Methodological bias and selective reporting of effects shape evidence on alcohol and cardiovascular health

In 2023, following a review concluding that methodological shortcomings are mainly responsible for reported beneficial health effects of alcohol, public health institutions recommended abstaining from drinking. Yet reports of health benefits from moderate drinking persist. A team of researchers aimed to explore whether known sources of bias and distortion were accounted for in the underlying analyses.
In a systematic literature review, papers on associations between alcohol consumption and all-cause mortality and cardiovascular outcomes published between January 2023 and July 2025 were identified. Study population and analysis characteristics were described, and the acknowledgement and addressing of relevant methodological issues were examined.
Five of eight studies reported protective effects of low or moderate alcohol intake, while three reported less positive effects. Studies showing protective effects used non-drinkers or lifetime abstainers as reference categories, which are known to be prone to misclassification and bias. Only one study discussed methodological issues, and none applied any method to assess or mitigate potential distortion. Reported hazard reductions of 40% for cardiovascular outcomes after minimal exposure (<1 glass/week) compared with non-drinkers seem implausible. In analyses showing less benefit, non-drinking participants were excluded or Mendelian Randomisation methods were used to account for residual confounding. Some analyses allowed reporting of beneficial or harmful effects.
Beneficial health effects of low alcohol consumption were largely due to methodological negligence, as misclassification, bias or residual confounding remained unaddressed. When authors selectively decide what to report as the main result, their responsibility towards public health is high to prevent the spread of misleading messages.
Source: Stolpe, S., Schlößler, K., Vollmar, H.C., & Kowall, B. (2026) The illusion of healthy drinking: Methodological bias and selective reporting of effects shape evidence on alcohol and cardiovascular health. Public Health, Volume 256, 106331.