Study: Vitamin D not related to risk of heart disease in blacks, Hispanics

SEATTLE -- A University of Washington study has found that white and Chinese people with low vitamin D blood levels are at greater risk of heart disease; however, black and Hispanic people with low vitamin D are not.

Previous research has suggested that low vitamin D, which people get from sunlight and certain foods, is associated with a higher risk of developing coronary heart disease among white people. But, these studies did not include a substantial number of people from other races, reports Dr. Cassianne Robinson-Cohen, lead author of the new UW study.

Knowing that people with darker skin pigments tend to have lower vitamin D levels and some of these populations have higher rates of heart disease, Robinson-Cohen decided to investigate whether the association applied to all races.

She found that while low vitamin D levels are linked to greater risk of heart disease in white and Chinese people, that is not the case in black and Hispanic people.

"Our study suggests that the results of ongoing vitamin D clinical trials conducted in white populations should be applied cautiously to people of other racial and ethnic backgrounds," Robinson-Cohen said.

Robinson-Cohen's team plans to conduct further research to determine whether vitamin D testing and supplementation are reasonable prevention measures for heart disease.

"Our future studies will examine the genetics affecting the levels and use of Vitamin D in the body to try to figure out why the link between low vitamin D blood levels and heart disease varies by race and ethnicity," she said. "We don't know for sure, but perhaps genes affecting the need for and use of vitamin D could have evolved to adapt to different levels of sun exposure in places where various ethnic subgroups of people originated."

This UW study enrolled more than 6,800 men and women from six regions across the United States between 2000 to 2002. All participants were free of any known cardiovascular diseases at the time they enrolled. Researchers tested their blood levels of vitamin D at the start of the trial and again upon the first incidence of coronary heart disease events - myocardial infarction, angina, cardiac arrest, or death from coronary heart disease until May 2012.