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The gene fucosyltransferase 2 (FUT2), which is not active in all mothers, is responsible for the production of certain sugars in breast milk, Californian scientists have discovered. These sugars are not digested by the child but serve as nutrition for bacteria that colonise the gut. In this manner, the composition of breast milk has effect on the gut microbiota, according to an article published in Microbiome.

Before birth, children’s guts are sterile. Only after their first exposure to bacteria do babies gradually develop their own gut microbiota. Nutrition plays an important role in this process, since the available nutrients determine which bacteria strains will be able to colonise the gut. A recent study has shown that bifidobacteria are found earlier and at a higher percentage in children from mothers with a functional FUT2 gene. This was discovered by a four month analysis of baby faeces in children drinking breast milk with and without FUT2-generated sugars.

Previous research has demonstrated that gut microbiota with bifidobacteria are associated with a well-functioning immune system. Furthermore, breast feeding by mothers with an active FUT2 gene is thought to transfer immunity to diarrheal disease. However, senior study author, David Mills, chair of Dairy Food Science at the University of California, Davis, states that “the non-functional FUT2 mother's milk is in no way less healthy, and their babies are at no greater risk.”

In the United States, approximately eighty percent of women harbour an active FUT2 gene. This has not only implications for their offspring: the FUT2 gene has additional functions in the human body and is associated with certain disease risks. For example, people with FUT2 function are less likely to develop diabetes mellitus type I and Crohn’s disease, while non-functional FUT2 is associated with rotavirus, norovirus and Helicobacter pylori resistance.

Sources: Eurekalert and Microbiome

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