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Your very good health — as long as you are a moderate drinker over the age of 40. Credit: IMAGESTATE/ALAMY

A drink a day keeps the doctor away from some of us, concludes a review by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) in the United States. But you need to ask your doctor if your level of drinking is healthy, it adds.

Many people assume that a tipple or two a day is a tonic, but researchers believe this assumption is based chiefly on misleading media reports and wishful thinking. The institute reviewed scientific literature showing the relative risks and benefits of drinking in moderation (L. Gunzerath, V. Faden, S. Zakhari & K. Warren Alcohol. Clin. Exp. Res. 28, 829–847; 2004).

Rather than producing an easy rule of thumb, the review concludes that the healthiest level of consumption depends on an individual's age, sex, overall health and lifestyle — a calculation best totted up in the doctor's office. “We cannot give a blanket statement that alcohol is good for you so go out and enjoy,” says the institute's Samir Zakhari, one of the authors of the report.

The case for alcohol is based on findings that moderate drinkers are at lower risk of heart disease than either abstainers or heavy imbibers. The review weighs these benefits against alcohol's myriad detrimental effects, such as the increased risk of injury, breast cancer, liver disease and other conditions.

When both benefits and risks are factored into the equation, the reviewers conclude, people still seem to reduce their overall health risks by having one or two alcoholic drinks a day. But the degree of benefit varies from person to person, says Zakhari. People aged 40 or more, who are already under some threat from heart disease, seem to benefit the most, whereas younger drinkers may gain very little.

The NIAAA review adds that there is little consensus among experts about what constitutes ‘moderate’ drinking. Some studies consider this to be one drink a week, others as many as four a day.

The review's contents are likely to provide the basis for the alcohol section of new dietary advice due to be released by the US government next year.

Despite its complicated conclusions, experts welcomed the attempt to weigh up the pros and cons of moderate drinking. “It's as good as it could have been,” says Kenneth Mukamal, who studies alcohol and health at Harvard Medical School, Boston.

But some researchers doubt that the report's contents, and other reliable advice on healthy drinking, are reaching those already at the bar (see Nature 428, 598–600; 2004). Rather than disseminating a vague notion of moderation, drinks labels and trained bar staff should advise people not to exceed one or two drinks a day, suggests alcohol-policy expert Thomas Babor at the University of Connecticut, Farmington. “It's now a question of getting the message out there,” he says.