MILKBIOME · Variations in biochemical and microbiological milk composition among highly diverse human populations and their impact on infant gut ecosystem

Variations in biochemical and microbiological milk composition among highly diverse human populations and their impact on infant gut ecosystem

Human milk is universally considered as the best source of nutrition for the newborn infant. In addition to its recognized nutritional value, and to the vast array of immunological components it provides to the newborn infant, human milk represents a constant supply of commensal, non-pathogenic and potential probiotic bacteria to the infant gastrointestinal tract. Milk is also a rich source of human milk oligosaccharides (HMOs), which have been shown to interrupt the attachment of enteric pathogens to the intestinal mucosa and to act as prebiotic substrates within the infant intestine, where they can promote the growth of certain beneficial bacteria. Therefore human milk strongly influences the establishment and composition of the new born intestinal microbiota, known to be closely related to survivorship. The rationale behind this multidisciplinary and cooperative project is that human milk composition may have evolved differentially in response to different selective pressures driven by socio-ecological and environmental factors. In order to investigate how selected population-specific factors can contribute to variation of various main human milk components, this study will depict human milk composition at multiple levels on samples obtained from samples living in very different environmental, economical, dietary and socio-ecological settings, including 10 geographical locations encompassing both developed and developing countries. To achieve these goals human milk and infant fecal samples have been collected from 410 mother-infant pairs. During samples collection, socio-ecological data have been collected and analyzed on the studied populations, providing further insights on the environmental factors, including sanitation and hygienic conditions, dietary habits and recent diseases history, that may be associated to the observed variability on human milk composition and, therefore, might have conditioned evolutionary adaptation of human milk composition to particular environmental settings. Several human milk components were studied by multiple methodologies: the microbiological composition of human milk has been studied through culture-independent and culture-based methodologies, HMO profiles were determined through GC-MS and an array of immunological components, including immunoglobulins, chemokines and growth factors, which were determined through flow-cytometry based analysis. Sampling has been successfully completed and, therefore, both biological samples and socio-ecological information is already available for analysis. Microbiome has already been performed and the still ongoing bioinformatics analysis of the data is expected to provide the first global-wide picture of human milk microbiomes variation. A preliminary analysis of our results suggests a strong clustering of sample profiles directed by samples location although whole picture require statistical analysis including biological, biochemical and socio-ecological meta-data integration. Results obtained will be of great value to the scientific community and will influence the way “normal” human milk composition is regarded up to the present. Besides, this study will provide unique information on microbiomes evolution under different environmental settings and set up the basis to define further research in the area of microbiomes modulation during perinatal life. Furthermore, the interdisciplinary and cooperative nature of the MILKBIOME project is contributing to establish collaborations with world-wide leaders of closely related research fields and will undoubtedly reinforce European research visibility at a global scale. Further collaborations to keep on analyzing other components of human milk with potential biological activity have arisen and will expand the herein generated results.

Data: CORDIS, © European Union