Chitosan microplastic excretion research has attracted attention following a 2025 animal study investigating whether indigestible dietary materials could influence how ingested microplastics move through the gastrointestinal tract.

The study found that chitosan promoted the fecal excretion of the tested polyethylene microplastic particles in rats. Researchers proposed that chitosan may adsorb microplastics inside the digestive tract and help carry them out through feces.

These findings provide an interesting proof of concept. However, they do not prove that chitosan produces the same effect in humans or removes microplastics that have already entered the bloodstream or accumulated in tissues.

Why Study Microplastic Excretion?

People may encounter microplastics through food, drinking water and airborne particles. After ingestion, many larger microplastic particles are expected to remain within the gastrointestinal tract and eventually pass through feces.

However, particle behaviour may depend on several factors:

• Plastic type
• Particle size and shape
• Surface chemistry
• Duration of gastrointestinal exposure
• Food composition
• Condition of the digestive tract

Researchers are therefore studying whether dietary materials can influence the retention, aggregation or excretion of ingested particles.

Chitosan is of particular interest because its polymer structure and surface charge allow it to interact with different negatively charged materials.

For a broader introduction to the proposed interaction, read Can Chitosan Bind Microplastics in the Digestive Tract?.

What Did the 2025 Study Investigate?

The study, published in Scientific Reports, evaluated how several indigestible materials affected the gastrointestinal retention and fecal excretion of polyethylene microplastics in rats.

The researchers included groups receiving materials such as:

• Chitosan
• Indigestible dextrin
• Cellulose
• Apple fiber
• A control diet

The animals received polyethylene microplastic particles with an average size of approximately 200 micrometers. Researchers then measured the particles found in fecal samples and those remaining within the gastrointestinal tract.

This allowed them to compare how the different dietary materials influenced microplastic movement and excretion.

Read the original paper: Ingesting chitosan can promote excretion of microplastics.

What Were the Main Findings?

The study produced two particularly important observations.

First, the researchers found that some ingested microplastic particles remained within the gastrointestinal tract even after several days. In the control group, approximately 12% of the ingested microplastics reportedly remained in the gastrointestinal tract 144 hours after administration.

Second, chitosan demonstrated the strongest apparent microplastic-excretion effect among the tested dietary materials.

The researchers suggested that chitosan adsorbed the polyethylene particles and facilitated their movement through the digestive system. Increased fecal output may also have contributed to the amount of material passing from the gastrointestinal tract.

These results support further investigation of chitosan microplastic excretion, but they require careful interpretation.

Why Did the Reported Excretion Rate Exceed 100%?

One result from the study may initially appear confusing: the estimated fecal microplastic-excretion rate in the chitosan group exceeded 100%.

This does not mean that chitosan created additional microplastic particles or removed more particles than the animals consumed.

The researchers acknowledged limitations in the sampling and measurement process. The entire fecal sample could not be analysed, so results were estimated using sampled material. Variation during sampling and pretreatment could therefore produce an estimate above 100%.

This methodological limitation is important. The result supports a difference between the study groups, but the percentage should not be presented as an exact consumer-product removal rate.

For example, the study should not be converted into a claim that chitosan “removes more than 100% of microplastics.” That would misrepresent the research.

How Might Chitosan Support Microplastic Excretion?

Chitosan is a polysaccharide containing amino groups that may become positively charged under suitable conditions. Some microplastic particles can develop negatively charged surfaces after exposure to water, food or biological environments.

This creates the possibility of charge-based interaction.

Possible mechanisms include:

• Electrostatic attraction
• Surface adsorption
• Polymer bridging
• Particle aggregation
• Physical entrapment within digestive material

If chitosan associates with microplastic particles, it may help form larger complexes that remain within the gastrointestinal contents and pass through feces.

Chitosan is also an indigestible dietary material. Its influence on stool volume and gastrointestinal transit may contribute to the excretion process observed in the study.

Learn more about how the positive charge of chitosan works.

Was the Study Conducted in Humans?

No. The 2025 study was conducted in rats.

Animal studies are useful for investigating biological mechanisms under controlled conditions. They can identify promising research directions before human trials are undertaken.

However, animal findings cannot automatically be applied to humans. Differences may exist in:

• Gastrointestinal anatomy
• Digestive transit time
• Diet
• Chitosan dosage
• Microplastic exposure
• Metabolism
• Gut microbiota
• Body size

The current research therefore does not establish an effective human dosage or confirm that humans would experience the same microplastic-excretion effect.

What the Study Does Not Prove

The research does not demonstrate that chitosan:

• Removes every type of microplastic
• Removes nanoplastics from the body
• Clears microplastics from human blood
• Removes particles from organs or tissues
• Prevents all microplastic absorption
• Treats health conditions associated with microplastic exposure
• Produces proven long-term benefits in humans

The study examined a specific polyethylene particle size under controlled animal conditions. Other particles may behave differently.

A clear distinction must also be maintained between binding ingested particles inside the digestive tract and removing particles that have already crossed into other parts of the body.

Could Plastic Type and Particle Size Change the Results?

Yes. Microplastics are not a single uniform material.

Common plastic polymers include:

• Polyethylene
• Polypropylene
• Polystyrene
• Polyethylene terephthalate
• Polyvinyl chloride
• Nylon and other synthetic fibers

Each material can have different surface properties. Particle size, shape, weathering and exposure to proteins or fats may also affect how it interacts with chitosan.

The 2025 study focused on polyethylene particles of a particular size. More research is needed to determine whether comparable results occur with smaller microplastics, nanoplastics, fibers or other polymer types.

What Human Research Is Still Needed?

Before firm conclusions can be made, controlled human studies would need to investigate:

• Whether orally consumed chitosan increases microplastic excretion in people
• Which microplastic types and sizes may be affected
• Which chitosan properties influence binding
• Appropriate human dosage and timing
• Short-term and long-term safety
• Possible interactions with medications
• Possible effects on nutrient absorption
• Whether the interaction produces meaningful health outcomes

Researchers would also need reliable analytical methods for measuring microplastics in food, fecal samples and human tissues. Contamination control and accurate particle identification remain significant challenges in microplastic research.

How Microplastic Protect Relates to the Research

Microplastic Protect supplement is formulated with mushroom-derived chitosan for use as part of an everyday mealtime wellness routine.

The product’s approach relates to the charge-based properties of chitosan and emerging research into its potential interaction with ingested particles inside the gastrointestinal tract.

The 2025 animal study provides relevant background research, but it should not be interpreted as direct clinical proof for any finished supplement. Product-specific human research would be required to establish clinical effectiveness.

Consumers should combine informed supplement decisions with practical efforts to reduce unnecessary plastic exposure.

Frequently Asked Questions

Does research show that chitosan increases microplastic excretion?

A 2025 rat study found that chitosan promoted fecal excretion of the tested polyethylene microplastic particles. Equivalent results have not yet been confirmed through large human clinical trials.

Why might chitosan interact with microplastics?

Chitosan may carry a positive charge, while certain microplastic surfaces may be negatively charged. Electrostatic attraction and adsorption could encourage interaction between them.

Did the study test mushroom-derived chitosan?

The study evaluated chitosan as an experimental dietary material. Its results should not automatically be treated as clinical evidence for every source, grade or finished chitosan product.

Does chitosan remove microplastics from human organs?

Current research does not demonstrate that orally consumed chitosan removes microplastics already present in human organs, blood or tissues.

Does a fecal excretion rate above 100% mean complete removal?

No. The researchers explained that sampling and analytical limitations could produce an estimated value above 100%. It should not be presented as an exact removal percentage.

Can chitosan replace efforts to reduce plastic exposure?

No. Avoiding unnecessary plastic contact with food and beverages remains an important practical step while research into dietary approaches continues.

Conclusion

Current chitosan microplastic excretion research provides a promising but preliminary scientific signal. In a 2025 rat study, chitosan promoted the fecal excretion of polyethylene microplastics and reduced their apparent gastrointestinal retention compared with the control conditions.

The proposed mechanism involves adsorption, charge-based attraction and changes in gastrointestinal passage. However, the experiment involved animals, a specific plastic material and controlled exposure conditions.

The findings justify further research, but they do not prove that chitosan removes microplastics from the human body or from tissues outside the digestive tract. Well-designed human trials are necessary before clinical conclusions can be made.