A new study led by an international team of scientists reveals that several bioactive components that are found in human milk are closely related to the reduction of HIV transmission from a HIV-positive mother to her child. The study is published in the online journal American Journal of Clinical Nutrition.
The senior author of the study, Lars Bode, an assistant professor at the UCSD (University of California, San Diego) School of Medicine, says that in most less-developed countries around the world, HIV-positive mothers are unsure whether to breastfeed their newborns or not. “Breastfeeding exposes the baby to the virus and increases the risk of the baby dying from HIV infection; but not breastfeeding increases the risk for the baby to die from other intestinal or respiratory infections”, added Dr Bode.
Dr Bode and his research team wanted to find out why most children that were born from a HIV-positive mother do not contract the HIV virus. Previous studies have shown that only a small number, around 15 percent, of infants receive the HIV infection, even though most of them receive their mother’s milk for more than a few months.
The team discovered that human milk contains an immunologically active component called oligosaccharide (or HMO – human milk oligosaccharide). This is a saccharide polymer that consists of a small number of simple sugars that are linked together. The team also discovered that oligosaccharides are found abundantly in the human milk and are not digestible. This translates into high concentrations of oligosaccharides found on the surface of the child’s gastrointestinal tract.
Dr Bode says that these human milk oligosaccharides have the role of prebiotics, adding that one of their most important role is to aid the growth of bacteria. Furthermore, the aspect of these oligosaccharides resembles that of glycans (polysaccharides that are found on the surface of epithelial cells). Finally, the human milk oligosaccharides have also been linked to the inflammatory response and were discovered to regulate the immune response in both animal and cellular models.
The research team analyzed the amount of human milk oligosaccharides from the breast milk of more than 200 women. The women participated in an extensive study in Lusaka, the capital of Zambia, a country in the south of the African continent. The women and their children were followed from birth until the child reached the age of 2. Most of the women that participated in the study did not have access to antiretroviral therapy, thus allowing scientists to study the effect human milk oligosaccharides has on HIV-transmission.
The study concludes that a higher concentration of human milk oligosaccharides in breast milk is associated with a better protection against HIV transmission. Future studies will reveal a better understanding on the exact mechanism that allows human oligosaccharides to facilitate or obstruct the transmission of HIV. Researchers suggest that understanding this process will open up new therapy possibilities and new prevention methods for postnatal HIV transmission.