Why Findings on Alcohol and Health Are So Confusing

Source: Azerbaijan Stockers/Freepik

If you've been perplexed by current findings on alcohol and health, there's a good reason. Results from recent scientific studies run the gamut from finding that modest alcohol consumption is better for your health than not drinking at all, to the World Health Organization stating that no level of alcohol is safe. How can there be such wide discrepancies in these findings? To understand why, I recently attended the National Academy of Sciences, Engineering, and Medicine public meeting, Review of Evidence on Alcohol and Health. Presenters illustrated several issues with how these studies are conducted that have led to the current confusion.

First, let’s cover the classic pattern of alcohol and health, which is something scientists call a J-shaped curve, in which low alcohol consumption (no more than zero to two drinks a day) has a lower risk of health problems than abstaining from alcohol. Health risks increase noticeably from low consumption to moderate and from moderate to high. While those of us who enjoy modest consumption of alcohol are happy to hear about such findings, the results are counterintuitive. Why would abstainers have worse outcomes than those with modest alcohol consumption?

As explained by Tim Stockwell, former director of the Canadian Institute for Substance Use Research at the University of Victoria, lifetime abstainers start out less healthy than their drinking peers, beginning at the legal drinking age. In early adulthood, lifetime abstainers tend to have more disabilities, worse health, and less income than young adults who consume alcohol. This difference in overall health status then increases with age. He noted, “The widening disparity in the health status of these groups leads to larger apparent health benefits from drinking alcohol for older adults.”

The classification of abstainer vs. drinker matters

Additionally, when people become unwell, they reduce or abstain from drinking. If they participate in an alcohol study, these people often are classified based on their current status as abstainers rather than as former drinkers. Indeed, Stockwell described how former drinkers at all levels have higher health risks than their current-drinker counterparts.

These selection biases can lead to the appearance of a health benefit from modest alcohol intake that does not exist. Stockwell and his colleagues demonstrated that longitudinal studies that exclude former and occasional drinkers from the abstainer category find that low-volume drinkers have an equivalent mortality risk as abstainers, whereas studies that do not take these biases into account find the "typical" reduced mortality risk for low volume drinkers compared to abstainers. Thus, the J-shaped curve goes away in studies that control for important selection biases.

Drinking regularly is not great for your health

While there has been controversy regarding the results pertaining to low-volume drinkers, the results for heavier volumes of drinking are consistent: The more you drink, the greater the health risk. How great is the risk? Compared to lifetime abstainers, medium-volume drinkers (averaging two to three drinks per day) have a 5% greater risk; people who average three-to-four-and-a-half drinks per day have a 19% greater risk of all-cause mortality compared to lifetime abstainers; those who average 5 or more drinks per day have a 35% greater risk for all-cause mortality.

Unfortunately for women, their increased health risks begin at a lower volume of drinking than for men. Women face a significantly greater risk for all-cause mortality starting at an average of two-to-three drinks per day, whereas for men, a similar level of risk appears when averaging three-to-four-and-a-half drinks per day. When I asked Stockwell if this disparity is simply due to typical sex differences in body size, he said that it’s difficult to tell. For one thing, men and women tend to have different drinking patterns. Importantly, he noted that there fewer good alcohol and health studies have focused on women.

What does this mean for you?

What do these findings mean for everyday people? According to Stockwell, “It’s important to be skeptical of claims that modest alcohol consumption is good for health. Regardless of the type of alcoholic beverage, they all contain ethanol, which has toxic, addictive, and carcinogenic effects.” In other words, if you currently imbibe two or more drinks a day, you may want to consider making alcohol more of an occasional treat rather than a part of your daily routine.