Vitamin D supplements significantly reduced blood pressure in the first large controlled study of the effects of supplementation on African Americans blood pressure, according to a journal report.
In the prospective trial, published in the April issue of the American Heart Association journal Hypertension, a three-month regimen of daily vitamin D increased serum vitamin D and resulted in a decrease in systolic blood pressure ranging from 0.7 to 4 mmHg (depending upon the dose given), compared with no decrease in participants who received a placebo.
“Although this needs to be studied further, the greater prevalence of vitamin D deficiency among African Americans may explain in part some of the racial disparity in blood pressure,” John P. Forman, MD, MSc, the studys lead author and an assistant professor of medicine in the Renal Division and Kidney Clinical Research Institute at Brigham and Womens Hospital in Boston, said in a news release.
African Americans have higher rates of hypertension and lower levels of circulating 25-hydroxyvitamin D than the rest of the U.S. population, according to information in the study. Few studies have included enough African Americans to determine whether vitamin D supplements might reduce the racial disparity, the researchers noted.
To investigate the issue, researchers from seven major teaching hospitals conducted a four-arm, randomized, double-blinded study of 250 African-American adults. They tested blood pressure after a three-month regimen of daily vitamin D supplementation at one of three doses, and compared the findings with a group taking placebo vitamins.
They found that taking 1,000 units of vitamin D each day for three months was associated with a 0.7-mmHg decrease in systolic blood pressure. Taking 2,000 units was linked to a 3.4-mmHg decrease, while taking 4,000 units netted a 4-mmHg drop.
Participants taking placebo supplements had an average increase of 1.7 mmHg.
“The gains we saw were significant but modest,” Forman said. Furthermore, diastolic blood pressure didnt change in any of the four groups.
In prospective studies, lower blood levels of 25-hydroxyvitamin D have been independently linked with an increased risk of developing hypertension, the researchers noted.
The study abstract is available at http://hyper.ahajournals.org/content/61/4/779.abstract.