Krill oil can lower LDL cholesterol, but the effect is modest and the evidence is mixed. Some clinical trials show meaningful reductions, particularly compared to fish oil, while others show LDL levels actually increasing slightly. The inconsistency across studies means krill oil is not a reliable standalone strategy for managing high LDL.
What the Clinical Evidence Shows
Meta-analyses of clinical studies have found that krill oil supplementation lowers both total cholesterol and LDL cholesterol on average. But individual trial results tell a more complicated story. In one well-known study, both krill oil and fish oil groups actually saw LDL levels increase compared to a control group. In another trial, all groups receiving krill oil or fish oil saw LDL reductions, but the krill oil groups experienced a greater decrease than those taking fish oil.
This inconsistency likely reflects differences in study design, participant health status, dosage, and how long people took the supplement. The reductions that do occur tend to be small, nowhere near the 30% to 50% drops you’d see with prescription cholesterol-lowering medications. If your LDL is only slightly elevated, krill oil might nudge it in the right direction. If your levels are significantly high, it’s unlikely to be enough on its own.
How Krill Oil Affects Cholesterol in the Body
Animal research, particularly a study published in Marine Drugs, offers a detailed picture of how krill oil works at the cellular level. In rats fed a high-cholesterol diet, krill oil supplementation reduced the activity of an enzyme called HMG-CoA reductase, which is the same enzyme that statin drugs target. Krill oil appears to suppress this enzyme by activating a cellular energy sensor (AMPK) that essentially puts the brakes on cholesterol production in the liver.
Krill oil also increased the number of LDL receptors on liver cells. These receptors act like docking stations that pull LDL particles out of the bloodstream and into the liver for processing. More receptors means more LDL gets cleared from your blood. At the same time, krill oil reduced levels of a protein involved in packaging and exporting cholesterol from the liver back into the bloodstream. So it works on multiple fronts: less cholesterol gets made, more LDL gets pulled from the blood, and less gets shipped back out.
The researchers attributed these effects to the omega-3 fatty acids in krill oil, specifically EPA and DHA, which are bound to phospholipids rather than the triglyceride form found in standard fish oil. This structural difference is what sets krill oil apart.
Krill Oil vs. Fish Oil for LDL
The omega-3s in krill oil appear to be more bioavailable than those in fish oil. When researchers compared equal doses of EPA and DHA from krill oil and fish oil, krill oil produced higher plasma levels of these fatty acids. One study found the improvement in the omega-3 index (a measure of omega-3 levels in red blood cells) was roughly double with krill oil compared to fish oil.
This better absorption seems to translate into slightly greater effects on cholesterol. In head-to-head comparisons, krill oil was more efficient at reducing LDL and blood sugar than fish oil at most doses. However, “more efficient” doesn’t mean dramatically better. The differences between the two are relatively small, and both remain modest tools for cholesterol management compared to dietary changes or medications.
Effects on Other Lipid Markers
LDL cholesterol is the number most people focus on, but it doesn’t tell the whole story. Apolipoprotein B (ApoB) is a protein carried by every LDL particle, and many cardiologists consider it a more accurate measure of cardiovascular risk because it reflects the actual number of harmful particles in your blood rather than just the cholesterol they carry.
On this front, krill oil’s performance is underwhelming. In clinical trials, changes in ApoB levels were minor and not statistically significant between groups. One trial did find a significant within-group change for the krill oil group specifically, but the overall picture suggests krill oil doesn’t meaningfully reduce LDL particle count even when it slightly lowers the cholesterol concentration measured on a standard blood panel. This is an important distinction for anyone relying on krill oil as their primary cholesterol strategy.
Why Absorption Matters
The phospholipid structure of krill oil isn’t just a marketing talking point. Phospholipids are the same type of molecule that makes up your cell membranes, so they mix easily with the watery environment of your gut and get absorbed more readily than the triglyceride-bound omega-3s in most fish oil capsules. Your body doesn’t need to break them down as much before using them.
This is why lower doses of krill oil can sometimes match the blood-level effects of higher doses of fish oil. For people who struggle with the large capsule sizes or fishy aftertaste of standard fish oil, krill oil’s smaller dose requirement and generally milder taste can be practical advantages, even if the cholesterol-lowering benefits are similar.
Side Effects and Interactions
Krill oil is generally well tolerated. The most common side effects are the same ones associated with fish oil: fishy aftertaste, heartburn, nausea, diarrhea, and occasionally a rash. These tend to be mild.
The more important concern is bleeding risk. Omega-3 fatty acids have a mild blood-thinning effect, and taking krill oil alongside anticoagulant or antiplatelet medications could increase the chance of bleeding. High doses may also slightly raise stroke risk in some people. Because krill comes from crustaceans, there’s an unresolved question about whether people with shellfish allergies should avoid it. The allergenic proteins in shellfish are concentrated in the flesh and shell rather than the oil, but the safety data isn’t definitive enough to rule out a reaction.
What This Means Practically
If you’re hoping krill oil will be a natural alternative to cholesterol medication, the evidence doesn’t support that expectation. The LDL reductions seen in studies are inconsistent and, when they do occur, relatively small. Krill oil is better understood as a general omega-3 supplement that may offer a slight edge over fish oil in absorption and has some favorable effects on lipid metabolism, particularly triglycerides.
For someone with borderline LDL levels who is also making dietary changes, losing weight, and exercising more, krill oil could be a reasonable addition. For someone with significantly elevated LDL or existing cardiovascular disease, it’s not a substitute for proven therapies. Major cardiology guidelines from organizations like the American Heart Association do not specifically recommend krill oil for cholesterol management, and no large-scale trials have demonstrated that krill oil reduces heart attacks or strokes.