Several studies have indicated that moderate drinkers have a lower risk of both nonfatal myocardial infarction and fatal heart disease than do abstainers. To determine whether alcohol truly prevents coronary heart disease or whether other factors may contribute to this observed relationship, researchers conducted a systematic literature review and a combined analysis (ie., meta-analysis) of 42 published studies. This analysis found that consumption of up to two drinks per day can promote changes in the levels of molecules that reduce the risk of heart disease while also increasing the levels of certain molecules that promote heart disease. Alcohol also may affect the risk of heart disease by acting on other various other molecules involved in a variety of physiological processes related to heart disease. Finally, the relationship between alcohol consumption and heart disease may be modulated by genetic factors. KEY WORDS: heart disorder; risk factors; beneficial vs. adverse drug effect; moderate alcohol and other drug (AOD) use; AOD abstinence; lifestyle; high density lipoprotein; platelet aggregation; blood pressure; endothelial cell; genetics and heredity; alcohol dehydrogenases; pathologic process; meta-analysis
ince the early part of the 20th century, clinicians have noted that coronary heart disease appears to S occur less commonly among people who consume alcohol than among abstainers. Over the last 30 years, formal scientific inquiry has confirmed this observation. Such analyses included studies that compared alcohol use between people with and without confirmed coronary disease (i.e., case-control studies) as well as studies that followed healthy drinkers and abstainers over time to determine their risk of coronary disease (i.e., prospective cohort studies). Both types of studies found that people who consumed alcohol in moderation had lower rates of coronary heart disease compared with abstainers. For example, in a prospective study of 51,529 healthy men, Rimm and colleagues (1991) found that men who consumed 5.1-30 grams of alcohol (about 0.3-2 standard drinks') per day had a 29 percent lower risk of suffering either nonfatal myocardial infarction or fatal heart disease than did abstainers. Similarly, the drinkers had a 16 percent lower risk of undergoing bypass surgery or angioplasty compared with abstainers. These findings were confirmed in a review of over 50 epidemiological studies, which concluded that compared to total abstinence, consumption of one drink every 1 to 2 days is associated with a 17 percent lower risk of nonfatal myocardial infarction (Maclure 1993).
This article reviews the evidence that it is indeed the consumption of alcoholic beverages rather than other unrelated factors that reduces the risk of coronary heart disease. It also presents a recent approach to determine the relationship between alcohol consumption and coronary heart disease. This approach explores alcohol's influence on known risk factors for coronary disease as well as other pathways through which alcohol may affect the risk for heart disease. Finally, the article investigates the role of genetic factors in modifying the relationship between alcohol consumption and the risk of coronary heart disease. DOES ALCOHOL TRULY PREVENT CORONARY HEART DISEASE? Although the evidence of a lower risk of coronary heart disease among moderate drinkers is substantial and consistent, controversy remains about whether the relationship is truly causal-that is, whether moderate alcohol consumption really prevents coronary heart disease. For example, some investigators have argued that abstainers are an inappropriate control population because at least some of these people may abstain because of illness or former alcohol abuse. Furthermore, other dietary, lifestyle, and developmental factors may differ between abstainers and drinkers. Both of these concerns warrant closer scrutiny.
The first of these concerns, also called the "sick quitter" hypothesis, was proposed by Shaper and colleagues (1988) in the United Kingdom. …