HMOs AND THE INFANT MICROBIOTA

HMOs and the infant microbiota

On 20 March 2019, a CPD meeting for midwives and health visitors was held at the Royal College of Obstetricians and Gynaecologists in London. John Bonner reports on the proceedings

It has been known since the 19th century that there is a direct relationship between early diet and health. Breastfed infants had been shown to have lower incidence of infectious diseases and a higher survival rate than those fed formula. In the guts of healthy breastfed babies, the microbiota is dominated by Bifidobacteria (beneficial bacteria). Professor Sharon Donovan, Professor of Nutrition at the University of Illinois, presented the evidence for the unique relationship that has evolved between these bacteria and the human species.

Bifidobacteria use human milk oligosaccharides (HMOs) as their preferred source of food to grow. HMOs are a diverse group of complex carbohydrates that have a prebiotic effect. HMOs cannot be broken down by human digestive enzymes and instead pass into the colon. While these HMOs can be metabolised by other components of the microbiota, bifidobacteria are more efficient at absorbing and processing these compounds and will often out-compete other bacteria, including potentially harmful strains.

Since the 1990s, formula milk manufacturers have tried to reproduce the health benefits of breast milk by including two prebiotic components, galacto-oligosaccharide (GOS) and fructo-oligosaccharide (FOS) in their products. However, GOS/FOS are compounds that have a much simpler structure than HMOs. The latter will often contain two more saccharides, either fucose or sialic acid and tend to be more biologically active. With advances in technology, it has been possible to produce two structurally identical HMOs, 2'-fucosyllactose (2’-FL) and lacto-N-neotetraose (LNnT), in sufficient quantities to be included in commercial products.