Can microplastics affect the breast milk microbiome and infant gut bacteria?
Animal research says maternal polystyrene microplastic exposure can change the milk microbiome and affect offspring gut bacteria and immune markers. Human risk is still being studied.
What's actually in it
Microplastics are tiny plastic pieces. Polystyrene is used in some disposable cups, foam food containers, and packaging.
Breast milk carries nutrients and bacteria that help seed a baby's early gut microbiome. That early gut community helps train the immune system.
What the research says
A 2026 animal study in FASEB Journal exposed pregnant and nursing dams to polystyrene microplastics in drinking water. Maternal exposure changed the milk microbiome and the offspring gut microbiome.
The study found lower levels of beneficial bacteria such as Ligilactobacillus and higher levels of bacteria such as Escherichia-Shigella. Offspring also showed excessive weight gain, reduced IL-6, fewer splenic T-cell proportions, and weaker intestinal barrier markers.
This was animal research, not proof that plastic packaging changes human breast milk. It does support lowering avoidable plastic contact with food and drinks during pregnancy and breastfeeding. Glass and stainless steel are better choices for hot drinks, leftovers, and daily food storage.