Are microplastics digestible?

Are microplastics digestible?

⚕️ MEDICAL DISCLAIMER: This article is for informational and educational purposes only and is not intended as medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider before making any changes to your health regimen, diet, or supplement use, especially if you have existing medical conditions or take medications. The information presented here should not be used to diagnose, treat, cure, or prevent any disease.

Our digestive system was designed to consume all kinds of vegetables, meats, fruits, nuts, and other natural creations. Unfortunately, it wasn’t made to break plastics down into usable energy. And yet, today, we’re swallowing and inhaling microplastics and nanoplastics daily. The source? All kinds of foods, our water, the air, and even our personal care products [1, 7, 10].

So, what happens after we eat, drink, or breathe in microplastics? Are microplastics digestible?

The short answer: we can’t digest them, but most of them pass right through us. The long answer: it’s extremely complicated and still an emerging field of scientific study.

Are Microplastics Digestible – No, Not Like Food

Microplastics are made from polymers like polyethylene (PE), polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC). While there are natural polymers, like DNA, synthetic polymers, like the aforementioned plastics, are not digestible by human enzymes [1-3]. Man-made plastics are designed to be chemically stable, moisture-resistant, and nonreactive. This is why they’re used in packaging, textiles, and nearly every industry.

However, because of their stability, once ingested, these microplastic particles survive the acidic environment of the stomach and the enzymatic processes of the small intestine [1,3]. Because of their durability, most of them pass through our guts and out of our bodies when we go to the bathroom. For those that pass through the intestine and into the bloodstream, many leave through the kidneys and bladder when we go to the bathroom. The outcome of microplastic consumption depends on many factors.

Particle Size and Surface Chemistry Influence Where Microplastics Go

Although microplastics aren’t digestible in the traditional sense, some particles do make their way into the bloodstream in a similar way to nutrients from foods. Their fate depends on their size, surface chemistry, and coatings.

In discussing size, larger microplastic particles (>150 µm, or about the width of two human hairs) tend to remain in the gut and are eventually excreted through going to the bathroom [1,3,4]. Smaller particles (<20 µm, or the size of a white blood cell) can interact more directly with the gut lining, and some are absorbed through M cells in Peyer’s patches, which are specialized lymphoid tissues in the small intestine [3,5]. Lastly, nanoplastics (<100 nm, the size of some viruses) may bypass cell walls entirely, via endocytosis, entering the bloodstream and traveling to our organs [1,3,5].

The surface charge of microplastic particles also plays a role. Positively charged and hydrophobic particles are more likely to interact with gut cell membranes, which influences how they’re absorbed or retained [3,5].

What Happens to Microplastics Inside Our Gut?

Microplastics are physically and chemically inert, meaning that they’re not reactive, but that doesn’t make them harmless. Their presence can irritate gut tissue, disrupt mucosal immunity, and even alter our gut microbiome. For example, animal studies have shown that microplastics disrupt tight junction proteins, alter microbiota composition, and increase local inflammation. Microplastics weaken the intestinal barrier, the outside walls, and increase its permeability, often called “leaky gut” [2,3].

Additionally, they can reduce the diversity of the gut microbiome, resulting in less beneficial species like Lactobacillus and Bifidobacterium [3,6]. Lastly, they can cause the release of pro-inflammatory cytokines and oxidative stress markers [2, 6]. This combination of mechanical irritation, immune disruption, and microbial imbalance sets the stage for broader health issues including metabolic syndrome, food sensitivities, and autoimmune activation.

Are Microplastics Absorbed Into Our Bloodstream?

Yes, some fraction of microplastics and nanoplastics can cross the intestinal wall and enter systemic circulation [3,5,7]. The exact absorption rate depends on things like the microplastics’ particle size and shape and their chemical composition, and can also depend on the individual’s gut health, intestinal barrier integrity, existing inflammation, and existing disease.

Once absorbed, these particles may be transported via the lymphatic system or portal vein to the liver, kidneys, brain, and beyond [3,5,7]. But, absorption is different from digestion. These particles remain chemically intact even after systemic uptake. This allows them to potentially accumulate, lodge in tissues, and cause localized immune responses.

Can Gut Bacteria Break Down Microplastic Particles?

Very few bacterial species in the human gut have any capacity to degrade plastics. Even those that do, such as Ideonella sakaiensis, primarily act on specific forms like PET, commonly used for water bottles, and only under controlled conditions with extended exposure times and specialized enzymes [1]. In short, based on what we currently know, there is no evidence that the human microbiome can meaningfully digest the kinds of microplastics typically consumed through diet or inhalation. In fact, exposure to microplastics often reduces microbial enzyme activity and diversity, making the gut less effective at digestion overall [3,6].

So Where Do Microplastics Go After We Eat Them?

In most healthy adults, ingested microplastics take one of three routes. They either pass through the gastrointestinal tract and exit via feces, bind to mucus and eventually leave through bile or urine, or are absorbed into the bloodstream and accumulate in tissues.

It’s important to note that microplastics may not leave our bodies. Studies have shown that with repeated intake, some particles accumulate in the aforementioned Peyer’s patches and the liver [3,5,7]. This accumulation poses a long-term toxicological risk, especially since these particles can carry heavy metals, and endocrine-disrupting chemicals on their surface and have been shown to induce inflammation [3,5].

Infants and the Elderly May Be More Sensitive to Microplastics

Infants may be uniquely vulnerable to microplastic retention due to immature gut barriers and developing immune systems. One study found fecal microplastic concentrations in infants to be ten times higher than in adults [3]. Additionally, older adults with gut inflammation, reduced motility, or compromised immunity may also be at greater risk for microplastic retention and systemic exposure [3,6].

Microplastic Digestion vs. Detoxification

It’s critical to separate digestion from detoxification. While your gut can’t digest microplastics, your organs involved with “detoxification”, like the liver and kidneys, do attempt to manage the fallout from microplastic exposure, with a special focus on the oxidative and inflammatory byproducts they generate [3,5,7]. However, this process requires a lot of energy, and sustained exposure can potentially impair detox capacity, damage organ tissues, and worsen age-related disease processes.

How Can I Remove Microplastics Naturally?

We’re eating and drinking nano- and microplastics everyday. Because we can’t degrade them, at least in a traditional sense, they can disrupt our guts and cause inflammation. Even with a healthy, balanced diet and plastic-avoidant lifestyle, it’s not realistic to avoid microplastics entirely.

This is why we created Deplasto. Our platform, consisting of a natural supplement, a microplastic intake and tracking app, and lifestyle recommendations is intended to help you avoid microplastic exposure. Our science-based supplement’s formulation targets oxidative stress, hormone-sensitive detox pathways, and cellular repair systems that help your body support balanced hormones. Our lifestyle-centered, microplastic intake app measures and tracks your estimated daily intake based on the food, drinks, and activities you enjoy every day.

In the future, managing gut exposure to microplastics will become routine, much like managing gut health is today. With proper support, your body has powerful tools to minimize long-term damages.

Sources

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