Drinking alcohol every day protects against heart disease in men but not in women, Danish research shows.
A study of 50,000 people found that men who drank daily had a 41% reduced risk of coronary heart disease compared with a 7% drop in men who drank once a week.
In women, the risk of heart disease fell by a third with a weekly drink but did not fall further in daily drinkers. Experts warned the results, published in the British Medical Journal, should not be used to justify heavy drinking.
Previous research has shown that moderate alcohol intake is associated with a lower risk of heart disease, but up until now most studies have been in men.
Men and women aged 50-65 who took part in this study were questioned on their drinking behaviour and then followed for an average of six years.
Women drank an average of five and a half drinks a week, and men consumed 11.
In men, the risk of heart disease fell significantly with increased frequency of drinking - with men who drank a little every day having the lowest risk.
But for women, although drinking on at least one day a week was associated with a 36% reduced risk of heart disease compared to those who drank more rarely, the risk was the same whether women had one drink a week or drank moderately each day.
The researchers said how much women drank may be more important for protection against heart disease than how often they drank.
The researchers said there could be several explanations for the differences found between men and women.
It may be hormonal, or related to the type of alcohol consumed or there may be differences in the way men and women's bodies process alcohol.
Lead researcher Professor Morten Gronbaek from the National Institute of Public Health in Denmark said: "It has been shown that frequency of drinking has a larger role than amount but this points towards the fact there is a gender difference."
He added that the benefits of alcohol had to be weighed against the increased risk of cancer and liver damage.
"One or two drinks in men, or one drink a day in women, would be sufficient for heart disease - you wouldn't get any more beneficial effects from drinking more."
In an accompanying editorial, Dr Annie Britton, senior lecturer at University College London warned that the study participants had a high risk of heart disease because of their age.
And added that the study had a low response rate and so may not have been fully representative.
She said: "We do not yet know whether cardioprotective effects accrue over a lifetime or whether, purely from a health perspective, we should defer drinking alcohol until older age, when heart disease is manifest."
Judy O'Sullivan, medical spokesperson for the British Heart Foundation (BHF) said: "This study does not change the fact that alcohol should be enjoyed in moderation only, both by men and women.
"If you are teetotal you should not start consuming alcohol in order to reduce your risk of developing coronary heart disease. However, if you enjoy alcohol you should be aware that the risks of drinking large quantities significantly outweigh any potential benefits.