Dietary Nanoplastics: From Everyday Consumption to Cellular Disruption

Introduction

A typical meal is expected to provide nutrients essential for survival—proteins, fats, carbohydrates, and micronutrients. However, in modern environments, it may also contain something far less expected.

Imagine this: What if your daily diet already includes plastic— without you ever knowing it? While this may sound exaggerated, current estimates suggest that humans ingest nanoplastics regularly through food and beverages.These particles are not simply passing through the digestive system as they may interact with cells, tissues, and physiological pathways in ways that are only beginning to be understood.

What are Dietary Nanoplastics?

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Nanoplastics are plastic particles with the size of 1–1000 nanometers. They originate from the degradation of larger plastics or are unintentionally released from consumer products. Unlike microplastics, nanoplastics are small enough to exhibit colloidal behaviour, which also indicates that they don’t just sink; they float, interact with biomolecules, and can cross biological barriers that stop larger particles.

Because of their tiny size, nanoplastics can interact directly with cells and tissues in ways that microplastics cannot. This makes them a unique and growing concern in bioscience.

How Much Are We Actually Consuming?

In 2019, the World Wide Fund for Nature (WWF) famously estimated that humans ingest roughly 5 grams of microplastics per week – about the weight of a credit card. But what about nanoplastics? They’re much harder to measure, yet recent studies are giving us worrying clues.

Bottled water is a major source. Advanced detection methods have found that a single litre can contain hundreds of thousands of nanoplastic particles, which are far more than microplastics alone. Human stool contains microplastics (nanoplastics likely present but undetectable), and blood contains nanoplastics up to 1.6 µg/mL, proving that they can cross the gut barrier.

How Do Nanoplastics Enter the Body?

Source	Mechanism
Drinking water	Shedding of nanoscale fragments from plastic bottles
Food packaging	Migration during heating or storage (especially fatty foods)
Environmental contamination	Entry into food chain (seafood, salt, crops, honey)

Once ingested, the size of nanoplastic determines the absorption and toxicity potential:

• Particles <20 nm may passively cross tight junctions

• Particles 20–200 nm enter cells via endocytosis (active uptake)

• Particles >200 nm are mostly trapped in mucus or excreted

Nanoplastics from Gut to Systemic Circulation

After ingestion, nanoplastics interact with the gastrointestinal tract: the mucus layer (150–400 µm thick) allows some particles to diffuse through, especially if they are neutral or PEGylated (A molecule that has been chemically attached to polyethylene glycol, PEG to improve its stability, solubility, and circulation time in the body),  but once they reach the intestinal epithelium, particles larger than ~20 nm cannot pass passively and must hijack endocytosis to enter cells.

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There are 3 key biological routes for nanoplastics to be absorbed in the intestinal lumen in order to reach the systemic circulation: 

1. Transcellular uptake: Nanoplastics are internalized by enterocytes via endocytosis, the same pathways used for nutrient absorption.

2. Paracellular transport – Nanoplastics can pass between adjacent epithelial cells only when tight junctions are disrupted, for instance during intestinal inflammation or disease.

3. M‑cell mediated transport – Specialized microfold cells (M cells) capture nanoplastics and transfer them directly to underlying immune cells such as macrophages and dendritic cells.

Once absorbed, nanoplastics can enter the bloodstream directly through the intestinal capillaries or indirectly via the lymphatic system, particularly during lipid transport. From there, they can distribute to secondary organs, with the liver being a primary accumulation site. Studies have also detected nanoplastics in the kidneys, spleen, and placenta. This systemic distribution indicates the ability of nanoplastics to translocate beyond the gastrointestinal tract and accumulate in distant tissues, raising concerns about their long-term health effects.

Cellular and Molecular Mechanisms of Toxicity

Once nanoplastics cross the intestinal barrier and enter the bloodstream, they do not remain inert. At the cellular and molecular level, they trigger a cascade of harmful responses:

1)  Oxidative Stress and Mitochondrial Dysfunction

Nanoplastics cause cells to produce too many harmful molecules called reactive oxygen species (ROS). They damage cell membranes and mitochondria (the cell's power plants), while also weakening the cell's natural defences against oxidation. This leads to damaged cell membranes, broken DNA, and harmed proteins. Together, these effects speed up cellular aging and can trigger programmed cell death (apoptosis).

2)  Activation of Inflammatory Pathways 

Nanoplastics activate the NF‑κB pathway, a master switch for inflammation. Recognizing the nanoplastics as foreign particles, they trigger NF‑κB to enter the nucleus and turn on pro‑inflammatory cytokines. Their sustained release causes chronic low‑grade inflammation and tissue damage, linking nanoplastic exposure to metabolic and cardiovascular diseases.

3)  Disruption of Intestinal Barrier Function

Nanoplastics weaken the gut lining by reducing the proteins (occludin and claudin) that seal cells together. They also damage the cells that absorb nutrients. This leads to a "leaky gut," where toxins and bacteria can escape into the bloodstream, setting off body‑wide inflammation.

4)  Gut Microbiome Dysbiosis

Nanoplastics disrupt the delicate balance of bacteria living in our gut. They stick to bacterial surfaces and release toxic chemicals, which reduces the variety of beneficial bacteria and allows harmful bacteria to multiply. This imbalance, called dysbiosis, can alter our metabolism and weaken the immune system. Even worse, these changes may persist long after nanoplastic exposure stops.

5)  Chemical Toxicity and Endocrine Disruption

Nanoplastics act like sponges for environmental pollutants and also release their own harmful additives. Before we eat them, they pick up heavy metals, pesticides, and other toxins from the environment. Once inside the body, they leak out chemical additives like Bisphenols and Phthalates. Together, these exposures disrupt hormone balance, damage cells, and may affect reproduction.

Challenges and Limitations

1.  Most studies use "virgin" plastics instead of real‑world particles.

 Laboratory research typically uses “virgin plastics” like spherical polystyrene beads, which do not reflect the irregular shapes, surface roughness, and chemical complexity of environmental nanoplastics. Real‑world particles are altered by their biological behaviour, making current lab findings potentially misleading.

2. Limited human data 

 Most evidence comes from animal models or cell cultures; long‑term human studies on chronic low‑dose exposure are still lacking.

3. No established safety thresholds or regulatory limits

Due to insufficient human data and inconsistent study designs, regulatory agencies (WHO and EFSA) have not yet set safe exposure limits for nanoplastics in food or water. This leaves consumers unprotected and researchers without clear risk assessment targets.

Tips to Reduce Further Exposure to Nanoplastics

While completely avoiding nanoplastics is nearly impossible in today's world, certain practical steps can be taken to significantly reduce our daily intake of nanoplastics.

Action	Why it helps
Use glass or stainless steel bottles	Avoids plastic shedding into drinking water
Never microwave food in plastic	Heat accelerates nanoplastic release into food
Choose natural fibres (cotton, wool)	Synthetic fabrics shed microplastics during washing
Install a reverse osmosis water filter	Removes most nanoplastic particles from tap water
Buy fresh, unpackaged produce	Avoids plastic wrapping and container leaching

Conclusion

Dietary nanoplastics aren't just an environmental buzzword. They're actually getting into our bodies. Their tiny size lets them slip past our gut, enter our blood, and reach organs like the liver and placenta. Once inside, they trigger inflammation, leaky gut, and chemical chaos. That sounds scary, but we also have to be honest: we don't have all the answers yet. Most studies use perfect lab-made plastics, not the real weathered stuff we actually eat. So for now, just be smart – skip single-use plastic, don't microwave food in plastic, and use a water filter. And for us bioscience students? This is a wild, important frontier to explore.

Citation

1. Di Fiore, C., & Avino, P. (2026). Microplastics and nanoplastics in the human diet. Nature Health, 1(1), 48–57. https://doi.org/10.1038/s44360-025-00025-6

2. Gigault, J., Halle, A. ter, Baudrimont, M., Pascal, P.-Y., Gauffre, F., Phi, T.-L., El Hadri, H., Grassl, B., & Reynaud, S. (2018). Current opinion: What is a nanoplastic? Environmental Pollution, 235, 1030–1034. https://doi.org/10.1016/j.envpol.2018.01.024

3. Zhang, Z., Xu, M., Wang, L., Gu, W., Li, X., Han, Z., Fu, X., Wang, X., Xu, L., & Su, Z. (2023). Continuous oral exposure to micro- and nanoplastics induced gut microbiota dysbiosis, intestinal barrier and immune dysfunction in adult mice. Environment International, 108353–108353. https://doi.org/10.1016/j.envint.2023.108353

4. Zhang, Y., Jia, Z., Gao, X., Zhao, J., & Zhang, H. (2024). Polystyrene nanoparticles induced mammalian intestine damage caused by blockage of BNIP3/NIX-mediated mitophagy and gut microbiota alteration. Science of the Total Environment, 907, 168064. https://doi.org/10.1016/j.scitotenv.2023.168064

5. He, Y., Li, Z., Xu, T., Luo, D., Chi, Q., Zhang, Y., & Li, S. (2022). Polystyrene nanoplastics deteriorate LPS-modulated duodenal permeability and inflammation in mice via ROS drived-NF-κB/NLRP3 pathway. Chemosphere, 307, 135662. https://doi.org/10.1016/j.chemosphere.2022.135662

6. WWF. (2019). Revealed: plastic ingestion by people could be equating to a credit card a week. Panda.org. https://wwf.panda.org/wwf_news/?348337/Revealed-plastic-ingestion-by-people-could-be-equating-to-a-credit-card-a-week

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This article was prepared by Yap Chi Keat (Yonsei University).

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