African-American men need to spend a lot more time in the sun if they want to get all the vitamin D they need. That’s the word from a new study conducted at Northwestern University Feinberg School of Medicine. According to Adam Murphy, MD, a clinical instructor in urology at the School, “skin color and sunlight exposure need to be considered for recommended daily allowances of vitamin D.”
In this latest study, 63 percent of African-American men were deficient in vitamin D compared with 18 percent of Caucasian men. To make matters worse, the blood serum levels of vitamin D in the African-American men were even lower than those in Caucasian men who were deficient: vitamin D levels were only 17.2 ng/ml among black men compared with 24.2 ng/ml among the white men.
When vitamin D levels fall below 20 ng/ml, “the bone starts to become brittle in adults and in kids it causes rickets,” noted Murphy. Vitamin D deficiency is also associated with prostate cancer, diabetes, multiple sclerosis, and rheumatoid arthritis. The commonly used and healthier cutoff point is 30 ng/ml of vitamin D, although the Vitamin D Council recommends 50 ng/ml as the optimal minimal level for health.
Vitamin D deficiency among African-American men
All the men in this study were from Chicago, an area of low sunlight compared with more southern regions. When you combine insufficient exposure to sunlight with the fact that the pigment called melanin in darker skin blocks the ultraviolet rays needed by the body to produce vitamin D, the result is that African-American men need up to six times more exposure to sunlight than Caucasian men, Murphy noted.
Murphy, a Chicago-based African-American physician, pointed out that he needs 90 minutes of sunlight three times a week to get enough vitamin D compared with just 15 minutes three times a week for a Caucasian male in Chicago.
Murphy explained that all men who live in the northern third of the United States need to increase their vitamin D supplementation. To achieve a healthy level of vitamin D in their bloodstream, Murphy said African-American men who live in Chicago need to take nearly 2,500 International Units (IUs) of a vitamin D supplement. Yet the standard, one-size-fits-all recommendation from the Institute of Medicine is merely 600 IUs daily for adults.
All men, and especially African-American men, should evaluate their vitamin D intake and talk to their doctor about supplementation. Foods that contain vitamin D include cold-water fish such as salmon, herring, trout, sardines, and halibut; fortified orange juice and fortified cereals are moderate sources.
Murphy AB et al. Predictors of serum vitamin D levels in African American and European American men in Chicago. American Journal of Mens Health 2012 Sep; 6(5): 420-26