Pass the yogurt: can probiotics help negate the toxicity of plastic in our stomachs?

The topic of microplastics and our bodies is disconcerting. It seems like there’s little we can do about the tiny particles that have found their way into our blood, brains, lungs and beyond.

Encouragingly, a body of research now suggests we have at least one cheap, accessible line of defense against the damage associated with plastics in our digestive systems: probiotics. There is already evidence that these bacteria, found in fermented foods such as yogurt, sauerkraut and kimchi, support our immune systems and offer benefits that can alleviate gastrointestinal issues, inflammation and allergies. Now, it seems they could help us fight some effects of these pervasive petrochemical particles.

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How do microplastics affect our stomachs?

Multiple studies have demonstrated that nanoplastics can enter our blood and organs and cross the mucosal barrier into our gastrointestinal tracts.

While more research is needed to determine the relationship between plastic and gastrointestinal disorders, preliminary findings suggest ingesting plastic isn’t doing us any favors.

A Tufts University study published this June found that high concentrations of polystyrene particles “significantly triggered the secretion” of inflammatory proteins called cytokines in in vitro gut models. Cytokines are linked to inflammatory bowel diseases (IBD) including Crohn’s disease and ulcerative colitis, which have been rising globally from 3.7m cases in 1990 to more than 6.8m in 2017.

A causal link is not yet clear, because factors such as a diet high in ultra-processed foods, smoking and exposure to air pollution are also linked to IBD. But researchers increasingly believe microplastics, which are filled with various harmful chemicals including additives like bisphenol A (BPA), flame retardants and phthalates, also play a role.

For a January 2023 study published in the Journal of Hazardous Materials, French researchers added microplastics to a modeled gut biome and observed that beneficial bacteria declined, while two strains of bacteria associated with disease increased. A 2021 Chinese study determined that people with inflammatory bowel disease have 50% more microplastics in their feces than those with healthy stomachs.

When gut microbes feed on or adhere to microplastics in the stomach, it can alter their chemical composition, affecting bacterial diversity and causing other “negative effects, including changes in gut metabolic profiles and inflammation”, wrote the authors of a 2022 Spanish study. In more extreme cases, they said it could contribute to a condition called “dysbiosis”, in which bad bacteria outnumbers the good in our stomachs. Dysbiosis can increase the likelihood of developing other serious conditions, including diabetes, Crohn’s disease and colorectal cancer.

How do probiotics and microplastics interact?

Unfortunately, probiotics can’t magically pluck plastic particles out of our bodies. However, some research suggests that the good microbes could help ameliorate some of the toxicity and inflammation plastics promote in our gastrointestinal systems.

This summer, a team of Iranian researchers published a review study exploring how probiotics could protect against the adverse effects of plastics on gut flora. Probiotic micro-organisms may interact with polystyrene particles “to modify their toxic effects on different tissues”, they wrote.

They cite studies that show probiotics binding to, absorbing and neutralizing toxic heavy metals like cadmium and mercury in animals, as well as two separate studies from 2021 that determined probiotic strains including lactobacillus plantarum, found in fermented dairy and pickles, bound to and degraded BPA and phthalates, both harmful chemicals commonly found in plastic.

“The use of probiotic supplementation for improving the microbiome could be an effective intervention to counter different toxins,” including those that leach from plastic, the Iranian research team wrote.

For a separate 2023 study, Chinese researchers first observed that mice exposed to microplastics and their endocrine-disrupting chemicals experienced testicular inflammation, decreased sperm health and a depletion of healthy gut bacteria. They then found that supplementing the mice with probiotics increased sperm vitality, providing a solid foundation for further research into “male reproductive damage caused by environmental pollutants”.

Can probiotics affect microplastics before ingestion?

Not only could certain probiotics help our gut – they could help reduce the chemical additives that leach out of food and beverage packaging before they even make it into our bodies.

There is promising research on the interaction between probiotics and BPA in food containers. BPA, as well as other harmful bisphenols sometimes used in its place, is commonly found in cans and hard polycarbonate plastic bottles used to hold food and drink. These additives are known to leach from containers and into the consumer products we ingest.

A Chinese study from 2019 found that when a preparation of the probiotic lactobacillus reuteri was added to juice and teas packaged in BPA-containing cans, the probiotic reduced the concentration of the chemical in the beverages by at least 90% in one day.

In 2020, Iranian researchers reached a similarly encouraging conclusion by making yogurt out of various probiotic strains of bacteria and milk intentionally contaminated with 100 parts-per-million BPA; after 28 days of storage, yogurt made with lactobacillus plantarum and lactobacillus acidophilus had detoxified the BPA by 95% and 90% respectively.

Is there any reason to be cautious about probiotic use?

The science behind what plastic does to our bodies and what benefits probiotics may offer is still preliminary. Yet researchers are finding support for the theory that common strains of probiotics, particularly lactic acid bacteria like those found in yogurt, sourdough bread and pickles, could help counteract the effects of the chemicals that microplastics ferry into our bodies when ingested.

It’s wise to talk to your doctor before taking probiotic supplements, which aren’t always consistent in quality or effect; in the US, they’re not evenly regulated. However, probiotics from fermented foods are widely considered safe and generally beneficial for human health, so you can feel good about eating more of them. They’re affordable and delicious to boot. Just be sure to stick with recommended serving sizes, as large quantities of probiotics can lead to minor digestive upsets like gas and bloating. Pass the yogurt!