Omega XL is not krill oil. It is a green-lipped mussel oil supplement, so the real question is mussel oil versus krill oil, and no head-to-head trial has settled it. Mussel oil has a small, mixed set of joint studies, krill oil has its own, and neither is a proven fix for sore joints. Which one suits you comes down to what you can verify on the label, your allergies, and your budget.
Captains Krill Oil™ is the krill side of this comparison, so weigh our view accordingly. We will tell you where the other product has the stronger case.
What Omega XL actually is
An independent review of Omega XL on FitnessVolt (updated May 2026) describes it as a green-lipped mussel oil supplement in small softgels, with olive oil and vitamin E as supporting ingredients. The same review scores it 3.5 out of 5, with its lowest mark, 2.8, for label transparency. Its main complaint is the proprietary blend: the page says the blend makes dose comparison difficult and that you should not assume it gives the clearly disclosed EPA and DHA amounts of an ordinary fish oil. It also flags the price as often higher than clearer omega-3 alternatives, and says the product is not appropriate for shellfish-sensitive users.
That is one reviewer’s reading, not a lab test, and we have not tested the product. But it names the real issue for anyone comparing: with a proprietary blend you cannot easily tell what dose you are getting.
What the mussel oil trials show
Green-lipped mussel (Perna canaliculus) from New Zealand is the species behind most of the research. The best summary we found is a 2021 systematic review by Abshirini and colleagues in Inflammopharmacology (read it here). It covered nine trials and 452 participants with osteoarthritis. Pooling five of those trials (278 people), pain scores improved with a standardized mean difference of about 0.46, a moderate effect that the authors called clinically meaningful. They were also upfront about the limits: the evidence was limited by the number and quality of the studies, only four of nine scored as high quality, and one author is employed by a New Zealand mussel producer.
Two individual trials show why the picture is mixed:
- A positive but unblinded-in-part trial. Zawadzki and colleagues (Marine Drugs, 2013) randomized 50 osteoarthritis patients to 1,200 mg a day of a mussel lipid extract or 1,200 mg a day of fish oil for 12 weeks. Pain fell sharply in the mussel group and not in the fish oil group. But the trial had no placebo arm, was small, and its second stage was open-label. Read it as a promising signal, not proof.
- A placebo-controlled trial that found nothing on its main measure. Stebbings and colleagues (BMC Complementary and Alternative Medicine, 2017) gave 80 people with hip or knee osteoarthritis 600 mg a day of a mussel extract or a corn oil placebo for 12 weeks. There was no significant difference in the pain scores it was designed to detect. The supplier provided the product and had input into the design.
So the honest summary is a modest, uncertain signal in small studies, some funded by people who sell the stuff. That is not nothing, and it is not a settled benefit.
What krill oil has on joints
Krill oil’s record is the same shape: some small studies with encouraging numbers, and then a larger, cleaner trial that came back null. A 2024 Monash University trial in JAMA (262 people, 2 grams of krill oil a day for 24 weeks, knee osteoarthritis with MRI-visible inflammation) found no meaningful benefit over placebo. We covered it in Krill Oil vs Fish Oil for Joint Pain. If a seller tells you either oil is proven for joints, they are ahead of the evidence.
How to choose between them
- Allergy first. Both are shellfish. If you are allergic, skip both, ours included. See Can you take krill oil if you are allergic to shellfish?
- Can you read the dose? A label that states EPA and DHA lets you compare. A blend does not. Read our take on how much krill oil per day and on reading labels in which krill oil is best.
- Price per useful dose. Neither is cheap. See why krill oil is so expensive for what drives our side of it.
- How it was made. For krill, extraction method and freshness matter. See Boat to Bottle.
Where Captains fits
Captains is mechanically extracted on the boat with no chemical solvent, in small batches, and after 20 years in business we will still tell you it is a natural product. EPA and DHA vary a little from lot to lot, we test lots at random and they come back strong, and documentation is available on request. We don’t make joint claims for it, because the best recent krill trial didn’t earn one.
You might not need us (or Omega XL)
If you eat oily fish like salmon or sardines a couple of times a week, you already get EPA and DHA with a long track record behind them. If your joints hurt, the things with the strongest support are not supplements at all: movement, strength work, weight if it applies, and a conversation with your doctor. A marine oil, mussel or krill, is a maybe on top of that, not a substitute.
Frequently asked questions
Is Omega XL a krill oil?
No. Omega XL is sold as a green-lipped mussel oil supplement. Mussel oil is a different marine oil from a different animal, a mollusk rather than the Antarctic krill crustacean.
Is Omega XL better than krill oil for joint pain?
Nobody can say from the trials. We found no head-to-head trial of mussel oil against krill oil. Mussel oil has a small pile of osteoarthritis studies with mixed results, and krill oil’s best recent joint trial, a 2024 JAMA trial, was null.
Can I take Omega XL and krill oil together?
There is no strong reason to, and both are marine oils that may thin the blood a little at higher doses. If you take blood thinners or have surgery coming up, ask your doctor first, as with any omega-3.
Is green-lipped mussel oil safe if I have a shellfish allergy?
Mussels are shellfish, so people with a shellfish allergy are usually told to avoid mussel oil, and the same caution applies to krill. We wrote up the krill side of that in a separate article, linked below.
Why is it hard to compare Omega XL with krill oil by dose?
Because the label gives a proprietary blend rather than a clear EPA and DHA figure, as one independent review of the product points out. Krill oil labels usually state EPA and DHA, which at least lets you do the arithmetic.
Honest answer, not a pitch. — captainskrilloil.com