Hundreds of observational, epidemiological studies have found that moderate alcohol intake is associated with a lower risk of a range of health outcomes compared to alcohol abstention, but that risk increases with heavy drinking (a distribution commonly known as a ‘U-shaped’ or ‘J-shaped’ curve) . Many researchers, clinicians and the lay public now accept as common knowledge that moderate drinking is beneficial to one's health , and the association is hypothesized to be due to biological effects on several systems, including reduced blood pressure, increased blood lipoproteins and oxidation of low-density lipoprotein (LDL) cholesterol, among other pathways [3, 4].
The first issue raised by Dawson et al. , and documented in other studies as well, is the ‘sick quitter’ effect. Dawson et al. document that individuals with incident cardiovascular disease and those rating health as good/fair/poor (versus very good or excellent) at age 55+ were more likely to stop drinking, as well as individuals with liver disease at ages 18–34. Thus, when alcohol intake is measured at a single time-point, non-drinkers will constitute both former drinkers who quit due to poor health and life-time abstainers. Separating former drinkers from life-time abstainers in studies of the effects of alcohol consumption on mortality is thus essential. Indeed, a recent analysis that did this showed that the J-shaped curve disappeared after taking into account former drinkers who quit due to poor health and that the association between alcohol consumption and mortality changed to a simple monotonic function: greater levels of alcohol consumption are associated with higher mortality . > > > > Read More