African Americans may want to consider adding more vitamin D to their diets. Vitamin D supplements appear to help lower blood pressure, particularly among blacks.

A large study of African Americans by researchers at seven U.S. teaching hospitals found that daily vitamin D supplements significantly reduced systolic blood pressure in black adults.

It has long been observed that African Americans have lower circulating levels of vitamin D in their blood and higher rates of hypertension compared to the rest of the U.S. population, but few studies have enrolled enough black participants to determine the reasons for this racial disparity.

African Americans have lower circulating levels of vitamin D in their blood and higher rates of hypertension compared to the rest of the U.S. population.

Investigators divided 250 black adults into four groups. One group was given a placebo rather than vitamin D. People in the other three groups were given either 1000, 2000, or 4000 I.U. of vitamin D daily.

After three months, the group who took no vitamin D had a 1.7 mm Hg increase in Systolic pressure . The group assigned to receive 1000 I.U. had a .7 mm Hg reduction in systolic blood pressure.

In the 2000 I.U. and 4000 I.U. groups the reductions were 3.4 mm Hg and 4 mm Hg, respectively. "This degree of blood pressure reduction, if confirmed in future studies, would be considered clinically significant," John Forman, lead author of the current study, told TheDoctor in an e-mail.

Systolic blood pressure, the top number in a blood pressure reading, is the pressure in your arteries when your heart beats. Diastolic pressure, the bottom and lower number, is the pressure in your arteries between heart beats.

Forman, an assistant professor of medicine at Brigham and Women’s Hospital in Boston, stresses that further research is necessary to confirm these findings. He and his team are currently involved in two other randomized trials to examine the effects of vitamin D on blood pressure. The trials include a large number of African American participants, so the results of those trials can be compared with the results of this study.

As Andrew Chan, co-author of the study said in a statement, "If vitamin D supplementation lowered blood pressure among African-Americans, its widespread use could have major public health benefits."

The study is published recently in the journal, Hypertension.