Background:  Vitamin D has a potential role in preventing HIV-related complications, based on its extensive involvement in immune function. However, this relationship has not been examined in large studies or in resource-limited settings.

Methods:  Vitamin D levels were assessed in 884 HIV-infected pregnant women at enrollment in a trial of multivitamin supplementation (excluding vitamin D) in Tanzania. Information on HIV disease progression and related complications was recorded during follow-up (median, 70 months). Proportional hazards models and generalized estimating equations were used to assess the relationship of vitamin D status with these outcomes.

Results:  Women with low vitamin D status (serum 25-hydroxyvitamin D <32 ng/mL) had 45% higher risk of reaching a body mass index <18 kg/m² during the first 2 years of follow-up, compared to women with adequate vitamin D levels (incidence rate ratio, RR:  1.45; 95%CI 1.04 to 2.01). The relationship between continuous vitamin D levels and risk of body mass index <18 kg/m² during follow-up was inverse and linear (P=0.03; Figure 1). Low vitamin D status was associated with a 25% higher risk of progression to WHO HIV disease stage III or IV during follow-up (RR:  1.25; 1.05 to 1.50), compared to adequate vitamin D status. This risk decreased with increasing vitamin D levels linearly (P =0.05; Figure 2). Women with low vitamin D levels had significantly higher incidence of acute upper respiratory infections (RR: 1.28, 1.05 to 1.55) and thrush (RR:  2.92, 1.43 to 5.96) diagnosed during the first 2 years of follow-up. Women in the lowest vitamin D quintiles had higher incidence of mouth and throat ulcers, painful tongue or mouth, difficult or painful swallowing, diarrhea, and fatigue during the first 2 years of follow-up.

Conclusions:  Vitamin D status has a protective association with HIV disease progression and HIV-related complications during follow-up in HIV-infected women. If confirmed in randomized trials, vitamin D supplementation could represent a simple and inexpensive method to prolong the time to ART initiation in HIV-infected patients and improve health and quality of life, particularly in resource-limited settings.

Figure 1. Relationship of Vitamin D Status with Wasting
(BMI <18 kg/m²) in the First 2 Years of Follow-up

Figure 2: Relationship of Vitamin D Status with HIV Disease Progression
(Stage III/IV) during Follow-up

*Adjusted for baseline age, CD4 T cell count, HIV disease stage and multivitamin regime