We ve known for a long time that people can reduce their risk of cardiovascular events (heart attacks and strokes) if they habitually consume moderate amounts of alcoholic beverages no more than one or two standard drinks per day. But the data on stroke in particular have been somewhat inconclusive. Now a huge new meta-analysis demonstrates that some alcohol consumption may significantly reduce the risk of stroke.
Dr. Chi Zhang from the Shanghai Seventh People's Hospital, Shanghai, China and colleagues performed a meta-analysis of 27 prospective studies that included over 1.4 million people. The studies had to have examined more than two categories of alcohol intake so that a dose-response effect could be established.
In short, they found that the overall risk of stroke was reduced by 15 percent, while that of ischemic stroke (strokes caused by an arterial blockage due to fatty occlusion or a clot) was reduced by 19 percent in those with a low intake of alcohol about 1.5 to 2 standard drinks per day (10-20 grams of alcohol). In addition, there was a highly significant reduction (by 33 percent) risk of stroke mortality. There was no effect on the risk of hemorrhagic stroke strokes caused by bleeding.
The researchers found no association beneficial or harmful between moderate alcohol intake and risk of either type of stroke. But they did find that heavy alcohol intake (over about 3 standard drinks per day or 40-45 grams of alcohol) was associated with a 20 percent increased risk of total stroke.
A standard drink is defined as one 12-ounce can of beer, one 5-ounce glass of wine, or a mixed drink containing 1.5 ounces of 80-proof spirits. Each of these standard servings contains 14 grams of alcohol.
As noted in a review of the study on MedPage Today, there was no information on the pattern of alcohol consumption in these studies, and the alcohol consumption data were self-reported by the participants. These factors tend to weaken the results, however the size of the study and inclusion of only prospective studies with several levels of alcohol intake are strong points.
ACSH s Dr. Gilbert Ross commented, Ischemic stroke is far and away the most common type we see, and thus these results support the idea that individuals might benefit from light alcohol consumption. It is equally important, he emphasized, to warn people that heavy consumption is unlikely to benefit them and not just in terms of stroke, of course.