Thursday, September 22, 2011
African-American men living in low sunlight areas are more likely to experience vitamin D deficiency than European-American men living in the same environment
Researchers evaluated the marker for vitamin D - the 25 hydroxyvitamin D level (25-OH D level) - in 492 men aged 40 to 79 years who lived in Chicago, a low ultraviolet radiation (UVR) part of the country. Of that group, 93% of African-American men and 69.7% of European-American men were vitamin D deficient; having 25-OH D levels of less than 30 ng/mL. Results showed that vitamin D levels were low in African American men, those with lower income and those with higher body mass index. Low sunlight exposure is a known factor in lower levels of vitamin D, but researchers found that African American men still had lower levels of vitamin D in sunnier seasons. Researchers attribute low vitamin D levels to the composition of African-American skin, which contains more of the dark pigment melanin than lighter skin. When UVR light hits the skin cells, it reacts with the molecule 7-dehydrocholesterol to begin the production of vitamin D, which is then further processed by the body to make active vitamin D. In African-Americans, though, dark melanin blocks UVR rays from being absorbed, thus reducing the amount of vitamin D naturally produced. Vitamin D deficiency has been linked to multiple diseases, including breast cancer, prostate cancer, diabetes, rheumatoid arthritis and multiple sclerosis, which is why the researchers believe it is essential to adjust recommendations to reflect differences between African Americans and European-Americans.