African-American women battling vitamin D deficiencies need the same dose as Caucasian women to treat the condition, according to a recent study accepted for publication in The Endocrine Society's Journal of Clinical Endocrinology & Metabolism (JCEM).
Although women with darker skin tones tend to have lower levels of the biomarker used to measure Vitamin D levels, called 25-hydroxyvitamin D or 25OHD, the study found that older African-American and Caucasian women responded in the same way when they received vitamin D supplements.
Unlike many vitamins that are absorbed primarily from foods, the body's main source of vitamin D is sunlight. Vitamin D deficiency, which is primarily caused by inadequate exposure to sunlight and very poor diet, can result in abnormalities in calcium, phosphorus and bone metabolism. Vitamin D deficiency can cause rickets in children or a bone-softening condition called osteomalacia and muscle weakness in adults.
In a double-blind study that gave varying vitamin D doses to African-American and Caucasian women of similar body size, levels of the 25OHD biomarker were very similar. The findings suggest that vitamin D absorption and metabolism is the same in both groups. Researchers concluded that African-American women tend to have lower levels of the biomarker 25OHD because they naturally produce less vitamin D in the skin after sunlight exposure.
"African-American women don't have to worry about taking larger doses of vitamin D to compensate," said J. Chris Gallagher, MD, of Creighton University School of Medicine in Omaha, Neb., and lead author of the study. "They should follow the current medical guidelines for vitamin D supplementation suggested recently by the Institute of Medicine."