Long-chain n-6 polyunsaturated fatty acids in breast milk decrease the risk of HIV transmission through breastfeeding.

Background: Breastfeeding accounts for a sizable proportion of infant HIV infections. Some fatty acids (FAs) are potent immunomodulators with virucidal activity, and their primary source in breastfed children is breast milk.

Objectives: The aims of the study were to examine whether the percentage weight concentration of FAs in breast milk was associated with the risk of mother-to-child transmission (MTCT) of HIV by breastfeeding and with shedding of cell-free virus (CFV) or cell-associated virus (CAV) in breast milk.

Design: We conducted a case-control study nested within a cohort of HIV-infected Tanzanian women and children. We matched 59 incident breastfeeding MTCT cases to 59 nontransmitting controls based on the child's age at sample collection. We quantified FAs, CFV, and CAV in a breast milk sample collected before the infant's first positive HIV test.

Results: After adjustment for indicators of maternal HIV disease stage, the risk of MTCT was inversely related to 11c,14c-eicosadienoic acid [odds ratio (OR) for quartile 4 compared with quartile 1: 0.21; P for trend = 0.04], arachidonic acid (OR: 0.21; P for trend = 0.03), and dihomo-gamma-linolenic acid (OR: 0.24; P for trend = 0.03); the latter 2 were also linearly, inversely related to virus shedding in breast milk. Lauric acid and pentadecanoic acid were associated with increased MTCT, whereas trans FAs were related to higher CAV and CFV.

Conclusion: Increasing concentrations of long-chain n-6 polyunsaturated FAs in breast milk might reduce the risk of MTCT.