Homocysteine, an amino acid, has been associated with higher risk of stroke and Alzheimer's disease. But the new study showed that folate may actually work independently of homocysteine levels to protect against one type of stroke - hemorrhagic strokes, or those caused by bleeding in the brain.

Dr Bethany Van Guelpen and colleagues from Umea University in Sweden said they examined blood and dietary levels of folate and vitamin B12 in 62 patients who had a hemorrhagic stroke and 334 who had an ischemic stroke.

Blood levels of folate were inversely associated with the risk of hemorrhagic stroke, even after accounting for homocysteine levels and other risk factors like high blood pressure.

They found no association between blood levels of vitamin B12 and either type of stroke.

Nor was dietary folate associated with the risk of ischemic stroke, although it was inversely associated with the risk of hemorrhagic stroke.

Van Guelpen's team notes that the lack of any association with ischemic stroke was unexpected.

They point out that the food in Sweden is not fortified with folate and intake of fruit and vegetables is relatively low, so folate levels might not have been high enough to show a protective effect against ischemic stroke.