In an early study on alcohol and coronary artery disease, Marmot et al. (3) screened 1422 middle-aged, male civil servants in and around London between 1967 and 1969 using a 3-day dietary recall format. Ten years later the investigators compared mortality rates of those who used various amounts of alcohol. Even correcting for smoking, systolic blood pressure, and serum cholesterol, the authors found the now-famous U-shaped curve. They grouped the men according to consumption of no alcohol per day, up to 9 g (approximately one alcoholic beverage) per day, 34 g (three to four beverages) per day, and over 34 g per day. Of note, the U-shaped curve was seen for all-cause mortality, with the cardiovascular death curve assigned a relative risk of 1.0 for the 0.1-9 g/day group. They found a relative risk of 1.5 for the 9.1-34-g/day group, and 0.9 for the over-34-g/day group. The abstainer group had a relative risk of death due to coronary artery disease of 2.1.
The London group, however, was not the first to publish the observation that alcohol may have a cardioprotective effect. In 1974, Klatsky, Friedman, and Siegelaub (4) published the first relatively large-scale (464 patients) epidemological study that demonstrated a cardioprotective effect of moderate drinking (defining moderate drinking as two or fewer alcoholic beverages per day). Yano et al. (5) published in 1977 that beer (up to 60 ml per day) had a protective effect in a cohort of 7705 Japanese men living in Hawaii against death due to coronary artery disease and also nonfatal myocardial infarction.
In 1979, St. Leger (6) looked at a number of different factors with the potential to influence risk of cardiovascular disease. The most significant finding was a strong negative association between deaths due to cardiovascular disease and alcohol consumption; St. Leger and his coauthors felt that this effect was attributable entirely to the drinking of wine.
Kozararevic et al. (7), in a cohort of 11,121 men, found that alcohol consumption was inversely related to risk of death from coronary artery disease, but increased the risk of trauma and stroke in Yugoslav men aged 35-62. Their 1980 study used a complex system of estimating alcohol intake, as they were trying to equalize a number of kinds of beverages with different alcohol contents. Briefly, they found that the death rate due to heart disease among those who consumed two or more drinks per day was about half that of infrequent drinkers (less than once per week).
Most recent studies have continued to support the hypothesis that moderate consumption of alcohol reduces the risk of coronary disease. Analyzing data from the Physician's Health Study, Camargo et al. (8) examined data obtained from 21,530 male physicians between the ages of 40 and 84. While they found that drinking two or more alcohol-containing drinks per day increased the risk of death from cancer, two to six drinks per day resulted in decreased total mortality. Men who consumed two or more drinks per day had a 56% lower risk of angina and 47% lower risk for myocardial infarction. They concluded that "alcohol consumption had strong, independent, inverse associations with the risk for angina pectoris and myocardial infarction."
The salutary effects of moderate intake of red wine may explain what has been called the "French paradox," the low rates of death due to coronary artery disease among French people, who have a diet high in saturated fat (9). Only Japan has lower male cardiac death rates than France (225 per 100,000 versus 201 per 100,000), and French women have lower risk (84 per 100,000) than women of all other nationalities (10).
Still other studies suggest that it is the ethanol itself that exerts the salutary effect, and therefore any alcoholic beverage could confer benefits. Rimm (11) reviewed a number of studies in 1996 demonstrating cardiac benefit in moderate drinking. Of 12 studies looking at one or more kinds of alcoholic beverages, seven demonstrated benefits from wine drinking, seven from beer, and six showed a positive effect from consumption of "spirits."
It should be noted that there are other cardioprotective agents, such as aspirin, that may negate relative protective effect of alcohol. The interaction of other medications and/or natural agents with alcohol in cardioprotection is not well known.
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