How healthy is moderate alcohol consumption really?

Is moderate alcohol consumption truly good for the heart? Researchers at Ruhr University Bochum show that reported health benefits often rest on methodological flaws and statistical bias.

For a long time, moderate alcohol consumption was thought to offer potential protection against cardiovascular disease. But how robust is the evidence supporting this assumption?
A recent study by Susanne Stolpe, Dr Kathrin Schlößler and Professor Horst Christian Vollmar from the Department of General Practice at Ruhr University Bochum, together with Professor Bernd Kowall from the Institute of Medical Informatics, Biometry and Epidemiology at University Hospital Essen, critically examines the existing evidence.

The researchers reviewed publications investigating whether moderate alcohol consumption is genuinely associated with a lower risk of cardiovascular disease. They identified a striking pattern: studies suggesting positive health effects of moderate alcohol consumption consistently exhibited methodological weaknesses. These included potential biases that can play an important role when investigating the relationship between alcohol consumption and health. By contrast, studies that better accounted for these potential biases tended not to find any beneficial effects of moderate alcohol consumption.

Particularly noteworthy were findings suggesting unusually large or even implausible effects – for example, a lower incidence of liver disease among moderate drinkers compared with non-drinkers. Such findings do not appear to have been subjected to sufficient critical scrutiny in every case. One possible explanation is that even unusually large effects can initially appear convincing when they are statistically significant.

The study therefore highlights the importance of critically evaluating epidemiological research and demonstrates why statistical significance alone does not establish a causal relationship. As reactions to the published article have also shown, the debate surrounding the health effects of moderate alcohol consumption is far from settled. For controversial research questions in particular, it is important to disclose potential conflicts of interest transparently and to analyse data according to clear, methodologically robust and as independent as possible criteria. Ultimately, the aim is not to confirm or refute a particular finding, but to determine how reliable the scientific evidence actually is.

Read the publication: The illusion of healthy drinking: Methodological bias and selective reporting of effects shape evidence on alcohol and cardiovascular health

Susanne Stolpe