Drinking any amount of alcohol puts the heart at risk, study says

Last week, two patients asked cardiologist Stanley L. Hazen of the Cleveland Clinic in the United States how much alcohol consumed daily would benefit their heart health.

Hazen responded to the two with widely accepted medical advice: an average of one drink of alcohol a day protects the heart.

“I didn’t think twice before answering,” he commented.

Then he saw an article published in JAMA Network Open with information that revolutionized his ideas about what to say to his patients. That article, says Hazen, “changed my life completely.”

The conclusion of the article is that there is no level of alcohol consumption that does not cause a risk of heart disease. The risk is low if people have an average of seven drinks a week compared to none. But it grows rapidly as consumption increases.

“The number of doses makes a big difference,” said Krishna G. Aragam, a preventive cardiologist at Massachusetts General Hospital and one of the study’s authors. “You have to understand that when we go beyond modest consumption, the risk increases a lot.”

The study, which could help resolve medical disputes over the effects of alcohol on the heart, involved sophisticated analyzes of the genes and medical data of nearly 400,000 people who participate in the UK Biobank, a British repository used by researchers to study genes and their relationship to the health. The average age of the subjects selected for the alcohol consumption survey was 57 years, and they said they had an average of 9.2 drinks per week.

Some researchers have reported that modest alcohol consumption protects the heart, because moderate drinkers overall have less heart disease than heavy drinkers or teetotalers. Aragam and his colleagues also found this effect. But the reason, they say, is not that alcohol protects the heart. It’s just that light to moderate drinkers — up to 14 drinks a week — tend to have other characteristics that reduce their risk, such as smoking less, exercising more, and weighing less than people who drink heavily or those who don’t. drink.

According to Aragam, it is not known why those who consume moderately tend to be healthier than abstainers. But the Biobank study did not ask why people drink or refrain from drinking. Instead, it sought to separate the effects of alcohol on the heart from the effects of other habits, behaviors and characteristics. The researchers used a method known as Mendelian randomization to do this.

Scientists have found genetic variants that predispose a person to drink more or less. Because they are randomly distributed in the population, the variants can serve in a study as the equivalent of randomly choosing subjects to abstain from alcohol or to drink to varying degrees. Researchers might ask whether people with variants linked to higher alcohol consumption have more heart disease and hypertension than people with variants linked to lower consumption.

Statistical analysis performed by the researchers revealed an exponential risk curve with the genetic variants that suggest people drink more. The risks of heart disease and hypertension began to rise slowly, following the increase in the amount of alcohol consumed. But that increase quickly intensified, reaching high levels as people entered the binge drinking range, with 21 drinks a week or more.

The actual risks for each individual depend on whether the person has other problems, such as diabetes or obesity. But, Aragam said, extrapolating from the study results, a typical middle-aged person participating in the study who didn’t drink had an estimated 9% chance of having coronary heart disease. A person who had one drink of alcohol a day had an estimated risk of 10.5%, which is low. From then on, however, the risk increased rapidly.

Much previous research on alcohol consumption and heart health was observational, meaning subjects were followed over time to see if there was a relationship between their alcohol consumption and their heart health.

According to the researchers, these studies found correlations, but did not determine cause and effect. The use of Mendelian randomization in Biobank research is more suggestive of causality, so its results may carry more weight.

“We need to start thinking about these moderate levels of consumption and inform patients,” Aragam said. “If the person chooses to drink, they need to know that if they go beyond a certain level, the risk increases substantially. And if they choose to drink less, they will have greater benefit if they go down to up to seven drinks of alcohol a week.”

Hazen, the Cleveland cardiologist, said the new Biobank study led him to speculate about the effects of increased alcohol consumption during the pandemic. Researchers have noted that people have been drinking more since the pandemic began, and a recent study found that the number of alcohol-related deaths rose by 25% in 2020.

People’s blood pressure also rose during the pandemic. Hazen and his colleagues concluded from national data that it rose on average by nearly three millimeters.

“We had no idea how this was happening,” Hazen said.

The participants’ body weight changes were not responsible for the high blood pressure during the pandemic. The increase, which took place in all 50 US states and Washington, is a mystery.

Now Hazen has a new chance. “Perhaps the increase in alcohol consumption is responsible for the rise in blood pressure,” he suggested.

Translation by Clara Allain