Drinking red wine, rather than mineral water, with dinner every night for 2 years was associated with improvements in cholesterol markers, according to a randomized controlled trial (RCT) of patients in Israel with well-controlled type 2 diabetes. A group assigned to white wine did not show significant differences on these markers from the water group. However, patients who were found to be slow ethanol metabolizers on genetic testing had improvements in fasting plasma glucose, insulin resistance, and HbA1c compared to fast metabolizers.
The study was published in the Oct. 20, 2015, Annals of Internal Medicine and summarized in the November 2015 ACP Diabetes Monthly. The following commentary by Meera Jain, MD, ACP Member, and Richard Wernick, MD, ACP Member, was published in the ACP Journal Club section of the Feb. 16 Annals of Internal Medicine.
Does moderate alcohol consumption reduce cardiovascular (CV) events? Evidence for such an association exists but only in cohort studies. A recent meta-analysis of cohort studies found a 25% relative risk reduction in CV mortality in drinkers, with the lowest risk for persons who consumed 1 to 2 drinks per day. However, we are reminded of the convincing epidemiologic link between hormone replacement therapy and reduced risk for CV events—a finding that was ultimately reversed in a subsequent large RCT.
The RCT by Gepner and colleagues supports the biological plausibility of causality between alcohol consumption and CV risk. It adds to an existing evidence base, comprising mostly crossover and before-after studies, which supports the notion that biomarkers of CV risk are improved with alcohol consumption. However, the findings are based on surrogate outcomes only, so the effects on clinical outcomes are unclear.
Without a large RCT assessing clinically relevant outcomes—and it is unlikely that such a trial will be done—we cannot be certain about the benefits of alcohol. Further, benefits must be weighed against such potential risks as problem drinking and its sequelae: breast cancer, violence, and motor vehicle accidents. Our best judgment under uncertainty is to continue to recommend optimization of treatable CV risk factors for all and not to recommend alcohol—red wine or otherwise—to our patients who abstain.