Introduction
Omega-3 fatty acids EPA and DHA are among the most extensively researched supplements in the world. The European Food Safety Authority (EFSA) has confirmed that EPA and DHA contribute to the normal function of the heart (at 250 mg per day) (EFSA Panel on Dietetic Products, Nutrition and Allergies, 2010). But which source should you choose — classic fish oil or newer krill oil?
Both have their advantages and drawbacks. In this article, we compare them honestly and help you make an informed decision.
What is fish oil?
Fish oil is extracted from the tissues of fatty fish (salmon, mackerel, sardines, anchovies). It contains EPA and DHA fatty acids in triglyceride form (Calder, 2015). Fish oil is the most widely studied omega-3 source — the majority of clinical trials have been conducted with fish oil.
Fish oil capsules are widely available and typically more affordable than krill oil. Quality fish oils are molecularly distilled to remove heavy metals and contaminants (Bourdon et al., 2023).
What is krill oil?
Krill oil is derived from small crustaceans (Euphausia superba) that live primarily in Antarctic waters. Krill oil is distinct because its EPA and DHA are bound to phospholipids rather than triglycerides (Ulven et al., 2011).
Additionally, krill oil contains natural astaxanthin — a red carotenoid that acts as a potent antioxidant and gives krill oil its characteristic red colour (Ambati et al., 2014).
Key differences
| Feature | Fish Oil | Krill Oil |
|---|---|---|
| EPA/DHA form | Triglycerides | Phospholipids |
| Typical EPA+DHA per capsule | 500–1000 mg | 100–300 mg |
| Astaxanthin | Not present | Naturally occurring |
| Fishy taste/burping | Possible | Usually less |
| Price per 1 g EPA+DHA | More affordable (€0.05–0.15) | More expensive (€0.20–0.50) |
| Research volume | Very extensive | Growing but limited |
| Sustainability | Varies (look for MSC label) | Generally well-regulated |
When to choose fish oil
- You want higher EPA/DHA doses (above 500 mg per day) — fish oil is more practical and affordable for reaching high doses
- Budget is a consideration — fish oil offers better value per gram of EPA+DHA
- You want the most extensively researched option — fish oil has thousands of clinical studies behind it
- You are looking for concentrated formulas — high-concentration fish oils (60–90% EPA+DHA) are readily available
When to choose krill oil
- You prefer a phospholipid-based form — some studies suggest phospholipid-bound omega-3 may be absorbed more efficiently into certain tissues
- Fish oil capsules cause unpleasant aftertaste — krill oil typically causes less fishy burping
- You value the added astaxanthin — a natural antioxidant is a bonus of krill oil
- You prefer smaller capsules — krill oil capsules tend to be more compact
Can you combine them?
Yes, combining fish oil and krill oil is safe. Some people use fish oil for their main dose and add krill oil for the phospholipids and astaxanthin. Just monitor your total daily EPA+DHA intake.
Frequently asked questions
Is krill oil better absorbed than fish oil?
Some studies indicate that omega-3 in phospholipid form may be absorbed more efficiently into certain tissues (Ramprasath et al., 2013), but the difference is not always significant. Both forms effectively raise blood EPA/DHA levels (Yurko-Mauro et al., 2015).
Is krill oil safe for people with shellfish allergy?
No. Krill is a crustacean and can trigger allergic reactions in people with crustacean allergies. Fish oil is not suitable for fish allergy. Consult your doctor.
How much omega-3 should I take daily?
The EFSA-approved claim applies at 250 mg EPA+DHA per day for normal heart function. This is the minimum recommended amount.
Is krill oil more sustainable?
Antarctic krill fishing is strictly regulated by CCAMLR (Nicol & Foster, 2016). Quality krill oils carry MSC certification. For fish oil, also look for MSC or FOS labels.
Do omega-3 supplements replace eating fish?
Supplements complement but do not replace a healthy diet. EFSA recommends eating fish 1–2 times per week.
References
1. EFSA Panel on Dietetic Products, Nutrition and Allergies (2010). Scientific Opinion on the substantiation of health claims related to EPA and DHA. EFSA Journal, 8(10), 1796.
2. Calder, P. C. (2015). Marine omega-3 fatty acids and inflammatory processes: Effects, mechanisms and clinical relevance. Biochimica et Biophysica Acta, 1851(4), 469-484.
3. Bourdon, J. A. et al. (2023). Contaminant levels in fish oil supplements: A comprehensive review. Food Chemistry, 405, 134770.
4. Ulven, S. M. et al. (2011). 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, 46(1), 37-46.
5. Ambati, R. R. et al. (2014). Astaxanthin: Sources, extraction, stability, biological activities and its commercial applications — a review. Marine Drugs, 12(1), 128-152.
6. Ramprasath, V. R. et al. (2013). Enhanced increase of omega-3 index in healthy individuals with response to 4-week n-3 fatty acid supplementation from krill oil versus fish oil. Lipids in Health and Disease, 12, 178.
7. Yurko-Mauro, K. et al. (2015). Similar eicosapentaenoic acid and docosahexaenoic acid plasma levels achieved with fish oil or krill oil in a randomized double-blind four-week bioavailability study. Lipids in Health and Disease, 14, 99.
8. Nicol, S. & Foster, J. (2016). The fishery for Antarctic krill: Its current status and management regime. In Biology and Ecology of Antarctic Krill, Springer, pp. 347-370.
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Disclaimer
A food supplement is not a substitute for a varied and balanced diet and a healthy lifestyle.
