Low Vitamin D Linked to Fatal Stroke among Whites

Kathleen Blanchard's picture
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Data extracted from the Third National Health and Nutrition Examination Survey of Americans (NHANES-III), presented at the American Heart Association Scientific Sessions 2010, shows low vitamin D levels can double the chances of stroke in whites, but had no effect on blacks for increasing the risk. The findings are of interest to researchers because study participants who were black generally had a 60 percent higher chance of stroke compared to whites.

Erin Michos, M.D., M.H.S., the study’s lead researcher and an assistant professor of medicine at Johns Hopkins University School of Medicine in Baltimore, Md explains, “We thought maybe the lower vitamin D levels might actually explain why blacks have higher risks for stroke . “But we did not find the same relationship between vitamin D and stroke in blacks.”

Low Vitamin D should Considered Risk Factor for Stroke among Whites

The researchers say blacks may have a natural resistance to low vitamin D that also seems to protect from fractures despite higher prevalence of deficiency in the vitamin.“Since stroke is the No. 3 cause of death in the United States, it’s important for us to consider low vitamin D as a possible risk factor for stroke at least among whites,” Michos said.

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The study included of 7,981 black and white adults. Compared to 7 percent of whites, 32 percent of blacks were found to be vitamin D deficient. Even after adjusting for socioeconomic and other stroke risk factors that included smoking, alcohol use, body mass index, high blood pressure, physical activity and cholesterol, researchers still found whites with low levels of the vitamin were twice as likely to suffer a fatal stroke, but the same association was not found for blacks.

Shortcomings of the study were vitamin D levels were measured at the beginning of the study. Researchers also did not have access to information about stroke survivors. The study, conducted between 1988 and 1994 found 116 deaths from stroke in whites who were also deficient in vitamin D and only 60 among blacks, obtained from the National Death Index.

The researchers say clinical trials may be needed to determine if treatment for vitamin D deficiency can reduce the chances of stroke. Low levels of the vitamin doubled the chances of stroke in whites, but not in blacks, found in the analysis. Deficiencies of the vitamin have been linked in recent studies to atherosclerosis, high blood pressure and other nervous system pathologies.

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