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By Mary Carpenter
NEW LIGHT on the question of whether drinking alcohol might benefit health came in the past six months from two large-data studies. But because the data come from two different Biobanks—in the UK and at Mass General —and the studies focus on different health risks (either cardiovascular disease or a range of diseases), people are still arguing.
Questions persist mainly because earlier research—“gold-standard” double-blind studies—that demonstrated health benefits of drinking alcohol made the mistake of using people who abstained entirely as a control group. As it turns out, according to CNN, “nondrinkers often don’t drink because they can’t, perhaps due to health conditions or medication use…could make drinking look less harmful or even beneficial.”
The CDC, echoing findings from the UK Biobank study, states that ”compared to not drinking, drinking alcohol in moderation may increase your overall risks of death and chronic disease…Even low levels of alcohol use (less than one drink per day) can raise the risk of certain cancers.” The CDC site also notes, in addition to non-drinking control groups, “some past studies failed to consider genetic factors or behaviors like exercise, diet or tobacco use.
Rather than using non-drinkers as controls, Spanish researchers used the UK Biobank data to compare health effects at different levels of daily drinking for adults—average age of 64 at the start of the study and no one under age 60—between 2006 and 2010. According to their report in JAMA, they found “health risks, including cancer and heart disease, at every level of regular daily drinking.”
The control group, labeled “occasional drinkers,” drank less than about 20 grams of alcohol—less than two drinks—per week. The National Institute on Alcohol Abuse and Alcoholism site (NIAAA) states that “one standard drink (or one alcoholic drink equivalent), defined in the United States as any beverage containing 0.6 fl oz or 14 grams of pure alcohol,” refers to 12 ounces of regular beer; 5 ounces of wine; or 1.5 fluid ounces of “distilled spirits,” which include rum, vodka, gin, etc.
Even in the “low risk” group, women whose daily alcohol consumption was less than one standard drink, at 10 grams of alcohol, were about 10% more likely to die of cancer than the occasional drinkers. And in the high-risk group, women drinking more than 20 grams or a little under two standard drinks per day were about 33% more likely to die of cancer, heart disease and any other cause than the control group. With per-day amounts twice as high for men, the health risks were similar.
Forty-nine underlying health conditions —along with places of residence as an indicator of income level—were among variables taken into account by the Spanish researchers, according to CNN. Increased risks associated with drinking were more pronounced in people who scored as having lower incomes and more health conditions, while people who mostly drank wine or beer or who drank alcohol only in certain situations, such as with meals, “had slightly lower risks…compared with those who drank only on occasion.”
“So what we think is that maybe what is causing this beneficial effect is not wine itself or drinking with meals itself but other factors that we cannot control,” UK Biobank study author Rosario Ortola, professor of preventive medicine at the Universidad Autonoma de Madrid, told CNN. People in these two groups might, according to Ortola, “appreciate moderation in other areas of their lives…more likely to have other healthy behaviors.”
Cardiovascular disease was the single health risk evaluated by the study that used Mass General Biobank data on 53,064 patients, median age 60 and 60% women, with a 3.4-year follow-up. According to the report on Time, “One reason why alcohol might be linked to better heart health: it reduces stress signals in the brain in a sustained way, leading to less of a burden on the heart.”
Brain scans from 713 participants showed dampening of activity in the amygdala in “light/moderate” drinkers, who consumed one to 14 drinks/week—compared to activity in the “none/minimal” group drinking less than one drink per week, according to the researchers from Yale and Mass General. Panic signals sent from the amygdala form part of the brain’s stress-related neural network activity (SNA)—known, as the study authors explain,”for its association with cardiovascular disease.
“Drinking alcohol is known to ease the amygdala’s alarm effect,” Mass General cardiologist Ahmed Tawakol told Time. “But we asked a different question: Does it have long-lasting effects on these systems?” Ongoing dampening of activity in the amygdala among light/moderate drinkers over the course of the study occurred, along with a 22% reduction in cardiovascular disease. But the authors add that, “given alcohol’s potential health detriments, new interventions with similar effects on SNA are needed.”
“It remains unclear whether the potential cardiovascular benefits of light/moderate alcohol consumption result from alcohol itself or whether they may stem from confounders (e.g., associated health behaviors, socioeconomic factors),” the authors write. Also, they noted that “subjects with no/minimal alcohol intake were more likely to be female, hypertensive, diabetic, and to have a history of anxiety and depression…light/moderate drinkers were more likely to be male, smokers, and physically active, and had a higher neighborhood income compared with participants with no/minimal alcohol consumption.”
Important caveats exist in both studies, mainly that Biobank participants tend to be healthier than people who do not enroll. In addition, most of the UK Biobank information about drinking habits was self-reported, and 94% of participants were white. In the end, Ortola’s “factors that we cannot control” —i.e. individual differences—may play the greatest role in long-term health effects of drinking alcohol.
Rather than resolving arguments among my friends, these studies seem to be prolonging them. But because I am a non-drinker for various reasons—and thus reluctant to weigh in on the topic—I appreciate having published data on both sides that I can talk about. Also, I can admit to possibly having less good health—more subject to the ravages of anxiety—than my friends who drink in moderation.
—Mary Carpenter regularly reports on topical subjects in health and medicine.
Fascinating!!