The J-shaped curve and changes in drinking habit.

The accepted interpretation of the J-shaped curve relating alcohol intake to mortality or coronary heart disease is that the lowest point on the curve (light/moderate drinking) represents optimum exposure to alcohol and that the increased risk in non-drinkers reflects the consequence of sub-optimum exposure. However, non-drinkers, both ex-drinkers and lifelong teetotallers, consistently show 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. Changes take place in alcohol intake in individuals over time, with a strong downward drift from heavy or moderate drinking towards non-drinking, affected to a considerable extent by the accumulation of ill health. Reduction in alcohol intake or giving up drinking is associated with higher rates of new diagnoses than remaining stable in alcohol intake and also with higher rates of both cardiovascular and non-cardiovascular mortality. The use of non-drinkers as a baseline, and failure or inability to adequately take into account the characteristics of subjects in the different alcohol intake categories, exaggerates the risk of coronary heart disease events and all cause mortality in non-drinkers and the benefits of light/moderate alcohol intake.