeble that they withdrew from contact with their peers and the objects in their surroundings (Levitsky and Strupp, 1995). Similar findings were shown to be present in children living in deprived third-world communities (Chávez and Martínez, 1982).

The extent to which PEM affects intellectual potential has been explored by studying the effect of protein-energy supplementation on behavioral development. In spite of different study designs that focused on prenatal supplementation (Rush, Stein, et al., 1980), on postnatal supplementation (Grantham-McGregor, Meeks Gardner, et al., 1990; Husaini, Karyadi, et al., 1991), or in both (Waber, Vuori-Chirstiansen, et al., 1981; Chávez and Martínez, 1982), results from these studies are consistent in showing that a significant proportion of the variability in mental and motor developmental scales during the first two years of life may be accounted for by nutritional supplementation.

The extent to which the differences in intellectual performance found at early ages in children affected by PEM carries on to later stages in life has been addressed by Pollitt et al. in a long-term follow-up study of Guatemalan children, who received supplements during the prenatal period and the first 2 years of life and were later followed up between the ages of 13 and 19 years old (Pollitt, Gorman, et al., 1995). This study found that children who had received a protein-energy supplement had significantly higher scores on tests of knowledge, numeracy, reading, and vocabulary, as well as a faster reaction time in information-processing tasks compared with children who had received only an energy supplement. This effect was particularly strong for protein-energy supplemented children at the lowest end of the socioeconomic distribution, an interesting finding when compared to only energy supplemented children, in whom the higher cognition test scores varied as a positive function of socioeconomic status, as expected. The authors interpretation is that the protein-energy supplement acted as a social equalizer in relation to the differences in performance usually found in populations as a function of differences in socioeconomic status.

Another long-term supplementation study was carried out in a Mexican village, where women received nutritional supplements during pregnancy and their offspring continued to receive micronutrient supplements from 12 weeks until 10 years of age. Compared to a control group (mothers and children from the same village, recruited two years before supplementation began), children who received supplements showed significantly better IQs, school performance, and behavior (Chávez, Martínez, et al., 1995).

The studies of the effects of iron deficiency on intellectual and motor abilities were addressed specifically during the 1980s and 1990s. Several well-designed intervention-control studies have shown that, before treatment, average mental scores on the Bayley Scales of Infant Development of infants with anemia were 6 to 14 points lower than the scores of non-anemic controls (Lozoff, Brittenham, et al., 1982; Grindulis, Scott, et al., 1986; Lozoff, Brittenham, et al., 1988; Walter, De Andraca, et al., 1989), and average motor development scores were 9 to 11 points lower, differences of statistical and clinical significance. No significant improvement on the test scores of initially iron-deficient children were noted following iron supplements for two to three months (Aukett, Parks, et al., 1986; Lozoff, Brittenham, et al., 1988; Walter, De Andraca, et al., 1989). Fewer studies have addressed whether these deficits prevail in later ages. In a long-term follow-up study of Costa Rican children at age 5 years whose iron status had been documented and consequently treated in infancy under careful supervision, Lozoff et al. found that at five years of age, all children had excellent iron status. However, those children who had been severely iron deficient during infancy (hemoglobin ≥100 g per liter) showed lower mental and motor functioning scores at school entry than did the rest of the children, even after controlling for background factors that were potential confounders (Lozoff, Jimenez, et al., 1991). Further, even anemic children with hemoglobin levels < 100 g per liter before and after treatment also had poorer outcomes at five years of age, compared to non-anemic children. Strong as this evidence may be, it is relevant to point out that, to date, there is no definite proof that iron deficiency is the cause of children's lower test scores. For obvious ethical reasons, the gold standard of experimental designs, the double-blind placebo-control study, has not been carried out.

Protein-energy malnutrition also may affect children's performance on cognitive tests by other, indirect mechanisms (often conceptualized as confounding variables in studies that attempt to establish links between PEM and impaired cognition).These include social and economical disadvantages (Johnston, Low, et al., 1987), differences in parental education (LeVine, LeVine, et al., 1991), years of schooling (Ceci, 1991), inadequate attention or affection from caregivers (Engle and Ricciuti, 1995), and other environmental factors, which may include peer interaction, parental presence in the home, etc. (Engle and Lhotska, 1999).

Recent research has addressed the role of breastfeeding (the gold-standard of good nutrition during the first months of life) on cognitive development, adjusting for the aforementioned variables. The results of a meta-analysis that included 11 studies that controlled for ≥ 5 covariates on the effect of breast-feeding on cognitive function, a statistically significant increment in cognitive function of 3.16 points was seen in breast-fed infants, consistent through all the studies, at 6 to 23 months of age. This study found a greater benefit of breast-feeding for cognitive development of premature babies (an adjusted benefit of 5.18 points), and a larger benefit in relation to duration of breast-feeding (an increase of the weighted mean benefit of 1.68 points with 8–11 weeks of breast-feeding to 2.91 points with ≥28 weeks) (Anderson, Johnstone, et al., 1999).

Concluding Remarks

Over the years, much has been learned about protein-energy malnutrition, its causes, and its effects. Without pretending that all is known, available knowledge can alleviate this burden on human development and social inequalities. Although the treatment of malnourished children all over the world is a clear imperative, the key to solving the problem is to focus on prevention. Preventive actions should be interdisciplinary. These actions should encompass a broad focus on education, particularly directed to women; they should include actions to improve sanitary conditions, schooling opportunities, employment, agricultural produce, and access to diverse food sources, particularly those rich in micronutrients. All sectors of society, including government and nongovernment organizations, should work together toward a common end. The opportunities to make a substantial improvement in the nutritional status of children all over the world are here, as never before in history. We have studied the causes of malnutrition, its mechanisms, and its consequences. It is now time to study the impact of specific interventions tailored to solve persistent problems.

BIBLIOGRAPHY

ACC/SCN. Third Report on the World Nutrition Situation. Geneva, Switzerland, 1997.

Allen, Lindsay H. "Malnutrition and Human Function: A Comparison of Conclusions from the INCAP and Nutrition CRSP Studies." Journal of Nutrition 125 (1995): 1119S–1126S.

Allen, Lindsay H. "The Nutrition CRSP: What is Marginal Malnutrition and Does It Affect Human Function?" Nutrition Reviews 51 (1993): 255–267.

Anderson, James W., Bryan M. Johnstone, et al. "Breast-feeding and Cognitive Development: A Meta-analysis." American Journal of Clinical Nutrition 70 (1999): 525–535.

Aukett, M. A., Y. A. Parks, et al. "Treatment with Iron Increases Weight Gain and Psychomotor Development." Archive of Disease in Childhood 61 (1986): 849–857.

Bairagi, R., M. K. Chowdhury, et al. "Alternative Anthropometric Indicators of Mortality." American Journal of Clinical Nutrition 42 (1985): 296–306.

Bentley, Margaret. "The Household Management of Childhood Diarrhea in Rural North India." Social Sciences and Medicine 27 (1988): 75–85.

Brown, Kenneth. H., and William C. MacLean, Jr. "Nutritional Management of Acute Diarrhea: An Appraisal of the Alternatives." Pediatrics 73 (1984): 119–125.

Ceci, S. J. "How Much Does Schooling Influence General Intelligence and Its Cognitive Components? A Reassessment of the Evidence." Developmental Psychology 27 (1991): 703–722.

Chandra, Ranjit. "Nutrition and Immunity: Lessons from the Past and New Insights into the Future." American Journal of Clinical Nutrition 53 (1991): 1087–1101.

Chávez Adolfo, Celia Martínez, et al. "The Effect of Malnutrition on Human Development. A 24-year study of well-nourished and malnourished children living in a poor Mexican village." In Community-Based Longitudinal Nutrition and Health Studies: Classic Examples from Guatemala, Haiti, and Mexico, edited by N. S. Scrimshaw. Boston, International Nutrition Foundation for Developing Countries, (1995).

Chen, Lincoln. "Interactions of Diarrhea and Malnutrition: Mechanisms and Intervention." In Diarrhea and Malnutrition, edited by L. C. Chen and N. S. Scrimshaw pp. 3–19. New York: Plenum Press, 1983.

Chen, Lincoln C., A. Chowdhury, et al. "Anthropometric Assessment of Energy-Protein Malnutrition and Subsequent Risk of Mortality among Preschool Aged Children." American Journal of Clinical Nutrition 33 (1980): 1836–1845.

de Onis, Mercedes and Monika Blössner, WHO Global Database on Child Growth and Malnutrition. Geneva, Switzerland: World Health Organization Programme of Nutrition, 1997.

Engle, Patrice L. and Henry N. Ricciuti "Psychosocial Aspects of Care and Nutrition." Food and Nutrition Bulletin 16 (1995): 356–377.

Gomez, Federico, Rafael Ramos-Galvan, et al. "Mortality in Second and Third Degree Malnutrition." Journal of Tropical Pediatrics 2 (1956): 77–83.

Gómez-Santos, Federico. "Desnutrición." Boletin Medico del Hospital Infantil de Mexico 3 (1946): 543–551.

Grantham-McGregor, Sally. "A Review of Studies of the Effect of Severe Malnutrition on Mental Development." Journal of Nutrition 125 (1995): 2233S–2238S.

Grindulis, H., P. H. Scott, et al. "Combined Deficiency of Iron and Vitamin D in Asian Toddlers." Archives of Diseases in Childhood 61 (1986): 843-848.

Haas, Jeree D., E. J. Martinez, et al. "Nutritional Supplementation During the Preschool Years and Physical Work Capacity in Adolescent and Young Adult Guatemalans." Journal of Nutrition 125 (1995): 1078S–1089S.

Habicht, Jean-Pierre, and Reynaldo Martorell "Objectives, Research Design and Implementation of the INCAP Longitudinal Study." Food and Nutrition Bulletin 14 (1992): 176–190.

Heywood, Peter. "The Functional Significance of Malnutrition: Growth and Prospective Risk of Death in the Highlands of Papua New Guinea." Journal of Food and Nutrition 39 (1982): 13–19.

Husaini, M., L. Karyadi, et al. "Developmental Effects of Short-term Supplementary Feeding in Nutritionally-at-risk Indonesian Infants." American Journal of Clinical Nutrition 54 (1991): 799–804.

Johnston, R. E., W. M. Low, et al. "Interaction of Nutritional and Socioeconomic Status as Determinants of Cognitive Development in Disadvantaged Urban Guatemalan Children." American Journal of Physical Anthropology 73 (1987): 501–506.

Kochan, I. "Role of Iron in the Regulation of Nutritional Immunity." Advanced Chemistry Series No. 162. Washington, D.C.: American Chemical Society (1977): 55–62.

LeVine, R. A., S. E. LeVine, et al. "Women's Schooling and Child Care in the Demographic Transition: A Mexican Case Study." Population Development Reviews 17 (1991): 459–496.

Levitsky, D., and B. Strupp "Malnutrition and the Brain: Changing Concepts, Changing Concerns." Journal of Nutrition 125 (1995): 2212S–2220S.

Lozoff, B., G. M. Brittenham, et al. "The Effects of Short-term Oral Iron Therapy on Developmental Deficits in Iron-deficient Anemic Infants." Journal of Pediatrics 100 (1982): 351–357.

Lozoff, B., G. Brittenham, et al. "Iron Deficiency Anemia and Iron Therapy Effects on Infant Developmental Test Performance." Pediatrics 79 (1987): 981–995.

Lozoff, B., E. Jimenez, et al. "Long-term Developmental Outcome of Infants with Iron Deficiency." New England Journal of Medicine 325 (1991): 687–694.

Lunn, P., and C. A. Northrop-Clewes. "The Impact of Gastrointestinal Parasites on Protein-energy Malnutrition in Man." Proceedings of the Nutrition Society 52 (1993): 101–111.

Lutter, C. K., J. O. Mora, et al. "Age-specific Responsiveness of Weight and Length to Nutritional Supplementation." American Journal of Clinical Nutrition 51 (1990): 359–364.

Martorell, Reynaldo, Dirk G. Schroeder, et al. "Patterns of Linear Growth in Rural Guatemalan Adolescents and Children." Journal of Nutrition 125 (1995): 1060S–1067S.

Mendez, Michelle A., and Linda S. Adair "Severity and Timing of Stunting in the First Two Years of Life Affect Performance on Cognitive Tests in Late Childhood." Journal of Nutrition 129 (1999): 1555–1562.

Pelletier, David. "The Relationship between Child Anthropometry and Mortality in Developing Countries: Implications for Policy, Programs and Future Research." Journal of Nutrition 124 (1994): 2047S–2081S.

Pelletier, David, Ed Frongillo, Jr., et al. "Epidemiologic Evidence for a Potentiating Effect of Malnutrition on Child Mortality." American Journal of Public Health 83 (1993): 1130–1133.

Pollitt, Ernesto. "Iron Deficiency and Educational Deficiency." Nutrition Reviews 55 (1997): 133–141.

Pollitt, Ernesto, K. S. Gorman, et al. "Nutrition in Early Life and the Fulfillment of Intellectual Potential." Journal of Nutrition 125 (1995): 1111S–1118S.

Rivera, Juan A., Cecilia Cortés, et al. "Capacidad de peso para edad y longitud para edad para predecir desmedro a los tres años de vida." Salud Publica de Mexico 40 (1998): 127–132.

Scrimshaw, Nevin S. "Synergism of Malnutrition and Infection. Evidence from Field Studies in Guatemala." Journal of the American Medical Association 212(10) (1970): 1685–1692.

Scrimshaw, Nevin, C. Taylor, et al. Interactions of Nutrition and Infection. Geneva: World Health Organization, 1968.

Trowbridge, Frederick L., and Alfred Sommer. "Nutritional Anthropometry and Mortality Risk." American Journal of Clinical Nutrition 34 (1981): 2591–2592.

UNICEF Strategies of Improving Nutrition of Children and Women in Developing Countries. New York: United Nations Children's Fund, 1990.

Waber, D. P., L. Vuori-Christiansen, et al. "Nutritional Supplementation, Maternal Education, and Cognitive Development of Infants at Risk of Malnutrition." American Journal of Clinical Nutrition 34 (1990): 807–813.

Walter, T., I. De Andraca, et al. "Iron Deficiency Anemia: Adverse Effects on Infant Psychomotor Development." Pediatrics 84 (1989): 7–17.

Waterlow, John C. "Classification and Definition of Protein-calorie Malnutrition." British Medical Journal 3 (1972): 566–569.

WHO Expert Committee Physical Status: The Use and Interpretation of Anthropometry. Geneva: World Health Organization, 1995.

Williams, Cicely D. "A Nutritional Disease of Childhood Associated with a Maize Diet. " Archives of Diseases in Childhood 8 (1933): 423–433.

Homero Martínez

The Importance of Marginal Malnutrition

The borderline between normal nutrition and malnutrition is so thin that, in clinical practice, there is no foolproof way to distinguish them. This is at least one of the reasons why so little attention was given to marginal malnutrition (i.e., malnutrition that borders normal limits). A further reason, though, obeyed a misconstruct that prevailed for a long time; that is, that only children with severe malnutrition had an increased risk of dying. This concept was probably triggered by the initial clinical observations on the increased risk of death in hospitalized children with third degree malnutrition (Gomez, Ramos-Galvan, et al., 1956), and was reinforced further by epidemiological observations in the field.

In a classic study, Chen and colleagues reported their findings on 2,019 Bangladeshi children between the ages of 13 and 23 months, who were followed for a period of 24 months, assessing death rate (Chen, Chowdhury, et al., 1980). The study team had precise information on the age of these children and had performed a cross-sectional nutritional assessment at baseline. Further, a demographic surveillance team identified all deaths occurring during the study period, recording age and probable cause of death. Child mortality rates were analyzed stratifying by percentage weight-for-age, weight-for-height, and height-for-age. The authors found that severely malnourished children experienced about a twofold higher mortality risk over the first twelve months of the study, and fourfold during the second twelve months of the study, as compared to normally nourished and mildly and moderately malnourished children, who shared the same level of mortality risk. The nutritional index with the strongest discriminative power to identify risk of death was weight-for-age.

This article, and others that followed in the literature (Trowbridge and Sommer, 1981; Heywood, 1982; Bairagi, Chowdhury, et al., 1985), seemed to find a threshold effect for mortality at the cutoff corresponding to third-degree malnutrition, below which the risk of death increased sharply. It was not until 1993 that Pelletier, Frongillo, and Habicht questioned this model (Pelletier, Frongillo, et al., 1993). Following their reasoning, the threshold effect reflects a model in which a population's mortality rate increases as a linear function of malnutrition.

An alternative model is a quadratic one that accounts for the sharp increase in mortality found beyond the threshold. Pelletier et al., however, sustained that a synergistic or multiplicative model, in accordance with the clinical observations that child mortality is a function of the adverse synergism between malnutrition and morbidity (Scrimshaw 1970), provides a much better explanation of the relationship. When testing their multiplicative (i.e., synergistic or exponential) model on a set of available data from several large-scale population studies, they found that an exponential model fit the available data best. Based on the best fit of the exponential model, they calculated that the odds of dying increased at a compound rate of 7.3 percent for each percentage point deterioration in weight-for-age.

In summary, these authors provided strong evidence that a threshold effect does not exist. Their model is consistent with the view that because of the greater number of affected children, mild to moderate malnutrition is associated with a greater absolute risk of dying. The policy implications of this conclusion are striking. Considering that the majority of malnourished children fall in the mild to moderate category, and that their risk of dying is higher than that of non-malnourished children, the attention of health-care programs should be immediately drawn to this population.

Certainly, a larger number of childhood deaths would be prevented if efforts were directed to improve the nutritional status of this group and to lower morbidity burden of all malnourished children, and not just for the ones who are in the worst condition. Therefore, the authors estimate that 45 percent to 83 percent of all malnutrition-related deaths occur in children who present mild to moderate malnutrition, a group that is usually excluded from direct interventions based on the impression that their risk of dying is small. Also, it highlights that either reducing morbidity or reducing malnutrition would reduce child mortality, but a much larger effect (actually, a synergistic effect) would be achieved if both conditions were addressed simultaneously (Pelletier, 1994).

MALNUTRITION

Good nutritional status is essential to the maintenance of health and quality of life among older people. Normal changes associated with aging, along with physical illness and cognitive or emotional problems, can lead to dietary changes and contribute to undernutrition. Consequently, any deterioration in nutritional status can be considered a major determinant of morbidity and mortality in persons, especially those living in institutions or nursing homes.

Numerous changes in body composition occur after the age of seventy. Decreased bone mass, changes in the size of body organs, decreases in skeletal muscle and body water, and changes in body fat content contribute to losses in lean and fat body mass. Age-related decline in height is common, but its physiological or clinical importance to health is unknown. However, weight losses after age fifty are generally associated with deterioration in nutritional and overall health and mobility (Losonczy et al.)

Food and nutrient needs

Although food intake tends to decrease with age as a function of social, psychological, and physiological changes, distinct requirements exist for a range of nutrients to compensate for age-related changes in absorption, utilization, and excretion (ADA). For example, even though energy needs decline with age because of decreased basal metabolism, reduction in lean body mass, and a more sedentary lifestyle (Ausman and Russell), it becomes difficult to ensure adequate diet quality (Blumberg) when daily energy intake is too low (less than 1,500 calories or 6.3 megajoules). Furthermore, protein requirements exceed those of younger adults (1.0 to 1.25 gram/kilogram versus 0.8 gram/kilogram body weight, respectively) (Garry and Vellas), which argues for continued consumption of sufficient intakes of high-quality protein food. Finally, even though vitamin A requirements lessen with age, other nutrient needs may increase.

In addition to appropriate intakes of energy and high-quality protein, and sufficient complex carbohydrates and fats (especially the mono- and polyunsaturated fats), older people require specific levels of micronutrients (vitamins and minerals) to ensure metabolic function and overall health. Also, since degenerative changes of aging are believed to result, in part, from the oxidative destruction of cells and tissues, much recent study has centered on the risk-lowering properties of antioxidant nutrients that may protect against such damage at the cellular level (Masaki et al.). Emerging research thus is now targeting nutrients found in a group of common foods, many of which have antioxidant properties. These so-called functional foods are ordinary foods eaten in usual quantities.

Micronutrient requirements, published as the dietary reference intakes, or DRIs (NAS), were revised in 2001 for all age groups (see Table 1), and new evidence is emerging on the potential protective nature of adequate intake levels of specific vitamins and minerals in aging individuals. Nutrients such as folic acid, riboflavin, and vitamins B₆, B₁₂, and C may prevent some age-related decline in memory loss (Rosenberg and Miller), and reduce risk for vascular disease. Adequate calcium is needed to prevent osteoporosis, and vitamin D can have favorable effects on muscle strength, bone mineral, and fracture risk (Heaney). Vitamins A and C and zinc are essential for competent immune system response and wound healing (Chandra). The antioxidants alpha-tocopherol (vitamin E), beta-carotene, and vitamin C may have consequences for aging and longevity (Hallfrisch et al.). These nutrients may also protect against cataract formation and age-related macular degeneration (Jacques), and the carotenoids lutein and zeaxanthin may protect the retina (Blumberg). Vitamin E in foods or supplements helps lessen risk of developing disorders such as Alzheimer's dementia and Parkinson's disease (Perkins et al.) as well as atherosclerosis (Kromhout). Vitamin K helps maintain bone density and lowers risk of reduced bone mass (Ferland). Sufficient dietary fiber is essential for prevention and/or treatment of constipation, hemorrhoids, diverticulosis, hiatal hernia, varicose veins, diabetes, elevated blood lipids, and obesity, and adequate fiber intake has also been related to decreased rates of heart disease and cancer (Ausman and Russell). Finally, adequate fluid intake is essential to prevent dehydration, which results in constipation, fecal impaction, cognitive impairment, functional decline, and, in extreme cases, death.

A varied diet can provide nutrient balance and adequate quantities of healthful foods. Physical activity, wise food selection, and greater intakes of enriched foods help increase total intake, nutrient density, and micronutrient levels. The modified Food Guide Pyramid was developed in the United States for people over the age of seventy to help them select appropriate foods (Russell et al.). This guide emphasizes nutrient-dense foods, dietary fiber, sufficient fluid intake, and the role of dietary supplements in maintaining adequate nutrient intakes. Recommendations include eating whole-grain cereals and breads; dark green, orange, and yellow fruits and vegetables to favor those with high levels of antioxidants; and using low-fat dairy products. The narrower base of the modified pyramid reflects the decreased needs for energy (calories) among older people.

Causes of malnutrition

In community-dwelling older people, dietary and nutritional adequacy depend on the ability to purchase and prepare food, and to eat independently. Among those living in institutions, the availability of dietary assistance when needed and appropriate meal presentation are additional nutrition considerations. The presence of disease or chronic conditions such as mobility problems, depression, or dementia, or medications with an effect on appetite can lead to a worsening nutritional situation. Aging adults, particularly those dependent on others, have been recognized as a group at nutritional risk (Sullivan and Walls). In sum, inadequate food intake and/or increased nutritional requirements can lead to malnutrition, and poor nutritional status is considered a key determinant of morbidity and mortality in elderly individuals (Sullivan and Walls).

In older people, most malnutrition is the consequence of decreased or inappropriate food intake. Common causes are loss of appetite, dysphagia, oral health problems such as poor dentition or dryness of the mouth, depression, polymedication, inappropriate use of restricted or modified diets, physical and cognitive impairments, dementia, slowness in eating, inability to feed oneself, inadequate assistance in eating, sub-optimal dining environment, and limited menu choices (Keller; Sullivan et al.). In addition, sensory problems, such as olfactory or taste dysfunction, may affect desire for and appreciation of food, thereby diminishing intake and increasing risk of chronic diseases. Finally, it has been shown that people with adequate dental status (especially those with natural teeth) have better dietary patterns than those with ill-fitting dentures or who are toothless, and this contributes to higher protein, vitamin, and mineral levels, and lower fat and cholesterol intakes. On the other hand, obesity in elderly people may be related to dietary imbalances, such as insufficient fruit and vegetable intakes and excessive meat intakes, or consumption of easily prepared, easy-to-chew, empty-calorie foods, which may contribute to or exacerbate health problems.

Weight loss, which signals an imbalance between energy intake and expenditure, is a well-known marker of nutritional status in older people. It leads to decline in functional abilities, increased risk of hip fracture, and early institutionalization and mortality, independent of coexisting disease states. Furthermore, this phenomenon has been observed in studies of widely different groups of elderly persons, ranging from those in good health (Harris et al.) to hospital patients (Franzoni et al.) and to individuals who require home care in order to continue living in the community (Payette et al.).

Loss of skeletal muscle mass, or sarcopenia (Rosenberg) is observed with aging even in well elderly people at a stable, healthy weight and the obese (Melton et al.). Sarcopenia is associated with decreased functional abilities and increased risk of falls among very old people (Rosenberg). This lowers energy needs (Poehlman et al.) and increases the likelihood of mobility problems and fractures resulting from osteoporosis (Melton et al.). In addition, it appears that older people with both sarcopenia and obesity are more likely than their nonobese sarcopenic or nonsarcopenic counterparts to suffer from physical disabilities and problems with balance and gait, and to experience falls (Baumgartner).

It now appears that many diseases associated with aging, including heart disease, diabetes, and infectious diseases, are associated with weight loss and wasting, or cachexia (Roubenoff and Harris). Intensive nutritional intervention has the potential to halt and reverse weight loss, and may even contribute to weight gain (Franzoni et al.), which could delay mortality in elderly chronic care patients (Keller). Indeed, it has been shown that women who maintain a consistent body weight after menopause are less likely to suffer fractures than those who systematically lose weight (Cummings et al.).

Prevalence of malnutrition

Estimates of nutrition risk in older persons vary by setting. For example, while it has been reported that some 15 percent of community-dwelling elders are undernourished, the prevalence of protein-energy malnutrition (PEM) among those living in nursing homes or institutions may range from 30 to 60 percent (Omran and Morely), depending on the component measured.

Risk of PEM increases with loss of appetite, decrease in usual weight, increased percentage of weight change in the previous year, and low body mass index (BMI) (White et al.). It has been suggested that loss of more than 4 percent of body weight in a one-year period predicts an increased risk of mortality. Indeed, weight loss alone usually heralds increased morbidity and mortality in elderly people (Losonczy et al.). Furthermore, unintentional weight loss is generally associated with advanced age, lower educational level, and poor health status. In the long-term care setting, malnourished residents are older and more dependent on others, and require more eating assistance than those with adequate nutrition status. Among participants in the Canadian Study of Health and Aging, low BMI, poor appetite, weight loss, and low levels of albumin (a protein that reflects nutrition status in older people) were highly intercorrelated and characterized nutritional risk, which was a significant independent predictor of mortality (Keller and Ostbye).

Weight loss and undernutrition in dementia

"Dementia" is a generic term covering degenerative diseases of the brain leading to problems with memory and other cognitive functions. Decreased food intake, eating behavior disturbances, and loss of body weight are significant problems among patients with Alzheimer's dementia (AD) (White et al.). Indeed, it is typically observed that AD patients are at greater risk of weight loss and a worsening in their nutritional status than individuals without cognitive problems. Data collected over time suggest that weight loss precedes the onset or diagnosis of dementia (Barrett-Connor et al.) or occurs in the early stages of the disease (White et al.). While weight loss and undernutrition in this group are believed to have multiple origins, it also appears that resting metabolic rate is no higher in those with AD than in older persons with no cognitive problems (Donaldson et al.). Finally, although a poor dietary environment can have a negative effect on food intake, adequate nutritional status can be maintained even among institutionalized older people as long as patients have a favorable eating environment and appropriate dietary assistance (Shatenstein and Ferland).

Consequences of undernutrition

In elderly people, weight loss and undernutrition affect functional and cognitive abilities, and the immune response (Chandra). This may result in serious complications including difficulty in swallowing, dehydration, and pressure ulcers. Poor nutritional status also leads to decreased lean body mass, and lessened muscular strength and aerobic capacity. These changes contribute to a state of chronic fatigue, as well as alterations in gait and balance, which increase the probability of falls and fractures. For many older people, this sequence of events leads to a deterioration in their overall quality of life, causing the affected individual to become increasingly dependent on others. The ultimate cost to the individual and society is great.

Bryna Shatenstein

See also Congregate and Home Delivered Meals; Dementia; Dental Care; Nutrition; Sarcopenia; Taste and Smell; Vitamins.

BIBLIOGRAPHY

American Dietetic Association. "Position of the American Dietetic Association: Nutrition, Aging, and the Continuum of Care." Journal of the American Dietetic Association. 100 (2000): 580–595.

Ausman, L. M., and Russell, R. M. "Nutrition in the Elderly." In Modern Nutrition in Health and Disease, 9th ed. Edited by M. E. Shils, J. A. Olson, M. Shike, and A. C. Ross. Baltimore: Williams & Wilkins, 1999. Pages 869–881.

Barrett-Connor, E.; Edelstein, S.; Corey-Bloom, J.; and Wiederholt, W. "Weight Loss Precedes Dementia in Community-Dwelling Older Adults." Journal of American Geriatrics Society 44 (1996): 1147–1152.

Blumberg, J. "Nutritional Needs of Seniors." Journal of the American College of Nutrition 16 (1997): 517–523.

Chandra, R. K. "Effect of Vitamin and Trace Element Supplementation on Immune Response and Infection in Elderly Subjects." Lancet 340 (1992): 1124–1127.

Cummings, S. R.; Nevitt, M. C.; Browner, W. S.; Stone, K.; Fox, K. M.; Ensrud, K. E.; Cauley, J.; Black, D.; and Vogt, T. M. "Risk Factors for Hip Fracture in White Women. Study of Osteoporotic Fractures Research Group." New England Journal of Medicine 332, no. 12 (1995): 767–773.

Donaldson, K. E.; Carpenter, W. H.; Toth, M. J.; Goran, M. I.; Newhouse, P.; and Poehlman, E. T. "No Evidence for a Higher Resting Metabolic Rate in Noninstitutionalized Alzheimer's Disease Patients." Journal of American Geriatrics Society 44, no. 10 (1996): 1232–1234.

Ferland, G. "The Vitamin K-Dependent Proteins: An Update." Nutrition Reviews 56, no. 8 (1998): 223–230.

Franzoni, S.; Frisoni, G. B.; Boffelli, S.; Rozzini, R.; and Trabucchi, M. "Good Nutritional Oral Intake is Associated with Equal Survival in Demented and Nondemented Very Old Patients." Journal of the American Geriatrics Society 44 (1996): 1366–1370.

Garry, P. J., and Vellas, B. J. "Aging and Nutrition." In Present Knowledge in Nutrition, 7th ed. Edited by E. E. Ziegler and L. J. Filer, Jr. Washington, D.C.: ILSI Press, 1996. Pages 414–419.

Hallfrisch, J.; Muller, D. C.; and Singh, V. N. "Vitamin A and E Intakes and Plasma Concentrations of Retinol, Beta-Carotene, and Alpha-Tocopherol in Men and Women of the Baltimore Longitudinal Study of Aging." American Journal of Clinical Nutrition 60 (1994): 176–182.

Harris, T. B.; Looker, A. C.; Madans, J.; and Bacon, E. C. "Weight Loss and Risk of Hip Fracture in Postmenopausal White Women Aged 60–74. The NHANES-1 Epidemiologic Follow Up Study." Journal of American Geriatrics Society 40 (1992): SA5.

Heaney, R. P. "Age Considerations in Nutrient Needs for Bone Health: Older Adults." Journal of the American College of Nutrition 15 (1996): 575–578.

Jacques, P. F. "The Potential Preventive Effects of Vitamins for Cataract and Age-Related Macular Degeneration." International Journal of Vitamin and Nutrition Research 69 (1999): 198–205.

Keller, H. H. "Weight Gain Impacts Morbidity and Mortality in Institutionalized Older Persons." Journal of American Geriatrics Society 43, no. 2 (1995): 165–169.

Keller, H. H., and Ostbye, T. "Do Nutrition Indicators Predict Death in Elderly Canadians with Cognitive Impairment?" Canadian Journal of Public Health 91, no. 3 (2000): 220–224.

Kromhout, D. "Fatty Acids, Antioxidants, and Coronary Heart Disease from an Epidemiological Perspective." Lipids 34, supp. (1999): S27–S31.

Losonczy, K. G.; Harris, T. B.; Cornoni-Huntley, J.; Simonsick, E. M.; Wallace, R. B.; Cook, N. R.; Ostfeld, A. M.; and Blazer, D. G. "Does Weight Loss from Middle Age to Old Age Explain the Inverse Weight Mortality Relation in Old Age?" American Journal of Epidemiology 141, no. 4 (1995): 312–321.

Masaki, K. H.; Losonczy, K. G.; Izmirlian, G.; Foley, D. J.; Ross, G. W.; Petrovitch, H.; Havlik, R.; and White, L. R. "Association of Vitamin E and C Supplement Use with Cognitive Function and Dementia in Elderly Men." Neurology 54 (2000): 1265–1272.

Melton, L. J.; Khosla, S.; Crowson, C. S.; O'Connor, M. K.; O'Fallon, W. M.; and Riggs, B. L. "Epidemiology of Sarcopenia." Journal of the American Geriatrics Society 48 (2000): 625–630.

National Academy of Sciences (NAS). "Dietary Reference Intakes: Applications in Dietary Assessment," 2000. www.nap.edu

Omran, M. L., and Morely, J. E. "Assessment of Protein Energy Malnutrition in Older Persons, Part 1: History, Examination, Body Composition, and Screening Tools." Nutrition 16 (2000): 50–63.

Payette, H.; Coulombe, C.; Boutier, V.; and Gray-Donald, K. "Weight Loss and Mortality Among the Free-Living Frail Elderly: A Prospective Study." Journal of Gerontology: Medical Sciences 54A (1999): M440–M445.

Perkins, A. J.; Hendrie, H. C.; Callahan, C. M.; Gao, S.; Unverzagt, F. W.; Xu, Y.; Hall, K. S.; and Hui, S. L. "Association of Antioxidants with Memory in the Multiethnic Elderly Sample Using the Third National Health and Nutrition Examination Survey." American Journal of Epidemiology 150 (1999): 37–44.

Poehlman, E. T. "Energy Expenditure and Requirements in Aging Humans." Journal of Nutrition 122 (1992): 2057–2065.

Rosenberg, I. H. "Sarcopenia: Origins and Clinical Relevance." Journal of Nutrition 127 (1997): 990S–991S.

Rosenberg, I. H., and Miller, J. W. "Nutritional Factors in Physical and Cognitive Functions of Elderly People." American Journal of Clinical Nutrition 55 supp. (1992): 1237S–1243S.

Roubenoff, R., and Harris, T. B. "Failure to Thrive, Sarcopenia, and Functional Decline in the Elderly." Clinical Geriatric Medicine 13 (1997): 613–621.

Russell, R. M.; Rasmussen, H.; and Lichtenstein, A. H. "Modified Food Guide Pyramid for People Over Seventy Years of Age." Journal of Nutrition 129, no. 3 (1999): 751–753.

Shatenstein, B., and Ferland, G. "Absence of Nutritional or Clinical Consequences of Decentralized Bulk Food Portioning in Elderly Nursing Home Residents with Dementia in Montreal." Journal of the American Diet Association 100, no. 11 (2000): 1354–1360.

Sullivan, D. H., and Walls, R. C. "Impact of Nutritional Status on Morbidity in a Population of Geriatric Rehabilitation Patients." Journal of the American Geriatrics Society 42 (1994): 471–477.

White, H.; Pieper, C.; Schmader, K.; and Fillenbaum, G. "Weight Change in Alzheimer's Disease." Journal of the American Geriatrics Society 44, no. 3 (1996): 265–272.

MANAGED CARE

See Medicare

MALNUTRITION

MALNUTRITION. Malnutrition results from the chronic dietary intake of nutrients or energy that provides considerably less or more than is required to be considered adequate or appropriate to support the everyday needs of the human body. Such adverse nutrient intakes are detrimental to human health and may lead to a state of deficiency, dependency, toxicity, or obesity. Malnutrition includes undernutrition, which means the body is not receiving nearly enough nutrients, and overnutrition, which means the intake of nutrients is grossly excessive.

Undernutrition

Undernutrition continues to be a significant cause of malnutrition in developing countries, although it is relatively rare in developed countries. Poverty in developing countries contributes more to undernutrition than a lack of global food production and is considered the chief cause of malnutrition. Families that are poor do not have the economic, social, or environmental resources to purchase or produce enough food. Poor soil conditions may also contribute to a family's inability to grow enough food to prevent malnutrition and the accompanying complications to health. Additionally, for the urban poor, low wages, underemployment, and food prices beyond the reach of families also contribute to undernutrition.

Prolonged dietary intakes deficient in energy or calories, protein, fat, vitamins, and minerals lead to illness and eventually death if not corrected. Undernutrition may also be the result of psychological disorders, such as anorexia nervosa, which manifests as an unwillingness to eat enough food to sustain life. Elderly adults often have a decrease both in appetite and intestinal function and are at an increased risk for undernutrition. Children, particularly infants and those under five years of age are also at an increased risk for undernutrition due to a greater need for energy and nutrients during periods of rapid growth and development. Infants born to undernourished mothers are more likely to be low birth weight infants. Addiction to alcohol or drugs may also lead to undernutrition when the addicted individuals favor alcohol and/or drug intake over adequate food intake. Severe, prolonged diarrhea, renal failure, infection, or diseases that cause the malabsorption of nutrients in the small intestine also may cause undernutrition even if dietary intake is adequate. It is obvious that the causes of undernutrition are varied and complex, requiring solutions that may also be complex.

Nutrients Required to Prevent Undernutrition

The nutrients required in adequate amounts by the body to prevent undernutrition are carbohydrates, fat or lipids, protein, vitamins, minerals, and water. Carbohydrates provide the body with energy (about 4 kilocalories per gram of carbohydrate consumed). Carbohydrates also protect protein stores in the body. A minimal intake of 50 to 100 grams (1.8 to 3.5 oz.) of carbohydrates is required to prevent the development of ketones that the brain can use somewhat inefficiently for energy. The brain optimally uses carbohydrate for energy, but when carbohydrate intake is inadequate for several weeks, the body does not metabolize fatty acids completely in order to produce ketones for energy. In addition to ketone formation resulting from insufficient carbohydrate consumption, body protein will also be lost, and the body will generally become weakened.

Fats or lipids provide essential fatty acids upon metabolism following consumption. Essential fatty acids are obtained from dietary lipids and are termed essential because the human body cannot synthesize them. Essential fatty acids are important for human health because they participate in immune processes, vision, are an integral part of cell structures, and participate in hormone-like compound production. If an inadequate intake of lipids is routinely consumed, the body becomes deficient in essential fatty acids. This results in skin problems, diarrhea, and an increase in infections with a corresponding decrease in the ability of the body to heal wounds. Lipids also provide energy for the body (about 9 kilocalories per gram (28 kilocalories per ounce of fat consumed), can be stored for future use as energy, insulate the body and protect body organs, and aid in the absorption and transport of fat-soluble vitamins (vitamins A, D, E, and K) throughout the body. The fat-soluble vitamins are important for vision (vitamin A), bone metabolism (vitamin D), providing antioxidant protection from free radicals (vitamin E), and blood coagulation (vitamin K), among other functions.

Protein is a very important nutrient because so many substances in the body are made from it. Proteins are made when amino acids are combined in specific sequences to form specific proteins. The sequence of the amino acids determines the shape of the protein, and the shape of the protein, in turn, determines the function of the protein. Amino acids can be obtained from plant or animal sources. There are nine essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. The human body is not able to synthesize these amino acids, so they must be derived from the foods we eat. There are eleven nonessential amino acids that the human body is able to make: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine. As stated previously, amino acids are necessary for protein synthesis, but they are also important because they provide the body with a special form of nitrogen that the body cannot get from carbohydrates or lipids. Protein, like carbohydrate, provides approximately 4 kilocalories per gram of protein consumed, but requires much more metabolizing and processing by the liver and kidneys to put the energy from protein to use. Protein is a part of every cell in the human body. Blood proteins enable the body to maintain the right balance of fluid inside and outside of cells. When adequate protein is not consumed, there is a lower concentration of blood proteins in the bloodstream, which causes the balance of fluids inside and outside of cells in tissues to be thrown off, resulting in swelling of tissues or edema, which can lead to serious medical problems. Proteins also help regulate the pH, or acid-base balance, in the blood, are necessary for the synthesis of many hormones and enzymes, and participate in important cell formation for cells vital for the immune system. Amino acids from protein can also be used to produce glucose, which is a positive thing for providing glucose after an overnight fast. But in the case of starvation, excessive muscle tissue is wasted and results in diminished health. Protein-energy malnutrition results from near starvation and may be seen in the body tissues in either a wet, dry, or combined form. The dry form, marasmus, is caused by deficiency of protein and nonprotein nutrients, with the individual being very thin from the loss of muscle and body fat. The wet form, kwashiorkor, is caused primarily by protein deficiency, with energy deficiency being secondary, and is accompanied by edema. The combined form, marasmic kwashiorkor, results from protein and energy deficiency with edema and more body fat than is seen in marasmus.

There are also water-soluble vitamins in addition to the fat-soluble vitamins. Because water-soluble vitamins are not stored in any appreciable amounts in the body, but are excreted readily in urine, it is relatively easy to become depleted of them. Fat-soluble, in contrast, are stored in adipose tissue and the liver, and consequently it is more difficult to become deficient of them. The water-soluble vitamins are the B vitamins and vitamin C. The B vitamins are thiamin, riboflavin, niacin, pantothenic acid, biotin, pyridoxine, folate, and vitamin B₁₂. All of the water-soluble vitamins except vitamin C have coenzyme functions and are involved in a variety of reactions including energy metabolism, DNA synthesis, nerve function, protein and carbohydrate metabolism, and fat synthesis. Vitamin C is involved in protecting the body from oxidative damage caused by substances called free radicals. It also functions in connective tissue synthesis, hormone synthesis, and neurotransmitter synthesis. Physiological consequences of deficiency include inflammation of the mouth and tongue (riboflavin deficiency); diarrhea, dermatitis (niacin deficiency); edema, weakness (thiamin deficiency); tongue soreness, anemia (biotin deficiency); fatigue, tingling in hands (pantothenic acid deficiency); poor growth, inflammation of the tongue (folate deficiency); poor nerve function, macrocytic anemia (vitamin B₁₂ deficiency); and poor wound healing, bleeding gums (vitamin C deficiency).

Minerals are important nutrients that must be obtained from foods consumed, as the human body is unable to synthesize them. Some factors that influence mineral bioavailability (the extent to which minerals in food consumed is available for the body to put to use) are the amount of mineral content in the soil in which the food providing the mineral was grown; dietary fiber consumed in the same meal as a food containing the minerals; mineral-mineral interactions; and vitamin-mineral interactions. Sodium, potassium, chloride, calcium, phosphorus, magnesium, and sulfur are the major minerals. Deficiencies of these minerals lead to such symptoms as muscle cramps (sodium), irregular heartbeat (potassium), convulsions in infants (chloride), an increased risk for osteoporosis (calcium), diminished bone support (phosphorus), and poor heart function (magnesium). There are also so-called trace minerals that are only required in very small amounts to contribute to optimal health. These trace minerals are iron, zinc, selenium, iodide, copper, fluoride, chromium, manganese, and molybdenum. When inadequate amounts of foods containing the trace minerals are consumed, symptoms begin to appear. These symptoms include low blood iron (iron), skin rash/poor growth and development (zinc), muscle weakness (selenium), goiter (iodide), anemia/poor growth (copper), increased risk for dental cavities (fluoride), and high blood glucose after eating (chromium).

Developed countries typically have water supplies that are monitored for safety by government agencies and are provided in large enough quantities that a lack of drinking water is not the norm. Developing countries, however, may not have water that is free from contamination, or because of drought or other natural disasters do not have a large enough water supply for human consumption or to provide water for livestock or crops. Water is vital for life and, without it, an adult can survive only a few days because the human body does not have the ability to store water. Water is found inside of cells as intracellular fluid and outside of cells as extracellular fluid. A proper balance between intracellular and extracellular water is necessary to prevent complications such as edema. Water also is responsible for regulating body temperature, most notably through the cooling-off process accomplished by perspiration. Water is necessary to provide lubrication for joints such as the knees. Without adequate water in the form of amniotic fluid in the womb of a pregnant woman, the growing fetus does not have sufficient support to prevent injury should the mother fall or be otherwise jarred abruptly. Water is also the primary avenue utilized by the body to rid itself of waste products. While water does not supply energy as carbohydrates, protein, and fats are able to do, it is still a very important nutrient necessary to prevent malnutrition.

Overnutrition

Overnutrition results when energy expenditure is grossly exceeded by energy intake and leads to overweight and obesity. Developed countries, with their abundant food supplies and processed foods, are most afflicted with overnutrition and the medical complications associated with it. Due to the excessive intake of food products, the amount of fat-soluble vitamins and minerals in the body can rise to toxic levels because they are stored in the body. Developed countries have greater incidences of cardiovascular disease, blood lipids, diabetes mellitus, hypertension, respiratory problems, gallbladder disease, arthritis, and cancer, all of which are connected to complications stemming directly from overnutrition.

Methods of Evaluating Malnutrition

Malnutrition is diagnosed based on the findings of a medical and diet history, physical examination, and laboratory tests. The results are then compared with norms of weight for height, body mass index (body weight in kilograms divided by height in meters squared), dietary intake, physical findings, and plasma levels of nutrients and nutrient-dependent substances such as hemoglobin. The physical examination would necessarily include anthropometric measurements, as well as close examination of the skin, hair, and mouth for symptoms of malnutrition. For example, depigmentation of the hair is indicative of undernutrition, and a body weight that is 20 percent above the average desirable body weight as determined by insurance company standardized charts would indicate overnutrition. A triceps skinfold test may be utilized to determine the body's energy stores. Laboratory tests are used to reveal the extent to which amino acid nutrition is meeting the body's needs to determine undernutrition, or plasma lipids in the diagnosis of overnutrition. In the field when assessing nutritional status, the medical and diet history and physical examination may be the only tools accessible to the physician or nurse, particularly in developing countries.

Who is at Increased Risk for Malnutrition?

The risk for malnutrition is increased for a variety of reasons. Increased nutritional needs during growth, pregnancy, lactation, old age, infection, certain cancer therapies, or immune deficiency disorders increase the risk of malnutrition. Diets that focus on a narrow range of foods may not provide the variety of nutrients required and lead to deficiencies. Those experiencing famine, with the accompanying reduction in available food, are at great risk for malnutrition in the form of undernutrition. Lack of money to purchase an adequate diet or cultural practices that dictate which members in the family get a large or small amount of food may also lead to malnutrition. Any medical condition that effects the absorption of nutrients from foods, or requires medication that has adverse consequences on appetite, may cause malnutrition if the condition is long term. Taking megadoses of vitamin/mineral supplements may result in toxic levels of the substances taken in the body with the outcome being a state of overnutrition.

Correcting Malnutrition in the United States

Since the Great Depression of the 1930s, the federal government of the United States has undertaken the task of alleviating and/or preventing malnutrition. In the 1960s, President John F. Kennedy reestablished the federal government's efforts to end debilitating hunger. Individuals and families who have low incomes may take advantage of several federally sponsored programs to ensure a better quality of nutrient intake. Food stamps are available to those who are usually employed but having difficulty purchasing an adequate food supply by using coupons to purchase food from grocery stores. The Commodity Supplemental Food Program distributes U. S. Department of Agriculture surplus foods through county agencies to such low-income populations as pregnant women and families with young children. The School Lunch and Breakfast Programs offer free or reduced-priced meals based on the Food Guide Pyramid to children of low-income families, with the cost of the reduced-priced meals being based on family income. The Summer Food Service Program offers free, nutritious meals and snacks to low-income children and distributes the meals from a central location during lower and secondary school vacations. There are also programs targeted specifically at different age groups. Preschool children enrolled in organized child-care programs receive meals at no cost, and the child-care program receives reimbursement for the meals through participation in the Child-Care Food Program. For individuals 60 years or older, a free noon meal is provided at centralized sites as part of the Congregate Meals for the Elderly Program. Homebound individuals over 60 years of age can take advantage of home-delivered meals at no cost or for a fee, depending on income, at least five days per week.

World Hunger: Addressing a Global Problem

In 1798 the English clergyman and political economist Thomas Malthus suggested that the world's population was growing at a rate faster than the food supply. The year 2002 finds world population growth exceeding economic growth, and poverty on the rise. Globally less than one-half of 1 percent of the world's yearly production of goods and services goes exclusively to economic development assistance, yet 6 percent goes to support the world's military operations. Civil wars in some countries have substantially retarded progress of the poor and continue to contribute to massive undernutrition. Environmental factors such as soil erosion or lack of fresh water for irrigation of crops exacerbate the problem of providing sufficient quantities of foods for many countries. What is being done to overcome all of these detriments to feeding the world's hungry? Since the 1960s, an American program, the Peace Corps, has been instrumental in providing education, distributing food and medical supplies, and building structures for locals to use in developing nations. National surveys such as the National Family Health Survey conducted in India are valuable tools in the determination of whether any progress is being made to improve the nutritional status of the nation. Advances in biotechnology to genetically alter plants and animals to improve the nutritive quality of the foods produced from them may help to meet increasing food needs both now and in the future. The United Nations and the World Health Organization cry out for governments in developed countries to facilitate greater strides in improvements in malnutrition in undeveloped countries by financial, educational, and scientific interventions. What will be required to eradicate malnutrition in this world is a coming together of the leaders of rich and poor nations to the same degree. Globally, there is an adequate food supply and the technical expertise necessary to address the problems and complications of malnutrition. All that is lacking is the political cooperation to address this devastating situation.

See also Anorexia, Bulimia; Aversion to Food; Body Composition; Caloric Intake; Disease: Metabolic Diseases; Eating: Anatomy and Physiology of Eating; Fasting and Abstinence; Fluoride; Food Politics: United States; Hunger, Physiology of.

BIBLIOGRAPHY

Agarwal, S., et al. "Birth Weight Patterns in Rural Undernourished Pregnant Women." Indian Pediatrics 39, no. 3 (2002): 244–253.

Berkman, D. S., et al. "Effects of Stunting, Diarrhoeal Disease, and Parasitic Infection during Infancy on Cognition in Late Childhood: A Follow-Up Study." Lancet 359, no. 9306 (2002): 564–571.

Bouis, H. E. "Plant Breeding: A New Tool for Fighting Micronutrient Malnutrition." Journal of Nutrition 132, sup. 3 (2002): 491S–494S.

Charlton, K. E., et al. "Poor Nutritional Status in Older Black South Africans." Asia Pacific Journal of Clinical Nutrition 10, no. 1 (2001): 31–38.

Chen, C. C., L. S. Schilling, and C. H. Lyder. "A Concept Analysis of Malnutrition in the Elderly." Journal of Advanced Nursing 36, no. 1 (2001): 131–142.

Fenton, M., and S. Simon. "Legislating Good Sense: It's Time for Medical Nutrition Therapy to be Part of Standard Care for People with HIV/AIDS." Positive Living 11, no. 1 (2002): 44–45.

Gillet, R. M., and P. V. Tobias. "Human Growth in Southern Zambia: A First Study of Tonga Children Predating the Kariba Dam (1957–1958)." American Journal of Human Biology 14, no. 1 (2002): 50–60.

Griffiths, P. L., and M. E. Bentley. "The Nutrition Transition Is Underway in India." Journal of Nutrition 131, no. 10 (2001): 2692–2700.

Hunt, J. M. "The Agricultural-Industrial Partnership for Eliminating Micronutrient Malnutrition: The Investment Bargain of the Decade." Biomedical and Environmental Sciences 14, no. 1–2 (2001): 104–123.

Ke-You, G. and F. Da-Wei. The Magnitude and Trends of Under-and Over-Nutrition in Asian Countries. Biomedical and Environmental Sciences 14, no. 1–2 (2001): 53–60.

Krishnaswamy, K. "Perspectives on Nutrition Needs for the New Millennium for South Asian Regions." Biomedical and Environmental Sciences 14, no. 1–2 (2001): 66–74.

Leube, M. G., and I. Fernandez-Abad. "The Applied Nutrition Project of Eastern Kenya: An Initiative for Reducing Hunger and Malnutrition." Collegium Antropologicum 25, no. 2 (2001): 665–672.

Lipton, M. "Challenges to Meet: Food and Nutrition Security in the New Millennium." Proceedings of the Nutrition Society 60, no. 2 (2001): 203–214.

Malekafzali, H., et al. "Community-Based Nutritional Intervention for Reducing Malnutrition among Children under Five Years of Age in Islamic Republic of Iran." Eastern Mediterranean Health Journal 6, no. 2–3 (2000): 238–245.

Nantel, G., and K. Tontisirin. "Functional Consequences of Adult Malnutrition in Developing Countries: A Review." Journal of Physiological Anthropology and Applied Human Science 21, no. 1 (2002): 1–9.

Nantel, G., and K. Tontisirin. "Policy and Sustainability Issues." Journal of Nutrition 132, sup. 4 (2002): 839S–844S.

Salomon, J., T. P. De, and J. C. Melchior. "Nutrition and HIV Infection." British Journal of Nutrition 87, sup. 1 (2002): S111–110.

Shils, Maurice E., et al. Modern Nutrition in Health and Disease. 9th ed. Baltimore, Md.: Williams and Wilkins, 1999.

Wardlaw, Gordon M., and Margaret W. Kessel. Perspectives in Nutrition. 5th ed. Boston, Mass.: McGraw-Hill, 2002.

Rebecca J. (Bryant) McMillian

Malnutrition

Definition

Malnutrition is the condition that develops when the body does not get the right amount of the vitamins, minerals, and other nutrients it needs to maintain healthy tissues and organ function.

Description

Undernutrition

Malnutrition occurs in people who are either undernourished or overnourished. Undernutrition is a consequence of consuming too few essential nutrients or using or excreting them more rapidly than they can be replaced.

Infants, young children, and teenagers need additional nutrients. So do women who are pregnant or breastfeeding. Nutrient loss can be accelerated by diarrhea, excessive sweating, heavy bleeding (hemorrhage), or kidney failure. Nutrient intake can be restricted by age-related illnesses and conditions, excessive dieting, food allergies, severe injury, serious illness, a lengthy hospitalization, or substance abuse.

The leading cause of death in children in developing countries is protein-energy malnutrition. This type of malnutrition is the result of inadequate intake of calories from proteins, vitamins, and minerals. Children who are already undernourished can suffer from protein-energy malnutrition (PEM) when rapid growth, infection, or disease increases the need for protein and essential minerals. These essential minerals are known as micronutrients or trace elements.

Two types of protein-energy malnutrition have been described—kwashiorkor and marasmus. Kwashiorkor occurs with fair or adequate calorie intake but inadequate protein intake, while marasmus occurs when the diet is inadequate in both calories and protein.

About 1% of children in the United States suffer from chronic malnutrition, in comparison to 50% of children in southeast Asia. About two-thirds of all the malnourished children in the world are in Asia, with another one-fourth in Africa.

Overnutrition

In the United States, nutritional deficiencies have generally been replaced by dietary imbalances or excesses associated with many of the leading causes of death and disability. Overnutrition results from eating too much, eating too many of the wrong things, not exercising enough, or taking too many vitamins or other dietary replacements.

Risk of overnutrition is also increased by being more than 20% overweight, consuming a diet high in fat and salt, and taking high doses of:

• Nicotinic acid (niacin) to lower elevated cholesterol levels
• Vitamin B₆ to relieve premenstrual syndrome
• Vitamin A to clear up skin problems
• Iron or other trace minerals not prescribed by a doctor.

Nutritional disorders can affect any system in the body and the senses of sight, taste, and smell. They may also produce anxiety, changes in mood, and other psychiatric symptoms. Malnutrition begins with changes in nutrient levels in blood and tissues. Alterations in enzyme levels, tissue abnormalities, and organ malfunction may be followed by illness and death.

Causes and symptoms

Causes

Poverty and lack of food are the primary reasons why malnutrition occurs in the United States. Ten percent of all members of low income households do not always have enough healthful food to eat. Protein-energy malnutrition occurs in 50% of surgical patients and in 48% of all other hospital patients.

Loss of appetite associated with the aging process. Malnutrition affects one in four elderly Americans, in part because they may lose interest in eating. In addition, such dementing illnesses as Alzheimer's disease may cause elderly persons to forget to eat.

There is an increased risk of malnutrition associated with chronic diseases, especially disease of the intestinal tract, kidneys, and liver. Patients with chronic diseases like cancer, AIDS, intestinal parasites, and other gastric disorders may lose weight rapidly and become susceptible to undernourishment because they cannot absorb valuable vitamins, calories, and iron.

People with drug or alcohol dependencies are also at increased risk of malnutrition. These people tend to maintain inadequate diets for long periods of time and their ability to absorb nutrients is impaired by the alcohol or drug's affect on body tissues, particularly the liver, pancreas, and brain.

Eating disorders. People with anorexia or bulimia may restrict their food intake to such extremes that they become malnourished.

Food allergies. Some people with food allergies may find it difficult to obtain food that they can digest. In addition, people with food allergies often need additional calorie intake to maintain their weight.

Failure to absorb nutrients in food following bariatric (weight loss) surgery. Bariatric surgery includes such techniques as stomach stapling (gastroplasty) and various intestinal bypass procedures to help people eat less and lose weight. Malnutrition is, however, a possible side effect of bariatric surgery.

Symptoms

Unintentionally losing 10 pounds or more may be a sign of malnutrition. People who are malnourished may be skinny or bloated. Their skin is pale, thick, dry, and bruises easily. Rashes and changes in pigmentation are common.

Hair is thin, tightly curled, and pulls out easily. Joints ache and bones are soft and tender. The gums bleed easily. The tongue may be swollen or shriveled and cracked. Visual disturbances include night blindness and increased sensitivity to light and glare.

Other symptoms of malnutrition include:

• anemia
• diarrhea
• disorientation
• night blindness
• irritability, anxiety, and attention deficits
• goiter (enlarged thyroid gland)
• loss of reflexes and lack of muscular coordination
• muscle twitches
• amenorrhea (cessation of menstrual periods)
• scaling and cracking of the lips and mouth.

Malnourished children may be short for their age, thin, listless, and have weakened immune systems.

Diagnosis

Overall appearance, behavior, body-fat distribution, and organ function can alert a family physician, internist, or nutrition specialist to the presence of malnutrition. Patients may be asked to record what they eat during a specific period. X rays can determine bone density and reveal gastrointestinal disturbances, and heart and lung damage.

Blood and urine tests are used to measure the patient's levels of vitamins, minerals, and waste products. Nutritional status can also be determined by:

• Comparing a patient's weight to standardized charts
• Calculating body mass index (BMI) according to a formula that divides height into weight
• Measuring skinfold thickness or the circumference of the upper arm.

Treatment

Normalizing nutritional status starts with a nutritional assessment. This process enables a clinical nutritionist or registered dietician to confirm the presence of malnutrition, assess the effects of the disorder, and formulate diets that will restore adequate nutrition.

Patients who cannot or will not eat, or who are unable to absorb nutrients taken by mouth, may be fed intravenously (parenteral nutrition) or through a tube inserted into the gastrointestinal (GI) tract (enteral nutrition).

Tube feeding is often used to provide nutrients to patients who have suffered burns or who have inflammatory bowel disease. This procedure involves inserting a thin tube through the nose and carefully guiding it along the throat until it reaches the stomach or small intestine. If long-term tube feeding is necessary, the tube may be placed directly into the stomach or small intestine through an incision in the abdomen.

Tube feeding cannot always deliver adequate nutrients to patients who:

• Are severely malnourished
• Require surgery
• Are undergoing chemotherapy or radiation treatments
• Have been seriously burned
• Have persistent diarrhea or vomiting
• Whose gastrointestinal tract is paralyzed.

Intravenous feeding can supply some or all of the nutrients these patients need.

Prognosis

Up to 10% of a person's body weight can be lost without side effects, but if more than 40% is lost, the situation is almost always fatal. Death usually results from heart failure, electrolyte imbalance, or low body temperature. Patients with semiconsciousness, persistent diarrhea, jaundice, or low blood sodium levels have a poorer prognosis.

Some children with protein-energy malnutrition recover completely. Others have many health problems throughout life, including mental retardation and the inability to absorb nutrients through the intestinal tract. Prognosis for all patients with malnutrition seems to be dependent on the age of the patient, and the length and severity of the malnutrition, with young children and the elderly having the highest rate of long-term complications and death.

Prevention

Breastfeeding a baby for at least six months is considered the best way to prevent early-childhood malnutrition. The United States Department of Agriculture and Health and Human Service recommend that all Americans over the age of two:

• Consume plenty of fruits, grains, and vegetables
• Eat a variety of foods that are low in fats and cholesterols and contain only moderate amounts of salt, sugars, and sodium
• Engage in moderate physical activity for at least 30 minutes, at least several times a week

• Achieve or maintain their ideal weight
• Use alcohol sparingly or avoid it altogether.

Every patient admitted to a hospital should be screened for the presence of illnesses and conditions that could lead to protein-energy malnutrition. Patients with higher-than-average risk for malnutrition should be more closely assessed and reevaluated often during long-term hospitalization or nursing-home care.

Resources

BOOKS

Beers, Mark H., MD, and Robert Berkow, MD, editors. "Malnutrition." Section 1, Chapter 2. In The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 2004.

Flancbaum, Louis, MD, with Erica Manfred and Deborah Biskin. The Doctor's Guide to Weight Loss Surgery. West Hurley, NY: Fredonia Communications, 2001.

PERIODICALS

Alvarez-Leite, J. I. "Nutrient Deficiencies Secondary to Bariatric Surgery." Current Opinion in Clinical Nutrition and Metabolic Care 7 (September 2004): 569-575.

Amella, E. J. "Feeding and Hydration Issues for Older Adults with Dementia." Nursing Clinics of North America 39 (September 2004): 607-623.

Bryan, J., S. Osendorp, D. Hughes, et al. "Nutrients for Cognitive Development in School-Aged Children." Nutrition Reviews 62 (August 2004): 295-306.

Grigsby, Donna G., MD. "Malnutrition." eMedicine December 18, 2003. 〈http://www.emedicine.com/ped/topic1360.htm〉.

Gums, J. G. "Magnesium in Cardiovascular and Other Disorders." American Journal of Health-System Pharmacy 61 (August 1, 2004): 1569-1576.

Halsted, G. H. "Nutrition and Alcoholic Liver Disease." Seminars in Liver Disease 24 (August 2004): 289-304.

Reid, C. L. "Nutritional Requirements of Surgical and Critically-Ill Patients: Do We Really Know What They Need?" Proceedings of the Nutrition Society 63 (August 2004): 467-472.

ORGANIZATIONS

American College of Nutrition. 722 Robert E. Lee Drive, Wilmington, NC 20412-0927. (919) 452-1222.

American Institute of Nutrition. 9650 Rockville Pike, Bethesda, MD 20814-3990. (301) 530-7050.

Food and Nutrition Information Center. 10301 Baltimore Boulevard, Room 304, Beltsville, MD 20705-2351. 〈http://www.nalusda.gov/fnic〉.

OTHER

World Health Organization (WHO) Nutrition web site. 〈http://www.who.int/nut/index.htm〉.

KEY TERMS

Anemia— Not enough red blood cells in the blood.

Anorexia nervosa— Eating disorder marked by malnutrition and weight loss commonly occurring in young women.

Bariatric— Pertaining to the study, prevention, or treatment of overweight.

Calorie— A unit of heat measurement used in nutrition to measure the energy value of foods. A calorie is the amount of heat energy needed to raise the temperature of 1 kilogram of water 1°C.

Kwashiorkor— Severe malnutritution in children primarily caused by a protein-poor diet, characterized by growth retardation.

Marasmus— Severe malnutritution in children caused by a diet lacking in calories as well as protein. Marasmus may also be caused by disease and parasitic infection.

Micronutrients— Essential dietary elements that are needed only in very small quantities. Micronutrients are also known as trace elements. They include copper, zinc, selenium, iodine, magnesium, iron, cobalt, and chromium.

Malnutrition

Malnutrition is a condition in which a person's diet is inadequate to meet minimum daily requirements for nutrients such as proteins, fats, vitamins, and minerals. It is caused by one of two factors. First, a person simply may not get enough food to eat and, thus, fails to take in the nutrients needed to remain healthy. Someone who is hungry all the time obviously is not eating enough food to remain healthy. Second, a person may eat a limited diet that fails to deliver vital nutrients to the body. Anyone who tries to survive on a diet consisting of potato chips, candy bars, and sodas will not be getting the complete range of nutrients his or her body needs.

Individuals at risk for malnutrition

The single most important factor that leads to malnourishment is poverty. Vast numbers of people who live in less-developed countries of the world either do not get enough to eat or do not eat the correct foods. Those who are most at risk of malnutrition where conditions of poverty exist are infants, children, pregnant women, and the elderly.

Malnutrition is not restricted to less-developed nations, however. Even countries with high standards of living, such as the United States, have their share of poor people who are underfed or poorly fed and may develop malnutrition. According to some estimates, at least 20 million Americans go hungry periodically within any given month.

Throughout the world, the death toll from malnutrition caused by hunger is estimated to range from 40,000 to 50,000 people a day. An additional 450 million to 1.3 billion people face the prospect of starvation from their limited food supplies.

Elderly people in nursing homes or hospitals suffering from long-term illnesses or chronic metabolic disorders (which affect the way one's body processes food for energy) are also at risk for malnutrition. Health professionals have procedures to monitor the nutritional condition of these individuals. Malnutrition is also experienced by those suffering from a condition called anorexia nervosa, a disorder marked by a person's intentional refusal to eat properly that can lead to starvation.

Nutritional deficiency diseases

The human body requires a wide range of nutrients in order to remain healthy, grow normally, and develop properly. These nutrients include carbohydrates, fats, proteins, vitamins, and minerals. Other substances, such as water and fiber, have no nutritional value but are needed to maintain normal body functions.

Words to Know

Bone marrow: The spongy center of many bones in which blood cells are manufactured.

Dermatitis: An inflammation of the skin that is often a symptom of a vitamin deficiency disorder.

Edema: An abnormal collection of fluids in the body tissues.

Hemolytic anemia: A type of anemia caused by destruction of red blood cells at a rate faster than which they can be produced.

Hemorrhage: Bleeding.

Kwashiorkor: A protein-deficiency disorder found among children characterized by wasting, loss of hair and skin pigmentation, anemia, blindness, and other symptoms.

Marasmus: A protein- and calorie-deficiency disorder characterized by the wasting away of muscle and skin in children.

Night blindness: Inability to see at night often caused by a vitamin A deficiency.

Protein: Large molecules that are essential to the structure and functioning of all living cells.

Nutrients serve a number of functions in the human body. Carbohydrates and fats, for example, are used by the body to produce the energy humans require to stay alive and healthy and to grow and develop normally. Proteins are used in the production of new body parts, to protect the body against disease and infection, in the regulation of bodily functions, and in a variety of other ways. Vitamins and minerals are used in the body for a number of different purposes, such as controlling the rate at which many chemical changes take place in the body. Overall, more than 50 different nutrients are needed to keep the human body healthy. The absence of any one of these nutrients can result in the development of a nutritional deficiency disease. Some common nutritional deficiency diseases are discussed below.

Kwashiorkor and marasmus. Kwashiorkor (from the West African word for "displaced child") is a nutritional deficiency disease caused when infants and very young children are weaned from their mother's milk and placed on a diet consisting of maize flour, cassava, or low-protein cereals. That diet is generally high in calories and carbohydrates, but low in protein. The most striking symptom of kwashiorkor is edema, a bloating caused by the accumulation of liquids under the skin. Other symptoms may include loss of hair and skin pigmentation, scaliness of the skin, and diarrhea. As the disease progresses, a person may develop anemia (a disorder in which a person's red blood cell count is low and they lack energy), digestive disorders, brain damage, a loss of appetite, irritability, and apathy (lack of interest in things).

Most children do not die of kwashiorkor directly. Instead, they develop infections that, if left untreated, can be fatal. They die from measles, the flu, diarrhea, or other conditions that could be treated relatively easily in a healthy child.

Marasmus (from the Greek word for "to waste away") is a more severe condition than kwashiorkor. It results when a person's diet is low in both calories and protein. The disease is characterized by low body weight, wasting of muscle tissue, shriveled skin, and diarrhea. The most prominent feature of marasmus is a severely bloated belly. A child with marasmus has the appearance of an old person trapped in a young person's body.

Scurvy. Scurvy is one of the oldest deficiency diseases recorded and the first one to be cured by adding a vitamin to the diet. It was a common disease among sailors during the age of exploration of the New World. Portuguese explorer Vasco da Gama (c. 1460–1524) is said to have lost half his crew to scurvy in his journey around the Cape of Good Hope at the end of the fifteenth century.

The main symptom of scurvy is hemorrhaging, the heavy discharge of blood that results when a blood vessel is broken. The gums swell and usually become infected. Wounds heal slowly and the bleeding that occurs in or around vital organs can be fatal. The disease is slow to develop and its early stages are characterized by fatigue (tiredness), irritability, and depression. In the advanced stages of the disease, laboratory tests will show an absence of the vitamin needed to protect against the disease.

In 1747, a British naval physician, James Lind (1716–1794), discovered the cause of scurvy. He found that sailors who were given oranges, lemons, and limes to eat along with their regular food did not develop scurvy. In spite of this finding, it was not until the end of the eighteenth century that the British navy finally had its sailors drink a daily portion of lime or lemon juice to prevent scurvy. The American slang term for English sailors, "limeys," originated from that practice.

The active ingredient in citrus fruits that prevents scurvy was not discovered until the 1930s. Then, two research teams, one headed by Hungarian-American biochemist Albert Szent-Györgyi (1893–1986) and the other by American biochemist Charles G. King, found that the antiscurvy agent in citrus fruits is a compound now known as vitamin C.

Beriberi. Beriberi is a disease that occurs widely in China, Indonesia, Malaysia, Burma, India, the Philippines, and other parts of Asia and the South Pacific Ocean. It is characterized by edema (accumulation of water in body tissues), fatigue, loss of appetite, numbness or tingling in the legs, and general weakness of the body. In fact, the name beriberi comes from the Singhalese word for "weakness."

Beriberi is caused by an absence of vitamin B₁ (thiamine) in the diet. The disease can be prevented by eating foods that are rich in this vitamin, foods such as meats, wheat germ, whole grain and enriched bread, legumes (beans), peanuts, peanut butter, and nuts.

Pellagra. The symptoms of pellagra are sometimes referred to as the "three Ds": diarrhea, dermatitis, and dementia. Dermatitis refers to skin infections while dementia means deterioration of the mind. If the disease is not treated, it may lead to death. The cause for pellagra was discovered in the early twentieth century by Joseph Goldberger (1881–1929), a member of the United States Public Health Service. Goldberger established that pellagra is caused by an insufficient amount of niacin (vitamin B₃).

Niacin occurs naturally in foods such as liver, meat, fish, legumes, and dried yeast. Today it is added to many processed foods such as bread, flour, cornmeal, macaroni, and white rice. This practice has essentially eliminated pellagra as a medical problem in developed countries, although it remains a serious health problem in some less-developed countries of the world.

Rickets. Rickets is a bone disorder caused by a lack of vitamin D. Vitamin D is often called the "sunshine" vitamin because it can be produced in the human body by the effects of sunlight on the skin. Rickets was once a common disease of infants and children. However, all milk and infant formulas now have vitamin D added to them. Thus, the disorder is rarely seen today in countries where "fortified" milk is available. Symptoms of rickets include legs that have become bowed by the weight of the body and wrists and ankles that are thickened. Teeth may be badly affected and take a longer time to mature.

Other vitamin deficiency diseases. The most common problem associated with a deficiency of vitamin A is night blindness. Night blindness is the inability to see well in the dark. Vitamin A is needed for the formation of a pigment needed by the eyes for night vision. Another eye disease caused by vitamin A deficiency is xerophthalmia, which can lead to blindness. This condition affects the cells of the cornea, other eye tissues, and the tear ducts, which stop secreting tears. Vitamin A deficiency is also responsible for a number of skin conditions, problems with tasting and smelling, and difficulties with the reproductive system.

Important sources of vitamin A that can protect against such problems include fish-liver oils, butter, egg yolks, green and yellow vegetables, and milk.

Vitamin E and K deficiencies are rare. A deficiency of vitamin E may be related to sterility (inability to have children) and to more rapid aging. Vitamin K promotes normal blood clotting.

Vitamin B₁₂ (cobalamin) provides protection against pernicious anemia and mental disorders. Vitamin B₆ also protects against anemia as well as dermatitis, irritability, and convulsions.

Mineral deficiency diseases. About 25 mineral elements are required in the human body for the maintenance of good health. Calcium and phosphorus, for example, are needed to produce teeth and bones. Diseases resulting from the lack of a mineral are relatively rare among humans. One of the exceptions is the disorder known as goiter. Goiter is a condition caused by an insufficient amount of iodine in the diet. Iodine is used by the thyroid to produce hormones that control the body's normal functioning as well as its normal growth. If sufficient iodine is not available in a person's diet, the thyroid gland begins to enlarge its cells in an effort to produce the needed hormones. This enlargement produces the characteristic swelling in the neck characteristic of goiter. Today, goiter has virtually disappeared from most developed nations because of the practice of adding small amounts of iodine (in the form of sodium iodide) to ordinary table salt.

Perhaps the most common of all mineral deficiency disorders is anemia. The term anemia literally means "a lack of blood." The condition is caused when the number of red blood cells is reduced to a level lower than that necessary for normal body functioning.

The human body gets the energy it needs to stay alive and function normally by oxidizing nutrients in cells. The oxygen needed for this process is carried from the lungs to cells on red blood cells. The "working part" of a red blood cell is a complex molecule called hemoglobin. Each hemoglobin molecule contains a single atom of iron at its center. The iron atom combines with oxygen from the lungs to form a compound known as oxyhemoglobin. It is in this form that oxygen is transferred from the lungs to cells.

If the body fails to receive sufficient amounts of iron, an adequate number of hemoglobin molecules will not be formed. In that case, there are not enough functioning red blood cells to carry all the oxygen that cells need to produce energy. A person becomes weak and listless and may suffer headaches, soreness of the mouth, drowsiness, slight fever, gastrointestinal disturbances, and other discomforts.

More than 30 different forms of anemia have been recognized. These forms may result from a wide range of causes. For example, a person who has surgery may lose enough blood to develop anemia. A form of anemia known as aplastic anemia develops when bone marrow is destroyed by radiation, toxic chemicals, or certain types of medication. Loss of bone marrow inhibits the production of red blood cells. Hemolytic anemia is caused by the rupture of red blood cells, a problem that can be caused by hereditary factors or by toxic agents.

Treatment

The treatment for malnutrition and for nutrient deficiency diseases is obvious: a person who lacks adequate amounts of food or fails to eat the right kinds of food must change his or her diet. That instruction is easy to give but in many parts of the world it is impossible to follow. Marasmus, kwashiorkor, beriberi, scurvy, rickets, and other deficiency disorders are common in less-developed countries of the world because sufficient food is either not available or, if it is, it is not sufficiently nutritious.

In more-developed countries of the world, people often have ready access to nutritious foods in sufficient quantities so that malnutrition is less of a problem than it is in less-developed countries. In addition, a very large variety of supplements are available, such as vitamin and mineral pills. Anyone who fears that he or she may not be receiving enough of any given vitamin or mineral can easily supplement his or her diet with products available at the corner grocery store.

[See also Blood; Nutrient deficiency diseases; Nutrition; Sicklecell anemia ]