If you’re still telling patients that a glass a day is good for the ticker, we have bad news.
The Back Page loves optimists. Optimists like the people who keep running studies to see if alcohol is good for you.
Observational studies have repeatedly recorded lower CVD risk among light-to-moderate drinkers than abstainers and heavy drinkers – a J-shaped curve – though they usually come with big caveats: light-to-moderate drinkers are probably better off in general lifestyle-wise and those abstaining might be doing so for reasons.
But any lingering hopes that some alcohol is cardioprotective may be dispelled by this large study of more than 370,000 individuals using UK Biobank data, published in JAMA Network Open, which found all amounts of alcohol consumption were associated with increased cardiovascular risk.
The researchers got around the confounding issues of purely epidemiological studies by using mendelian randomisation, looking at the genes most associated with a drinking disposition; these are distributed randomly and free from lifestyle associations, allowing causal inferences to be drawn.
They rated drinking types as abstainers, light (up to 8.4 drinks/week), moderate (between 8.4 and 15.4), heavy (between 15.4 and 24.5) and abusive (more than 24.5), and measured other lifestyle variables such as smoking, red meat eating etc.
When they compared drinking with indicators of CVD risk, such as hypertension, coronary artery disease and cholesterol levels, they found the usual J-shaped curve; but they also found lifestyle behaviour was much healthier among light/moderate drinkers than abstainers, accounting for the apparently beneficial effect: “Adjusting for only a few lifestyle factors … we observed attenuation in the apparent protective associations between modest alcohol intake and cardiovascular risk, suggesting that adjustments for yet unmeasured or unknown factors may further attenuate—if not, eliminate—the residual, cardioprotective associations observed among light drinkers.”
The researchers also set out to map the relationship between alcohol consumption and CVD risk, suspecting it to be non-linear. With some fancy statistical footwork, they found minimal increase in risk at the lighter end of the spectrum, but exponential increases in risk with each additional drink in heavier drinkers.
“[O]ur results suggest that consuming as many as 7 drinks per week is associated with relatively modest increases in cardiovascular risk,” they conclude. “However, nonlinear modeling uncovered unequal increases in cardiovascular risk when progressing from 0 to 7 vs 7 to 14 drinks per week in both men and women.” And this overlaps with the “safe” limit of eight drinks per week for women as recommended by the Dietary Guidelines for Americans.
All of which makes your Back Page correspondent want to
If you see something that makes you want to drown your sorrows, email felicity@medicalrepublic.com.au
