Alcohol studies, rather like alcohol itself, can make you feel pretty woozy. One day a study appears telling you that moderate drinking is actually good for you, and the next there’s a study that says even one drink could be ruining your health.
This week, the pendulum has swung back in the “unhealthy” direction, with a new study in the journal Hypertension on the effects of alcohol on blood pressure. It’s an impressive size, with more than 19,500 participants recording their alcohol consumption and being followed up for an average of more than five years to check how their blood pressure changed.
The average person’s blood pressure increases with age. But the study found that those who drank more alcohol – any amount above full teetotalism – had more of an increase in blood pressure over time.
That overall result does obscure something interesting: when the authors split the results by sex, they found that the result was mainly in men, where there’s a clear, linear relation between more alcohol and faster increases in blood pressure.
But if you’d only looked at women, you probably wouldn’t have concluded there was much going on at all. This might have been because far fewer women than men drank high amounts of alcohol, so the relation between blood pressure and alcohol consumption becomes much fuzzier as you get to the higher end of the scale.
Looking in subgroups, though, is often misleading. The authors write that future studies should look in more detail at the effect specifically in women, to try and work out what’s happening.
Compare this study to another, published just a month ago. It had an even bigger sample – more than 142,000 people – but found something rather different. They didn’t look at blood pressure specifically, but at death. And here, they found that moderate drinkers of either sex (who drank less than 10g per day) were healthier than teetotallers. They had about 13 per cent lower risk of dying in the 12 or so years after the study started. They were also healthier than heavier drinkers: those who drank more than 20g of alcohol per day were up to 17 per cent more likely to die before the end of the study.
These studies can only take us so far. They’re observational, meaning we might get misleading results if drinkers differ from non-drinkers in ways other than their alcohol consumption.
There’s a big, under-discussed tragedy here. In the early 2010s, the US National Institutes of Health (NIH) set up a large-scale randomised trial into moderate alcohol drinking. The plan was to include 7,800 participants, randomised to drink one drink per day or no alcohol at all. It seemed as if we’d finally get a strong answer to the question of whether moderate drinking was beneficial.
But the trial’s sheer size meant that it became reliant on external funding – and some of that funding came from the alcohol industry.
A New York Times investigation in 2018 found that the trial’s organisers had “actively and secretly courted” funders including Anheuser-Busch, the makers of Budweiser beer, and potentially allowed the industry to influence the choice of the study’s leading scientist.
The study’s credibility was, at least in the eyes of the NIH, shot to pieces. They scrapped it entirely just a few months later.
Scientists were perhaps chastened by this experience. There don’t seem to be plans to organise another randomised experiment on alcohol consumption anytime soon.
All the studies in the world, of course, shouldn’t dictate our behaviour: we all have to weigh up health risks on the one hand with living our lives on the other. If you enjoy moderate drinking, as many do, then that should be part of the calculation.
And given the sheer level of uncertainty about the effects of moderate drinking, it’s perfectly reasonable to weight your enjoyment pretty strongly in the equation.
