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Krill oil is an oil extracted from shrimp-like crustaceans called krill. Krill are marine animals that eat mainly phytoplankton, and the krill themselves are food for fish, penguins, seals, and whales. In fact, in Norwegian the word “krill” means “whale food.”
What is Krill Oil?
Krill oil, like fish oil, is a rich source of omega-3 essential fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA have anti-inflammatory properties and have been acknowledged by the American Heart Association for their ability to reduce the risk of cardiovascular disease and sudden death, slightly lower blood pressure, and decrease arrhythmias. (Lichenstein 2006) Krill oil is also used to treat cancer, osteoarthritis, depression, premenstrual syndrome (PMS), and painful menstruation.
How Krill Oil Works
At a molecular level, krill oil has a phosphate molecule attached, which makes the EPA and DHA in krill oil phospholipids. This is important because phospholipids significantly increase the absorption or bioavailability of the EPA and DHA in krill oil, allowing the omega-3s to be more readily available throughout the body. Fish oil is in a triglyceride form, which is less bioavailable. One important benefit of krill oil’s higher bioavailability is that you need much less krill oil to achieve the same benefits of omega-3 fatty acids, as the following study shows.
Krill Oil Studies
A new study illustrates the more efficient bioavailability of krill oil regarding its effects on lipid levels (e.g., cholesterol, triglycerides), inflammation, and oxidative stress as does fish oil, but krill oil can provide the same benefits with lower doses of EPA and DHA. In the seven-week study, 113 participants were randomly assigned to one of the following groups: 3 grams of krill oil daily, which contained 543 mg of EPA and DHA each, 1.8 grams of fish oil daily, with 864 mg of EPA and DHA, or no supplements.
Participants in both the fish oil and krill oil groups had similar increases in plasma levels of EPA and DHA, but the krill oil achieved these increases with about a third less EPA and DHA. These findings indicate that the bioavailability of the omega-3s from krill oil is more efficient than the bioavailability of the omega-3s from fish oil, which are in triglyceride form. (Ulven 2011)
Although there are studies showing how men who eat fatty fish rich in EPA and DHA may reduce their risk of prostate cancer (Chavarro 2008; Hedelin 2007; Leitzmann 2004), so far there are no studies that indicate krill oil itself provides the same benefit. However, because krill oil is a rich source of both EPA and DHA and these omega-3 fatty acids are readily bioavailable, the findings from the studies of fish intake and prostate cancer may be extrapolated to include krill oil. One study published in Lipids in Health and Disease has reported that krill oil was shown to be effective in inhibiting cell growth of colon cancer cells. (Zhu 2008)
The anti-inflammatory activity of omega-3 fatty acids also may reduce the risk of BPH and prostatitis, and studies have shown that blood levels of omega-3s are lower in men who have BPH. However, again there are no specific studies linking use of krill oil and either BPH or prostatitis.
Krill Oil vs. Fish Oil
Krill oil may be of higher quality than fish oil, and one reason is that krill are at the lower end of the food chain and so are much more unlikely to accumulate toxins (e.g., dioxin, PCBs, mercury) than are fish. Krill oil is also generally produced from krill harvested from cold Antarctic waters, which tend to be less contaminated than waters from which fish are harvested for fish oil. However, there are fish oil supplements made from fish caught in unpolluted waters as well.
Unlike fish oil, krill oil contains higher levels of a potent antioxidant called astaxanthin, which in addition to its ability to fight free radicals and oxidative stress, also helps make krill oil less perishable than fish oil.
One major problem with fish oil is that it oxidizes, which means every time you open the bottle to take a dose, the fish oil loses a bit more of its potency. Oxidation also leads to the formation of harmful free radicals. Fish oil capsules mostly eliminate this problem.
One major concern about krill oil is that krill, along with plankton, make up the largest biomass on the planet. As such they are a critical and basic source of food for marine animals. While krill oil makers and others who harvest krill for food insist krill are an easily renewable food source, not everyone agrees, especially given the declining state of health of the oceans, even the Antarctic from which much of the krill is harvested.
How to Take Krill Oil
The American Heart Association recommends eating two servings of fatty fish per week, which is equivalent to about 250 to 500 mg of EPA and DHA per day. The dose used in the most recent study mentioned above provided 543 mg of EPA and DHA daily. Consult your healthcare provider before taking krill oil supplements. Krill harvested from the Antarctic is usually the species Euphausia superb, which should be indicated on the supplement label.
Side Effects
Krill oil appears to be safe when it is taken as recommended and for a short amount of time (no longer than 3 months). Although krill oil side effects have not been studied as extensively as have those for fish oil, they appear to be similar and may include bad breath, heartburn, loose stools, nausea, and upset stomach. Krill oil usually is not associated with a fishy taste or fishy burps, however. Omega-3 fatty acids have blood-thinning properties, so they should not be taken along with blood-thinning medications without first consulting your healthcare provider.
References
Chavarro JE et al. A 22-y prospective study of fish intake in relation to prostate cancer incidence and mortality. Am J Clin Nutr 2008 Nov; 88(5): 1297-303
Hedelin M et al. Association of frequent consumption of fatty fish with prostate cancer risk is modified by COX-2 polymorphism. Intl J Cancer 2007 Jan 15; 120(2): 398-405.
Leitzmann MF et al. Dietary intake of n-03 and n-6 fatty acids and the risk of prostate cancer. Am J Clin Nutr 2004 Jul; 80(1): 204-16.
Lichtenstein AH et al. Diet and lifestyle recommendations revision 2006: a scientific statement from the American Heart Association Nutrition Committee. Circulation 2006; 114:82-96
Ulven SM et al. Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteers. Lipids 2011; 46:37-46
Zhu JJ et al. Effects of krill oil on serum lipids of hyperlipidemic rats and human SW480 cells. Lipids Health Dis 2008 Aug 29; 7:30
