Plastic Baby Bottles Make Milk Allergies Worse

Polypropylene baby bottles release nano- and microplastics when you prepare formula in them. A 2026 study in J Agric Food Chem found those plastics make cow's milk allergy significantly worse.

What the study found

Researchers gave mice oral doses of polypropylene (PP) microplastics alongside cow's milk protein. The PP exposure made allergic symptoms worse: antibody reactions increased, the gut barrier broke down, and the immune system shifted toward the allergy-promoting Th2 response.

PP also suppressed the immune cells that normally build tolerance to foods. Fewer of these cells means the body has a harder time learning "this food is okay." That's a problem for babies, whose immune systems are still developing that tolerance.

The plastics came from polypropylene infant feeding bottles during formula preparation. Hot water in a PP bottle releases more particles.

What to use instead

Stainless steel and glass baby bottles don't release plastics. If you're using PP bottles (most standard baby bottles are PP), switching to glass or stainless steel removes this exposure route entirely.

This matters most in the infant stage, when immune programming happens fast and gut tolerance is being built. Non-toxic baby products include glass and stainless steel feeding options.

Also see glass food storage for safer alternatives.

Source: Shi Q, et al. (2026). J Agric Food Chem.