LIFESTYLES AND HEALTH

Lifestyles are a major determinant of who shall live and who shall die (Fuchs 1974; McKinlay and Marceau 1999). Mechanic (1978, p. 164) argues that the concept of lifestyles refers to a diverse set of variables, including nutrition, housing, health attitudes and beliefs, risk-taking behavior, health behavior and habits, and preventive health behavior.

CONFIRMING THE LINK BETWEEN LIFESTYLES AND HEALTH

Establishing the causal linkage between lifestyles and health is not a simple task. Variables included in lifestyles interact with each other (Mechanic 1978), making it difficult to adjust for confounding variables such as race and ethnicity, gender, social class, and psychological distress.

In addition, there are problems in specifying the nature of the etiological relationship between lifestyles and disease. Not every person who engages in an unhealthy lifestyle will die prematurely. For example, some heavy smokers do not develop lung cancer. Genetic predisposition, comorbidities, other health habits, and access to adequate medical care are factors that may intervene in the relationship between host and disease. For certain conditions, it may be complicated to determine the precise role of risky lifestyle behaviors in the development of disease.

The most convincing models of the relationship between lifestyles and health are those built on triangulated evidence from animal, clinical, and epidemiological studies. As an example, consider the link between tobacco use and cancer. In controlled randomized trials using animal subjects that are genetically the same, the experimental group of animals is exposed to tobacco smoke while the control group is not. If the experimental group has a higher incidence of cancer than the control group, the study provides evidence to link tobacco smoke to cancer. Another strategy to link lifestyle behavior to health involves clinical studies with human subjects. Lung tissue of smokers is compared with lung tissue of nonsmokers. If more smokers than nonsmokers have cancerous cells in the lung tissue, this provides additional data to confirm that smoking causes lung cancer. A final strategy uses epidemiological methods. In prospective studies, separate groups of smokers and nonsmokers are followed over time to ascertain the risk of developing cancer within each group. All else being equal, if smokers develop more cases of cancer, the causal relationship between smoking and cancer is confirmed.

With these methodological issues in mind, four selected behaviors are used below to illustrate how lifestyles impact on health: tobacco use, alcohol consumption, diet, and sexual behavior and injection-related practices that increase the risk of acquiring the human immunodeficiency virus (HIV). For each behavior, extensive animal, clinical, and epidemiological data exist to support the causal relationship between each agent and disease. Gender differences in these behaviors are used to illustrate how lifestyles vary across social groups. Men are more likely to engage in these risky behaviors compared to women; this helps explain why women live longer than men do (Crose 1997). Finally, examples of successful efforts to change risky life-style behaviors are provided.

TOBACCO USE

Tobacco use has been defined as the most important single preventable cause of death and disease in society. Smoking causes an average of 430,700 deaths per year in the United States. One in every five deaths is smoking related (Centers for Disease Control and Prevention 1997a). Careful epidemiological studies have determined that tobacco use increases the risks for heart disease, lung cancer, emphysema, and other lung diseases. Smoking during pregnancy increases the risk for premature births, complications of pregnancy, low-birthweight infants, stillbirths, and infant mortality. Fetuses exposed to smoke in utero and young infants exposed to secondhand smoke are at increased risk for sudden infant death syndrome, poor lung development, asthma, and respiratory infections (Centers for Disease Control and Prevention 1997b; Environmental Protection Agency 1992; Floyd et al. 1993). Secondhand smoke is also associated with adult illnesses (Centers for Disease Control and Prevention 1997a). Increased risks for lung cancer and heart disease are reported for nonsmokers who live with smokers.

Age-adjusted rates indicate that 27 percent of men smoked in 1995, compared to 23 percent of women (National Center for Health Statistics 1998). The gender gap used to be wider. In 1965, men were 1.5 times more likely to smoke than women were. Today, the gender difference is only 17 percent. The decline in cigarette smoking has been greater among men. While the prevalence of smoking among men dropped by almost half from 1965 to 1995, the rate for women dropped by only one-third. Traditionally, smoking by women was not condoned, but over time these attitudes have changed. As a result, the smoking rates for men and women are nearly the same. This translates into a 400 percent increase in deaths from lung cancer among women between 1960 and 1990 (Centers for Disease Control and Prevention 1997a).

Various prevention efforts have reduced the prevalence of smoking in the United States. Smokefree workplaces are the norm rather than the exception. Warning labels appear on cigarette packages, and billboards advertising cigarettes are banned. Community-based public education campaigns and worksite programs have been successful in smoking reduction (COMMIT Research Group 1995).

ALCOHOL

The National Institute on Alcohol Abuse and Alcoholism (NIAAA 1997) estimates that alcohol use is responsible for 100,000 deaths in year in this country. About 44 percent of the motor vehicle fatalities in 1994 were alcohol related (National Highway Traffic Safety Administration 1994). Alcohol use is frequently implicated in accidental injuries and deaths from falls, drowning, interpersonal and family violence, occupational hazards, and fires (NIAAA 1997).

From 10 to 20 percent of heavy drinkers develop cirrhosis of the liver, which was the tenth leading cause of death in the United States in 1996 (DeBakey et al. 1995; National Center for Health Statistics 1998). The liver is the primary site of alcohol metabolism, and drinkers are at risk for other forms of liver disease, including alcoholic hepatitis and cancer.

Heavy alcohol use causes loss in heart muscle contractile function, arrhythmias, degenerative disease of the heart muscle, and heart enlargement, and also increases the risk for hypertension and stroke. Alcohol is implicated in esophageal, breast, and colorectal cancer, and it may increase the risk for other types of cancer as well. NIAAA concludes, "The range of medical consequences of alcohol abuse is both immense and complex—virtually no part of the body is spared the effects of excessive alcohol consumption" (1990, p. 127).

Alcohol also functions as a teratogen, producing defects in the human fetus in utero. The possible effects of alcohol on the fetus include gross morphological defects as well as cognitive and behavioral dysfunctions. Alcohol ingestion during pregnancy causes a variety of birth defects, including fetal alcohol syndrome, alcohol-related birth defects, and alcohol-related neurodevelopmental disorder. Fetal alcohol syndrome is the most severe consequence of the mother's heavy drinking during pregnancy and is characterized by craniofacial anomalies, mental retardation, central nervous system dysfunction, and growth retardation. Fetal alcohol syndrome is one of the leading causes of preventable birth defects (Stratton et al. 1996).

Men are more likely to drink alcohol than women are. Twenty-two percent of men are lifetime abstainers from alcohol, versus 45 percent of women. About 56 percent of men are current drinkers, compared to 34 percent of women. Heavy drinking is gender related. Almost 12 percent of men average more than fourteen alcoholic drinks per week, compared to less than 4 percent of women (NIAAA 1998).

Various prevention efforts are directed toward decreasing alcohol consumption. The alcohol beverage warning label, implemented in 1989, warns drinkers about birth defects, drunk driving, operating machinery, and health problems; however, its impact has been modest. Other alcohol prevention programs have been implemented, including dram shop liability (servers are legally responsible for damage or injury caused by drunk patrons), training servers of alcohol to avoid selling to intoxicated persons and to minors, lowering the allowable blood alcohol concentration levels for drivers, changing the availability of alcohol, enforcing impaired driving laws, and designating one person in a car as the nondrinking driver. These community intervention programs have reduced alcohol-related traffic deaths significantly (NIAAA 1997).

DIET

Dietary factors have been linked to mortality from cardiovascular disease (heart disease and stroke) and cancer; these diseases are the leading causes of death in the United States. Diet affects four of the major risk factors for cardiovascular disease: hypertension, obesity, diabetes, and high cholesterol. Obesity, as well as diets high in saturated fats, trans fatty acids, and cholesterol, raise blood cholesterol concentration and blood pressure, thus increasing the risk for coronary heart disease and stroke. Diets low in saturated fats but high in fiber and some omega-3 fatty acids (found in walnuts, certain oils [fish, canola, soybean], and green leafy vegetables) lower the risk for heart disease (Hu et al. 1997; Ascherio et al. 1996).

Diet also affects cancer risk. While the link between dietary intake and breast cancer is controversial, there is evidence that a diet high in saturated fat plays an etiological role (Kolonel 1997; Hankin 1993). High fat intake increases the risk for prostate cancer, lung cancer, and colorectal cancer (Kolonel 1997). On the other hand, diets high in fruits, vegetables, and fiber lower the probability of developing various types of cancer, including breast, colorectal, stomach, and lung (Ziegler 1991; Hankin 1993).

Gender differences in diet and obesity exist. For example, women are more likely to be over-weight compared to men (39 percent versus 36 percent). Among the poor, the gender gap is larger: 46 percent of poor women versus 31 percent of poor men suffer from obesity (National Center for Health Statistics 1998). Despite this increased risk for obesity, women consume healthier food than men do. While men consume more meat, saturated fat, and high-calorie foods, women eat more fruits, vegetables, whole grains, and lower-calorie foods (Crose 1997). Successful programs have been developed to encourage healthier eating habits for men and women, including interventions in worksites and families (Sorensen et al. 1999). The public has responded to these efforts, as evidenced by a 4 percent drop in blood cholesterol levels from 1978 to 1990 (National Heart, Lung, and Blood Institute 1996).

SEXUAL AND INJECTION-RELATED PRACTICES

The human immunodeficiency virus (HIV) causes acquired immune deficiency syndrome (AIDS), the eighth leading cause of death in the United States in 1996 (Peters et al. 1998). HIV is transmitted through blood products, bodily fluids, and breast milk. Transmission of HIV can be prevented by the use of safe sexual practices and sterile needles.

There are clear gender differences in the way AIDS is contracted, and the infection rate among women has been rising. Forty-eight percent of AIDS patients acquire the disease through male homosexual contact. Another 10 percent of AIDS cases appear in men who have sexual relations with a male or female partner and also use intravenous drugs. Almost 26 percent become ill solely through infected needles, and 6 percent through heterosexual contact that was not related to intravenous drug use. Among women, the most common route of infection is intravenous drug use (by herself or her partner), 60 percent or unprotected sex with an infected partner, 22 percent (Centers for Disease Control and Prevention 1998a).

While some HIV prevention programs promote abstention from sex and cessation of drug injecting, most programs define harm reduction as the goal (Kelly 1999). This policy promotes using condoms correctly on a consistent basis, having sex with uninfected partners, and cleaning needles with bleach or exchanging contaminated syringes for sterile ones.

Programs designed to decrease (1) the rate of unprotected anal sex among men who have sex with men and (2) the proportion of men having unprotected sex with multiple male partners contributed to the reduction in AIDS cases among homosexuals during the 1980s and early 1990s. However, 1997 data suggest that unprotected anal sex among gay men and unprotected sex with multiple partners is increasing, especially among younger gay men (Centers for Disease Control and Prevention 1999).

The second major mode of HIV transmission, especially among women, is by infected needles. Syringe exchange programs or the use of bleach to clean syringes prevent the spread of HIV among injecting-drug users. The number of syringe exchange programs has grown rapidly; 17.5 million needles were exchanged in 100 programs in 1997 (Centers for Disease Control and Prevention 1998b). Other communities have distributed bleach kits that reduce the spread of HIV (CDC AIDS Community Demonstration Projects Research Group 1999).

DISCUSSION

Four examples were selected to illustrate the role of lifestyles and health. There are other lifestyles that are related to health, which are beyond the scope of this article. For example, stressful lifestyles have been linked to mental illness, gastrointestinal illness, and heart disease. Regular use of seatbelts reduces the likelihood of death or injury in automobile accidents. Proper dental hygiene decreases the rate of dental caries. Childhood immunizations prevent measles, mumps, and polio.

When discussing lifestyles and health, several unresolved issues remain. First, the role of lifestyles in health is still evolving. As Becker (1993) argues, what is said to be bad for us one day may be determined to be good for us the next (and vice versa). For example, while researchers have documented the deleterious effects of alcohol on health, there is some recent evidence that red wine consumption may lower cholesterol levels (NIAAA 1997).

Second, there is continuing debate about the pros and cons of changing an individual's lifestyle versus changing the social milieu (Kelly 1999). Should we invest in programs designed to encourage an individual to stop smoking? Is it better to develop strategies that change societal norms about the acceptability of smoking? Should we do both?

Third, policy makers note that healthy lifestyle programs must be tailored to the individual, the subgroup (gender, age, race or ethnicity, and social class) and the particular community at risk (Kelly 1999). Thus, designing successful interventions to alter lifestyles is challenging.

Finally, it must be emphasized that that while a healthy lifestyle may be a necessary condition for longevity; it is not a sufficient condition. Many variables interact with lifestyles to protect against disease and death. For example, evidence is mounting that genetic predispositions are very important in the etiology of certain diseases. Thus, the models predicting who shall live and who shall die involve complicated interactions of lifestyles, preventive health behavior, genetic risk, sociodemographic characteristics, and so on. Nonetheless, individuals who abstain from smoking and injecting drugs, drink alcohol in moderation, reduce the intake of saturated fat and cholesterol, and use safe sex practices have a better chance of survival than those who eat and drink excessively and do not follow recommended safe sex practices.

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Janet Hankin