What is krill oil as a dietary supplement?

Overview

Krill are tiny, shrimp-like crustaceans that flourish in the
Antarctic Ocean and provide food for numerous aquatic animals. Oil made from krill
appears on the market as an alternative to fish oil.
Like fish oil, krill oil contains the omega-3 fatty acids eicosapentaenoic acid
and docosahexaenoic acid. Krill also contains omega-6 fatty acids, an antioxidant
in the carotenoid family called astaxanthin, and substances called
phospholipids.

Sources

Many grains, fruits, vegetables, sea vegetables, and vegetable oils contain significant amounts of essential fatty acids, but krill oil is an especially rich source. Carotenoids are also found in many foods, especially yellow-orange and dark green fruits and vegetables. Carotenoids are not essential nutrients (except insofar as some can be converted to vitamin A), but they might offer some health benefits. Phospholipids are utilized in the body for numerous purposes, but they are not essential nutrients.

Therapeutic Dosages

A typical recommended dose of krill oil is 1 to 3 grams (g) daily.

Therapeutic Uses

Based on its omega-3 fatty acid content, krill oil would be expected to have many of the same effects as fish oil. A few studies have evaluated krill oil specifically. In one double-blind, placebo-controlled study, 120 people with high cholesterol were given krill oil, fish oil, or placebo. The results for a three-month-period showed that krill oil (taken at a dose ranging from 1 to 3 g daily, depending on body mass and what group the participants were assigned to) improved all aspects of cholesterol profile compared with placebo, and it was more effective than fish oil (taken at the fixed dose of 3 g daily). Krill oil also reduced blood sugar levels. Though these results need to be confirmed by independent trials, they are certainly promising.

Another double-blind study compared krill oil with fish oil for the treatment
of symptoms of premenstrual syndrome and dysmenorrhea
(menstrual cramps). This study had many problems in design and reporting, but it
appeared to show that krill oil was more effective than fish oil for treating both
of these conditions. A badly designed study hints that krill oil might be helpful
for both osteoarthritis and rheumatoid arthritis.

Safety Issues

Based on its known constituents, krill oil would be expected to have little to
no toxicity. Side effects seen in studies are limited to occasional digestive
distress and allergic reactions. The only known potential concerns relate to
possible blood-thinning effects: Fish oil is known to decrease blood coagulation,
and in one case report it increased the effect of the blood-thinning medication
warfarin (Coumadin). People who are at risk of bleeding
complications for any reason should consult a physician before taking krill oil.
Maximum safe doses in young children, pregnant or nursing women, and people with
severe liver disease have not been established.

Bibliography

Buckley, M. S., et al. “Fish Oil Interaction with Warfarin.” Annals of Pharmacotherapy 38 (2004): 50-52.

Bunea, R., et al. “Evaluation of the Effects of Neptune Krill Oil on the Clinical Course of Hyperlipidemia.” Alternative Medicine Review 9 (2005): 420-428.

Deutsch, L. “Evaluation of the Effect of Neptune Krill Oil on Chronic Inflammation and Arthritic Symptoms.” Journal of the American College of Nutrition 26 (2007): 39-48.

Sampalis, F., et al. “Evaluation of the Effects of Neptune Krill Oil on the Management of Premenstrual Syndrome and Dysmenorrhea.” Alternative Medicine Review 8 (2003): 171-179.