A study presented at UEG Week 2025 became one of the first to test how microplastics affect real human gut bacteria outside the body, rather than relying only on mouse studies.[1] Researchers grew gut microbiome cultures from stool samples donated by five healthy volunteers, then exposed those cultures to five common types of microplastic at levels matching estimated everyday human exposure.
Total bacterial counts stayed largely stable, but the mix of species shifted, along with measurable changes in compounds like valeric acid and lactic acid depending on which plastic type was tested.[1] The lead researcher noted that some of these shifts resembled patterns previously seen in depression and colorectal cancer research, though that overlap is a pattern that warrants more research, not proof that microplastics cause either condition.
What to do with this
Given that microplastics are already present in food, water, and air, this research doesn't give you a single food or product to avoid to eliminate exposure entirely. Reasonable, low-effort steps, using glass or stainless steel instead of plastic containers for hot food, avoiding microwaving food in plastic, and filtering tap water, reduce exposure without requiring major lifestyle changes. Treat this as an area to watch rather than a reason for alarm, since the health effects in real people, not lab cultures, still need to be established.
