Fish Oil vs Krill Oil: Which Is Better? (2026 Evidence Review)

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What the Science Shows: Fish Oil vs Krill Oil

Fish oil and krill oil are two of the most popular omega-3 fatty acid supplements on the market. Both are derived from marine sources, but they have distinct differences in terms of their bioavailability, EPA+DHA content, and price per dose. In this article, we’ll delve into the scientific evidence to determine which one is better.

Omega-3 Fatty Acids: The Benefits

Omega-3 fatty acids, particularly EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), have been extensively studied for their numerous health benefits. These include reducing inflammation, improving heart health, and supporting brain function. A 2019 American Heart Association science advisory concluded that 4 g/day of prescription omega-3s lowers very high triglycerides by at least 30% (1).

What the Science Shows: Fish Oil

Fish oil is extracted from the tissues of oily fish such as salmon, tuna, and mackerel. It is a rich source of both EPA and DHA, with an average ratio of 1:1. A 2019 meta-analysis of 26 trials found that EPA-rich formulas (at least 60% EPA, up to about 1 g of EPA a day) modestly improved depressive symptoms (2). However, the bioavailability of fish oil can be affected by factors such as the type of fish used, the extraction method, and the presence of impurities.

What the Science Shows: Krill Oil

Krill oil, on the other hand, is extracted from the Antarctic krill, a small crustacean that is rich in omega-3s. Krill oil contains both EPA and DHA, as well as other beneficial compounds such as astaxanthin and phospholipids. A 2023 meta-analysis of 14 trials found that krill oil modestly lowered triglycerides and total and LDL cholesterol, but had no effect on blood pressure, blood sugar or inflammatory markers (3).

Key Differences: Bioavailability, EPA+DHA Content, and Price

Which Should You Choose?

The choice between fish oil and krill oil depends on your individual needs and goals. If you’re looking for a more affordable option with moderate to strong evidence for heart health and depression, fish oil may be the better choice. However, krill oil may suit you if you want a lower dose in phospholipid form; it costs more per gram of EPA+DHA, and its evidence is mainly for lowering triglycerides.

Can You Take Both Together?

Yes, you can take both, but no trial has shown that combining them works better than the same total dose of EPA+DHA from one of them. If you combine them, add up the EPA+DHA from both labels.

Dosing & Timing for Each

The dosing and timing for fish oil and krill oil vary depending on your individual needs and goals. A general guideline is to take 1-2 grams of combined EPA and DHA per day. Take either one with a meal that contains some fat; the time of day does not matter.

Safety

Krill are crustaceans, so avoid krill oil if you are allergic to shellfish. If you take a blood thinner such as warfarin, have a bleeding disorder or have surgery coming up, check with your doctor first. Keep EPA+DHA from supplements under 5 g/day (the FDA’s safe limit); in heart trials, doses above 1 g/day were linked to a higher risk of atrial fibrillation.

Key Takeaways

• Fish oil and krill oil have distinct differences in terms of bioavailability, EPA+DHA content, and price per dose.
• Fish oil is generally cheaper per gram of EPA+DHA and has strong evidence for lowering triglycerides; evidence for preventing heart attacks and for depression is mixed.
• Krill oil may be absorbed somewhat better per gram in some trials (others found no difference), and its evidence is mainly for lowering triglycerides.
• You can take both together, but there is no evidence that the combination beats the same dose of EPA+DHA from one oil.
• Dosing and timing vary depending on your individual needs and goals.

References:

1. Skulas-Ray AC, et al. Circulation. 2019; 140(12): e673-e691.
2. Liao Y, et al. Translational Psychiatry. 2019; 9(1): 190.
3. Huang H, et al. Diabetes & Metabolic Syndrome. 2023; 17(12): 102909.

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