D-deficiency doubles stroke risk in whites

Vitamin D deficiency does not appear to confer an increased risk of fatal stroke among blacks -- in contrast to findings among white populations, according to an analysis of U.S. population data. Analysis of National Health and Nutrition Examination Survey (NHANES) data encompassing almost 8,000 people, showed that over a median of 14 years, whites with levels of 25-hydroxyvitamin D level below 15 ng/mL had double the risk of dying from stroke compared with those who had higher levels. However, no such association was found in black NHANES participants -- despite their lower overall vitamin D levels and greater fatal stroke risk compared with whites. The finding was surprising because it was thought that vitamin D deficiency might explain the higher stroke rate observed in blacks. Johns Hopkins researchers speculated that African-Americans might have developed an adaptive resistance to the adverse effects of low vitamin D levels -- an idea supported by their lower rates of fractures and osteoporosis compared with whites. Sources of vitamin D include exposure to ultraviolet B rays in sunlight, as well as fatty fish, egg yolks, and fortified foods such as milk products and breakfast cereals.