Fish oil and krill oil are popular dietary supplements used to increase the intake of beneficial marine-sourced fats. Both oils are derived from sea creatures and deliver long-chain omega-3 fatty acids. A common question is whether taking them together can maximize health benefits. Understanding the similarities and differences between these supplements is key to deciding on a responsible supplementation strategy.
The Core Components: EPA and DHA
People consume fish oil or krill oil primarily to obtain two specific long-chain polyunsaturated fats: Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA). These omega-3 fatty acids are fundamental components of cell membranes throughout the body, helping maintain their structure and function. Since the human body cannot produce these fats efficiently, they must be acquired through diet or supplementation.
EPA is noted for its role in inflammation modulation, producing signaling molecules that help resolve inflammatory responses. DHA is highly concentrated in the retina and brain, making it important for the structure and function of nerve cells and visual acuity. Together, EPA and DHA support cardiovascular function by maintaining healthy blood triglyceride levels.
Key Differences in Composition and Absorption
While both oils supply EPA and DHA, a key difference lies in the molecular structure, which impacts absorption. Fish oil typically delivers its omega-3s as triglycerides, which require breakdown by digestive enzymes before absorption. This process is effective but can sometimes lead to the common “fish burp” side effect.
Krill oil delivers a large portion of its EPA and DHA attached to phospholipids, which are the same type of fat molecule found in human cell membranes. This phospholipid structure is water-soluble and may allow the omega-3s to pass more easily through the gut wall, potentially increasing their bioavailability. Some research suggests that lower doses of krill oil may achieve similar blood levels of omega-3s compared to higher doses of fish oil.
Krill oil also contains astaxanthin, a powerful antioxidant not found in fish oil that gives the oil its reddish color. Astaxanthin protects the omega-3 fatty acids from oxidation, keeping the supplement fresh and stable. This added antioxidant benefit is a unique compositional advantage of krill oil.
Safety and Dosage When Combining
Combining fish oil and krill oil supplements is generally considered safe, as they provide the same core beneficial compounds, EPA and DHA. The primary safety consideration is the total combined dosage of omega-3s, not the act of combining the oils. The risk of adverse effects increases when the total intake of EPA and DHA significantly exceeds recommended levels.
Health organizations suggest that a combined daily intake of up to 3 grams of EPA and DHA is safe for most people. Exceeding this amount may increase the risk of side effects, notably a potential delay in blood clotting, which concerns individuals undergoing surgery or taking blood-thinning medications. Other common, mild side effects of very high omega-3 intake include gastrointestinal issues like diarrhea, acid reflux, or a fishy aftertaste.
Before combining supplements, carefully calculate the total milligrams of EPA and DHA from both product labels to ensure the overall intake remains within a safe range. Anyone taking prescription medications, especially blood thinners, or those with existing health conditions should consult a healthcare provider for personalized guidance on appropriate total dosage.
Maximizing Omega-3 Intake: Supplementation Strategy
The decision to combine fish oil and krill oil should be based on a clear goal, as the primary objective is achieving optimal levels of EPA and DHA. For general health benefits, taking a high-quality, single-source supplement—either fish or krill oil—is often sufficient and straightforward. Choosing one high-concentration product makes it easier to track the total daily intake of EPA and DHA.
Combining the two is useful if a person desires the unique characteristics of both, such as the high EPA/DHA concentration of fish oil along with the phospholipid delivery and astaxanthin from krill oil. However, this strategy is only beneficial if the total daily dose of EPA and DHA is calculated and respected across both supplements. A more fundamental strategy for maximizing omega-3 intake involves prioritizing dietary sources, such as fatty fish, over relying solely on supplement combinations.