For decades, Americans have been urged to limit alcohol consumption to one or two drinks a day — and even that amount, some said, is linked to higher health risks such as cancer, dementia, and liver disease.
Now the federal government is reportedly considering dropping recommendations on specific daily limits. A change in course would follow earlier guidance from the American Heart Association that more research was needed to determine the true cardiovascular health effects of alcohol consumption.
Gregory M. Marcus, M.D., MAS, UCSF cardiologist and professor of medicine
Gregory M. Marcus, M.D., MAS, UCSF professor of medicine and cardiologist, cautions against prematurely assuming that a drink a day is necessarily unhealthy. He believes that guidelines should reflect robust evidence but solid scientific research on alcohol consumption has long been missing. Here he digs into the health concerns and need for better research.
How much can we safely drink a day — can we drink at all?
The evidence is strong and consistent that consuming more than two drinks in a day is almost certainly harmful to essentially every type of heart disease that has been examined. For those prone to addiction, especially those with a history of alcohol use disorder, it is likely best to avoid alcohol. Most people who drink do so in moderation; for those people, the jury remains out regarding the health risks and still possible benefits of consuming one drink per day.
What does the American Heart Association recommend as the daily maximum?
Generally, the recommendation is for no more than two drinks a day for men and one drink a day for women. The data that suggest a possible protective effect is mainly for just one drink per day, but the studies about drinking one per day are really of insufficient quality to make firm recommendations. We need more rigorous study into the true health effects of one drink a day.
What is the evidence about alcohol and heart health?
Alcohol consumption can have profound effects on heart health in a multitude of ways. Binge drinking — consuming more than one drink on average — can increase risks of high blood pressure, heart failure, heart attack, and dangerous heart rhythm disturbances. It is possible that a drink a day might reduce some heart-related risks, including risks of heart attack, heart failure, and even some heart rhythm disturbances, but better-quality studies are needed.
What do we still need to learn about benefits and harms?
We really need to better understand the true health effects of drinking just one drink a day. It also appears that the health effects of alcohol, even when consumed in moderation, also vary substantially from one person to the next, and within any individual there may be some harms and some benefits. So, understanding how to identify which individuals may be most prone to alcohol-related adverse effects is also important and yet to be fully understood.
What should we do in the meantime?
For those who do not drink, there’s no strong evidence that anyone should initiate alcohol consumption. For those who do enjoy consuming alcohol, it is safest to do so in moderation, ideally avoiding more than one drink in 24 hours.
It is also important that the lay public understands that not all studies of alcohol are the same and that certain methods are far more reliable in identifying true causal effects than others. The randomized clinical trial is the best study design, and the new American Heart Association’s Scientific Statement clearly states that randomized trials of a drink a day versus abstinence are needed.
What is moderate drinking? How might it help or hurt cardiovascular health?
Moderate drinking generally means no more than one to two drinks per day. The mechanisms by which such a drinking pattern may increase or decrease cardiovascular health are not entirely understood and are likely multi-factorial. For example, alcohol consumed in moderation may increase blood pressure but may also help prevent diabetes and lower cholesterol.
The effects on the heart muscle itself are also likely complex, although there is strong evidence that alcohol consumed in excess can lead to weakening, scarring, and unhealthy enlargement of the heart chambers.
How much is heavy consumption and why is it bad for you?
Generally, consuming more than two drinks in 24 hours — and for most people probably more than one drink in 24 hours — can be unhealthy. It appears the healthiest way to consume alcohol is probably with a meal, such as dinner, and likely when the drink is a lower-alcohol and higher-polyphenol drink such as red wine or a dark beer. Higher concentrations of alcohol, such as can occur with drinking more, drinking spirits or hard liquor, and drinking on an empty stomach are more harmful.
What should people do for a healthy lifestyle?
Certainly, more exercise, avoiding tobacco, maintaining a healthy weight, and avoiding excess alcohol are all important to health. High-quality original research is still needed to reveal whether consuming about a drink a day (either once in a while or every day) is better or worse for overall health.
