Maternal dietary intervention during lactation impacts the maternal faecal and human milk microbiota.

AIMS:To determine the effect of a two-week reduced fat and sugar and increased fibre maternal dietary intervention on the maternal faecal and human milk (HM) microbiomes. METHODS AND RESULTS:Faecal swabs and HM samples were collected from mothers (n = 11) immediately pre-intervention, immediately post-intervention, and 4- and 8-weeks post-intervention, and were analysed using full-length 16S rRNA gene sequencing. Maternal macronutrient intake was assessed at baseline and during the intervention. Maternal fat and sugar intake during the intervention were significantly lower than pre-intervention (P=<0.001, 0.005, respectively). Significant changes in the bacterial composition of maternal faeces were detected after the dietary intervention, with decreases in the relative abundance of Bacteroides caccae (P=<0.001) and increases in the relative abundance of Faecalibacillus intestinalis (P = 0.006). In HM, the diet resulted in a significant increase in Cutibacterium acnes (P = 0.001) and a decrease in Haemophilus parainfluenzae (P=<0.001). The effect of the diet continued after the intervention, with faecal swabs and HM samples taken 4- and 8-weeks after the diet showing significant differences compared to baseline. CONCLUSION:This pilot study demonstrates that short-term changes in maternal diet during lactation can alter the bacterial composition of the maternal faeces and HM. Clinical trial registration: Australian New Zealand Clinical Trials Registry (ACTRN12619000606189). Website: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=377188&isReview=true.