Microplastics have been found in the human brain and may harm our mental health.

Plastics disrupt hormones and neurotransmitters, which may contribute to anxiety and depression.

Microplastics damage the gut microbiome, causing inflammation that affects the brain via the gut–brain axis.

You can reduce exposure: Filter your water, avoid plastic containers, eat fiber- and antioxidant-rich foods.

You can’t see them, taste them, or feel them, but they are inside of you right now. Microplastics are pieces of plastic that are smaller than 5 millimeters—about the size of a sesame seed—and they have infiltrated virtually every system in the human body. Researchers have found them in human blood, lungs, liver, placenta, breast milk, and the brain. While much of the public discussion has focused on how they increase our risk of cancer and cardiovascular disease, research now suggests that microplastics may be affecting our mental health.

A 2024 study published in the New England Journal of Medicine looked at arterial plaques (blockages in arteries) from 304 patients and found microplastics in the majority of samples. Individuals with plaques had higher rates of heart attack, stroke, and death. In 2025, a review described the presence of polystyrene microplastics in mouse brains, confirming that the particles can penetrate the blood-brain barrier.

Plastics Affect Our Hormones

One of the most well-documented mechanisms of microplastic toxicity is endocrine disruption. Plastics contain and absorb a range of chemicals that mimic or block estrogen, testosterone, thyroid hormones, and cortisol. A 2025 review found that micro- and nanoplastics disrupt the primary systems that control reproductive function, metabolism, sleep, stress response, and mood.

The hypothalamic-pituitary-adrenal (HPA) axis, which coordinates our response to stress, is particularly vulnerable. Experimental animal studies summarized in a 2025 review suggest that microplastics can disrupt neurotransmitter systems,........

© Psychology Today