Alcohol, coronary heart disease and stroke: an examination of the J-shaped curve.

The consistent findings of higher risk of coronary heart disease (CHD) and total mortality in non-drinkers compared to light to moderate drinking has been interpretated as showing that light or moderate drinking is beneficial to health. Non-drinkers, both ex-drinkers and lifelong teetotallers, have an increased prevalence of conditions likely to increase morbidity and mortality compared with occasional or light drinkers. In addition, regular light drinkers tend to have characteristics extremely advantageous to health. Whilst there is considerable evidence that alcohol intake at some level has a beneficial effect on CHD, the degree of protection claimed is almost certainly exaggerated by comparison with an inappropriate control group and by the limited adjustment procedures used to take into account the differing characteristics of the various alcohol intake groups. The benefit of light to moderate drinking for stroke and all-cause mortality is less convincing than the benefit for CHD. If occasional drinkers are used as a baseline, no benefit is seen for stroke or all-cause mortality in regular or light drinkers and all-cause mortality increases progressively from levels of 2 drinks a day. Non-drinkers or lifelong abstainers are unsuitable as a baseline group in studies of the effects of alcohol on morbidity and mortality. The public health message should emphasise the potential harm of heavier drinking rather than concentrating on the possible benefits of light drinking.