Are Microplastics Hurting Your Gut?

If you type "do microplastics" into Google, the suggestions include "leave the body," "cause inflammation," and "cause colon cancer." With "how to get rid of microplastics," it offers "in your body naturally." The FDA (the US Food and Drug Administration) says that plastic particles have been found in human urine, stool, blood, and organs, but nobody has shown that microplastics harm a healthy person's gut, and nobody has shown that they're harmless either. The human research is small, and some of the most-shared numbers are being challenged by the chemists who measure this stuff for a living.

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Microplastics are pieces of plastic smaller than 5 millimeters (about the size of a grain of rice, though the ones found in people are mostly far smaller), and nanoplastics are smaller still.

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Is there actually plastic in your gut?

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Yes, at least on its way through. In 2019, researchers in Vienna asked eight healthy adults in Europe and Asia to keep a food diary and send in a stool sample. All eight samples had microplastics in them, a median of 20 particles for every 10 grams of stool, across nine kinds of plastic. The authors were upfront about the limits: there were few participants, and each of them gave only 1 sample.

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A team in Malaysia then looked at colon tissue removed during surgery from 11 adults and found microplastics in all 11 of the specimens, almost all of them tiny fibers. So plastic reaches the wall of the colon, though the study had no way to tell whether it did anything there.

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So do microplastics leave the body? Mostly, as far as anyone can tell. When the WHO (World Health Organization) reviewed microplastics in drinking water, its water lead, Bruce Gordon, said that the vast majority, or all, of the particles more than 150 micrometres across pass through the gut without being absorbed, and that the "vast, vast majority" of the smaller ones do the same.

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Does it do anything once it's there?

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In people, the evidence comes down to one comparison. A 2022 study in China measured microplastics in the stool of 52 people with IBD (inflammatory bowel disease, which includes Crohn's and ulcerative colitis) and 50 healthy people. The IBD group had more, 41.8 particles per gram against 28.0, and people with more severe disease had more plastic. The authors wrote that this could mean that plastic is part of the disease process or that IBD makes the body retain more microplastics, so they couldn't say which one caused the other.

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A group of researchers in Japan published a reply pointing out why the numbers might be off. People with IBD often have diarrhea, and some with Crohn's are told to cut back on fiber, which changes what's in their stool and can make the same amount of plastic look more concentrated. They called for studies that follow people over time to see whether plastic exposure comes before IBD starts. The Crohn's & Colitis Foundation lists one, a Mount Sinai study called PLANET that follows pregnant women and their babies to find out how microplastics affect intestinal inflammation and the gut microbiome.

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Most of what's known beyond that comes from lab dishes and mice. At a 2025 meeting of United European Gastroenterology (Europe's main gut-doctor organization), researchers grew gut bacteria from five healthy volunteers' stool, added five common plastics, and found that the cultures turned more acidic and some groups of bacteria went up or down. The lead author said that it was too early to make any definitive claims about health.

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A 2026 review pooling 19 mouse studies found that eating microplastics did shift which bacteria were most common in the gut. It didn't significantly change how many different kinds lived there, though, and the amount of plastic the mice got didn't predict how big the change was. Most of those studies used a single plastic (polystyrene, the material in foam cups) rather than the mix of plastics people actually swallow.

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Even so, a journal of the American Gastroenterological Association (the main group of gut doctors in the US) ran a 2026 review that called microplastics a "ubiquitous threat to GI health that we are only beginning to understand." It also listed its own evidence's weak spots, including a lack of longitudinal human studies (studies that follow the same people for years) and limited data specific to humans, since most of the research on exposure to micro- and nanoplastics relies on animal models or in vitro experiments (in vitro means in a dish).

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Why some of the scariest numbers are in doubt

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You've probably heard that you eat a credit card's worth of plastic every week. That line comes from a 2019 WWF report, which said that people "could be ingesting approximately 5 grams of plastic every week, which is the equivalent weight of a credit card." Two years later, researchers in the Netherlands built a more careful model and put the typical adult at about 583 nanograms a day, which works out to roughly 4 micrograms a week (a microgram is a millionth of a gram). A 2022 paper checking the WWF math concluded that a person eats a credit card's worth of microplastics every 23 thousand years, not every week.

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To measure plastic in body tissue, labs often vaporize the sample and read the fumes, and body fat gives off a signal that looks a lot like polyethylene (the plastic in grocery bags). When a 2025 study reported high levels of plastic in human brains, the chemist Dušan Materić pointed out that fat is known to produce false positives for polyethylene, and that the brain is approximately 60 percent fat. He told the Guardian that he has serious doubts about more than half of the very high impact papers reporting microplastics in body tissue. Cassandra Rauert, a chemist whose own study tested that method, told the paper, "I think a lot of the concentrations [of MNPs] that are being reported are completely unrealistic." Matthew Campen, the brain study's senior author, answered that most of the criticism has been "conjectural and not buffeted by actual data."

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A 2024 study reported about 240,000 plastic particles in every liter of bottled water. In a published letter, Materić pointed out that the study's own supplement said the ultra-pure lab water used as a check seemed to have the same level of plastic contamination as the bottled water that was measured, and he called the result "fundamentally unreliable." The original team disputes that.

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Materić still thinks that the plastic is in you. He says, "We do have plastics in us," and adds that hard proof of how much is still to come.

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What do health agencies say?

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The FDA says that the scientific evidence so far doesn't show that the levels of microplastics or nanoplastics detected in foods pose a risk to human health. EFSA (the European Union's food safety agency) hasn't finished its own assessment, so it can't draw a conclusion on potential health effects and expects to publish a full review by the end of 2027. The WHO called the risk from drinking water low, and Gordon added that researchers would always talk about low risk rather than no risk, because there's so much uncertainty.

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What's worth doing?

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Each of these is cheap or free, so they don't have to wait for the science to settle.

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Don't microwave food in plastic

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In a 2023 lab study at the University of Nebraska, microwaving released more plastic from containers than any other way of using them, including months in the fridge. Some containers released as many as 4.22 million microplastic and 2.11 billion nanoplastic particles from a single square centimeter of plastic in 3 minutes (the researchers used water and a mild vinegar solution as stand-ins for food). The American Academy of Pediatrics already tells families to avoid microwaving food or drinks in plastic if possible, to avoid putting plastics in the dishwasher, and to use glass or stainless steel when they can. That advice comes from a statement about chemicals in food packaging rather than the particles themselves, and the FDA disagrees on one of those chemicals, saying that BPA is safe at the levels currently found in foods. Heating your leftovers on a plate costs you nothing, though.

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Keep drinking water, bottled or not

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Christopher Hine, a Cleveland Clinic researcher, told the clinic's newsroom that dehydration is a far worse condition than exposure to microplastics. His suggestion is to keep bottled water out of direct sunlight and somewhere cool. If you'd rather drink tap water, a 2024 lab study found that boiling hard water (water with a lot of dissolved calcium) can remove at least 80% of three common plastics, which got trapped in the chalky scale that forms as it boils. Materić's own suggestion is simpler: if you're concerned about water, filtering it through charcoal works.

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Eat less of the packaged stuff

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In a small 2024 study of 15 volunteers in Austria, eating highly processed food and using plastic to package and prepare food were both linked to more microplastics in stool. The study was funded by Plastics Europe, a group that represents plastic manufacturers. There are other reasons to eat less ultra-processed food anyway.

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Can you detox microplastics?

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There's no evidence that you can. A 2024 review looked at whether dietary fiber could grab onto microplastics in the gut and carry them out, and its authors wrote that "no studies have been conducted specifically on the adsorption of MPs accumulated in the gastrointestinal tract by human consumption of DFs" (DFs are dietary fibers). They added that their conclusions rest only on the physicochemical properties of DFs, meaning how fiber behaves in a test tube. Fiber is still good for your gut for plenty of other reasons.

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At-home blood tests for microplastics are for sale too. One kit's own page says, "We do not provide results interpretation," which means that you pay for a number and get nobody to tell you what it means. For how detox products work in general, see what actually happens during a detox or cleanse.

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