Microplastics in supplements and peptides: what studies found and how a lab tests for them

Microplastics in supplements: what published studies found

A 2026 review of the field highlights peer-reviewed studies on three kinds of supplement: omega-3 oils, fibre supplements and spirulina. Each study found plastic particles in most or all of the products it tested. The numbers cannot be compared with each other, because each study used its own method, size range and unit.

Study	Products tested	Method and particle sizes	Result (averages)	Polymers found most often
Kim et al., Foods 2024	14 raw omega-3 oils and 21 capsule products, Korean market	µ-Raman; particles from 5 µm	Raw oil 1.2 to 2.2 particles/g; capsule oil 3.5 to 10.6 particles/g	Polypropylene and PET, 83–95%
Panneerselvan et al., Environmental Pollution 2024	9 fibre supplements, powders and gummies, Australia	µ-FTIR; particles found from 120 µm to 3 mm	Particles in all 9; estimated average intake 5.89 particles a day	Polyamide (nylon)
Tutaroğlu et al., Environmental Science and Pollution Research 2024	29 spirulina products	Microscope, then µ-Raman; particles found from 0.07 to 5.7 mm	Suspected particles in 26 of 29; 13.77 particles per 100 g dry weight	Polypropylene, 31.6%

We found no peer-reviewed study of microplastics in magnesium supplements, collagen peptides or research peptides (literature search, October 2026). These studies measured particles in products. What the particles mean for health is outside what a product test can show.

Where the particles come from: manufacturing and packaging

Kim et al. tested raw oils and finished capsules separately. Animal-based capsule oil averaged 10.6 particles per g against 2.2 in animal-based raw oil. For plant-based oils the figures were 3.5 and 1.2. The authors concluded that manufacturing and packaging, not the raw material, were the main source.

A 2026 review of 129 publications on health-oriented foods (Kadac-Czapska et al., Toxics) lists the same release points: mixers, capsule-filling machines, tablet presses, plastic tubing and filters, and packaging that sheds particles through friction when it is opened, closed or squeezed. It cites reports that products in push-through blister packs had lower particle counts than products in PET bottles. In the spirulina study, powders averaged 17.34 particles per 100 g against 10.43 for capsules and tablets, a difference the authors did not find statistically significant.

Plastic containers can shed into liquids too. In 16 batches of injections supplied in polypropylene bottles, Wang et al. (Heliyon 2024) identified ethylene-propylene copolymer particles of 2–10 µm by µ-Raman, at 216 particles per mL. For what containers, stoppers and pens can release besides particles, see extractables and leachables.

How labs detect microplastics in food and supplements

A lab works in three steps: it separates the particles from the product, finds them under a microscope, and confirms from each particle’s spectrum that it is plastic. Our guide on how microplastics are detected covers each instrument in depth.

1. Isolate. The product is dissolved or digested so only insoluble particles remain, then filtered onto a membrane. Kim et al. washed the oil through a 5 µm silicon filter with acetone. Complex products make this step harder: the 2026 review notes that fats, proteins and other components complicate digestion and filtration and raise the spectral background.
2. Find. A microscope locates candidate particles and records size and shape.
3. Identify. Each spectrum is matched against a polymer library. Kim et al., and Whiting et al. in a 2022 surface-water study, both accepted a match only at a hit quality index of 0.7 (70%) or higher.

Method	What it reports	Reach in the studies cited here
µ-Raman	Count, size, shape and polymer of each particle	From 5 µm in omega-3 oil; 2–10 µm particles in injections
µ-FTIR	Count, size, shape and polymer of each particle	Used for the fibre supplements
LDIR (laser direct infrared)	Count, size, shape and polymer, with automated particle finding	Down to 20 µm in surface water, with 88.3% recovery
Pyrolysis-GC/MS	Mass of each polymer, with no particle count	1,000 to 100,000 ng/L of copolymer in the injection study

Blanks and recovery decide whether a count means anything

Lab air, water, reagents and clothing all carry plastic. Kim et al. worked under a laminar-flow bench with an ULPA filter and ran 12 procedural blanks with no product in them. The blanks averaged 0.3 ± 0.5 particles, which set a limit of detection of 1.8 particles per sample. In a recovery test, 117 of 118 added polyethylene spheres were found again on the filter. The 2026 review lists the controls to expect in every batch: procedural blanks, filtered reagents, covered glassware, clean air, few plastic consumables and cotton lab coats.

A microscope alone is not enough. In the spirulina study the team saw 251 suspected particles. Of those it analysed by µ-Raman, 73% (35 particles) were confirmed as plastic. The review states that visual inspection cannot confirm a particle’s chemistry. For the same reason, spotting specks in a supplement at home, even under a microscope, cannot show that they are plastic.

No standard method for supplements yet

The FDA says there are no standardised methods to detect, quantify or characterise microplastics and nanoplastics. It adds that many studies used methods of variable or limited accuracy. Its page describes microplastics as pieces typically under 5 mm in at least one dimension, and nanoplastics as under 1 µm.

ISO 16094-2:2025 sets out microscopy with vibrational spectroscopy for particles of 1 to 5,000 µm. Its scope is drinking water and other waters low in suspended matter, and it names 10 polymers, from polyethylene to polyurethane. Kim et al. note that standard methods exist for water but not yet for food or oil. The 2026 review adds that no law requires monitoring microplastics in these products.

So a microplastic result for a supplement has no official limit and no pass or fail. It is a count, or a mass, under the lab’s own method. Two results compare only when the size limit, polymer list and units match, the same rule that applies when peptide labs disagree.

Microplastics in peptides and collagen peptides

Collagen peptides are hydrolysed collagen, usually sold as a food powder. Research peptides are synthetic, freeze-dried and filled a few mg to a vial. Neither has published microplastic data that we could find. For collagen peptides, the powder methods above apply directly.

A research peptide vial raises a problem of scale. If a powder held particles at the highest average in the omega-3 study, 10.6 per g, a 10 mg vial would hold about 0.1 particle. That is well below the 1.8-particle detection limit those blanks set. A test of one vial can only detect particles present in larger numbers, for example from the stopper, the cap or the filling line, which do not scale with the mass of powder. Pooling several vials of one batch raises the mass analysed.

Injectable medicines already face a particle test. The harmonised pharmacopoeial chapter on sub-visible particles (USP <788>, Ph. Eur. 2.9.19) allows, for containers under 100 mL, up to 6,000 particles of 10 µm or more and 600 of 25 µm or more per container, by light obscuration. The chapter says particulate matter must be controlled “independent of its type”, and its methods count and size particles without identifying them. So the count does not say which particles are plastic. A research peptide has no such specification. A microplastic test would add what the count leaves out: the polymer of each particle.

How to read a microplastics result

What the report should state	Why it matters
Lower size limit	In the omega-3 study, 60–73% of particles were 5–20 µm, so a method that starts at 20 µm would have missed most of them
Method	Spectroscopy gives counts; pyrolysis-GC/MS gives mass. The two cannot be compared directly
Polymer library and match threshold	A method finds only the polymers it can identify
Blanks	How many, what they held, and whether they were subtracted
Recovery	The share of added particles the method found again
Sample mass, units and number of units	Per g, per serving, per 100 g dry weight and per vial are different numbers
Raw data	Particle images and spectra let you check each identification

What drives the cost of a microplastics test

Prices depend on the method a lab uses. These choices drive the work:

• The product. An oil, a gummy, a fibre powder and a peptide each need their own preparation.
• The size limit. In the omega-3 study, smaller particles were more numerous, so a lower limit means more particles to measure.
• Controls. Blanks, recovery checks and replicates each add runs.
• Count or mass. Spectroscopic counting and pyrolysis-GC/MS answer different questions; some studies use both.
• Units and batches. Each product, batch or pooled sample is a separate analysis.

Ask each lab to quote the size limit, polymer list, number of blanks and units, so two quotes describe the same test.

What HK Analytical does

We do not test for microplastics today. HK Analytical is adding microplastic, PFAS and BPA testing. Write to contact@hkanalytical.com to hear when it starts. You can also use the contact form. For peptides, our tests include identity (LC-MS), purity (HPLC), content per vial, endotoxin (LAL), Sterility (USP <71>, 14 days) and residual solvents, in any mix per sample. Results within days of receipt. Sterility (USP <71>, 14 days) is the one test that takes 14 days, because the method incubates for 14 days. Every number comes with its raw data, in a signed record you can check on our verify page. To price a panel, request a quote.