A Stomach Filter Made From Shrimp Shells: Inside GUNA's New Chitosan Patent for Microplastics

NUTRACEUTICALS

Harleen Singh

6/20/20266 min read

This is an AI generated illustration and does not represent actual product or service.

Microplastics have moved from an environmental talking point to a food-safety one. They've been found in seafood, salt, bottled water, and even human blood and arterial plaque. For an industry that lives and dies on consumer trust, "what's actually in this food" has quietly expanded to include "what got into this food from the packaging, the soil, or the sea."

A newly published international patent application from Italian pharmaceutical company GUNA S.p.A. (WO 2026/114786 A1) proposes a surprisingly low-tech answer: a specific type of chitosan, taken as a food supplement or pill, that binds microplastic and nanoplastic particles in the stomach before they can be absorbed.

It's a compelling pitch — plastics are everywhere, exposure is involuntary, and "detox" is one of the most durable narratives in the supplement world. But the patent is also a useful case study in how to read these filings critically: what's genuinely new, what's recycled from existing chitosan science, and where the gap between "binds plastic in a beaker" and "reduces your plastic exposure" still sits.

What the Patent Actually Claims

Strip away the regulatory framing and the core claim is narrow and specific. GUNA isn't claiming chitosan in general — chitosan as a fat-binding, cholesterol-lowering dietary fiber has been on the market for decades, derived from the shells of crustaceans (or fungal cell walls) by deacetylating chitin.

What's being claimed is chitosan within a defined window of two parameters:

Intrinsic viscosity of 90–400 cPs (measured in a specific acetic acid/sodium acetate buffer with a capillary viscometer), corresponding roughly to a molecular weight of 100–450 kDa
A degree of deacetylation of at least 70% (preferably 80–98%)

The claimed use is for binding microplastics (MPs, defined here as 100 nm–5 mm) and nanoplastics (NPs, under 100 nm) in the human gastrointestinal tract — specifically in the acidic environment of the stomach, around pH 3. The mechanism proposed is hydrogen bonding between the chitosan polymer and the plastic particle surfaces, which the inventor says causes the plastic to become entrapped in a gel-like mass that's then excreted rather than absorbed.

Beyond the core "use" claim, the application also covers a food supplement formulation, a pharmaceutical composition for treating diseases "derived from MPs or NPs," and a cosmetic use for "eliminating" MPs/NPs from the body. That's a deliberately broad set of claim types — food supplement, pharma, cosmetic — which reads as a strategy to keep multiple regulatory and commercial doors open rather than committing to one product category up front.

The Experiment That Actually Matters: Not All Chitosan Is Equal

The most useful part of this patent for industry readers isn't the headline claim — it's the comparative data buried in the examples, because it quietly undermines a lot of existing chitosan supplement formulations.

GUNA tested four chitosan samples (Chito 1–4), all with the same degree of deacetylation (85%) but very different viscosities and molecular weights, sourced from different suppliers (including Primex and Certmedica, both established chitosan producers). They ground down real-world plastic — HDPE from bottle caps, PVC from packaging film, PET from food containers — into microplastic particles, exposed them to each chitosan in simulated gastric fluid, and then checked for binding using SEM imaging and stereomicroscopy with image analysis.

The result was a clean split. Chito 1 (10–40 cPs, MW roughly 12–48 kDa) and Chito 2 (60–80 cPs, MW roughly 70–95 kDa) showed essentially no measurable binding — entrapment scores at or near zero across HDPE, PVC, and PET, at all tested concentrations. Chito 3 and Chito 4 (90–130 and 250–400 cPs respectively, MW in the 100–450 kDa range) showed entrapment in the range of roughly 60–87% at lower microplastic concentrations (0.5–1 µg/mL), dropping to a still-meaningful 42–82% at higher concentrations (2 µg/mL).

That's a sharp threshold effect, and it's the part of this filing with the most practical relevance. Many commercial chitosan ingredients — especially the lower-cost, more soluble grades commonly used in weight-management supplements — sit in the lower viscosity bands that this data says don't work. If this binding mechanism holds up under further scrutiny, it implies that "chitosan" as a generic ingredient claim on a label would be largely meaningless for this purpose; the molecular weight and viscosity specification would be the actual active variable, and that's a much narrower, more specialized ingredient category to source at scale.

Why Hydrogen Bonding to Plastic Is Plausible — But Not New

The proposed mechanism — chitosan's amino and hydroxyl groups forming hydrogen bonds with plastic particle surfaces — is chemically reasonable and consistent with chitosan's known behavior as a flocculant and adsorbent in water treatment. It's also not a novel discovery in the broadest sense. The International Search Report attached to this application cites prior literature on chitosan-nanoplastic interactions in water (specifically environmental remediation research published in Science of the Total Environment), and flags it as relevant to several of GUNA's claims covering the food supplement composition.

The Numbers Worth Sitting With

A few figures in the document are worth flagging for anyone doing due diligence on this space, not because they're necessarily wrong, but because they illustrate how easy it is for exposure estimates to get fuzzy.

The patent cites a calculation that average daily food intake (about 2.5 kg, including water) corresponds to roughly 0.24 µg/kg (or per liter) of MPs/NPs — and frames this as "three orders of magnitude lower" than the minimal concentrations tested in the binding experiments (0.5–2 µg/mL). On its face, that's an odd argument to make in a patent meant to demonstrate real-world relevance: if actual dietary exposure is that much lower than the concentrations where binding was demonstrated, it raises a fair question about whether the tested conditions reflect what a chitosan supplement would actually encounter in someone's stomach after a normal meal. It's the kind of gap that a regulator or a skeptical scientific reviewer would likely probe first.

Separately, the binding efficiency data shows a clear concentration-dependence: entrapment was strongest at the lowest microplastic concentrations and noticeably weaker as concentration increased. For a "detox" narrative, that's actually a reasonable result — you'd expect a finite binding capacity — but it complicates simple marketing claims like "removes microplastics from your body," since the percentage removed isn't constant and the in vivo concentration of microplastics in a real stomach after a real meal is, as the patent's own numbers suggest, not well established.

What This Means for the Industry

For ingredient suppliers, this is a signal that the chitosan market may bifurcate further. There's already a split between food-grade chitosan used for clarification, antimicrobial films, and fat-binding supplements, and pharmaceutical/specialty grades with tighter molecular weight specifications. If high-viscosity, high-MW chitosan becomes associated with a microplastic-binding claim, expect demand and pricing pressure on that narrower band of material — and expect competitors to start characterizing their own chitosan sources by exactly these parameters (viscosity, MW, degree of deacetylation, AFM-measured polymer length) rather than just "chitosan, derived from shrimp shell."

For brand owners and innovation teams, the more interesting question is regulatory rather than technical. Anti-microplastic positioning is an obvious next step for the "detox," gut health, and longevity supplement categories — the consumer anxiety is real and growing, and chitosan is an already-approved, well-understood ingredient with a long safety track record, which lowers the regulatory bar compared to launching a novel binder molecule. But making a substantiated health claim ("reduces microplastic absorption," "supports elimination of plastic particles") is a different matter entirely, particularly in the EU and US, where health claims require a much higher evidentiary bar than a single in vitro/ex vivo patent example set. The gap between "chitosan binds plastic particles in simulated gastric fluid" and "this supplement measurably reduces your microplastic body burden" is where most of the regulatory and reputational risk in this category will live.

What to Watch Next

For now, the most actionable takeaway for R&D and innovation teams isn't "microplastic-binding chitosan is coming to market." It's that the binding behavior appears to depend heavily on chitosan's molecular weight and viscosity — parameters that most supplement formulators don't currently specify or test for — and that any company exploring this space should treat ingredient sourcing and characterization as the first technical hurdle, well before marketing or claims strategy enters the picture.