Many people had strong reactions to the Canadian Centre for Substance Use and Addiction’s new guidelines for drinking alcohol. For some, alcohol is inextricably linked to their social habits, while others invoked the health benefits of “moderate” alcohol consumption, especially the cardioprotective benefits of red wine.
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Unfortunately, moderate alcohol consumption is a lot less than most people think it is and the supposed cardioprotective benefits of alcohol are most likely a statistical aberration.
Much as some people don’t want to hear this, alcohol is not that good for you.
Belief in the cardioprotective benefits of alcohol harkens back to a 60 Minutes story from 1991 that proposed red wine as the explanation for the French Paradox. At the time, there was some discussion about why heart disease rates were lower in France than the United States or Britain, and one researcher suggested red wine consumption could explain the difference. But problems with this theory have become evident. Early ideas that the resveratrol in red wine was responsible for reducing heart attack risk didn’t hold up over time. Studies like InCHIANTI didn’t find that resveratrol was useful. There is also very little resveratrol in red wine, so you couldn’t plausibly drink enough of it for it to have any effect.
Advocates for alcohol point to the admittedly many observational studies showing a U-shaped association between alcohol and cardiac risk. In a U-shaped association, risk is highest among people who drink zero alcohol and people who drink a lot, whereas it’s lowest in people who drink only a little.
There are two issues here. First, people drink more alcohol than they realize. When called upon to pour out a “standard” drink, people invariably get it wrong. A wine glass is not meant to be filled to the brim. A standard 750 ml bottle of wine has five servings of alcohol in it. If split between two people at one sitting, you have already surpassed the threshold for “moderate” drinking.
But even setting that aside, research over the past few years has not borne out the idea that alcohol is good for you. A large meta-analysis in the Lancet found that the United Kingdom’s alcohol recommendations were too high. Half the recommended amount was shown to increase the risk of cardiovascular disease.
What’s more, the U-shaped association that you see in observational analysis doesn’t hold up in more sophisticated research designs. A 2019 Mendelian randomization study combined traditional and genetic analyses to more accurately gauge alcohol’s health benefits and risks. In the traditional analyses, people who drank one or two drinks per day had lower risks than those who drank zero. But traditional analyses have a problem. Sometimes people drink zero alcohol for health reasons. Anyone with high blood pressure, heart arrhythmias, diabetes and a slew of other problems would likely benefit from cutting back and drinking less. This phenomenon, known as reverse causation, means that people who abstain from alcohol aren’t at higher risk for heart attacks and strokes. Rather high risk people end up abstaining from alcohol. When the researchers looked at their genetic analysis, which is free from this type of bias, the U-shaped association disappeared.
As disappointing as it might be to hear, alcohol is not good for your heart and the supposed protective benefit is a statistical artifact. Alcohol also increases your risk of cancer and is likely to make you gain weight. It is really not that good for you.
That being said, you can certainly enjoy alcohol if you choose to do so, in the same way that you can choose to have dessert or eat potato chips. But you aren’t doing yourself any favours by purposefully drinking two glasses of red wine per day. The thing to remember is that alcohol is an indulgence, not health food.
Christopher Labos is a Montreal physician and cohost of the Body of Evidence podcast.
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