Decades of research has found that people who drink light to moderate amounts of alcohol enjoy better cardiovascular health than abstainers, but that benefit quickly disappears as consumption rises into heavy drinking. But in recent years, a vocal group of public health advocates has argued that no level of drinking is safe. Now, a new study says that heavy drinkers who reduce their consumption to moderate levels stand to benefit in major ways, particularly when it comes to heart health.
The study is compelling because people who drink heavily may wonder if it’s worth cutting back—or if the damage has already been done. They may also wonder if they need to give up alcohol completely. The research could provide motivation to reduce alcohol consumption and embrace light to moderate drinking as part of a healthy lifestyle. It also gives clinicians concrete evidence to help them talk to patients about reducing drinking to moderate levels.
An Important Look at Heavy vs. Moderate Drinking
The study, published in March in the journal JAMA Network Open, analyzed data from roughly 21,000 subjects, most of whom were men, from the Korean National Health Insurance Service–Health Screening database and self-reported questionnaires. The participants were between 40 and 79 years old.
The researchers, based at Chungbuk National University Hospital in Cheongju, South Korea, and Korea University College of Medicine in Seoul, defined heavy drinking as more than 4 drinks a day or more than 14 drinks a week for men, with one standard drink containing 14 grams of pure alcohol. That’s the equivalent of a 5-ounce glass of wine at 12 percent alcohol by volume. For women, they defined heavy drinking as more than three drinks a day or more than 7 drinks per week.
The team compared people’s drinking habits and cardiovascular health outcomes over two consecutive three-year time periods. Over a follow-up period of 10 years, they found that people who reduced their drinking in the second time period experienced a 29 percent decrease in their overall risk of coronary artery disease. When considering all forms of major cardiovascular disease, the reduction in risk was 23 percent. The most notable reductions were for angina (chest pain caused by reduced blood flow to the heart) and ischemic stroke. In the group that reduced drinking, risk of ischemic stroke decreased by 34 percent.
Notably, the difference in risk between those who continued to be heavy drinkers and those who cut back to moderate consumption began to increase over time roughly three years after the individuals reduced their drinking. In other words, the longer people continued to drink moderately rather than heavily, the lower their risk of developing heart problems.
Study Strengths and Limitations
Most studies on drinking estimate average alcohol consumption at a single point in a person’s life. But, the researchers argue, “the association of alcohol consumption on future cardiovascular disease should be investigated in the context of habitual change rather than fixed behavior.” By examining people’s drinking habits over time, the study spotlights how behavioral changes, even relatively late in life, can significantly improve health.
The study also controlled for a number of variables, including age, gender, physical activity habits, income and more. The researchers attempted to control for the “sick-quitter effect,” the hypothesis that some alcohol abstainers are actually former heavy drinkers, by excluding people who abstained from alcohol during the second three-year time period. By comparing only people who continued drinking heavily with people who reduced their intake to moderate levels, the study could calculate a more accurate comparison of relative risk between the two groups.
The authors acknowledge several limitations. The study didn’t differentiate between types of alcohol consumed, and it was limited to South Koreans. The researchers relied on self-reported questionnaires, which tend to result in underreporting of alcohol consumption. Like almost all alcohol studies, this one is observational, which means it can’t establish causality. Even though researchers controlled for many variables, it’s possible that something other than how much people drank influenced the changes in heart health.
While the researchers call for further study, they say the investigation provides crucial evidence of the benefits of moderate drinking in an especially high-risk population: “Reducing alcohol consumption among people who drink heavily is potentially associated with a broad spectrum of benefits in future cardiovascular events.”
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