Krill oil and fish oil deliver the same omega-3 fatty acids (EPA and DHA), and head-to-head research shows no significant difference in their effects on triglycerides, cholesterol, or inflammation. Krill oil does get absorbed more efficiently, but it contains far less EPA and DHA per capsule and costs considerably more. For most people, standard fish oil is the better value.
How Absorption Differs
The biggest structural difference between these two supplements is how the omega-3s are packaged. In krill oil, EPA and DHA are bound to phospholipids, the same type of fat that makes up your cell membranes. In fish oil, they’re bound to triglycerides. This matters because phospholipid-bound omega-3s dissolve more easily in your gut, form micelles more readily, and get incorporated into cell membranes more directly.
In a crossover trial of 56 healthy adults, a phospholipid-bound omega-3 formulation produced 2.7 to 5 times higher plasma concentrations of EPA and DHA compared to an ethyl ester supplement. When researchers adjusted for the actual dose of omega-3 consumed, the phospholipid form still achieved 34% greater biological incorporation per milligram. Studies have also shown that krill oil produces greater plasma enrichment of EPA and DHA than fish oil at equal doses.
There’s a practical catch, though. Fish oil absorption improves significantly when you take it with a meal containing fat, while krill oil’s absorption is less dependent on what you eat. If you tend to take supplements on an empty stomach, krill oil has an edge. If you take your fish oil with dinner, the gap narrows.
EPA and DHA Content Per Capsule
Better absorption only matters if you’re comparing equal amounts of omega-3. In practice, krill oil capsules contain much less EPA and DHA than fish oil capsules. A standard 1,000 mg krill oil softgel typically delivers around 100 to 150 mg of combined EPA and DHA. A standard 1,000 mg fish oil capsule provides roughly 300 mg, and concentrated fish oil formulations can pack 500 to 900 mg into a single softgel.
So even with krill oil’s superior absorption rate, you’d often need to take two to three times as many capsules to match the omega-3 delivery of a single concentrated fish oil pill. The absorption advantage is real, but it doesn’t fully close the potency gap.
Effects on Heart Health
When it comes to the outcome that matters most, lowering cardiovascular risk markers, krill oil and fish oil perform nearly identically. A network meta-analysis found that one gram of omega-3s from fish oil lowered triglycerides by about 9.0 mg/dL, while one gram from krill oil lowered them by about 9.8 mg/dL. The difference was not statistically significant. The same analysis found no meaningful difference between the two for LDL cholesterol, HDL cholesterol, or total cholesterol.
This is the most important finding for anyone choosing between the two. Gram for gram of actual omega-3 content, krill oil doesn’t produce better cardiovascular results than fish oil.
Inflammation and Joint Pain
Krill oil is frequently marketed for joint health, but the clinical evidence is underwhelming. A randomized trial published in the JAMA Network tested 2 grams per day of krill oil against placebo in people with knee osteoarthritis and confirmed inflammation on MRI. After 24 weeks, krill oil did not improve knee pain compared to placebo. Pain scores dropped nearly identically in both groups. Joint stiffness scores showed no difference either.
The study also measured C-reactive protein, a key marker of systemic inflammation. There was no significant difference between the krill oil and placebo groups. While omega-3s in general have mild anti-inflammatory properties at higher doses, krill oil at typical supplement doses hasn’t proven superior for reducing inflammation or relieving joint symptoms.
The Astaxanthin Bonus
Krill oil contains astaxanthin, a natural pigment that gives krill their reddish color. Astaxanthin is an antioxidant that protects the omega-3 fats in the capsule from oxidative damage, which helps keep the oil stable and fresh. This is a genuine advantage over fish oil, which is more prone to going rancid if stored poorly. Whether the small amount of astaxanthin in a krill oil capsule provides meaningful antioxidant benefits inside your body is less clear, but it does contribute to a longer shelf life for the product itself.
Digestive Comfort
One of the most common complaints about fish oil is the fishy aftertaste and reflux that many people experience, sometimes called “fish burps.” Krill oil capsules are smaller and the phospholipid form tends to mix with stomach contents more easily, which generally means less reflux. Many people who couldn’t tolerate fish oil find krill oil easier on the stomach. If digestive comfort has been a barrier to taking omega-3 supplements, this is a legitimate reason to consider krill oil, or alternatively, enteric-coated fish oil capsules designed to dissolve further along in the digestive tract.
Cost Comparison
Krill oil is significantly more expensive per unit of omega-3. A cost analysis found that fish oil supplements range from 1 to 15 cents per 100 mg of EPA and DHA, while krill oil runs about 30 cents per 100 mg. That means krill oil can cost anywhere from 2 to 30 times more for the same amount of active omega-3. Since the cardiovascular and anti-inflammatory outcomes are equivalent gram for gram, this price difference doesn’t buy you better health results.
Which One to Choose
If your goal is getting enough omega-3s for general health or heart protection, concentrated fish oil taken with a meal is the most cost-effective option and delivers identical results to krill oil in clinical outcomes. The research is clear that when you match the actual omega-3 dose, neither supplement outperforms the other for triglycerides, cholesterol, or inflammation.
Krill oil makes sense in a few specific situations: if fish oil gives you digestive trouble, if you prefer a smaller capsule, if you often take supplements without food, or if the price difference doesn’t bother you. Its absorption advantage is real but modest, and you’ll still need multiple capsules to match the omega-3 content of a single concentrated fish oil softgel. For most people watching their budget and looking for the strongest evidence, fish oil remains the practical choice.