Omega-3 Fish Oil and Krill Oil Differences (5 min.)

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The health benefits of consuming omega-3 fatty acids in both food and supplement form are well known and well documented. More than 30,000 studies exploring the benefits of omega-3s from fish oil have proven that it aids in reducing inflammation and promoting heart and brain health†. The American Heart Association recommends eating two to three 3.5-ounce servings of fatty fish each week. Unfortunately, many people do not consume enough omega-3, commonly found in seafood, to experience these benefits to the fullest.

Summary: Omega-3 fatty acids are well known for supporting heart health and inflammatory balance, but not all omega-3 sources are the same. Fish oil and krill oil both contain EPA and DHA, yet they differ significantly in concentration, research support, sustainability, and cost. In this article, we explain how omega-3s work in the body, compare fish oil and krill oil side by side, and review why fish oil remains the most efficient (and researched) option for most people†.

Omega-3 Benefits for Inflammation and Heart Disease

The National Institutes of Health states the benefits of taking omega-3 supplements include:

• Decreases heart attack and coronary artery disease†
• Shows slight improvement in blood pressure†
• Supports overall heart health†
• Reduces high triglyceride levels, which have been associated with heart disease risk†
• It may relieve rheumatoid arthritis and symptoms of dry eyes†

(Learn about the health benefits of omega-3 throughout the body, or have a cardiologist talk specifically about the heart health benefits of omega-3.)

What is Krill?

Krill are small shrimp-like marine crustaceans, similar in size to a large paperclip, that live in the ocean and feed on algae and plankton. Krill play an important role in overall marine life, as they feed directly on algae and plankton, which are then converted into a form of energy (krill) that can be consumed by other sea life. Probably best known as the food of choice for giant blue whales, seals, squid, and cold-water fish also consume a diet rich in krill. In addition to converting algae and plankton into energy, because krill consume carbon-rich food near the ocean surface (and then excrete it in lower, colder waters), some believe they play a crucial role in removing the greenhouse gas carbon dioxide.

Krill fishing is banned in United States waters. Commercial krill fishing for supplements (and aquaculture feed) is almost entirely krill from the Antarctic. Although regulated (by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR)), krill populations around the world have declined by 80 percent since the 1970s, with global warming being the most likely cause. Due to sustainability concerns (coupled with low consumer demand), Whole Foods discontinued the sale of krill products more than a decade ago and recommends that consumers opt for fish oil supplements as an alternative.

Fish Oil vs. Krill Oil: Not All Omega-3 Sources are the Same

While both fish and krill oil contain omega-3 fatty acids, specifically DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), there are important differences between the two, especially in concentration, absorption, and research support.

Fish Oil Sources

Fish oil typically contains higher levels of EPA and DHA than krill oil. This type of oil is derived from oily fish such as:

• Salmon
• Mackerel
• Trout
• Herring
• Anchovies
• Sardines

For example, one softgel of Cooper Complete Advanced Omega-3 contains 360 mg EPA and 240 mg DHA, which is significantly more than what most krill oil supplements provide.

Krill Oil Composition and Research

Krill, the source of krill oil, are tiny reddish shrimp-like crustaceans that live in oceans around the globe. Wild salmon actually obtain their reddish-pink color from feeding on shrimp and krill. Krill oil contains EPA and DHA, like fatty fish, but in much lower concentrations. For instance, a common krill oil product contains just 128 mg of EPA and 60 mg of DHA per 1,000 mg capsule. With only about 1,500 studies on krill oil, the body of clinical research is far below that regarding omega-3 fatty acids and fish oil. Because there are fewer studies, there is more limited science-based information on its benefits.

Krill oil also contains phospholipids, which proponents claim may enhance the absorption of omega-3 fatty acids. However, the clinical data continues to be inconclusive. A 2011 study published in Lipids in Health and Disease found similar blood levels of EPA and DHA, but only when the krill oil dose was nearly double that of the fish oil. (The krill oil group took 3 grams of krill oil per day while the fish oil group took 1.8 grams of fish oil.)

Bottom Line

Fish oil remains the more widely researched and concentrated source of omega-3s. While krill oil may offer some additional compounds, such as phospholipids and astaxanthin (a carotenoid), the higher omega-3 content and lower cost per milligram make fish oil a more efficient and evidence-supported option for most people.

Feature	Fish Oil	Krill Oil
Omega-3 Content (EPA + DHA)	High (e.g., 600 mg per softgel in Cooper Complete)	Low (e.g., ~188 mg per 1000 mg capsule)
Form of Omega-3	Triglyceride or ethyl ester	Phospholipid
Absorption	Proven effective	It may be better absorbed, but more research is needed
Scientific Studies	30,000+ published studies	~1,500 published studies
Other Nutrients	Primarily EPA and DHA	Includes astaxanthin (antioxidant)
Sustainability	Widely available from sustainable fisheries	Some concerns about overfishing and krill population decline
Cost per mg of Omega-3	Lower	Higher

Takeaway Points About Omega-3 Supplements

Cooper Clinic Registered Dietitian Nutritionists recommend eating two to five servings of fish per week, including fatty fish such as salmon, mackerel, trout, herring, anchovies, and sardines, to obtain adequate omega-3. When this consumption is not possible, they encourage the incorporation of a fish oil supplement containing high levels of DHA and EPA.

While krill oil appears to be generally safe, the lack of scientific data suggests that the discussion surrounding its benefits is more hype than fact. With more than 30,000 studies to date on omega-3 concentrations in fish oil, Cooper Complete recommends taking a minimum dosage of 1,000 mg a day of omega-3 to reap its benefits to the fullest extent†.

Not sure how to choose the right omega-3 supplement? Consult with your physician or health care provider to determine if a product like Cooper Complete Advanced Omega-3 is suitable for you.

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About the Author: Jill Turner is the President of Cooper Complete® Nutritional Supplements, where she oversees product development and customer experience. She enjoys writing about vitamins, supplements, and preventive health to help consumers make informed, science-backed decisions.

Cooper Complete June 11, 2025