Omega-3 fatty acids are essential nutrients that play a crucial role in various bodily functions, including heart health, brain function, and inflammation regulation. Fish Oil and krill oil are two popular dietary supplements that provide significant amounts of two essential omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). While both sources offer similar benefits, they have some differences in terms of composition, cost, and potential advantages.
Krill Oil and Fish Oil Source and Composition:
Fish Oil: FO is derived from fatty fish such as salmon, mackerel, and sardines. It contains a higher concentration of EPA and DHA compared to krill oil. These fatty acids are present in the triglyceride form in fish oil.
Krill Oil: It is extracted from tiny crustaceans called krill. It contains EPA and DHA in the form of phospholipids, which some argue may enhance absorption. Krill oil also contains astaxanthin, a red-colored antioxidant.
Bioavailability and Absorption:
Fish Oil: While some studies suggest that the absorption of EPA and DHA from krill oil may be 30% to 100% greater than that from FO, the evidence is not definitive.
Krill Oil: The presence of phospholipids in krill oil may contribute to better absorption, but the extent of this advantage is still a subject of research.
Cost Considerations: 
Fish Oil: Supplements are generally more cost-effective, with lower price per dose compared to krill oil. This cost difference is significant, with krill oil being several times more expensive than FO.
Krill Oil: Capsules are often smaller than fish oil capsules, but the higher cost per dose may be a deterrent for some consumers.
Krill Oil Antioxidant Content:
Fish Oil: FO lacks the red-colored antioxidant astaxanthin found in krill oil.
Krill Oil: Astaxanthin in krill oil may provide additional antioxidant benefits, although the clinical significance of this is not entirely clear.
Spoilage Testing:
Fish Oil: FO supplements can be tested for spoilage, ensuring product safety and quality.
Krill Oil: Due to its astaxanthin content, cannot be tested for spoilage in the same way as FO, potentially posing challenges in ensuring product freshness.
Side Effects:
FO and Krill Oil: Both supplements have similar reported side effects, but one study suggested that krill oil may cause more frequent gas/bloating and flatulence.
Insulin Sensitivity:
Fish Oil: Some evidence suggests that FO may modestly improve insulin sensitivity.
Krill Oil: One study indicates that high doses of krill oil may reduce insulin sensitivity, emphasizing the importance of moderation.
In conclusion, both FO and krill oil are rich sources of omega-3 fatty acids with potential health benefits. The choice between the two depends on individual preferences, cost considerations, and the importance of factors such as absorption enhancement and antioxidant content. Before incorporating any supplement into one’s diet, it’s advisable to consult with a healthcare professional, especially for those with existing health conditions or concerns.
Stine M Ulven & Kirsten B Holven (2015) Comparison of bioavailability of krill oil versus fish oil and health effect, Vascular Health and Risk Management, 11:, 511-524, DOI: 10.2147/VHRM.S85165
