Krill Oil vs. Fish Oil for Heart Health: What's the Better Source?

Medically Reviewed By William C. Lloyd III, MD, FACS
Krill oil

You might have seen ads claiming that krill oil is even better than fish oil as a way to get omega-3 fatty acids for heart health. The science behind that statement is limited. So the jury is still out on whether a krill oil supplement is the better choice. Here is a summary of the information on krill oil so far.

The Basics on Omega-3 Fatty Acids

Like fish oil, krill oil contains polyunsaturated omega-3 fatty acids. These are good fats. You need them for many important body functions, such as blood clotting and healthy cell growth.

There are several types of omega-3 fatty acids. Alpha-linolenic acid (ALA) is in foods, such as vegetable oils and flaxseed. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are in fatty fish, such as salmon and tuna. Your body can convert ALA to EPA and DHA in small amounts. However, you can't make any omega-3 fatty acids on your own. You need to get them through food or supplements.

According to the American Heart Association, omega-3 fatty acids improve heart health. Getting them in your diet can decrease triglycerides, a type of fat in the blood. Omega-3s slow the buildup of fat in your arteries and lower blood pressure slightly. That's all good because fat in the blood, clogged arteries, and high blood pressure are risk factors for coronary heart disease.

Why Krill Oil Is Becoming Popular

Krill are shrimp-like crustaceans. They live in all the world’s oceans, but are particularly abundant in the icy waters around Antarctica. Krill oil has about the same amount of DHA as fish oil, but it has more EPA.

Only a few studies have looked at the benefits of krill oil over fish oil supplements. Researchers in Norway and Sweden published the results of one study in the journal, Lipids. They divided more than 100 participants with normal or slightly elevated levels of blood lipids (such as total cholesterol and triglycerides) into three groups. One group took krill oil, one group took fish oil, and the third group took no supplements.

The groups that took krill oil or fish oil supplements had higher levels of omega-3 fatty acids than the third group that had taken no supplements. There were, however, no significant differences in changes in blood lipid levels among any of the groups.

Researchers in Norway have also studied krill oil in mice. The results are available in the European Journal of Nutrition. They found that although fish oil and krill oil are comparable dietary sources of omega-3 fatty acids, krill oil may lower blood levels of certain fats.

Both of the studies have limitations. One was in animals, and the other did not follow people for a long period of time or include those who already had cardiovascular disease. Studies involving larger numbers of participants are needed. More research on the beneficial effects of krill oil is necessary.

More Krill Oil Benefits Are Being Studied

Krill are low on the food chain. That means krill may be less prone to pollution than other sources of fatty fish, such as salmon, mackerel, and tuna. But there’s not any conclusive evidence of this possible benefit of krill oil.

Krill oil may also provide more antioxidant activity than fish oil. Antioxidants protect your body from free radicals. Your body produces free radicals as a byproduct of breaking down food, or being exposed to environmental hazards, such as tobacco smoke and radiation. Krill oil gets its antioxidant power from vitamins A and E, astaxanthin, and the marine flavonoids that krill oil contains. However, no large studies have linked antioxidants directly to heart health.

If You Want to Try Krill Oil

According to the National Institutes of Health, fish oil supplements are generally safe, as long as people take less than three grams a day. The limits for krill oil are not known.

It’s important to know that omega-3 supplements can interact with blood thinners. So ask your doctor about taking fish oil or krill oil if you're on blood-thinning medication, or if you have a chronic medical condition.

Key Takeaways

  • There are heart-health benefits to omega-3 fatty acids, the good fats in fish, like salmon and tuna.

  • Krill oil has the potential to be a better choice. It contains about the same amount of the omega-3 fatty acid DHA as fish oil, but has more EPA.

  • It's too soon to tell if krill oil is better for heart health than fish oil. More research is necessary.
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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Aug 26
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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