Since ancient civilizations, the consumption of alcoholic beverages has been an important element of many societies. The benefits and drawbacks of alcohol have been argued throughout history. Although the original discussions were fueled by the public’s sense of intoxication, subsequent research has conclusively established the long-term physiological damage caused by excessive intake.
In an observational study of UK Biobank individuals, light to moderate drinkers had the lowest risk of heart disease, followed by abstainers; however, light to moderate drinkers tended to have healthier lifestyles than abstainers, which likely accounted for their better heart health. In this same cohort, genetic data revealed that all levels of alcohol consumption are related with an elevated risk of cardiovascular disease. Notably, the risk of cardiovascular disease associated with light alcohol consumption was moderate, but increased exponentially with larger intake, even at levels now recognized as ‘low risk.’
Although observational studies has suggested that moderate alcohol use may confer heart-related health advantages, a comprehensive study published in JAMA Network Open found that alcohol consumption at all levels was associated with an increased risk of cardiovascular disease. The findings, published by a team lead by researchers at Massachusetts General Hospital (MGH) and the Broad Institute of MIT and Harvard, show that the alleged benefits of alcohol intake may be related to other lifestyle variables typical among light to moderate drinkers.
The findings confirm that alcohol consumption should not be encouraged to promote cardiovascular health; rather, limiting alcohol consumption will likely reduce cardiovascular risk in all individuals, albeit to varying degrees depending on one’s current level of consumption
Krishna G. Aragam
The study comprised 371,463 persons from the UK Biobank, a large-scale biological database and research resource including detailed genetic and health information, with an average age of 57 years and an average alcohol intake of 9.2 drinks per week. Consistent with previous research, researchers discovered that light to moderate drinkers had the lowest risk of heart disease, followed by abstainers.
People who drank heavily were at the greatest risk. However, the researchers discovered that light to moderate drinkers had healthier lifestyles than abstainers, including increased physical activity and vegetable consumption, as well as less smoking. Taking only a few lifestyle factors into consideration dramatically reduced any advantage connected with alcohol use.
The study also applied the latest techniques in a method called Mendelian randomization, which uses genetic variants to determine whether an observed link between an exposure and an outcome is consistent with a causal effect — in this case, whether light alcohol consumption causes a person to be protected against cardiovascular disease.
“Newer and more advanced techniques in ‘non-linear Mendelian randomization’ now allow the use of human genetic data to evaluate the direction and magnitude of disease risk associated with different levels of an exposure,” says senior author Krishna G. Aragam, MD, MS, an MGH cardiologist and an associate scientist at the Broad Institute. “We used these novel approaches, as well as extensive genetic and phenotypic data from biobank populations, to better understand the relationship between frequent alcohol consumption and cardiovascular disease.”
When the scientists conducted such genetic analyses of samples taken from participants, they found that individuals with genetic variants that predicted higher alcohol consumption were indeed more likely to consume greater amounts of alcohol, and more likely to have hypertension and coronary artery disease.
The analyses also revealed significant differences in cardiovascular risk across the spectrum of alcohol consumption among both men and women, with minimal increases in risk when progressing from zero to seven drinks per week, much higher risk increases when progressing from seven to 14 drinks per week, and especially high risk when consuming 21 or more drinks per week. Notably, the data imply an increase in cardiovascular risk even at levels labeled “low risk” by national USDA guidelines (i.e. below two drinks per day for men and one drink per day for women).
A subsequent examination of data from 30,716 participants in the Mass General Brigham Biobank validated the discovery that the link between alcohol intake and cardiovascular risk is not linear but rather exponential. As a result, while cutting back on consumption can benefit persons who only drink one alcoholic beverage per day, the health benefits of cutting back may be more large – and possibly more clinically meaningful – in those who consume more.
“The findings confirm that alcohol consumption should not be encouraged to promote cardiovascular health; rather, limiting alcohol consumption will likely reduce cardiovascular risk in all individuals, albeit to varying degrees depending on one’s current level of consumption,” says Aragam.
