Krill Oil vs. Fish Oil: Which Omega-3 Supplement Is Right for You?
Explore the key differences in absorption, health benefits, and cost to find your best fit
By now you’ve probably heard about some of the many benefits of the omega-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). The omegas work together to tame inflammation and oxidative stress, cell-damaging processes that contribute to a host of health concerns. And while taking fish oil is a well-known way to increase your omega-3 levels, mounting evidence shows that krill oil, a supplement derived from small sea crustaceans, can do the job too. But is one better than the other? Read on to determine which is best for you.
Krill oil vs fish oil: The biochemical basics
“Both krill oil and fish oil are rich sources of omega-3 fatty acids, specifically EPA and DHA, which are known to support heart, brain, and metabolic health,” confirms Michelle Routhenstein, cardiology dietitian at EntirelyNourished.com. But there’s a key difference in their chemistry, since fish oil binds the fatty acids to fats called triglycerides, while krill oil binds them to fat molecules called phospholipids. “That phospholipid ‘coat’ seems to improve absorption, so a 500 mg krill capsule often raises omega-3 indices about as much as a 1 gram fish oil softgel,” notes Julio Baute, MD, medical communications and outreach expert at Invigor Medical. Plus, krill oil contains an antioxidant compound known as astaxanthin that fish oil usually lacks.
The health benefits of krill oil vs fish oil
Given krill oil’s krill oil’s added astaxanthin and superior absorption, it would seem the supplement is a better choice. But in a head-to-head health race, fish oil is far from out of the running. Here’s what experts say about the benefits of both.
Woman's World Answers
More science backs fish oil for lowering blood fats
“Fish oil has been more extensively studied, particularly for its ability to lower triglycerides and reduce cardiovascular events,” says Routhenstein. And as Peter Sulack, DC, founder of The Be Resilient Program notes, “Fish oil is clinically proven to lower triglycerides and support heart health at therapeutic doses.” Part of that proof: A report in the journal Systematic Reviews analyzed 16 studies on fish oil and concluded that taking it significantly reduced triglycerides.
And though Korean experts determined that krill oil and fish oil lowered triglycerides to a similar degree, fish oil may be specially beneficial if high triglycerides and cholesterol run in your family: In a 2024 study, supplementing with fish oil modified the effects of cholesterol-boosting genes and lowered triglycerides, total cholesterol and LDL (aka ‘bad’ cholesterol).
Krill oil may be better for quick thinking
“For brain health and mood, both fish oil and krill oil can be effective” says Luke Barr, MD, board-certified neurologist and chief medical officer at SensIQ. But he adds that krill oil’s phospholipid-bound omega-3s may allow for better absorption into brain tissue. Indeed, a study found that taking krill oil daily increased brain activity and response times during cognitive tasks more effectively than sardine oil—and authors credited krill oil’s superior absorption for the enhanced effects.
“That said, fish oil has a larger body of clinical research supporting its role in depression and cognitive aging,” he says. “For example, EPA-rich fish oil has shown promise in mood regulation, especially in individuals with inflammatory markers.”
Krill oil and fish oil run neck-and-neck for joint pain
The Arthritis Foundation notes that an analysis of 70 studies on fish oil and other supplements indicated that the oil eased morning pain and stiffness in rheumatoid arthritis sufferers. As for krill oil, Dr. Baute says small studies hint that its astaxanthin may offer an extra anti-inflammatory edge for mild knee pain. But he points out there’s no real winner, since the krill oil evidence is of “low certainty.” In an Australian investigation, folks who took krill oil supplements daily for six months experienced improvements in knee pain, stiffness and physical function. But authors of the study cited other research showing that fish oil was also helpful.
Other things to consider about krill vs. fish oil
“Krill oil is typically taken in lower doses because of its higher bioavailability—but that also makes it more expensive,” Dr. Barr explains. “Fish oil requires higher doses for equivalent EPA/DHA content, but it’s widely available and often more cost-effective.” Still, he notes that fish oil can trigger fishy burps and GI upset in some people If you’re one of them, krill oil could be easier to tolerate.
But no matter which supplement you opt for, it’s crucial to check with your doctor before dosing. “Both krill and fish oil can thin the blood, so patients on anticoagulants should speak with their provider before starting,” Dr. Barr cautions. “At very high doses, fish oil may also raise LDL in some individuals, which is why personalized monitoring is important. And of course, quality matters—look for third-party tested products free of heavy metals and rancidity.”
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