A stroke occurs when blood flow to the brain is interrupted because a blood vessel in the brain becomes obstructed (ischemic stroke) or ruptures (hemorrhagic stroke). Stroke is the third leading cause of death in the United States; in 1999, 167,366 people in the United States died from stroke. Stroke is also a major cause of disability. About 30% of stroke survivors are permanently disabled, and 20% of survivors must receive institutionalized care.

Observational studies have suggested that heavy alcohol consumption may increase the risk of stroke, but the link between light and moderate alcohol consumption and stroke remains unclear.

In the February 5, 2003 Journal of the American Medical Association , researchers from Tulane University School of Public Health and Tropical Medicine confirm that heavy alcohol consumption does increase the risk of stroke, but report that light to moderate drinking may protect against it.

About the Study

The scientists analyzed data from 35 observational studies, published between 1966 and 2002, which enrolled a combined total of nearly 500,000 men and women from around the world.

They examined the link between, ischemic stroke, hemorrhagic stroke, total stroke (ischemic and hemorrhagic) and alcohol consumption. Abstainers served as controls.

The Findings

Compared to the controls, study participants who consumed more than 60 grams per day of alcohol (about five drinks) were at a significantly elevated risk for total stroke (64% elevated risk), ischemic stroke (69% elevated risk) and hemorrhagic stroke (118% elevated risk).

On the other hand, light and moderate alcohol consumption significantly reduced stroke risk. Light alcohol consumption (less than 12 grams, or one drink per day) reduced risk of total stroke by 17% and the risk of ischemic stroke by 20% compared to controls. Moderate alcohol consumption (12–24 grams, or one to two drinks per day) reduced the risk of ischemic stroke by 28% compared to controls.

There was no additional benefit for any type of stroke of more than two drinks per day.

How Does This Affect You?

This study further supports the findings from other studies that heavy alcohol consumption increases the risk of stroke.

The results of this study are also consistent with other observational studies that have suggested a link between moderate alcohol consumption and beneficial health effects, in this case protection from total and ischemic stroke. The scientists speculated that this level of alcohol consumption might increase levels of protective high-density lipoprotein (HDL) cholesterol, and interfere with blood clot formation. This kind of observational study, however, provided no explanation for the observed effects.

If you already drink responsibly, these findings suggest that your risk of ischemic and total stroke may be lowered if you limit yourself to no more than one or two drinks per day. However, if you do not drink, these study results do not suggest that you should start.