BackgroundOne mechanism by which early life environment may influence long term health is through modulation of the gut microbiota. It is widely accepted that the optimal source of nutrition in early life is breast milk, with Human Milk Oligosaccharides (HMOs) thought to play an important role in nourishing the developing microbiota. However, mothers with inactive secretor genes have altered HMO composition and quantities in their breast milk. In this pilot study we examine the influence of secretor status and breast-feeding on microbiota composition at 2 to 3 years of age.Methods37 children and 17 eligible mothers were recruited. Secretor status was determined from blood and saliva samples using hemagglutination inhibition technique and faecal microbiota composition was examined by 16S rRNA gene sequencing.ResultsSecretor status was determined for 28 eligible children with 20 being secretors (S, 71.4%). Eleven of the 17 mothers were secretors (S, 64.7%). Unweighted UniFrac distances were significantly associated with child secretor status (R2 = 0.069, p = 0.030) and with mother secretor status in children exclusively breastfed for at least 4 months (R2 = 0.167, p = 0.028), suggesting an influence on the presence/absence of microbes, with Prevotella not detected in samples from secretor children and children of secretor mothers. In children who were exclusively breast-fed for at least 4 months of life the abundance of the known HMO consumers Bifidobacterium were increased in the children of secretor mothers compared to non-secretor mothers. The relative abundance of an OTU related to Bacteroides plebeius, a bacterium noted for its capacity to utilise sulphated polysaccharides for growth, was decreased in these children.ConclusionsChild and mothers’ secretor status have an impact on childrens’ microbiota composition at 2 to 3 years of age.

The first 1000 days (conception to 24 months) is when gut microbiota composition and eating patterns are established, and a critical period influencing lifelong health. The aim of this study is to examine the associations between food intakes and microbiota composition at the end of this period. Diet was quantified for 37 well-nourished Australian children aged between 2 to 3 years by using a food frequency questionnaire and 24 hr recalls. Both dairy and plant-based (fruit, vegetables, soy, pulses and nuts) food intakes were associated with distinct microbiota profiles. Dairy intake was positively associated with the Firmicutes:Bacteroidetes ratio, and in particular Erysipelatoclostridium spp., but negatively associated with species richness and diversity. Vegetable intake was positively associated with the relative abundance of the Lachnospira genus, while soy, pulse and nut intake was positively associated with the relative abundance of bacteria related to Bacteroides xylanisolvens. Fruit intake, especially apples and pears, were negatively associated with the relative abundance of bacteria related to Ruminococcus gnavus. In this cohort of young children dairy and plant based food intakes were found to be associated with altered microbiota composition. Further exploration is needed to elucidate the effect of these dietary and microbial differences on host phenotype.

This study suggests that strategies to reduce protein intake and growth velocity in early life may limit fat-free mass growth, potentially predisposing to increased adiposity in later life.

These results suggest that previously reported associations between microbiota composition and body size may be driven by an association with fat-free mass, particularly in males.

Data on typical diet were collected using a quantitative Food Frequency Questionnaire (FFQ) that asked parents to report their child's frequency of consumption and typical portion size of 128 items, over the past month. The FFQ was specifically designed for this research study to include items