Klean Omega

The practical details.

Before you buy

Evidence & sources.

Do creatine, fish oil, vitamin D and magnesium work? Our evidence review grades the research as Mixed. That grade is about the claim, not about this product.

• CertificationNSF's Certified for Sport database lists two US entries named "Klean Omega" by Klean Athlete. Each is a 60-count softgel with a serving size of 1, 1.5 g of fat and 10 calories. One (listing 820619) lists the flavor as unflavored and shows 19 lot numbers, two of them repeated, so 17 are different. The other (listing 1602043) lists the flavor as Other and shows 6 lot numbers. A third entry, for Canada, shows 6 lots.^{3–5, 12} Checked in NSF's own database. Klean's product page shows no product-specific NSF mark or lot lookup (the NSF logo appears only in the site footer and menu), and the label text doesn't name NSF. So the listings are the evidence of certification. Neither entry shows a certification date, EPA or DHA amounts or a SKU. NSF doesn't say how the two US entries relate. Their free-of lines differ, and the label lists natural orange flavor. You can match the lot number on your bottle to the listed lots. NSF says it verifies that the label matches the contents. It also says products don't contain unsafe levels of contaminants, prohibited substances or masking agents.
• Manufacturer claimKlean's page says Klean Omega provides essential omega-3 fatty acids from fish oil in triglyceride form. It says the product supports an athlete's cardiovascular, neurological and joint health needs. The page carries the standard FDA disclaimer.¹ These are Klean's own statements for a dietary supplement. The page's disclaimer says the FDA hasn't evaluated them. It also says the products aren't intended to diagnose, treat, cure or prevent any disease. This review didn't assess them.
• Independent testNIH's Office of Dietary Supplements says a typical fish oil supplement gives about 1,000 mg of fish oil. That holds 180 mg EPA and 120 mg DHA, though doses vary widely. It says FDA concluded that supplements giving 5 g a day or less of EPA and DHA are safe when used as recommended. It lists common side effects, usually mild: an unpleasant taste, bad breath, heartburn, nausea, stomach discomfort, diarrhea, headache and odoriferous sweat. It says fish oil can have antiplatelet effects at high doses and might prolong clotting times with warfarin.⁸ One Klean softgel gives 750 mg of EPA plus DHA, 2.5 times the 300 mg in the typical capsule ODS describes. That's far below 5 g. ODS says re-esterified triglycerides, natural triglycerides and free fatty acids have somewhat higher bioavailability than ethyl esters. It adds that all forms significantly raise plasma EPA and DHA. ODS advises people who take medications regularly to discuss possible interactions with their health care providers.
• Published studyA 2021 meta-analysis pooled 7 randomized trials of marine omega-3 supplements and cardiovascular outcomes (Gencer and colleagues, Circulation). It covered 81,210 participants, with a mean age of 65 and a weighted average follow-up of 4.9 years. It found an increased risk of atrial fibrillation (hazard ratio 1.25, 95% CI 1.07 to 1.46). The hazard ratio was 1.49 (95% CI 1.04 to 2.15) in trials testing more than 1 g a day. It was 1.12 (95% CI 1.03 to 1.22) in trials testing 1 g a day or less.⁹ Summarized from the abstract on Europe PMC. The trials were run to study cardiovascular outcomes and didn't test Klean Omega. One softgel gives 750 mg of EPA plus DHA. Klean doesn't state total omega-3s, so how it sits against the 1 g split isn't exact. Klean's directions are 1 softgel a day, and two would give 1,500 mg of EPA plus DHA.
• Published studyVITAL randomized 25,871 US adults to 1 g a day of marine omega-3 fatty acids or a placebo (Manson and colleagues, NEJM). They were men 50 and older and women 55 and older. Over a median 5.3 years, major cardiovascular events occurred in 386 participants on omega-3 and 419 on placebo. The hazard ratio was 0.92 (95% CI 0.80 to 1.06). Invasive cancer was diagnosed in 820 and 797 (hazard ratio 1.03, 95% CI 0.93 to 1.13). The abstract reports no excess risks of bleeding or other serious adverse events.^{8, 10} The trial's 1 g a day capsule held 460 mg EPA and 380 mg DHA, per NIH. That's 840 mg of EPA plus DHA, close to one Klean softgel's 750 mg. It didn't test Klean Omega. Its authors concluded that supplementation didn't result in a lower incidence of major cardiovascular events or cancer than placebo. NIH and others funded it.
• Regulator recordopenFDA's food enforcement reports returned no match for "Klean Athlete" in the product-description field on Oct 24, 2026. They also returned none for "Klean" or "Klean Athlete" in the recalling-firm field. A search of FDA's warning letters database for "Klean Athlete" returned no letters. FDA lists that content as current as of Oct 20, 2026.^{11, 13} These are name searches. They would miss a recall or letter filed under another name, such as a parent company or contract manufacturer. FDA's warning letters search may not cover older letters.