Krill oil is an omega-3 supplement derived from tiny Antarctic crustaceans, and it’s primarily used to support heart health, reduce joint pain, and provide anti-inflammatory benefits. It delivers the same key omega-3 fatty acids found in fish oil (EPA and DHA) but in a different chemical form that may offer absorption advantages. Here’s what the evidence actually supports.
How Krill Oil Differs From Fish Oil
The omega-3s in krill oil are bound to phospholipids, which are the same type of fat that makes up your cell membranes. Fish oil delivers its omega-3s primarily in triglyceride form. This structural difference matters because phospholipids mix with water more easily, which may help your body absorb the fatty acids more efficiently in the gut.
A standard 500 mg krill oil capsule contains roughly 60 mg of EPA and 30 mg of DHA. That’s considerably less per capsule than most fish oil supplements, which means you typically need to take more capsules to match the same omega-3 dose. Krill oil also naturally contains astaxanthin, a reddish pigment that acts as an antioxidant and helps prevent the oil from going rancid. It also contains choline, a nutrient important for liver function and brain health that many people don’t get enough of through diet alone.
Lowering Triglycerides and Supporting Heart Health
The strongest evidence for krill oil centers on its ability to lower triglycerides, a type of blood fat linked to heart disease risk. In a randomized, placebo-controlled trial of adults with borderline high or high triglyceride levels, krill oil supplementation reduced serum triglycerides by 10.2% compared to placebo.
A network meta-analysis published in Nutrition Reviews compared krill oil and fish oil head to head. Per gram of omega-3 fatty acids, both performed similarly: fish oil lowered median triglycerides by about 9.0 mg/dL, while krill oil lowered them by about 9.8 mg/dL. The practical takeaway is that krill oil works for triglyceride reduction, but the dose of omega-3s matters more than the source. Studies consistently show that higher omega-3 intake produces larger reductions. For example, 1.8 grams of omega-3s from fish oil lowered triglycerides by 33%, while 4.8 grams achieved a 58% reduction.
For cholesterol improvements beyond triglycerides, duration and dose both matter. A meta-analysis found that at least 12 weeks of supplementation is likely needed to see improvements in triglycerides, total cholesterol, and LDL. Doses of at least 2 grams per day appear necessary to raise HDL (the protective cholesterol).
Easing Joint Pain and Stiffness
Krill oil shows real promise for people dealing with knee osteoarthritis. A six-month, multicenter, double-blind, placebo-controlled trial tested krill oil in adults with mild to moderate knee osteoarthritis. Participants taking krill oil experienced significantly greater improvements in knee stiffness and physical function compared to those on placebo. The improvements were measurable and sustained over the full six months of the study.
There’s an important nuance, though. The trial did not find significant differences between the krill oil and placebo groups in inflammatory blood markers like C-reactive protein, and painkiller use was similar in both groups. This suggests the joint benefits may work through a mechanism other than simple systemic inflammation reduction, or that the anti-inflammatory effect is localized in ways blood tests don’t capture. A shorter trial using 2 grams per day for just four weeks found only minimal improvement in knee symptoms, reinforcing that consistent, longer-term use appears to be important for joint benefits.
Brain and Nervous System Protection
Krill oil’s combination of omega-3s, phospholipids, choline, and astaxanthin makes it particularly interesting for brain health. Omega-3 fatty acids are a major structural component of brain cell membranes, and the phospholipid form in krill oil may cross into the brain more readily than triglyceride-bound omega-3s.
Laboratory research using animal models of Parkinson’s disease has shown that krill oil protects dopamine-producing neurons from age-related degeneration. In these studies, krill oil decreased the clumping of alpha-synuclein (a protein whose buildup is a hallmark of Parkinson’s) and improved dopamine-dependent behavior and cognition. The protective effects appeared to work by supporting the signaling connections between neurons. While these results come from animal models rather than human clinical trials, they point to potential neuroprotective properties that go beyond what plain omega-3 supplements offer, likely because of krill oil’s unique combination of active compounds.
Typical Dosages
Dosages in clinical studies range widely, from 500 mg to 4 grams per day. For general cardiovascular support, most studies use between 1 and 3 grams daily. For joint health, the successful six-month trial used a dose sufficient to deliver meaningful omega-3s consistently over time. Because each krill oil capsule contains less EPA and DHA than a typical fish oil capsule, you’ll generally need two to four capsules per day depending on the product and your goals.
Results aren’t immediate. Most clinical benefits, particularly for cholesterol and joint function, take at least 12 weeks to become apparent. If you’re taking krill oil for heart health or joint stiffness, plan on giving it three months before evaluating whether it’s working for you.
Who Should Avoid Krill Oil
Krill are shellfish, so anyone with a shrimp, fish, or general seafood allergy should not take krill oil. Because omega-3 fatty acids have mild blood-thinning properties, people taking anticoagulant medications or those with bleeding disorders should talk to their doctor before starting supplementation. You should also stop taking krill oil at least two weeks before any scheduled surgery or procedure to reduce the risk of excessive bleeding.
Side effects are generally mild and similar to fish oil: occasional fishy burps, digestive discomfort, or loose stools. Many people find krill oil easier on the stomach than fish oil, and the smaller capsule size can be a practical advantage for anyone who struggles swallowing large softgels.