Human milk microbiome is shaped by breastfeeding practices

Area of Science:

• Human Microbiome Research
• Lactation Biology
• Indigenous Health Studies

Background:

• Breastfeeding practices influence milk microbiota diversity at the genus level.
• The impact of exclusive (EBF) versus non-exclusive breastfeeding (non-EBF) on milk microbiome species composition remains underexplored.

Purpose of the Study:

• To investigate how exclusive breastfeeding (EBF) and non-exclusive breastfeeding (non-EBF) practices affect the milk microbiome at the species level.
• To analyze changes in milk microbiome composition across early and late lactation stages in indigenous Mayan mothers.

Main Methods:

• Cross-sectional study of 64 indigenous Mayan mothers in Guatemala.
• Analysis of milk microbiome species composition based on breastfeeding status (EBF vs. non-EBF) and lactation stage (early vs. late).

Main Results:

• Four distinct milk microbial community clusters were identified, correlating with breastfeeding practices and lactation stage.
• Exclusive breastfeeding (EBF) showed a higher abundance of commensal and lactic acid bacteria, including *Lactobacillus gasseri*, compared to non-EBF.
• Non-exclusive breastfeeding (non-EBF), involving herbal teas or complementary foods, altered the milk microbiome, reducing oral bacteria and increasing environmentally sourced bacteria.

Conclusions:

• Exclusive breastfeeding (EBF) promotes a milk microbiome rich in beneficial bacterial species.
• Introduction of non-breast milk substances (herbal teas, foods) significantly modifies the milk microbiome composition.
• Breastfeeding practices and complementary feeding choices have a distinct impact on the milk microbial ecosystem species composition.