Vitamin D plays an important part in the human immune response and deficiency can leave individuals less able to fight infections like HIV-1. Now an international team of researchers has found that high-dose vitamin D supplementation can reverse the deficiency and also improve immune response. "Vitamin D may be a simple, cost-effective intervention¹, particularly in resource-poor settings, to reduce HIV-1 risk and disease progression," the researchers report in today's (June 15) online issue of Proceedings² of the National Academy of Sciences.

 

The researchers looked at two ethnic³ groups in Cape⁴ Town, South Africa, to see how seasonal⁵ differences in exposure to ultraviolet B radiation, dietary vitamin D, genetics, and pigmentation affected⁶ vitamin D levels, and whether high-dose supplementation improved deficiencies and the cell's ability to repel⁷ HIV-1.

 

"Cape Town, South Africa, has a seasonal ultraviolet B regime and one of the world's highest rates of HIV-1 infection, peaking in young adults, making it an appropriate location for a longitudinal study like this one," said Nina Jablonski, Evan Pugh Professor of Anthropology⁸, Penn State, who led the research.

 

One hundred healthy young individuals divided between those of Xhosa ancestry⁹ -- whose ancestors migrated from closer to the equator into the Cape area -- and those self-identified as having Cape Mixed ancestry -- a complex admixture of Xhosa, Khoisan, European, South Asian and Indonesian populations -- were recruited for this study. The groups were matched for age and smoking. The Xhosa, whose ancestors came from a place with more ultraviolet B radiation, have the darkest skin pigmentation, while the Khoisan -- the original inhabitants of the Cape -- have adapted to the seasonally¹⁰ changing ultraviolet radiation in the area and are lighter¹¹ skinned. The Cape Mixed population falls between the Xhosa and Khoisan in skin pigmentation levels.

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