New research suggests microplastics from ultra-processed foods may accumulate in the brain, potentially fueling rates of depression and dementia.
One study estimates the human brain may contain approximately "a spoonful" of microplastic particles, detectable at higher levels in those with dementia.
Researchers call for urgent investigation, propose a Dietary Microplastic Index, and explore methods like therapeutic apheresis for possible removal.
Microplastics from ultra-processed foods may be infiltrating the human brain—possibly contributing to the global surge in mental health disorders such as depression, anxiety, and dementia. That's according to a landmark collection of four papers published in the May 2025 issue of Brain Medicine.
The cover of the issue features an unsettling image: a brain speckled with microplastics next to a plastic spoon—a metaphor that drives home the finding that the average human brain could harbor "a spoonful" of plastic particles.
From processed foods to neurological harm
“Ultra-processed foods now make up more than 50% of daily energy intake in countries like the U.S.,” said Dr. Nicholas Fabiano. “And they contain dramatically more microplastics than whole foods—up to 30 times more in some cases, such as chicken nuggets compared to chicken breasts.”
These microplastics, defined as particles smaller than 5mm, are not just passing through the digestive tract, researchers warn. They can cross the blood-brain barrier—a protective shield once thought impermeable to such contaminants—and accumulate in brain tissue.
One cited Nature Medicine study reported that individuals with dementia had brain microplastic levels three to five times higher than average.
Biological pathways and the missing link
What makes this hypothesis especially urgent is its convergence with existing science. Both ultra-processed foods and microplastics are linked to inflammation, oxidative stress, mitochondrial dysfunction, and neurotransmitter disruption—factors long associated with mood and cognitive disorders.
Dr. Wolfgang Marx emphasized the overlapping damage mechanisms: “It’s not just a correlation. The biological pathways being affected by microplastics mirror those harmed by poor diet. We may have found a previously missing piece of the puzzle.”
The team proposes creating a Dietary Microplastic Index (DMI) to help researchers and clinicians better quantify exposure risks and correlate them with mental health outcomes.
Microplastic removal research
While prevention remains paramount, another study explores how existing medical technologies might help mitigate the damage.
Therapeutic apheresis, a blood-filtering procedure used for other contaminants, shows early promise in removing microplastics from the bloodstream. While still in its infancy, the research underscores the need for both preventive and interventional strategies as the presence of microplastics in the body becomes harder to ignore.
The authors stress that more longitudinal studies are essential, but they also call for immediate public health action to curb the consumption of ultra-processed foods and advance innovations in food packaging and waste reduction.
A cleaner future
This special issue of Brain Medicine—published by Genomic Press—adds a new dimension to the growing scrutiny of ultra-processed diets, not only from a metabolic standpoint but from a neurological and psychological one.
“With the rise of ultra-processed food intake, environmental contaminants like microplastics, and skyrocketing mental health issues, we must consider the connections,” Dr. Fabiano concluded. “This is more than diet—it’s about what we allow into the very fabric of our brains.”