A study suggests that supplementing vitamin D in those with atherosclerosis or "hardening of the arteries," may have different effects in black and white patients.
Experts at the Wake Forest University School of Medicine found that the supplement could actually do harm in black individuals.
Principal investigator Barry I. Freedman, John H. Felts III Professor and chief of the section on nephrology at the School of Medicine, said: "In black patients, lower levels of vitamin D may not signify deficiency to the same extent as in whites. We should use caution when supplementing vitamin D in black patients while we investigate if we are actually worsening calcium deposition in the arteries with treatment."
The team based their research on the relationship between circulating vitamin D levels and arterial calcium in 340 black men and women with type 2 diabetes.
Freedman, an affiliate of the Maya Angelou Center for Health Equity, part of the School of Medicine, continued: "We found that higher circulating levels of vitamin D in blacks were associated with more calcium in the artery walls. This is the opposite effect of what is felt to occur in white patients and shows that the accepted "normal" range of vitamin D may be different between blacks and whites.
Freedman further warned physicians to practice caution when supplementing vitamin D levels in blacks.
Freedman added: "Doctors frequently prescribe supplemental vitamin D. However, we do not know all of its effects and how they may differ between the races. The bottom line is that racial differences in calcium handling are seen and black and white patients have differing risk for bone and heart disease. We should more clearly determine the effects of supplementing vitamin D in black patients with low levels based on existing criteria and should not assume that the effects of supplementation will be the same between the races."
The study has been published in the Journal of Clinical Endocrinology and Metabolism.