For a while, it seemed the notion that light drinking was good for the heart had gone by the wayside, debunked by new studies and overshadowed by warnings that alcohol causes cancer.
Now the American Heart Association has revived the idea in a scientific review that is drawing intense criticism, setting off a new round of debate about alcohol consumption.
The paper, which sought to summarize the latest research and was aimed at practicing cardiologists, concluded that light drinking — one to two drinks a day — posed no risk for coronary disease, stroke, sudden death and possibly heart failure, and may even reduce the risk of developing these conditions.
Controversy over the influential organization’s review has been simmering since it was published in the association’s journal Circulation in July.
Public health groups and many doctors have warned on the basis of recent studies that alcohol can be harmful even in small amounts. Groups like the European Heart Network and the World Heart Federation have stressed that even modest drinking increases the odds of cardiovascular disease.
In anticipation of new dietary guidelines, however, the Trump administration in September withdrew a report emphasizing the links between alcohol and at least seven cancers, which found that the risk for oral and esophageal tumors begins rising at one drink a day.
The administration is relying instead on another report that concluded moderate drinkers had a lower risk of heart attacks and a lower-all-cause mortality than abstainers. But the report noted a higher breast cancer risk for women who drink.
Dr. Mariell Jessup, the chief science and medical officer at the heart association, said its review was focused on cardiovascular disease because that is the organization’s mission, adding that the review was not meant to serve as a guideline and that the group’s advice to patients has not changed.
“It says in all our guidelines right now, ‘If you don’t drink, don’t start.’ There’s not enough evidence to suggest conclusively that it prevents heart disease,” Dr. Jessup said in an interview.
But critics say even the suggestion of possible benefits for heart health is dangerous, because the risks of drinking are so great. They faulted how the heart association selected and weighed the studies it examined and said at least one author had ties to the alcohol industry in the past that should have disqualified him from participation.
“The cardiovascular benefits of moderate drinking are questionable at best,” said Dr. Elizabeth Farkouh, an internist and alcohol researcher. “But even if there was a benefit, there are so many other ways to reduce cardiovascular risk that don’t come with an associated cancer risk.”
Dr. Farkouh and her colleagues wrote a letter conveying their concerns to the A.H.A. in July. She said the organization did not acknowledge receipt until this month, when asked about it by The New York Times.
The new review’s conclusion is at odds with the Centers for Disease Control and Prevention’s guidance on alcohol, which notes that “even moderate drinking may increase your risk of death and other alcohol-related harms, compared to not drinking.”
The review also seems to diverge from the heart association’s diet and lifestyle recommendation to consume “limited or preferably no alcohol,” along with its 2023 statement that recent research suggests there is “no safe level of alcohol use.”
No one disputes that heavy drinking is harmful. The debate — and it is a perennial one — concerns light to moderate drinking and whether that provides more protection from cardiovascular disease than not drinking at all. Heart disease is the leading cause of death among Americans.
Questions about light drinking are cropping up again now because the U.S. dietary guidelines, which have long set parameters for safe alcohol use, are supposed to be updated by the end of the year.
The new guidance may be especially important for the alcohol industry, which is experiencing a slump in beer and wine sales, and more generally for Americans, who have greatly reduced their consumption. Only 54 percent still drink alcohol, and 53 percent say that even moderate drinking is bad for one’s health, a recent Gallup poll found.
There is no shortage of studies on the relationship between alcohol consumption and heart disease, but the quality of the evidence is variable, experts say. The results are often contradictory and interpretations differ.
The research has been financed at times by groups affiliated with the alcoholic beverage industry. Passions run high on both sides of the controversy, and scientists have been reluctant to run randomized controlled trials that deliberately expose participants to a harmful substance, even though such studies provide the most reliable evidence.
“There is a huge literature on this, but it’s almost entirely observational studies, which by definition are pretty weak,” said John Ioannidis, a professor at Stanford who has written about why many studies’ findings are not reproducible.
Observational studies follow individuals and can find associations between a behavior, like light drinking, and an outcome, like heart disease or death, but cannot prove cause and effect.
When a scientific review is conducted, “a lot depends on which studies you choose,” Dr. Ioannidis said. “Experts don’t agree on what the best studies are.”
“Some are clearly horrible, some are good, but a lot are in the gray zone, and people may just cherry-pick and select those that agree more with their narrative.”
Critics of the new review said the authors had done exactly that, and had failed to consider or give adequate weight to studies that undermined the hypothesis that light drinking had benefits.
Until 10 years ago, the federal government’s dietary guidelines endorsed the idea that moderate drinking was linked to a lower risk of cardiovascular disease and lower overall mortality, and might even help maintain cognitive function.
But in 2020, the guidelines were changed to say for the first time that “emerging evidence” indicated that even moderate drinking was harmful, and may raise the risk of dying from some cancers and some forms of heart disease.
Those guidelines still say it is safe for men to have up to two standard servings of alcohol a day and for women to drink up to one serving. (A serving is defined as 0.6 fluid ounces of pure alcohol — equivalent to 12 ounces of regular beer, five ounces of table wine, or 1.5 fluid ounces of distilled spirits.)
The Beer Institute maintains that current dietary guidelines should not be changed without objective and rigorous scientific review. WineAmerica, a national group that represents close to 500 wineries, says that the guidelines “allow our industry to promote responsible consumption.”
A J-Shaped Curve
The idea that a little alcohol is good for you was first put forth in the 1920s by Raymond Pearl, a scientist at Johns Hopkins, who described the effects of alcohol as a J-shaped curve.
His observational study that introduced the curve found that heavy drinkers had the highest death rates (the top of the ‘J’). Light drinkers had the lowest death rates (the bottom of the J), while abstainers were more likely to have heart disease and die than light drinkers, though not as much as the heavy drinkers (the upward tip of the J on the left).
Dozens of subsequent studies replicated the trend, and for years it was taken as gospel that light drinking was good for your health.
But in the early 2000s, Kaye Middleton Fillmore, a sociologist at the University of California, San Francisco, started raising questions about who the abstainers and moderate drinkers in the studies were.
Were some abstainers already sick, she wondered, or had they quit drinking because of illness? And could the moderate drinkers be people who had adopted other healthy lifestyle behaviors, like exercising regularly and eating in moderation, and had advantages like higher incomes and education?
More recent studies, called Mendelian randomization studies, have tried to control for these variables by studying people with genetic variants that change the way they metabolize alcohol so that drinking causes them discomfort and nausea.
They generally drink far less throughout their lives than other people, regardless of their socioeconomic class, prior illnesses or other behaviors. In these studies, such people were not found to be at higher risk for heart disease or early death, a finding that some experts said undermined the hypothesis that light drinking is beneficial.
But the heart association, in its July statement, gave short shrift to the Mendelian randomization studies “in favor of outdated, conflicting observational studies,” wrote Dr. Luis Seija, an internist who studies alcohol control policy and liver disease, in a post on his Substack, Last Call.
“This isn’t just an academic spat,” Dr. Seija wrote. People will “see headlines or quotes like ‘One to two drinks a day may reduce coronary artery disease.’ That’s the sound bite and exactly what the alcohol industry wants.”
Responding to the criticism that important studies were left out of its review, the heart association said that the authors were not required to describe the inclusion and exclusion criteria.
In an interview with The Times, Dr. Gregory Marcus, the vice chair of the review’s writing group, said an overwhelming majority of studies consistently showed that light drinkers live longer than both heavy drinkers and teetotalers.
“Most studies that look at overall mortality have this J shaped curve.” He added, “It is remarkable.”
Some critics have also questioned whether the authors of the heart association’s review were sufficiently screened for past relationships with the alcohol industry.
Among the eight authors was Dr. Kenneth Mukamal, who headed a $100 million clinical trial of alcohol that was aborted by the National Institutes of Health when it became public that he and officials from the National Institute on Alcohol Abuse and Alcoholism had solicited $60 million in financing from alcohol manufacturers. N.I.H. policies generally prohibit such solicitations.
The heart association said its policy only required scientists to disclose relationships with the industry during the year before they began the review. Dr. Mukamal was the opening speaker at a 2023 wine and lifestyle conference in Spain that fell within that period.
Asked by The Times about the conference, he said his expenses were covered by the University of Barcelona, one of the conference’s sponsors, and not by the wine industry. The website of the conference says that participants concluded that “the validity of the J curve was reconfirmed.”
There is one thing both sides in the debate agree on: Randomized controlled clinical trials would help resolve many lingering questions. But not all of them.
When patients with atrial fibrillation, a heart rhythm disorder, were instructed to stop drinking in a recent trial, their risk of experiencing a new episode dropped sharply.
Yet observational studies have found that people who drank one glass of wine a day are less likely to develop the disorder in the first place. The heart association review concluded that the effect of moderate drinking on atrial fibrillation “remains unknown.”
Roni Caryn Rabin is a Times health reporter focused on maternal and child health, racial and economic disparities in health care, and the influence of money on medicine.
The post Heart Association Revives Theory That Light Drinking May Be Good for You appeared first on New York Times.
