Moderate alcohol consumption and cardiovascular disease: is there evidence for a preventive effect?

It is well-known that the intake of large quantities of alcohol is hazardous to the health. During the last few decades, moderate alcohol consumption has been claimed to have a protective effect in the cardiovascular system. For this study, literature search and review on moderate alcohol consumption and cardiovascular disease was performed. Data from ecological studies indicate that the consumption of wine, but not hard liquor or beer, are associated with a reduced mortality from cardiovascular diseases. Data from case-referent studies indicate no beneficial effect at all, whereas data from prospective cohort studies indicate a beneficial effect from all types of alcohol. There are several interpretational problems involved in this issue. No results from interventional studies are available. In the absence of such data, less valid conclusions are drawn from other types of studies. The soundness of conclusions based on comparisons of moderate drinkers and abstainers in case-referent and cohort studies has been questioned, because abstainers may have a higher than normal incidence of cardiovascular disease due to self-selection. Several possible modes of action have been proposed. However, provided that there is a protective effect of moderate alcohol consumption, there is no hard evidence that any of the proposed modes of action would be the sole one. Probably more than one mechanism is involved.