Breastmilk and Human Microbiome Development

The importance of gut microbes to well-being is one of the hottest topics in health. Another is the benefits of breastfeeding. It’s popularly assumed that breastmilk supports a healthy microbiome in infants, but what does the research show? A new review article in Science outlines what we know and don’t know about how this support may work.

Whether breastmilk is the main delivery route for probiotics such as B. longum infantis is still unknown. Breastmilk contains microbes, but as yet no transport of such bacteria from a mother’s gut to her mammary glands has been demonstrated. Mother-infant skin contact, exposure during vaginal birth, and environmental exposures are other likely ways a baby may integrate these microbes into its gut flora.

A more well-understood role breastmilk plays is in delivering prebiotics—food for preferred microbial strains. For example, one factor that distinguishes human breastmilk from other primates is the presence of oligosaccharides indigestible by humans but loved by Bifidobacterium. These beneficial bacteria cleave the oligosaccharides into short-chain fatty acids that can then feed developing colon cells, support the immune system, and maintain an intestinal pH that’s hostile to pathogens.

Genetics offers another area for investigation. One gene, FUT2, has been widely studied for its role in a mother’s oligosaccharide production. Does baby have genes that make it more or less receptive to hosting the microbes that would receive these compounds? Might different mother-child genotype pairs work better together in establishing gut flora? Might the microbes themselves play a part in gene expression in developing intestinal cells? And finally, what health interventions for people of all ages might come from a better understanding of breastmilk and the infant microbiome?

With so many questions left to answer, clearly our knowledge of this area is still in its infancy.

Source: Science