Vitamin D supplements may help African-Americans lower their blood pressure, researchers report in the American Heart Association journal Hypertension. In fact, after three months, systolic blood pressure decreased for every 1000 units of vitamin D taken daily.

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

African-Americans have higher rates of hypertension and lower levels of vitamin D3 than the rest of the U.S. population.

“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,” said John P. Forman, M.D., M.Sc., lead author of the study and Assistant Professor of Medicine in the Renal Division and Kidney Clinical Research Institute at Brigham and Women’s Hospital in Boston, Mass.

More studies in larger groups of African-Americans are necessary to confirm the findings.