Breaking Down Krill Oil for Heart Health

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Not all fats are bad for your health. In fact, the American Heart Association recommends two servings of fatty fish every week for a healthy heart. That's because it’s a good source of omega-3 fatty acids. Choices include salmon, lake trout, mackerel, sardines, and albacore tuna.

You can get omega-3s from either food or nutritional supplements, such as fish oil. The two most important omega-3 fatty acids for heart health that are found in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). 

Some plant foods—such as flaxseed, walnuts, and canola oil—contain omega-3 fatty acids as well. However, plant-based food sources provide alpha-linolenic acid (ALA), not EPA or DHA. Your body can convert ALA from plants into EPA and DHA, but only in small amounts.

Oil from krill, tiny shrimp-like marine creatures, is another good source of omega-3 fatty acids. A small study out of Scandinavia found that krill oil supplements increase levels of EPA and DHA as effectively as fish oil supplements. And krill oil has been shown to lower blood fats in laboratory animals. However, the evidence in support of krill oil is limited and still being collected.

Krill Oil's Potential Advantages

Researchers believe krill oil has some advantages over fish oil:

Whales, sharks, seals, penguins, and other sea birds feed on krill. Because krill are at the bottom of the food chain, they aren’t likely to contain mercury or other heavy metals. Mercury may have a negative effect on the nervous system of unborn babies and young children.

Krill oil has about the same amount of DHA as oily fish, but it has significantly more EPA.

Krill oil is also a good source of vitamins A, D, and E, which are antioxidants. Antioxidants protect our cells from the damage caused by free radicals. Free radicals are the byproduct of oxidation—when we break down the air we breathe and the foods we eat. Environmental exposures, such as smoke and radiation, also produce free radicals.

Krill oil is a good source of a unique and potent antioxidant called astaxanthin. Most antioxidants can fight only one free radical at a time. Astaxanthin is believed to handle multiple free radicals at the same time, which is what makes it so powerful. However, no long-term studies to date have proved that taking antioxidants as supplements has value.

Shopping for Krill Oil

You can buy krill oil at most pharmacies, vitamin shops, at some big box stores, and online. It's available in capsules, ranging from 150 to 1000 milligrams (mg) each. Follow dosage instructions on the label. When choosing any nutritional supplement, look for seals on the label from the USP (United States Pharmacopeia),, or NSF International to ensure quality and purity.

There are cautions with krill oil. People who are on blood thinners or who are allergic to shellfish should not take krill oil. Krill oil can also cause problems with certain chronic medical conditions. The same holds true for fish oil. Ask your doctor about your specific risks of taking omega-3 supplement, regardless of whether you take blood-thinning medications.

Key Takeaways

  • Krill oil is a good source of the same heart-healthy omega-3 fatty acids found in fatty fish.

  • Krill oil is also a good source of antioxidants, including vitamins A, D, and E.

  • Krill oil capsules are readily available, but talk to your doctor before taking these supplements to make sure the supplement you want to purchase is safe and you will have no unwanted interactions.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2019 Aug 12

  1. Interview with Melinda Johnson, MS, RD, Lecturer / Director, Didactic Program in Dietetics Arizona State University, Spokesperson, Academy of Nutrition and Dietetics,;

  2. It’s about eating right, Academy of Nutrition and Dietetics. (;

  3. Potential health benefits of plant vs. marine omega-3 fatty acids, Stanford School of Medicine, Prevention Research Center. (;

  4. Krill oil health benefits, Disabled World. (;

  5. Fish and Omega-3 fatty acids, American Heart Association. (;

  6.  Questions & Answers, Heart Foundation Fish Oil Program. (;

  7. Metabolic Effects of Krill Oil are Essentially Similar to those of fish oil but at lower dose of EPA and DHA, in Healthy Volunteers, Lipids, Jan. 2011. (;

  8. Krill oil versus fish oil in modulation of inflammation and lipid metabolism in mice transgenic for TNF-α, European Journal of Nutrition, June 2013. (;

  9. Preventing Heart and Vascular Disease, University of Massachusetts Medical School. (;

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