Light to moderate alcohol consumption is associated with a reduced risk of coronary heart disease. This protective effect of alcohol, however, may be confined to middle-aged or older individuals. Coronary heart disease incidence is low in men < 40 years of age and in women < 50 years of age; for this reason, study cohorts rarely have the power to investigate the effects of alcohol on coronary heart disease risk in younger adults. This study examined whether the beneficial effect of alcohol on coronary heart disease depends on age.
In this pooled analysis of 8 prospective studies from North America and Europe including 192,067 women and 74,919 men free of cardiovascular diseases, diabetes, and cancers at baseline, average daily alcohol intake was assessed at baseline with a food frequency or diet history questionnaire. An inverse association between alcohol and risk of coronary heart disease was observed in all age groups; hazard ratios among moderately drinking men (5.0 to 29.9 g/d) 39 to 50, 50 to 59, and ≥ 60 years of age were 0.58 (95% confidence interval [CI], 0.36 to 0.93), 0.72 (95% CI, 0.60 to 0.86), and 0.85 (95% CI, 0.75 to 0.97) compared with abstainers. However, the analyses indicated a smaller incidence rate difference between abstainers and moderate consumers in younger adults (incidence rate difference, 45 per 100 000; 90% CI, 8 to 84) than in middle-aged (incidence rate difference, 64 per 100 000; 90% CI, 24 to 102) and older (incidence rate difference, 89 per 100 000; 90% CI, 44 to 140) adults. Similar results were observed in women.
The authors conlude that alcohol is also associated with a decreased risk of coronary heart disease in younger adults; however, the absolute risk was small compared with middle-aged and older adults.
Professor R Curtis Ellison comments: This analysis was based on a large number of subjects, making it possible to evaluate effects of alcohol consumption on heart disease risk among groups at low risk (i.e., younger people). The weaknesses of the study are pointed out by the authors: no information on the pattern of drinking, including some ex-drinkers in the non-drinking referent group, not knowing of potential changes in drinking amounts and patterns over time). Still, the results are clear in indicating that men and women at all ages who consume alcohol moderately are at lower risk of developing clinical coronary disease than those who abstain from alcohol. As shown in Figure 1 from the paper, overall the hazard ratio is lower for both women and men over a very wide range of intake. (This may mean that in some previous studies that suggested that coronary disease increases markedly with larger amounts of alcohol, a “J-shaped curve,” the increase at higher levels may relate to cardiac arrhythmias, cardiomyopathy, or non-cardiac conditions, and not to coronary disease.)
The hazard ratio for heart disease associated with moderate drinking in this analysis was 0.58 for younger subjects, but the estimated reduction in risk was less for those in the oldest group (HR = 0.85). This relation has been seen in some other studies, and has led to suggestions that the effects of alcohol are less in older people than in middle-aged people. Ken Rothman comments that “if absolute effects measuring risk reduction from alcohol were constant with age, one would expect the relative risk to approach one as age increased, and the baseline risk of heart disease increased, because the absolute difference in risk would be a smaller proportion of total risk as the total risk increased.” Other risk factors that affect the “ageing of arteries” (hypertension, smoking, poor diet, etc.) would be coming into effect over time, so the relative importance of a single risk factor (such as alcohol consumption) would be less.
Rothman adds: “If the benefits of alcohol consumption were proportional to the underlying risk, one would not see the attenuation of relative effect in older age groups. Because that attenuation was present in this study, it signals that the absolute risk reduction in heart disease from alcohol consumption does not increase to the extent that the underlying risk for heart disease increases with age. Thus, the relative benefit is greatest among younger ages.”
The importance of this study is the finding that moderate alcohol consumption is associated with lower risk of coronary heart disease regardless of age. Some may believe that this indicates that individuals should begin to consider moderate drinking as a way of reducing their risk of heart disease at a younger age (e.g., before age 50). However, it must be kept in mind that the absolute risk of heart disease at this age is very low, so effects on other aspects of health (and social effects) must also be considered. (The effects of alcohol on other diseases, or on cardiovascular or all-cause mortality, were not measured in this study.)
Source: Hvidtfeldt UA, Tolstrup JS, Jakobsen MU . . . Willett WC, Rimm EB, Ascherio A. Alcohol intake and risk of coronary heart disease in younger, middle-aged, and older adults. Circulation 2010;121:1589-1597.