Microplastics in Omega-3 Supplements: What We Actually Know

Every product tested had particles in it

Researchers in Korea tested 35 omega-3 oil products for microplastics and found them in all 35. Capsule oil from animal sources averaged 10.6 particles per gram. The raw animal oil it started as averaged 2.2.

That is the headline, and it is real. The study, by Kim and colleagues in Foods in 2024, is the clearest measurement we have. Before you draw conclusions from it, you need to know what it counted and what it missed.

The team cut open the capsules, rinsed out the oil and filtered it through a 5 µm filter. Particles were identified by Raman spectroscopy. That is a laser method that matches the chemical signature of each particle against a library. Anything smaller than 5 µm slipped through. So the figures are a floor, not a ceiling.

The short version: particles are present, they are small, and the count depends heavily on the form.

Capsules carry more than the oil they started as

Look at the split between raw oil and capsule oil, because it is where the study gets interesting.

Animal-based raw oil averaged 2.2 particles per gram (12 products). Animal-based capsule oil averaged 10.6 (14 products). The difference was statistically significant. For plant-based oils, raw was 1.2 and capsule 3.5, but only two raw plant-based oils were tested, so that comparison tells you very little.

The authors concluded that contamination appeared to come mainly from manufacturing and packaging, not from the source material. That fits the pattern. A later review of 129 publications reported a separate Korean survey of 88 omega-3 products, with particles in every sample. It put the mean at 16.3 per serving, and said capsule oil held three to five times more than raw oil.

One caveat on that figure. The capsule oils could not be matched to their own raw oils. These are group averages across different brands, not a before-and-after on the same batch.

What to take from it: if the particles arrive at encapsulation, the fix sits with manufacturers. You cannot filter them out at home.

Algae oil is not exempt

A lot of people assume plant-based means clean. The data do not support that.

Plant-based capsule oil averaged 3.5 particles per gram, against 10.6 for animal-based. That looks like a gap. But the survey tested only seven plant-based capsule products, and the authors report no significant difference between plant and animal sources for raw oil. Seven products is too few to build a claim on.

The more useful reading is mechanical. If the particles come from equipment, packaging and capsule shells, then any oil that passes through the same steps is exposed to them. Our own piece on how vegan DHA is actually made covers where those steps sit in an algae oil supply chain.

So treat algae oil as a different raw material, not a different process. Ask about the process.

How this compares with eating fish

The comparison people want is supplement versus a plate of salmon. The honest answer is that the methods differ too much for a clean number.

A 2022 review by Alberghini and colleagues found usually one or two particles per fish, mostly in the gut. Edible muscle rarely held any. EFSA made the same point in 2016. Fish guts are normally removed, so exposure is low. Mussels and oysters are different, because you eat the digestive tract.

For scale, the review estimated about 123 particles a year for UK mussel eaters and up to roughly 11,000 in high-consumption European countries. Three common fish species gave 112 to 842 a year under EFSA's assumptions. Take the 16.3-per-serving figure and multiply by 365 and you reach roughly 5,950 particles a year. That is our arithmetic, not a measured intake.

A separate 2024 Oregon survey found particles in 180 of 182 seafood samples. Most were fibres. Those were suspected particles, only partly validated, and the authors did not advise avoiding seafood. Particles turn up in nearly everything people have looked at.

Bottom line: a daily omega-3 capsule is a measurable source, but a small one next to everything else.

Why the numbers are hard to compare

Microplastic science has no shared yardstick yet. One lab filters at 5 µm, another at 1 µm. One counts particles, another weighs them. Some identify polymers by Raman, others by infrared spectroscopy or pyrolysis.

That matters for you. A count of 10.6 per gram in Korea cannot be set against a fish figure from Oregon without large error bars. The 2026 review of 129 publications says the same: methods are not standardised, which makes studies hard to compare. Contamination from lab air and plastic equipment is a live risk too, which is why the Kim team used glass tools and a laminar flow bench.

Treat every figure here as one lab's number. The direction is consistent across studies. The exact size is not.

What we do not know about harm

Here is the uncomfortable part. Nobody has shown that swallowing these particles harms you, and nobody has shown that it does not.

EFSA's 2016 statement said there were too few data on occurrence, toxicity and fate in the gut for a risk assessment. It reported no data at all for nanoplastics in food. The Alberghini review reached a similar verdict in 2022. It judged the risk from fishery products probably low, then added that the evidence was not enough for a reliable assessment. Most toxicity work is in animals and cell lines.

The particles in supplements are mostly 5–20 µm. Whether they cross the gut wall in meaningful numbers is exactly the sort of thing that is not yet settled. Nor do we know whether they break down into smaller ones on the way.

So the right stance is neither alarm nor shrugging. It is "unquantified, and worth watching".

The artery plaque study, read carefully

You may have seen the 2024 New England Journal of Medicine paper. It is the reason this topic feels urgent, so it deserves a careful read.

It is a striking number. It is also an observational study of patients who already had advanced disease. The authors state that it shows association, not causation. Laboratory contamination could not be ruled out. They did not measure diet, water or air pollution, so they could not say where the plastic came from.

Nothing in it links the plaque particles to omega-3 capsules. It tells you plastics are in human tissue and that the question is worth funding. It does not tell you what any single food or supplement contributes.

What to do with this

You cannot test your own capsules. You can change what you ask of the brand.

Ask whether the manufacturer tests finished product for particles, and by what method. Most will say no. That is useful information too. The 2026 review found no legal requirement to monitor these particles in supplements. Ask where the oil is encapsulated and what the packaging is. Prefer products with a batch-level certificate of analysis for oxidation and contaminants, as covered in our heavy metals piece.

Then keep the dose in proportion. If you take omega-3 for a reason, the dose matters more than the capsule count. Our guide to how much DHA you need per day and the Omega-3 Index test help you aim at a target rather than guess. Dropping a useful intake over an unquantified exposure is a trade you should make deliberately, with your GP, not out of a headline.

Finally, calibrate on study quality. One 35-product survey is a start. Our note on why small studies mislead applies here as much as anywhere.

You can see what goes into our own DHA, and what we test, on the Omega-3 DHA product page. We do not claim any oil is particle-free. Nobody can yet.

References

1. Kim, M., Kim, J., Park, S., Kim, D., Jung, J., Cho, D. (2024). "Determination of Microplastics in Omega-3 Oil Supplements." Foods, 13(10), 1434. PMID: 38790734. DOI: 10.3390/foods13101434.
2. Kadac-Czapska, K., Ośko, J., Jażdżewska, K., Grembecka, M. (2026). "Microplastics in Foods Intended for Health Purposes: From Dietary Supplements to Clinical Nutrition Products." Toxics, 14(6), 514. PMID: 42347412. DOI: 10.3390/toxics14060514.
3. EFSA Panel on Contaminants in the Food Chain (2016). "Presence of microplastics and nanoplastics in food, with particular focus on seafood." EFSA Journal, 14(6), 4501. DOI: 10.2903/j.efsa.2016.4501.
4. Alberghini, L., Truant, A., Santonicola, S., Colavita, G., Giaccone, V. (2022). "Microplastics in Fish and Fishery Products and Risks for Human Health: A Review." International Journal of Environmental Research and Public Health, 20(1), 789. PMID: 36613111. DOI: 10.3390/ijerph20010789.
5. Marfella, R., Prattichizzo, F., Sardu, C., et al. (2024). "Microplastics and Nanoplastics in Atheromas and Cardiovascular Events." New England Journal of Medicine, 390(10), 900-910. PMID: 38446676. DOI: 10.1056/NEJMoa2309822.
6. Traylor, S., Duncan, M., Granek, E., et al. (2024). Seafood microplastics survey, Portland State University. Frontiers in Toxicology. DOI: 10.3389/ftox.2024.1469995.

Ask every omega-3 brand what it measures

Microplastics are not yet part of routine supplement testing anywhere. Our DHA comes from fermented algae, and you can read what we test for on the product page.

See Omega-3 DHA →