Background: Optimizing nutrition during lactation is critical to mother and infant. The relationship between fermented food consumption and the mother’s gut microbiota, nutritional and inflammation status is unknown. Mageu is a fermented grain commonly consumed in Southern Africa.

Methods: We randomized South African mothers to consume a live-culture mageu (LCM), pasteurized store-bought mageu (SBM), or no mageu from 4 to 10 weeks postpartum. Clinical and dietary data, stool microbiota, and nutritional and inflammatory biomarkers were assessed until week 15.

Results: Plant protein intake was higher among mageu users than non-users. LCM increased gut alpha-diversity from weeks 4 to 10, and circulating ferritin was lower among LCM users at week 10 compared to non-users. In system analysis, bacterial, inflammation and nutritional signatures were associated with mageu intake, driven by IL-6, ferritin, soluble transferring receptor and Eubacterium halli.

Conclusions: These results suggest that mageu has benefits for lactating mother’s gut health, and therefore possibly their infants.