Low Vitamin D in African Americans
Vitamin D is acquired through diet and skin exposure to ultraviolet B light. The skin’s production of vitamin D is determined by length of exposure, latitude, season, and degree of skin pigmentation. African Americans produce less vitamin D than do White Americans in response to equal levels of sun exposure, and have dramatically lower vitamin D concentrations with some studies indicating up to 96 percent of the African American population as low. Yet both races tend to have similar capacities to absorb vitamin D and to produce vitamin D when exposed to light. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4030388/)
Overall when measured, African Americans tend to have lower vitamin D3 levels and are very frequently labeled “vitamin D deficient”, but also have confirmed stronger bones and fewer fractures. Powe and colleagues at the Brigham and Woman’s Hospital in Cambridge Massachusetts looked specifically at this paradox and looked at vitamin D3 and vitamin D-binding proteins.
“Lower levels of vitamin D–binding protein in blacks appear to result in levels of bioavailable 25-hydroxyvitamin D that are equivalent to those in whites. These data . . . suggest that low total 25-hydroxyvitamin D levels do not uniformly indicate vitamin D deficiency and call into question routine supplementation in persons with low levels of both total 25-hydroxyvitamin D and vitamin D– binding protein who lack other traditional manifestations of this condition.”
The result of these studies suggest that having both a low vitamin D level and a low vitamin D-binding protein in African Americans actually causes a ‘re-set’ of true deficiency. With both being low, it is vitamin D’s bioavailability that drives calcium levels, parathyroid hormone levels, and true bone risk.
Dr. Powe concluded:
“Vitamin D deficiency is certainly present in persons with very low levels of total 25-hydroxyvitamin D accompanied by hyperparathyroidism, hypocalcemia, or low BMD (bone mass density). However, community-dwelling blacks with total 25-hydroxyvitamin D levels below the threshold used to define vitamin D deficiency typically lack these accompanying characteristic alterations. The high prevalence among blacks of a polymorphism in the vitamin D–binding protein gene that is associated with low levels of vitamin D–binding protein results in levels of bioavailable 25-hydroxyvitamin D that are similar to those in whites, despite lower levels of total 25-hydroxyvitamin D. Alterations in vitamin D–binding protein levels may therefore be responsible for observed racial differences in total 25-hydroxyvitamin D levels and manifestations of vitamin D deficiency.”
So all of this would suggest that African Americans don’t need Vitamin D replacement or supplements.
Do we need additional Vitamin D or not??
Ken Batai and colleagues at the University of Arizona, after studying over two thousand people, found a direct benefit to Vitamin D supplements to preventing prostate cancer in African American men and a pro-carcinogenic effect (inducing effect) of calcium supplementation on the prostate. These findings were strongest in African Americans.
“Calcium and vitamin D are important nutrients, and they may have preventive effects against many health conditions. Although toxicity from high vitamin D supplementation may be low, high calcium intake is associated with increased prostate cancer risk as well as risk of cardiovascular disease and kidney stones. High calcium consumption might be harmful and for prostate cancer prevention, high dose calcium supplementation and fortification should be avoided, especially among AA (African American) men.”
High calcium intake in African American men may actually increase the risk for prostate cancer, but taking vitamin D can reduce the risk.
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- Sleep Differences in African Americans - February 10, 2018
- Low Vitamin D in African Americans - February 9, 2018
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