The reasons are unclear, but smoking and alcohol may interfere with vitamin C absorption or metabolism. Although blood vitamin C levels also rise with vitamin C supplements, it was rare to take vitamin supplements in this Japanese community when the study began and therefore researchers cannot confirm the same benefit from them. Another 33 strokes were of undetermined typed. Because a risk reduction was observed in both types of stroke, Yokoyama says the responsible mechanism probably extends beyond vitamin C's known antioxidant effects. Cerebral infarctions are considered to be the result of atherosclerosis, the build-up of fatty deposits in arteries.
Antioxidants can prevent the buildup.
Hemorrhagic stroke, on the other hand, results from a ruptured blood vessel in the brain. Although widespread screening to determine blood vitamin C levels might eventually be a good idea, it is too early to make such a recommendation, Yokoyama suggests. The researchers are preparing a database to analyze the association between blood levels of vitamin C and subsequent incidence of heart attack in the same population.