Can microplastics in breast milk disrupt a baby's gut bacteria and immune development?

What's actually in it

Breast milk isn't just food. It delivers beneficial bacteria from mother to baby, seeding the infant's gut with the microbes needed for healthy digestion and immune function. But breast milk also contains microplastics. These tiny plastic particles come from the food and water the mother consumes, the air she breathes, and the plastic products she uses daily. Studies have already confirmed microplastics are present in human breast milk.

What the research says

A 2026 study in FASEB J examined how polystyrene microplastics affect the vertical transmission of bacteria from mother to baby through breast milk. The results showed that microplastics disrupted the normal transfer of healthy bacterial communities to nursing offspring.

The babies exposed to microplastics through breast milk had altered gut colonization patterns. The wrong bacteria moved in, and the right ones didn't establish properly. This disruption had downstream effects on immune system development. The immune cells in the gut, which make up a large portion of the body's immune defenses, didn't mature normally.

You can't eliminate microplastics from breast milk entirely. But you can reduce them. Filtering your drinking water, avoiding heating food in plastic, and choosing glass or stainless steel containers all lower the amount of microplastics that make it into your body and your milk.