Diet and health

Definition

Diet has a tremendous effect on health. Diet plays a role in promoting health and reducing chronic disease for many conditions such as preventing obesity , diabetes mellitus , coronary heart disease, and cancer , as well as low birth weight in babies.

Description

The concept of diet quality in relation to health has changed over time. Nutrition scientists focused on preventing nutrient deficiencies early in this century, but now the shift has changed, exploring diets and chronic disease prevention and treatment. Adequate nutrition is essential to reduce morbidity and mortality from acute and chronic disease. Well-nourished people are more resistant to disease and are better able to tolerate other therapy and to recover from acute illnesses, surgery, and trauma. Nutrition also plays a key part in a patient's recovery from a disease or treatment.

Consumption of a wide variety of foods, with appropriate amounts of protein, carbohydrate, fat, vitamins and minerals is the basis of a healthy diet. However, today's major health care problems are increasingly the result of acute and chronic conditions related to dietary intake. In fact, eight of the 10 leading causes of death, including coronary heart disease, stroke, diabetes mellitus, and some cancers, can be attributed to diet and alcohol. Some chronic diseases continue to increase due to factors such as the rise in obesity in Western populations, Americans in particular.

There is no disputing that a healthy diet can help to prevent illness and promotes a feeling of well-being. A research study reported in the Journal of the American Medical Association suggested that by following the current dietary guidelines, women are able to live longer. Women whose diets included large amounts of fruits, vegetables, whole grains, low-fat dairy, and lean meats had a lower risk of death. Women who were considered to have the best diets (those eating the highest intake level of recommended foods from the current dietary guidelines) had a 30% lower risk of death from any cause compared with those eating the lowest level of recommended foods.

Viewpoints

The position of the American Dietetics Association on the role of nutrition and diet in health promotion and disease prevention programs includes steps for primary, secondary, and tertiary prevention. These steps include the following guidelines:

• Primary prevention (health promotion): Health promotion is a population-based approach that encourages behaviors for better health. For example, nutrition classes at a local adult education center could be considered a primary prevention measure.
• Secondary prevention (risk appraisal and risk reduction): For people at risk of illness who are beginning to encounter health-related problems, secondary prevention encompasses risk appraisal and screening to detect preclinical disease, and early intervention to promote health and well-being. For example, cholesterol screening for people with a family history of cardiovascular disease could be considered a secondary prevention measure.
• Tertiary prevention (treatment and rehabilitation): For people experiencing illness or injury, tertiary prevention includes treatment and rehabilitation to promote maximum health and prevent further disability and secondary conditions resulting from the initial health problem. Examples of tertiary prevention include medical nutrition therapy or diabetes education for people diagnosed with type 2 diabetes mellitus.

Experts in nutrition recommend a variety of foods and the maintenance of an ideal weight. Large amounts of fat, saturated fat, and cholesterol should be avoided. Individuals should consume adequate starch and fiber and avoid excess sugar and sodium.

Dietary guidelines

The Dietary Guidelines for Americans, published by the U.S. Department of Agriculture and Health and Human Services, can provide a broad overall view of good nutrition. These dietary guidelines include these basic recommendations:

• Eat a variety of foods; let the food pyramid guide your food choices.
• Control your weight.
• Be physically active each day.
• Eat a diet low in saturated fat and cholesterol, and moderate in total fat.
• Eat a variety of vegetables, fruits, and grains.
• Eat sugar in moderation.
• Use salt in moderation.
• If you drink alcohol, do so in moderation; no more than two drinks per day of wine, beer, or spirits.
• Keep food safe to eat; follow the government safety precautions as outlined on the food package.

The Food Guide Pyramid was created by the U.S. Department of Agriculture to help Americans choose foods from each food grouping. It focuses on fat intake, which is too high in most Americans. The food pyramid, developed by nutritionists, provides a visual guide to healthy eating. At its base are those foods that should be eaten numerous times each day, while at its apex are those foods that should be used sparingly. The pyramid suggests a range of servings in each group so that the number of servings can be adjusted to suit each individual's caloric requirements. The daily recommendations (from bottom to top) of the food pyramid include:

• bread, cereal, rice, and pasta: 6–11 servings
• vegetables: 3–5 servings
• fruits: 2–4 servings
• milk, yogurt, and cheese: 2–3 servings
• meat, poultry, fish, dried beans, eggs, and nuts: 2–3 servings
• fats , oils, and sweets: use sparingly

Other programs use the National Cholesterol Education Program Step 1 Diet guidelines, which may be followed to assist in controlling weight. The guidelines provided by the National Cholesterol Education Program can be followed for maintaining optimal blood lipid levels [total cholesterol, low-density lipoproteins (LDL), high-density lipoproteins (HDL), and triglycerides]. Health promotion and disease prevention are central components of national recommendations to improve the health of Americans in an initiative called Healthy People 2000. This program is a series of national health promotion and disease prevention objectives that examine the association between nutrition and chronic disease. A program called Healthy People 2010 is planned.

National and international trends

Major diet and health targets in the United States include:

• Obesity. Obesity has become a major problem for Americans due to inactive lifestyles and poor diets. Estimates suggest that over 50% of Americans are over-weight. Dietary modification can reduce obesity, in turn decreasing conditions and diseases such as coronary heart disease, atherosclerosis, hypertension , cancer, diabetes, and high blood cholesterol.
• Diabetes. Since 1990, type 2 diabetes has jumped by 33% nationwide in the United States. Being overweight and contracting diabetes are closely linked.
• Fat and cholesterol intakes. These are still too high. Since the 1960s, the average blood cholesterol level has decreased, mostly due to a shift from red meat to poultry, from whole to lower-fat milk, and from butter and lard to margarine and vegetable oils. Cholesterol has dropped to about an average of 205 mg/dl from the peak of the coronary epidemic in the 1960s of 220 to 230 mg/dl. Intake of saturated fat was about 16% in the 1960s; it has now been reduced to approximately 12%. Fat intake is too still too high. It is estimated that the average American consumes about 40% of their calories from fat. Fat source (i.e. saturated, monounsaturated, or polyunsaturated) is an important issue to consider when reducing overall fat in the diet, as some fats reduce cholesterol while others raise cholesterol.
• Stroke incidence. Stroke incidence and related deaths have dropped in the last 30 to 40 years, likely due to better blood pressure control, less smoking and drinking, and possibly an increase in fruits and vegetable consumption.
• Lack of exercise. Energy expenditure has declined due to more sedentary lifestyles. Those who sit at a computer all day expend fewer calories than in physicallabor jobs.
• "Fad" and herbal diets. Throughout the 1990s and into this century, the market for dietary supplements and herbal remedies has exploded. The nutritional implications of many of these compounds has not been established with scientific research, and therefore the health implications are unknown in many cases.
• Health supplements. There are a great many claims about particular vitamins, minerals, and/or antioxidants having beneficial health effects on the market today. Proper nutrition with an adequate diet is the best way to achieve vitamins, but a supplement may be required when intake is inadequate. It is important to check with a dietitian or doctor before taking nutritional supplements or alternative therapies if other medications are taken for chronic illness, because they may cause a drug interaction.

Dietary recommendations in Europe and Australasia are comparable with those in the United States. The European guidelines suggest, as do those in the United States, that total fat should provide 30% or less total energy, which implies that complex carbohydrates , fruits, cereals, and vegetables should be increased to replace the foods rich in total and saturated fat which have been eliminated. The European Atherosclerosis Society states that for those with total cholesterol levels of 200-250 mg/dl (5.2-6.5 mmol/L), dietary modification to reduce the risk of coronary heart disease (CHD) is required. While CHD incidence is declining in western Europe, Australia, and the United States, it is rapidly rising in central and eastern Europe and in some Asian countries. These regions are under-going unprecedented economic growth and rapidly changing lifestyles in many aspects including dietary intake. These changes have led to an increase in CHD incidence and death. Singapore, the most economically developed country in Asia, also has the highest prevalence of CHD deaths, at rates similar to those of the United States and Australia. This region may serve as a warning that Asia may expect an escalation in CHD. Although cholesterol levels vary widely over Asia, CHD mortality is evidenced where cholesterol levels have increased from previously low levels and in regions where the highest cholesterol levels predominate. Australasian (National Heart Foundation of New Zealand Scientific Committee and the National Heart Foundation of Australia) and European (British Hyperlipidaemia Association, British Hypertension Society) guidelines for the prevention of CHD in clinical practice emphasize the need to determine the absolute CHD risk for any individual in order to decide the most appropriate therapy. This, of course, includes dietary management to control fat intake and cholesterol. Clearer statements and guidelines on the prevention and control of diabetes and hypertension as well as diet, obesity, exercise , and smoking may be appropriate.

Professional implications

Qualified dietetics professionals assist in encouraging good nutrition and/or dietary change as a method of promoting health and preventing chronic disease. Nursing and allied health professionals can reinforce good dietary choices and provide nutrition guidance for patients in hospitals, long-term care facilities, or in community settings.

In general, only registered dietitians (R.D.) have sufficient training and knowledge to accurately assess the nutritional adequacy of a patient's diet, especially if chronic disease is present. A doctor may also have a nutrition background or specialization and may thus be able to conduct a dietary assessment or to provide general nutrition advice and/or diet therapy .

When an individual or patient is using dietary means to help recover or control a disease or condition, it is often called medical nutritional therapy. To maintain health in a patient with a nutrition-related illness, all health care team members and especially the patient must commit to achieving optimum health through medical nutritional therapy. Prioritized goals are critical when developing the nutrition treatment plan. Continuous assessment is made by the patient and health care team members to evaluate the importance of these and other goals. Physicians must understand the dietary approaches an individual is using and reinforce this diet therapy when interacting with the individual. The position of the American Dietetic Association is that medical nutritional therapy is effective in treating disease and preventing disease complications.

Resources

BOOKS

Institute of Medicine. Dietary Reference Intakes: Applications in Dietary Assessment. Washington, D.C.: National Academy Press, 2001.

Institute of Medicine, ed. Dietary Reference Intakes: Risk Assessment (Compass Series). Washington, D.C.: National Academy Press, 1999.

Larson-Duyff, Roberta. The American Dietetic Association's Complete Food & Nutrition Guide. New York: John Wiley & Sons, 1998.

Mahan, L. Kathleen, and Sylvia Escott-Stump., eds. Krause's Food, Nutrition, & Diet Therapy. London: W.B. Saunders Co, 2000.

Netzer, Corinne T. The Complete Book of Food Counts. New York: Dell Publishing Company, 2000.

Nutrition and Your Health: Dietary Guidelines for Americans. 5th edition. Hyattsville, MD: U.S. Department of Agriculture, U.S. Department of Health and Human Services, 2000.

Rodwell-Williams, Sue. Essentials of Nutrition and Diet Therapy (With CD-ROM for Windows and Macintosh). London: Mosby-Year Book, 1999.

PERIODICALS

American Dietetics Association. "Women's health and nutrition—Position of ADA and Dietitians of Canada." Journal of the American Dietetic Association 99 (1999): 738–751.

Hu F.B., et al. "Trends in the incidence of coronary heart disease and changes in diet and lifestyle in women." New England Journal of Medicine 343 (2000): 530–537.

Kant, Ashima K., et al. "A Prospective Study of Diet Quality and Mortality in Women." Journal of the American Medical Association 283 (2000): 2109–2115.

Patterson, Ruth E. "Is there a consumer backlash against the diet and health message?" Journal of the American Dietetic Association 101 (2001): 3741.

Stampfer M.J., et al. "Primary prevention of coronary heart disease in women through diet and lifestyle." New England Journal of Medicine 343 (2000): 16–22.

ORGANIZATIONS

American Dietetic Association. 216 W. Jackson Blvd.

Chicago, IL 60606-6995. (312) 899–0040. <http://www.eatright.org>.

American Heart Association National Center. 7272 Greenville Avenue, Dallas, Texas 75231. (800) AHA-USA1. <http://www.americanheart.org/>.

Food and Nutrition Information Center Agricultural Research Service, USDA. National Agricultural Library, Room 304, 10301 Baltimore Avenue, Beltsville, MD 20705-2351. (301) 504–5719, Fax (301) 504–6409. <http://www.nal.usda.gov/fnic/>. fnic@nal.usda.gov.

OTHER

Food and Nutrition Professionals Network <http://nutrition.cos.com>.

KEY TERMS

Dietitian —A health professional who has a bachelor's degree, specializing in foods and nutrition, and in addition undergoes a period of practical training in a hospital or community setting. Many dietitians further their knowledge by pursuing master's or doctoral degrees. The title "dietitian" is protected by law so that only qualified practitioners who have met education qualifications can use that title.

Crystal Heather Kaczkowski, MSc.