An investigation into the relationship between alcohol consumption and heart disease has challenged the long-held belief that drinking a glass of red wine a day is beneficial.

A study by the Centre for Addiction and Mental Health (CAMH) found that while there is a positive link between alcohol use and ischaemic heart disease, it cannot be assumed for all drinkers, even for those who have a limited intake.

Dr Juergen Rehm, director of social and epidemiological research at CAMH, said: “It’s complicated.

"We see substantial variation across studies, in particular for an average consumption of one to two drinks a day."

The positive associations may vary by gender, drinking patterns, and the specific health effects of interest. Differential risk curves were found by sex, with higher risk for morbidity and mortality in women.

Moreover, for any particular individual, the relationship between alcohol consumption and ischemic heart disease should not be isolated from other disease outcomes. Even at low levels, alcohol intake can have a detrimental effect on many other disease outcomes, including on several cancers.

"Even one drink a day increases risk of breast cancer, for example," says Dr Rehm.

"However, with as little as one drink a day, the net effect on mortality is still beneficial. After this, the net risk increases with every drink."

"If someone binge drinks even once a month, any health benefits from light to moderate drinking disappear." Binge drinking is defined more than four drinks on one occasion for women, and more than five for men.

Given the complex, potentially beneficial or detrimental effects of alcohol on ischaemic heart disease in addition to the detrimental effects on other disease categories, any advice by doctors on individual drinking has to take the individual risk constellation (such as familial predisposition for certain diseases and behavior with respect to other risk factors) into consideration.

Dr Rehm added: "More evidence on the overall benefit-risk ratio of average alcohol consumption in relation to ischaemic heart disease and other diseases is needed in order to inform the general public or physicians about safe or low-risk drinking levels.

"Findings from this study support current low-risk drinking guidelines, if these recognise lower drinking limits for women."