Having one or two alcoholic drinks a day is associated with a lower risk of stroke, a review of studies has found. But drinking more than that increases the risk.

The analysis, in BMC Medicine, used data from 27 studies.

Compared with nondrinkers or occasional drinkers, people who had one or two drinks a day had an 8 percent reduced risk of ischemic stroke. Ischemic strokes, caused by blockage of an artery supplying blood to the brain, account for about 87 percent of all strokes.

Heavier drinking, however, increased stroke risk. Having up to four daily drinks led to an 8 percent increased risk of ischemic stroke, and at more than four drinks, the risk increased by 14 percent.

Drinking more than four drinks a day also increased the risk of hemorrhagic stroke, the result of a burst or leaking blood vessel in or near the brain, by up to 82 percent. More moderate drinking did not raise hemorrhagic stroke risk.

The lead author, Susanna C. Larsson, an associate professor of epidemiology at the Karolinska Institutet in Sweden, warned that alcohol is not health food.

“Nondrinkers should not start to drink as a health measure,” she said. “And I wouldn’t recommend that a person who has a drink or two on the weekend increase his consumption.”