Does Moderate Drinking Have Health Benefits?

Study design and characteristics have a significant effect on estimates of mortality risk from alcohol, according to a new study.

“This literature suffers from several serious methodological problems,” said lead study author Tim Stockwell, PhD, of the Centre for Addictions Research of BC at the University of Victoria. “When we adjust for these and/or remove the most flawed studies, the appearance of health benefits from moderate drinking largely disappears.”
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The researchers conducted a systematic review and meta-regression analysis of studies investigating alcohol use and mortality risk after controlling for quality-related study characteristics in 3,998,626 individuals, among whom 367,103 had died.

Without adjustment, meta-analysis of all 87 included studies replicated the classic J-shaped curve, with low-volume drinkers (1.3-24.9 g ethanol per day) having reduced mortality risk (RR=0.86, 95% CI [0.83, 0.90]). Occasional drinkers (<1.3 g per day) had similar mortality risk (RR=0.84, 95% CI [0.79, 0.89]), and former drinkers had elevated risk (RR=1.22, 95% CI [1.14, 1.31]).

After adjustment for abstainer biases and quality-related study characteristics, the researchers observed no significant reduction in mortality risk for low-volume drinkers (RR=0.97, 95% CI [0.88, 1.07]). Analyses of higher-quality bias-free studies also failed to find reduced mortality risk for low-volume alcohol drinkers. Risk estimates for occasional drinkers were similar to those for low- and medium-volume drinkers.

“A big surprise for me was the finding that in the few studies which separated results for ‘occasional drinkers’ (defined in our study as less than one drink per week but more than one drink per year), this group had the same appearance of health benefits as did the ‘moderate drinkers’ when no correction was done for study quality,” Stockwell said. “In fact, the occasional drinkers were consistently similar in mortality risk to low-volume or moderate drinkers, which we interpret as suggesting it is unlikely that if health benefits are real they are actually due to the alcohol. It would be hard to have significant physiologically induced benefits from such a low level of drinking.”

His main take-home message? Be highly skeptical of the idea that drinking to improve health is an effective strategy.

“If there are cardiovascular benefits from drinking, they appear to be at least offset by an increased risk of other diseases (eg, cancers),” Stockwell said. “To minimize health risks, people should be careful to drink well within national low-risk drinking guidelines.”

-Mike Bederka

Reference:

Stockwell T, Zhao J, Panwar S, et al. Do “moderate” drinkers have reduced mortality risk? A systematic review and meta-analysis of alcohol consumption and all-cause mortality. J Stud Alcohol Drugs. 2016 Mar;77(2):185-98.