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Milk mineral composition is strongly associated with the milk microbiota and weakly with the maternal diet
Lilian Lopez Leyva (School of Human Nutrition, McGill University), Dr. Emmanuel Gonzalez (Canadian Centre for Computational Genomics (C3G), McGill Interdisciplinary Initiative in Infection and Immunity (MI4), McGill U), Dr. Corinne F. Maurice (McGill Centre for Microbiome Research, Microbiology & Immunology Dept, McGill U) and Dr. Kristine G. Koski (School of Human Nutrition, McGill U)
Background: Low concentrations of minerals in human milk may be insufficient for infant development. The relationships between maternal mineral intake, milk mineral composition, and the milk microbiota remain understudied, particularly in low-and middle-income countries.
Objective: To analyze the associations between milk mineral concentrations, maternal mineral intake, and the human milk microbiome in an indigenous Guatemalan population.
Methods: In this cross-sectional study, milk samples from 77 mothers were categorized as early (5–46 days, n=38) or established lactation (4–6 months, n=39). Concentrations of 12 milk minerals were measured, maternal dietary intake was assessed via two 24-hour recalls, and the milk microbiome was analyzed using 16S rRNA gene sequencing. Correlations and regressions were used to examine relationships between milk minerals, maternal diet, and bacterial diversity. Dietary intakes and milk mineral concentrations were compared to INCAP recommendations.
Results: Maternal intakes of Ca, Fe, Mn, K, and Se were inadequate throughout lactation, and Cu was deficient in established lactation. Correlations between maternal mineral intake and milk mineral concentrations were weak. Milk Ca, Se, Mg, Na, and K were below reference values at specific stages. Fe and Mn correlated significantly with microbial composition, including unique taxa at each lactation stage, while Mg influenced Euryarchaeota in early lactation. Bifidobacteria and Lactobacillus showed no associations with milk or maternal mineral intake.
Conclusions: The interplay between milk minerals and the microbiome is dynamic and operates largely independently of maternal diet, varying by lactation stage. These findings underscore the complexity of milk composition and its potential implications for infant health.
