FRIDAY, Oct. 15, 2004 (HealthDayNews) -- Moderate alcohol use has been shown to be healthier for the heart than abstinence or heavy drinking, but consuming large amounts of alcohol in a short period of time has been linked to higher death rates from all causes, including cardiovascular ones.
Why such contradictory outcomes? Alcohol's effect on platelets in the blood may provide part of the answer, a new Dutch study suggests.
Platelets are the disk-shaped cells responsible for forming clots and repairing small breaks in the walls of blood vessels. When people binge on alcohol, it increases platelet aggregation, meaning more platelets stick together, according to the study in the October issue of Alcoholism: Clinical & Experimental Research.
Drinking large qualities in a short span of time -- "binge drinking" -- also inhibits platelet adhesion, meaning platelets won't stick as readily to a damaged vessel wall.
Preventing platelets from adhering to vessel walls could be a good thing, said study author Dr. Dylan W. de Lange, a researcher at the Thrombosis and Haemostasis Laboratory of the University Medical Center in Utrecht. It may prevent blood vessels from clogging and starving the heart or brain of needed oxygen.
It goes back to the delicately balanced process of blood clotting, de Lange explained: "Too little of it and we bleed to death; too much of it and we get cardiovascular infarction [heart attack]."
But at binge-consumption levels, it's doubtful any benefit from diminished adhesion would completely compensate for the increase in platelet aggregation, the authors said.
Strikingly, the researchers found that binge drinking red wine did not increase platelet aggregation. That may help explain why red wine drinkers exhibit less heart disease.
In the United States, scientists are trying to understand the link between moderate drinking and lower cardiovascular risk. The National Institute on Alcohol Abuse and Alcoholism defines moderate drinking as no more than one drink per day for most women, and no more than two drinks per day for most men.
The Dutch research is unusual because there have been few studies on binge drinking's impact on the cardiovascular system, de Lange said.
"And very, very few studies have focused on platelet adhesion," he added. Of those studies, most focus on platelet aggregation "in vitro," meaning in a test tube, not in humans.
For the experiment, 20 healthy volunteers drank either three glasses of alcohol or red wine in a 45-minute period. Another 45 minutes were allowed for the alcohol to be absorbed. Blood samples were collected 90 minutes after the start of the experiment. The entire cycle was repeated, resulting in the volunteers consuming six drinks in three hours.
In the lab, researchers looked at whether platelets from the participants adhered to collagen or fibrinogen, two proteins that are exposed when the normal internal lining of a vessel is damaged. At the rate of blood flow normally found in vessels that are narrowed by atherosclerosis, alcohol inhibited platelet adhesion to fibrinogen, de Lange noted.
Should you drink moderately for your health? There still isn't sufficient evidence to determine the optimal amount people might want to consume for good health, de Lange cautioned.
"Alcohol still isn't a panacea for cardiovascular disease," he said.
Visit the National Institute on Alcohol Abuse and Alcoholism to learn more about alcohol's effects on the heart.