Drinking moderate amounts of wine, especially red, may lower the risk of heart disease, studies have shown. But researchers have not determined whether it's the alcohol or something else in wine that protects the heart.
So Dr. Martin Bobak of the University College London in England and colleagues compared the drinking habits of 735 healthy men with 206 men who had recently suffered a heart attack, in a population-based case-control study. They were between 25- and 64-years-old, lived in the Czech Republic, and drank on average 148 grams of alcohol per week. Beer was their beverage of choice, as opposed to wine or spirits, almost exclusively.
The researchers grouped the men according to their average weekly intake of beer: non-drinkers and those who drank less than about 18 grams of alcohol; men who drank between 18 to 144 grams; those who drank 145 to 324 grams; and men who consumed over 325 grams.
The men least likely to have a heart attack drank daily or almost daily, consuming four to nine liters of beer per week, which is 145 to 324 grams of alcohol (or about 15 beers a week at 12 ounces each), the researchers write in a letter in the May 20 British Medical Journal. "This was true even when men with a history of heart disease, stroke, diabetes, or cancer were excluded from the analysis," the researchers report.
As other studies have shown, heavy drinkers didn't benefit from alcohol. Men who drank twice a day had the same risk of having a heart attack as non-drinkers, the researchers report.
"These results support the view that the protective effect of alcohol intake is due to ethanol rather than to specific substances present in different types of beverages," the team concludes. For example, wine contains molecules called flavanoids that are thought to be cardioprotective.
Could people who drink alcohol have something in common that protects them against heart disease, other than their consumption of ethanol? "It is unlikely," Dr. Bobak told HeartInfo/Mediconsult. For one, many studies have ruled out other factors, such as diet. Secondly, "there is good experimental evidence that alcohol influences blood lipids and
blood clotting, both of which influence heart disease," he said. Alcohol may raise levels of HDL ("good") cholesterol.
Bad news for non-drinkers: the chemical characteristics of ethanol can't be added to pills, he said.
Commenting on the study, Dr. Andrew P. Levy, Medical Advisor for HeartInfo, says " It is true that alcohol in moderation appears to protect against heart disease. This may be due to the effect on blood lipids. But alcohol also raises blood pressure significantly, which increases the risk of stroke, heart attack and kidney disease. People should not begin drinking in order to decrease their risk of heart disease."