This article is about the effects of krill oil supplementation in cholesterol, triglycerides, and the omega-3 index. Krill oil is an oil derived from tiny, shrimp-like marine animals called krill. It is rich in omega-3 fatty acids, primarily EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid).
While this may sound like krill oil is basically the same as fish oil, there are some key differences. First, krill is a much more sustainable source than the much larger fish that fish oil is derived from. Second, the fatty acids in fish oil are in the form of triglycerides. In krill oil, the fatty acids are phospholipids. The body uses triglycerides and phospholipds differently. Generally, phospholipids are a more efficient delivery form of omega-3 fatty acids than triglycerides.1
| Characteristic | Triglyceride | Phospholipid |
|---|---|---|
| Composition | Three fatty acid chains bound to glycerol | Two fatty acid chains and a phosphate group bound to glycerol |
| Function | Energy storage in the body | Structural component of cell membranes and other biological membranes |
| Solubility | Hydrophobic (does not mix with water) | Amphipathic (has both hydrophilic and hydrophobic regions) |
| Common Sources | Dietary fats and oils | Found in foods like egg yolks, krill oil, and soybeans; used as emulsifiers in food processing |
In addition, krill oil contains the carotenoid astaxanthin, which fish oil does not contain. Astaxanthin is the substance that gives flamingos, shrimp, salmon, and krill their red/pink colour. Astaxanthin is a powerful antioxidant. It is so strong that studies have shown that astaxanthin taken internally protects human skin from sun damage. It’s basically an internal sunscreen. It has lots a lot more health benefits than just protecting our skin. But more on astaxanthin in another article.
Krill oil increases HDL and lowers LDL cholesterol
A 2004 study2 randomly assigned a total 120 patients to one of four groups. Group A received krill oil at a body mass index (BMI)-dependent daily dosage of 2-3 g daily. Patients in Group B were given 1-1.5 g krill oil daily, and Group C was given fish oil containing 180 mg eicosapentaenoic acid (EPA) and 120 mg docosahexaenoic acid (DHA) per gram of oil at a dose of 3 g daily. Group D was given a placebo containing microcrystalline cellulose. The study used krill oil from Canadian company; it is not clear whether the company was otherwise involved in the study.
The primary parameters tested (baseline and 90-day visit) were total blood cholesterol, triglycerides, LDL, HDL, and glucose. Krill oil supplementation at 1-3 g per day (BMI-dependent) was found to be effective for the reduction of glucose, total cholesterol, triglycerides, and LDL, and increasing HDL, compared to both fish oil and placebo. At lower and equal doses, krill oil was significantly more effective than fish oil for the reduction of glucose, triglycerides, and LDL levels. The 2-3g dose was more effective than the 1-1.5g dose. After the 90 days, the group that had been taking the 1-1.5g dose was given a dose of 0.5g. This turned out to be an effective maintenance dose. For more details on the study, together with some charts, see the summary by ErgoLog. The study itself is not available as open access.
Similarly, a 2013 study3 investigated the effects of 12 weeks daily krill oil supplementation on fasting serum triglyceride (TG) and lipoprotein particle levels in subjects whose habitual fish intake was low and who had borderline high or high fasting serum TG levels (150-499 mg/dL). Low fish intake was defined as defined as not consuming fatty fish and seafood more than twice a month.
A total of 300 subjects were randomized into five groups and were supplemented with either placebo (olive oil) or one of four krill oil doses (0.5g, 1g, 2g, or 4 g/day). See Figure 1 below. The krill oil capsules were from a Norwegian company.
69% of the subjects were male, the rest female. Blood work was measured at the start of the study and then again after 6 and 12 weeks of supplementation.
The primary parameters tested were the omega-3 index (amount of omega-3 in the blood), serum triglycerides (amount of a type of fat in the blood), and serum lipoproteins (total cholesterol, LDL-C, and HDL-C).
The results showed that the omega-3 index of the krill oil groups increased significantly after 6 and 12 weeks. The more krill oil consumed, the higher the omega-3 index. The olive oil placebo lowered the omega-3 index. The increase of the omega-3 index was associated with a reduced risk for sudden cardiac death and primary cardiac arrest.
| Omega-3 index | Placebo | 0.5 g krill oil | 1 g krill oil | 2 g krill oil | 4 g krill oil |
|---|---|---|---|---|---|
| Baseline | 3.54 ± 1.05 | 3.66 ± 0.9 | 3.56 ± 0.82 | 4 ± 0.88* | 3.65 ± 0.7 |
| 6 weeks | 3.44 ± 0.88 | 3.83 ± 0.75* | 4 ± 0.75* | 4.76 ± 0.86* | 5.54 ± 0.87* |
| 12 weeks | 3.43 ± 0.77 | 3.97 ± 0.8* | 4.19 ± 0.79* | 5.17 ± 0.96* | 6.3 ± 0.99* |
Krill oil also reduced fasting serum triglyceride levels. It does not look like more was better, as you can see below.
| Triglyceride levels | Placebo | 0.5 g krill oil | 1 g krill oil | 2 g krill oil | 4 g krill oil |
|---|---|---|---|---|---|
| Baseline | 236.5 ± 80.9 | 230.1 ± 71.4 | 238.9 ± 69.8 | 237.5 ± 73.1 | 220.2 ± 63 |
| Change after 6 weeks | 12.0 ± 10.7 | −13.1 ± 10.8 | −19.9 ± 10.8* | −19.9 ± 10.8* | −18.6 ± 10.3* |
| Change after 12 weeks | 6.4 ± 12.7 | −23.0 ± 12.7 | −9.1 ± 12.8 | −16.1 ± 12.7 | 2.1 ± 12.1 |
Supplementing with krill oil did not affect either LDL-C, HDL-C, or total cholesterol in a statistically relevant manner. This is in contrast to the first study highlighted in this article. In that study, supplementing with krill oil lowered LDL-C and raised HDL-C. Why the studies showed different outcomes is unknown.
In general, though, we see that krill oil is beneficial for cardiovascular health. It lowers triglycerides, possibly increases HDL-C, and improves the omega-3 index. Krill oil also appears to be better than fish oil in this respect. This is likely because of the phospholipid structure of krill oil in contrast to fish oil’s triglyceride structure.
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- Berge, Kjetil et al. “Krill oil supplementation lowers serum triglycerides without increasing low-density lipoprotein cholesterol in adults with borderline high or high triglyceride levels.” Nutrition research (New York, N.Y.) vol. 34,2 (2014): 126-33. doi:10.1016/j.nutres.2013.12.003. ↩︎
- Bunea, Ruxandra et al. “Evaluation of the effects of Neptune Krill Oil on the clinical course of hyperlipidemia.” Alternative medicine review : a journal of clinical therapeutic vol. 9,4 (2004): 420-8. ↩︎
- Berge, Kjetil et al. “Krill oil supplementation lowers serum triglycerides without increasing low-density lipoprotein cholesterol in adults with borderline high or high triglyceride levels.” Nutrition research (New York, N.Y.) vol. 34,2 (2014): 126-33. doi:10.1016/j.nutres.2013.12.003. ↩︎
