Wednesday, April 25, 2018

Alcohol consumption, mortality, and cardiovascular disease

The graphs below summarize key results from a study published in April of 2018 by the highly influential journal The Lancet (). The study reported having included at least 599,912 drinkers in the analysis and having recorded 40,310 deaths and 39,018 cardiovascular disease events. The authors of the study concluded that “For all-cause mortality, we recorded a positive and curvilinear association with the level of alcohol consumption, with the minimum mortality risk around or below 100 g per week.

The study was presented as being somewhat pessimistic: one cannot drink as much as previous data suggested. Let’s see. Two drinks of a spirit (e.g., whiskey) served “neat” (i.e., with nothing added to it) will typically add up to about 84 g; or 3 oz. If the alcohol content is 40 percent, such a double drink will contain about 33 g of alcohol. So, according to this study, you can still enjoy three double drinks of spirit per week, or six single drinks – which is almost one per day. That is not so little.

This study is consistent with most studies of the effect of alcohol consumption on health, which generally show results in terms of averages within fixed ranges of consumption. For example, they will show average mortality risks for people consuming 1, 2, 3 etc. drinks per day. These studies suggest that there is a J-curve relationship between alcohol consumption and health. That is, drinking a little is better than not drinking; and drinking a lot is worse than drinking a little.

Contrary to popular belief, the positive health effects of moderate alcohol consumption have little, if anything, to do with polyphenols such as resveratrol. Resveratrol, once believed to be the fountain of youth, is found in the skin of red grapes.

It is in fact the alcohol content that has positive effects, apparently reducing the incidence of coronary heart disease, diabetes, hypertension, congestive heart failure, stroke, dementia, Raynaud’s phenomenon, and all-cause mortality. Raynaud's phenomenon is associated with poor circulation in the extremities (e.g., toes, fingers), which in some cases can progress to gangrene.

In most studies of the effects of alcohol consumption on health, the J-curves emerge from visual inspection of the plots of averages across ranges of consumption. Rarely you find studies where nonlinear relationships are “discovered” by software tools such as WarpPLS (), with effects being adjusted accordingly.

Still, this study is indeed consistent with some past studies suggesting that the amount of alcohol intake that is optimal maybe less than most of us think ().