Low vitamin D doubles whites' stroke risk

CHICAGO, Nov. 15 (UPI) -- Not getting enough vitamin D doubles the risk of stroke in whites, but not in African-Americans, U.S. researchers say.

But the researchers at the Johns Hopkins University School of Medicine in Baltimore say they still don't know why blacks are much more likely to suffer a stroke than Caucasians.

The researchers studied nearly 8,000 initially healthy men and women of both races. Of this group, 6.6 percent of whites and 32.3 percent of African-Americans had severely low blood levels of vitamin D, or less than 15 nanograms per milliliter.

Dr. Erin Michos, a co-lead investigator, says of the 176 study participants who died of stroke during the 14-year study period 116 were white and 60 were black.

However, African-Americans had a 65 percent greater risk of suffering severe bleeding in, or interruption of blood flow to, the brain than whites after age, other risk factors for stroke and vitamin D deficiency were factored in.

"Higher numbers for hypertension and diabetes definitely explain some of the excess risk for stroke in blacks compared to whites, but not this much risk," Michos says in a statement. "Something else is surely behind this problem. However, don't blame vitamin D deficits for the higher number of strokes in blacks."

Michos emphasizes clinical trials are needed to verify that vitamin D supplements do prevent heart attacks and stroke.

The findings are scheduled to be presented at the American Heart Association's annual scientific sessions in Chicago.