In two analyses of HIV-positive mothers in Tanzania, those who took vitamin A and beta-carotene supplements had significantly higher HIV loads in their breast milk than women who did not take them (P=0.02), as well as a higher risk of subclinical mastitis. This inflammatory response leads junctions in the mammary epithelium to open and allow extracellular fluid to flow from plasma to milk; it could thus could explain the higher viral load, said Eduardo Villamor, MD, PhD, of the University of Michigan, a member of both study teams.
"Daily supplementation with these nutrients at the doses tested in the trial should probably not be given to HIV-infected lactating women," Villamor said.
Both analyses come from a randomized, controlled trial of 1,078 HIV-positive women who received either: vitamin A (5,000 IU) and beta-carotene (30 mg); B-complex vitamins and vitamins C and E; a multivitamin and vitamin A; or placebo.
In a group of 594 women, the proportion of breast milk samples with detectable viral load was significantly higher in those who took regimens with vitamin A and beta-carotene than in the other groups (51.3 percent vs. 44.8 percent, P=0.02). This effect was evident at least six months after birth, when there was a 34 percent increased risk of HIV shedding in milk (relative risk 1.34; 95 percent confidence interval 1.04 to 1.73). No significant differences were noted between women who took multivitamins and those who took the placebo. Breast milk concentrations of beta-carotene were related to increased detectable viral load in milk.
In the second study, the subclinical mastitis of 674 women was assessed by the sodium-to-potassium ratio in breast milk. The researchers noted a 45 percent increased risk of severe subclinical mastitis (P=0.03) in those on vitamin A and beta-carotene, with non-significant trends toward greater risk of moderate subclinical mastitis or any degree of the condition.
Compared to the placebo group, the women receiving multivitamins without vitamin A and beta-carotene had a 33 percent increased risk of subclinical mastitis (P=0.005) and a 75 percent higher risk of severe subclinical mastitis (P=0.0006). A trend toward increased risk for women receiving multivitamins plus vitamin A and beta-carotene was noted but was not significant. For women with CD4+ T-cell counts of 350 or greater, multivitamin use resulted in a 49 percent increased risk of any subclinical mastitis (P=0.006). Multivitamins had no effect on women with lower counts.
Villamor noted that the findings about other vitamins are not particularly concerning, as previous studies have shown them to have beneficial effects. Regarding vitamin A and beta-carotene, however, there are now "strong arguments to consider the implications of supplementation to pregnant or lactating women who are HIV-positive. It does not look like it's a safe intervention for them."
"Effect of Vitamin Supplements on HIV Shedding in Breast Milk" was published in the American Journal of Clinical Nutrition (doi: 10.3945/ajcn.2010.29339). "Vitamin Supplementation Increases Risk of Subclinical Mastitis in HIV-Infected Women" was published by the Journal of Nutrition (doi:10.3945/jn.110.122713).