New Study Challenges Claims That Moderate Alcohol Extends Life

Research suggesting that moderate alcohol consumption may benefit health – or even lengthen life – could rest on flawed methodologies, according to scientists seeking to correct what they regard as a widespread misconception.

This paper is the latest chapter in an increasingly prolonged dispute between a University of Victoria-led research group and the International Scientific Forum on Alcohol Research (ISFAR).

Psychologist Tim Stockwell and epidemiologist Jinhui Zhao, both based at Canada’s University of Victoria, led the latest investigation into whether this assertion – and the evidence cited in its support – can withstand close examination.

Alcohol and all-cause mortality evidence

Their meta-analysis reviewed 107 scientific studies examining the link between alcohol use and the risk of death from any cause. Collectively, these studies covered 4,838,825 participants and documented 425,564 deaths.

To identify where bias might have distorted the interpretation of results, the researchers compared studies according to their quality.

They classed studies as 'high quality' when the cohort’s average age was 55 years or below, follow-up continued beyond age 55, and former or occasional drinkers were not included in the reference group.

This approach removed studies vulnerable to 'abstainer bias', which occurs when people are placed in the control group because they currently do not drink alcohol, without considering their drinking history over their lifetime.

The concern is that people whose prolonged drinking caused them to stop for health reasons may be counted in the control group, despite not being representative examples of lifelong abstinence.

Comparing the lifespan of somebody who drinks one glass of wine a day with that of a former heavy alcoholic who is now sober is not equivalent to comparing that moderate drinker with someone who has never consumed alcohol.

Research involving older participants is more likely to face this problem, as current abstainers have had more time in which they may previously have drunk alcohol and developed related health conditions. Those conditions can skew the average all-cause mortality rate in the abstainer group.

"That makes people who continue to drink look much healthier by comparison," says Stockwell.

The meta-analysis found that the average relative risk of death from any cause was substantially higher among low-volume – that is, 'moderation' – drinkers in the studies that Stockwell and his colleagues classified as 'high-quality' using several criteria.

"There is simply no completely 'safe' level of drinking," Stockwell says.

Study quality, smoking and socioeconomic status

High-quality research included studies without abstainer bias in their reference group, as well as those using younger cohorts; excluding participants who were ill; measuring fewer than 30 days of alcohol use; not adjusting for smoking status; and not adjusting for socioeconomic status.

The researchers found that the lower-quality studies – those involving older people and failing to separate former drinkers from lifelong abstainers – were the studies that associated alcohol consumption with greater longevity.

Alcohol and mortality studies frequently adjust for smoking because smoking is associated with both drinking and increased mortality. Yet smoking may also affect the way alcohol influences health. Alcohol, for instance, can prompt smoking and intensify cravings among heavy drinkers, while lower alcohol consumption has been associated with stopping smoking.

Several studies reported no reduced mortality risk among low-volume drinkers after accounting for smoking. Stockwell and Zhao say future research should establish whether adjusting for smoking incorrectly creates the impression that moderate drinking is beneficial.

The authors also say the connection between socioeconomic status (SES) and alcohol-related mortality requires more investigation. A 2023 study found that high alcohol consumption raised mortality risk among people with low SES, did so to a lesser extent among those with medium SES, and had no effect among those with high SES.

"If you look at the weakest studies," Stockwell says, "that's where you see health benefits."

The University of Victoria team’s dispute with ISFAR

Stockwell and Zhao have raised this issue repeatedly before, and their work has attracted criticism. Although objections from parties with obvious financial interests may be easy to discount, criticism from other scientists is harder to set aside.

"The present study is a response to the criticism that we should have excluded studies from our meta-analysis that did not meet pre-registered quality criteria," the authors write, referring to criticism published earlier this year by ISFAR scientists.

ISFAR is directed by former clinical pharmacologist Creina Stockley and nutrition researcher Henk Hendriks. Between them, they have received grants, funding and paid consultancy work from several alcohol industry bodies, although the source of ISFAR’s funding is unclear.

Stockwell’s group also declared earlier research funding from "government alcohol monopolies", along with travel support from IOGT-NTO, a not-for-profit non-governmental organisation that campaigns against alcohol use.

The study appeared in the Journal of Studies on Alcohol and Drugs.