Human Milk Microbiota and Oligosaccharides: A Glimpse into Benefits, Diversity, and Correlations

Abstract

Human milk represents a cornerstone for growth and development of infants, with extensive array of benefits. In addition to exceptionally nutritive and bioactive components, human milk encompasses a complex community of signature bacteria that helps establish infant gut microbiota, contributes to maturation of infant immune system, and competitively interferes with pathogens. Among bioactive constituents of milk, human milk oligosaccharides (HMOs) are particularly significant. These are non-digestible carbohydrates forming the third largest solid component in human milk. Valuable effects of HMOs include shaping intestinal microbiota, imparting antimicrobial effects, developing intestinal barrier, and modulating immune response. Moreover, recent investigations suggest correlations between HMOs and milk microbiota, with complex links possibly existing with environmental factors, genetics, geographical location, and other factors. In this review, and from a physiological and health implications perspective, milk benefits for newborns and mothers are highlighted. From a microbiological perspective, a focused insight into milk microbiota, including origins, diversity, benefits, and effect of maternal diet is presented. From a metabolic perspective, biochemical, physiological, and genetic significance of HMOs, and their probable relations to milk microbiota, are addressed. Ongoing research into mechanistic processes through which the rich biological assets of milk promote development, shaping of microbiota, and immunity is tackled.

Keywords: breastfeeding; human milk; human milk benefits; human milk oligosaccharides; maternal diet; milk microbiota.

Figure 1

A summarized description of the benefits of breastfeeding and effects of human milk on the early and long-term infant health, as well as benefits for the mother.

Figure 2

Functions of human milk microbiota and human milk oligosaccharides (HMOs).

Figure 3

Basic structures of Human Milk Oligosaccharides (HMOs). The core HMO structures are shown in yellow and blue in the center of the figure. The upper panel shows fucosylated HMOs, and the lower panel shows sialylated ones. The building blocks are shown in the lowermost part of the figure [191].