Most Japanese men drink alcohol on a regular basis. Epidemiological data suggesting a protective effect of light to moderate drinking on CHD comes predominantly from studies of white people. Evidence for such an effect in native Japanese is sparse because of the relatively low incidence of CHD in Japan. An earlier prospective study showed a trend towards an inverse association between alcohol use and CHD which failed to reach significance because of the small number of cases. To examine the relationship between drinking and CHD further, this group used the data from an 8.8 year follow-up study of middle-aged urban male workers, a population with a higher incidence of CHD than rural populations.

Study took men most at risk

Subjects were 8,476 male workers aged 40 to 59, participating in CHD risk surveys between 1975 and 1984. Alcohol use and other CHD risk factors were assessed at baseline examinations. Overall, 70% of the subjects had retained their drinking status three to five years later. Potential confounders assessed were total cholesterol, blood pressure, history of diabetes and evidence of left ventricular hypertrophy. During follow-up, CHD end-points were ascertained from death certificates, absenteeism reports, insurance claims and annual risk factor surveys. To confirm the diagnosis, all living patients were visited or invited to risk factor surveys.

Moderate drinkers ran less risk of CHD

During the employment period under survey, 83 CHD events occurred (54 cases of myocardial infarction, 32 of angina pectoris). Relative to never-drinkers, the age-adjusted risk for CHD decreased with increasing drinking level until a level of 69 grams per day. Multivariate analysis adjusting for age, serum total cholesterol, smoking, weight, left ventricular hypertrophy and history of diabetes, revealed a RR relative to never-drinkers of 0.83 for ex-drinkers, 0.69 for those drinking 1 to 22 grams per day, 0.55 for 23 to 45 grams per day, 0.41 for 46 to 68 grams per day, and 0.59 for over 69 grams per day. The inverse association between alcohol use and CHD risk was similar for myocardial infarction and angina pectoris.

The benefit lies in the alcohol

Alcohol use seems to prevent the premature incidence of CHD among urban Japanese middle-aged men. Because, in this population, only 0.5% of the alcohol consumed was derived from grape wine, versus 42% from beer, 25% from rice wine (sake) and 32% from spirits, a large portion of the benefit is from alcohol, rather than from other components of grape wine.

Reference Kitamura A, Iso H, Sankai T et al. Alcohol intake and premature coronary heart disease in urban Japanese men; Am J Epidemiol 147 (1998) 59-65.