Effects of Heavy Drinking on Heart Health Differs Between Genders

If you are like many Americans, you probably drink alcohol, at least on occasion. Previous studies have shown that moderate drinking (one drink a day for women or anyone over 65, and two drinks a day for men under 65) is probably safe, and may even have health benefits. However, heavy alcohol consumption can negatively affect almost every system in the body, and new findings indicate that women face greater risks to their heart health than their male counterparts.

A Japanese Collaborative Cohort Study, led by Dr. Hiroyasu Iso, professor of public health at Osaka University, followed 34,776 men and 48,906 women to analyze the effects alcohol consumption had on the different genders. The study participants, with ages ranging from 40 to 79, were followed for an average of 14.2 years. During that time, 1,628 subjects died from stroke and 736 died from coronary heart disease. Prior to the study, none of the participants had previously experienced cancer, stroke or heart disease.

The researchers found that light-to-moderate drinking seemed to reduce mortality from cardiovascular disease for both sexes; 12 percent for men and 25 percent for women, lending support to previous reports that suggest light-to-moderate alcohol consumption might be linked with a lowered risk of heart disease in women. However, heavy alcohol consumption had a significantly different effect on men and women in terms of coronary heart disease. In men, heavy drinking reduced mortality from cardiovascular disease by 19 percent, while it increased a woman's risk of death due to heart disease 310 percent. These results suggest that "an amount of alcohol that may be beneficial for men is not good for women at all," said Dr. Iso in an American Heart Association news release.

Dr. Iso said the protective benefit seen is likely due to the increase in so-called good cholesterol that's linked to alcohol. "Alcohol increases the level of good cholesterol, known as HDL, and inhibits arterial sclerosis and platelets from clotting, and reduces the risks of getting heart disease, while it surges the blood pressure in heavy drinking," Dr. Iso said in a telephone interview on July 8, as reported by Bloomberg. "The results show benefit from taking alcohol exceeded the harm in men."

Both men and women who drank heavily saw an increased mortality from stroke; for men—a 48 percent from total stroke, 67 percent from hemorrhagic stroke, and 35 percent from ischemic stroke, and for women—a 92 percent increased risk of death from total stroke, 61 percent from hemorrhagic stroke, and 143 percent from ischemic stroke.

Dr. Iso noted that, because Japanese culture imposes social restrictions against women drinking as they get older, there may not have been enough data to detect a protective effect in women. Only 15 percent of the women in the study had any liquor, wine or beer during the study, which indicates there may have been other factors that affected their heart disease and stroke risk. "In women, there's a possibility we couldn't analyze the preventative effects enough because there were few heavy drinkers," he said. "Therefore a small number of people developed heart disease and died. It's difficult to show a statistical significance when death cases are low."

According to the World Health Organization (WHO), cardiovascular diseases, which includes heart attack, stroke and hypertension, are the number one cause of death globally, and is expected to remain so. The WHO estimates that, if current trends are allowed to continue, 20 million people will die from cardiovascular disease by 2015 (mainly from heart attacks and stroke), compared to an estimated 17.5 million, or 30 percent of all global deaths in 2005. Approximately 80 percent of these deaths occurred in low and middle income countries.

The U.S. Dietary Guidelines for Americans advise men to have no more than two drinks per day and women to have no more than one drink per day. Because women's bodies generally have less water than men's, alcohol is less diluted in a woman's body than in a man's. Therefore, when a woman drinks, the alcohol in her bloodstream usually reaches a higher level than a man's, even if both consume the same amount.

The study was published online in the American Heart Association's July 11 issue of the journal Stroke, and was funded by Japan's Ministry of Education, Culture, Sports, Science and Technology.