Can Gut Microbes Repair Damage from Microplastics?
The damage from microplastics may have more to do with the gut than the brain.
Posted May 13, 2026 | Reviewed by Lybi Ma
“Not only are plastics polluting our oceans and waterways and killing marine life, it’s in all of us and we can’t escape consuming plastics.” —Marco Lambertini, Director General of World Wildlife Fund International
We are slowly getting buried in microplastics. Since they were first mass-produced in the 1950s, we have been accumulating these tough materials, which should not have been a surprise to their inventors. After all, they were looking for something so tough that even in thin sheets, it could stand abuse.
Of course, humans create trash all over the world, all the time. The difference is that plastic doesn’t decompose. Plastic bags are used for a few minutes but last for centuries.
Their toughness gave rise to the term “forever chemicals.” We shouldn’t be shocked that something that never breaks down must surely pile up. It isn’t far-fetched to think that a layer of sediment will be accredited to our era, and might be called the Plastocene by future paleontologists.
What is all that plastic doing to our health? For one thing, these tiny particles are insinuating themselves into many of our body tissues. How bad is that?
On the one hand, these plastics are forever because they don’t break down and don’t react with anything. But that non-reactivity is hard to square with active damage. If they are chemically inert, so what? Maybe microplastics are like grounds in our coffee: annoying, but not deadly?
Some new research is casting doubt on the more flamboyant stories about microplastics clogging our system. Researchers may not be accounting for contamination in our zeal to find plastics. Perhaps a third of the plastic we identify may be contamination from lab gloves and other sources. More problematic is that some of the plastics found in brain tissue may actually be bits of nerve cell membranes that look a lot like polyethylene to certain assays. The teaspoon of plastic that Robert F. Kennedy says is in our brain may be overstated.
Yet, there are observable mental effects from microplastics. A recent Chinese study demonstrated this connection. They showed that microplastic exposure induced anxiety and depression in mice. The effect was dose-dependent; the more plastic they were exposed to, the greater the effect. This makes a strong case that, at least in mice, microplastics can cause mental dysfunction. But how?
They used fluorescence to track the microplastics and were surprised that very little ever reached the brain. Instead, they found them piling up in the gut, which immediately made them look at the microbiome . The researchers discovered that the microplastics altered the equilibrium of the gut microbiome, causing what is called dysbiosis. That disruption enables pathogens to run amok and damage the gut lining.
Gut cells are tightly glued together in a translucent sheet, a single cell thick. That lining has the tricky job of letting nutrients in, while keeping toxins out. It’s vulnerable to pathogens that pry cells apart by weakening the glue holding them together. That allows toxins and microplastics to pass through and enter the bloodstream, where they can do a lot of damage as the heart pumps them to every organ in the body.
This is how systemic inflammation starts.
The brain is a privileged organ in the body. Toxins and rogue microbes often damage our organs, but they are usually fully repaired. However, you can’t repair the brain without losing precious connections that give rise to our memories and cognitive abilities. That’s why there is a blood-brain barrier designed to keep the riffraff out. But over time, systemic inflammation can wear down that barrier. Toxins and even bacteria can then enter the brain, quickly followed by immune cells that track them down and destroy them. But immune cells are not known for subtlety, and there may be a lot of collateral damage.
We can’t directly feel this battle in our brains, but it is interpreted as anxiety and depression.
Because the gut-brain axis is now well established in scientific circles, the researchers looked at the possible connection between this dysbiosis and mental health. If the problem starts in the gut, perhaps they could renew the gut and help the brain. They knew that probiotics had been used this way with some success, and they thought to try prebiotics: the food for probiotics. They picked a fiber that is a favorite of gut researchers: galacto-oligosaccharide or GOS.
To their surprise, GOS all by itself — without probiotics — repaired the microplastic-induced dysbiosis. With GOS, beneficial gut microbes bloomed, and a better balance of microbes took over the gut, despite the accumulation of microplastics. These microbes restored a healthy microbial metabolism, with improved serotonin production, an important neurotransmitter in many antidepressants . Improved butyrate production led eventually to the growth of new neurons in the brain, improving cognition and memory .
The researchers say, “GOS restored intestinal homeostasis and ameliorated these anxiety- and depression-like behavioral and metabolic deficits. Therefore, maintaining intestinal health, particularly through dietary GOS, represents a viable strategy to mitigate the neurotoxicity induced by plastic pollution.”
The study was conducted with mice, and it deserves a follow-up human trial to see if the same remedy holds for people. But GOS is not an exotic prebiotic and has shown efficacy for gut issues and inflammation in humans for years, so it seems to be a safe weapon in our battle against microplastics.
GOS or other prebiotics may provide a stopgap to soothe our increasingly plasticized interior. But that should not distract us from cleaning up the mess we’re making of our planet.
Liu, Chang, Bixuan Wu, Meixia Luo, Lin Li, and Lu Li. “ Galacto-Oligosaccharides Ameliorate Polystyrene Nanoplastic-Induced Anxiety- and Depression-like Behaviors via a Gut-Initiated Serotonergic Cascade .” Environmental Pollution. 2026.
Gwinnett, C., and R. Z. Miller. “ Are we contaminating our samples? A preliminary study to investigate procedural contamination during field sampling and processing for microplastic and anthropogenic microparticles .” Marine Pollution Bulletin 173 (December 2021): 113095.
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Scott C. Anderson is a science journalist and coauthor with John Cryan and Ted Dinan of "The Psychobiotic Revolution" from National Geographic.
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This article is part of the Bringwise Psychology Journal — daily insights on human behavior, mental health, and personal growth.