There is plastic in your brain. Not a metaphor — actual fragments of polyethylene, smaller than a virus, lodged in the tissue of your frontal cortex. A 2025 study published in Nature Medicine confirmed it, and the number has been rising every year.
This is not a story designed to frighten you into buying something. It’s a story about what the science is starting to say — carefully, cautiously — about an old food and a new problem. Because buried in a March 2026 paper from the World Institute of Kimchi is a finding that deserves more attention than it has received: a bacterium found in fermented cabbage can bind to nanoplastics in the gut and carry them out of the body.
We are nowhere near a solution. But we may be looking at the first biological mechanism that points in the right direction.
The plastic already in you
Researchers at the University of New Mexico analysed brain, liver, and kidney tissue from autopsies conducted in 2016 and 2024. What they found was striking: nanoplastics accumulated at far higher levels in brain tissue than in any other organ — in some samples, up to 30 times more than in the liver or kidney from the same body. Between 2016 and 2024, total plastic mass in brain samples increased by approximately 50%.
The researchers also found something more specific and more troubling. In individuals with diagnosed dementia, nanoplastic concentrations were three to five times higher than in those without — concentrated near cerebrovascular walls and immune cells. The study does not prove causation. But it raises a question that is hard to put down.
These particles enter the body through food, water, and air. Once they reach the gut, the smallest ones — nanoplastics under 1 micrometer — can cross the intestinal barrier, enter the bloodstream, and eventually reach the brain. Once there, they do not leave easily.
People are being exposed to ever-increasing levels of micro and nanoplastics. We think this is simply mirroring the environmental buildup.
— Matthew Campen, University of New Mexico
How bacteria bind plastic
The gut is where nanoplastics first accumulate in meaningful quantities. It is also, it turns out, where a biological intervention might be possible.
A 2025 study published in Frontiers in Microbiology screened 784 bacterial strains for their ability to adsorb microplastics. Two strains — Lacticaseibacillus paracasei DT66 and Lactiplantibacillus plantarum DT88 — proved particularly effective. In animal studies, mice given these probiotics excreted significantly more plastic particles in their feces than those who received none. The mechanism is physical: bacteria form biofilms, sticky matrices that bind to plastic surfaces through hydrophobic interaction, and carry them through the digestive tract before they can cross into the body.
The critical variable is stability. Many bacteria that adsorb plastic in lab conditions fall apart under the actual conditions of the human gut — the acidity, the bile, the temperature fluctuations. This is where the kimchi finding becomes meaningful.
What makes the kimchi bacterium different
The strain isolated from kimchi, Leuconostoc mesenteroides CBA3656, was tested under simulated human intestinal conditions alongside a reference probiotic strain. The reference strain’s adsorption efficiency collapsed from 85% to 3% under gut conditions. CBA3656 held at 57%.
In germ-free mice, administration of CBA3656 more than doubled nanoplastic excretion in feces compared to controls. The bacterium also showed stable binding across a wide range of pH levels, temperatures, and nanoplastic concentrations — suggesting it could function across the variable environment of a real digestive system, not just a controlled one.
Dr. Se Hee Lee, who led the research, framed it plainly: “Our findings suggest that microorganisms derived from traditional fermented foods could represent a new biological approach to address this emerging challenge.”
Microorganisms derived from traditional fermented foods could represent a new biological approach to address this emerging challenge.
— Se Hee Lee, World Institute of Kimchi
What this means for how we eat
It would be easy to turn this into a headline: eat kimchi, remove plastic from your brain. That is not what the science says. These studies were conducted in mice. Clinical trials in humans have not been done. The quantities involved, the long-term effects, the optimal delivery method — all of this remains unknown.
What the science does say is more modest and more interesting: the gut microbiome may be a meaningful site of intervention for nanoplastic accumulation, and fermented foods rich in lactic acid bacteria are a reasonable place to look. The traditional practices that have produced kimchi, miso, sauerkraut, and kefir for centuries were not designed with nanoplastics in mind — but the microbial communities they cultivate appear to have properties that are newly relevant.
This is not a reason to eat kimchi instead of reducing your plastic exposure. The more important work is upstream — avoiding plastic packaging where possible, filtering drinking water, being wary of heavily processed food that has been stored in plastic for extended periods. The bacterial intervention addresses what has already entered the body. The structural problem is the amount that enters in the first place.
But for those already thinking about fermented foods as part of a diet oriented toward gut health and lower environmental impact, this research adds a dimension worth knowing about. The old food and the new problem are not as separate as they first appear.
Further reading
If the relationship between your gut microbiome and your broader health is new territory, these two books are the clearest starting points available.
Fiber fueled — Will Bulsiewicz (2020)
A gastroenterologist's case for why dietary diversity — not restriction — is the foundation of gut health. Bulsiewicz draws on the latest microbiome research to argue that the variety of plants you eat directly shapes the bacterial community in your gut. The book is thorough without being clinical, and the connection to fermented foods and fiber as microbial fuel is directly relevant to what the kimchi research is pointing toward.
The good gut — Justin Sonnenburg & Erica Sonnenburg (2015)
Two Stanford microbiologists make the case that the gut microbiome is a second genome — one we can actually influence, unlike our DNA. The book traces how modern diets, antibiotic overuse, and over-sterilization have depleted our microbial diversity, and what that loss might mean for immunity, mood, and long-term disease risk. Written before nanoplastics entered the conversation, it nonetheless provides essential context for understanding why a healthy, diverse gut microbiome is worth protecting.
Still early, still worth watching
The research on nanoplastics and the gut is moving fast. Two years ago, the accumulation of nanoplastics in human brain tissue was a hypothesis. Today it is documented in Nature Medicine. Two years from now, we may have the first human trials on probiotic-based nanoplastic excretion.
In the meantime, the honest answer is: we don’t yet know how much this matters clinically, or whether eating more fermented foods will make a measurable difference to the plastic load in your body. What we know is that the gut is where this story begins, that lactic acid bacteria show a specific and testable mechanism, and that a jar of kimchi in the fridge is not a bad place to start — for reasons that now go a little further than anyone expected.
Browse the full Health & Nutrition archive for more.
References
- Lee, J. et al. (2026). Efficient biosorption of nanoplastics by food-derived lactic acid bacterium. Bioresource Technology. DOI: 10.1016/j.biortech.2026.134234
- Nihart, A.J. et al. (2025). Bioaccumulation of microplastics in decedent human brains. Nature Medicine. DOI: 10.1038/s41591-024-03453-1
- Teng, X., Zhang, T. & Rao, C. (2025). Novel probiotics adsorbing and excreting microplastics in vivo show potential gut health benefits. Frontiers in Microbiology. DOI: 10.3389/fmicb.2024.1522794
- Demarquoy, J. (2025). Microplastics and probiotics: mechanisms of interaction and their consequences for health. AIMS Microbiology. DOI: 10.3934/microbiol.2025018