High Doses of Vitamin D May Reduce HIV Progression

Vitamin D supplementation may help boost patients’ immune responses, especially in winter months.

Researchers recently conducted a longitudinal study of patients in order to determine whether vitamin D supplementation modifies the response to HIV infection. Additionally, the researchers aimed to identify major determinants of vitamin D status, such as ultraviolet B (UVB) radiation exposure, diet, pigmentation, and genetics.

South Africa was the ideal site for this study because it has a large population of individuals with different skin tones, great variation in UVB radiation from north to south, and a high prevalence of serious infectious diseases such as HIV and tuberculosis, lead researcher Nina Jablonski, PhD, told Pharmacy Times.

“In the Western Cape, where the study was conducted, winter levels of UVB are low, and production of vitamin D in the skin can’t occur because of this,” Dr. Jablonski said. “I predicted that the seasonal fluctuation in vitamin D status might affect the competence of [individuals’] immune systems.”

The 160 study participants were divided into 2 groups based on self-reported ethnicity: a Xhosa group and another group with mixed ancestry, including Khoisan, European, South Asian, and Indonesian backgrounds. All of the individuals, but particularly the women, experienced varying degrees of vitamin D deficiency during winter months.

The Xhosa group was given 6 weeks of supplemental vitamin D, which brought 77% of those participants to ideal vitamin D levels, the researchers reported.

Dr. Jablonski said one of the most surprising findings was the dramatic effect of high-dosage vitamin D supplementation in reducing HIV progression.

The researchers took both winter- and summer-month blood samples from the participants and examined them for HIV infection. After 9 days, the winter samples had higher levels of infection than the summer samples.

In the winter samples from the Xhosa group, which was given the vitamin D supplement, the HIV infection rates were the same as the summer-month samples.

“The clearest implication of our study is not for [those] who are already infected with HIV, but rather for those who are at risk of infection,” Dr. Jablonski said. “In these [individuals], vitamin D supplementation will likely improve their immune responses, especially if they were deficient in the first place.”

Dr. Jablonski stressed that the study was conducted with a small sample size. However, many city dwellers are seriously vitamin D-deficient in the winter, which can affect the competence of their immune systems, she noted.

“In an increasingly urbanized world, vitamin D supplementation is a cheap, low-risk intervention that could help to reduce morbidity from infectious disease,” Dr. Jablonski concluded.

These findings were published in Proceedings of the National Academy of Science.