Women Who Drink Moderately Have Lower Cardiovascular Risk
Women who drink moderately may have a lower risk of cardiovascular disease (CVD) and death from CVD in part because of how alcohol affects the body’s processing of fats and sugar in the blood, researchers report in Circulation: Journal of the American Heart Association.
In an analysis of data from the Women’s Health Study, researchers compared non-drinkers to moderate drinkers and found that an intake of one-half to one drink a day was associated with:
• 26 percent lower risk of CVD;
• 35 percent decrease in total mortality; and
• 51 percent decrease in CVD mortality.
CVD is a term that encompasses all diseases of the heart and blood vessels, including stroke and was defined in this study as a presence of heart attack, coronary bypass or angioplasty, stroke, or death from any of these conditions.
Moderate drinking was defined as 5 to 14.9 grams of alcohol a day — one-half to one drink. However, the risk of CVD among women consuming 15 to 30 grams of alcohol a day (more than one but no more than two drinks a day) was not significantly different from the risk of CVD among non-drinkers.
“Our data show that beyond one drink a day there isn’t any benefit,” said Luc Djousse, M.D., D.Sc., lead author of the study, assistant professor of medicine at Harvard University and associate epidemiologist at Brigham and Women’s Hospital and Veterans Affairs Healthcare System in Boston, Mass.
The effects of alcohol on blood fat was the most significant contributor to lowering the risk of CVD. It explained almost 29 percent of the lowered risk. Alcohol’s effects on glucose metabolism accounted for about 25 percent of the lowered risk.
The effects of moderate drinking on inflammatory/hemostatic factors and blood pressure had a neglible contribution to the reduction in CVD risk, accounting for 5 percent and 4.6 percent respectively. These mediating factors explained 86.3 percent of the lower risk of CVD, but only about 19 percent of total mortality and 22 percent of CVD mortality.
“The findings add to a large body of evidence showing that moderate drinking favorably affects lipids and glucose metabolism, and thus contributes to a lower risk of cardiovascular disease in women,” Djousse said.
“The American Heart Association suggests a limit of one drink per day for women who already drink alcohol,” said Jennifer H. Mieres, M.D., spokesperson for the association’s Go Red For Women campaign and director of Nuclear Cardiology at New York University. “However, those who do not currently drink alcohol don’t need to start drinking to prevent cardiovascular disease. As the study’s authors point out, alcohol can raise the risk of breast cancer, high blood pressure and alcohol abuse. There are many ways women can lower their risk of cardiovascular disease.”
In the study, researchers analyzed alcohol consumption in the past 12 months of 26,399 women, average age 55 years. The researchers assumed that 12 ounces of beer contains 13.2 grams of alcohol, 12 ounces of light beer contains 11.3 grams, four ounces of wine contains 10.8 grams and 1.5 ounces of liquor contains 15.1 grams of alcohol. Total alcohol intake was computed as the sum of alcohol content in beer, wine and spirits. Infrequent drinkers, moderate drinkers who drank one-half to one drink a day (5 – 14.9 grams per day), and heavy drinkers were compared to non-drinkers.
Alcohol intake was strongly related to higher levels of high-density lipoproteins (HDL), the good cholesterol, as seen in previous studies, Djousse said. “It may be that moderate drinking improves fat and muscle cells’ ability to absorb glucose and may improve the levels of adiponectin, a hormone known to lower the risk of diabetes.”
The effects of moderate drinking on inflammatory and hemostatic factors as well as blood pressure were minimal in explaining the lower risk of CVD in moderate drinkers, he said. “Drinking alcohol can be a double-edged sword, as alcohol can raise blood pressure.”
During follow-up of more than 12 years, 1,039 CVD events, 785 confirmed total deaths and 153 CVD deaths occurred. The lowest CVD risk was in women who consumed 5 to 14.9 grams — or about one-half to one drink of alcohol a day.
Similarly, researchers found a relationship between alcohol consumption and total and CVD mortality, with the largest effect observed in women consuming half to one drink a day. However, no single factor explained most of the reduction in mortality.
“Even when putting all the factors together, only about 20 percent of the reduction in mortality was explained by the effects of moderate drinking on lipids, glucose metabolism, blood pressure and inflammation/hemostatic factors,” Djousse said.
Besides limiting alcohol to no more than one drink a day — due to the potential increased risk of breast cancer — “women should also stop smoking, eat a healthy diet, maintain a normal weight and exercise,” he said.