Krill Oil

  • Vitamins & Supplements
  • Updated August 25, 2017

Krill oil is derived from krill, the small crustaceans that feed on plankton. Like fish oil, krill oil contains docosahexanoic acid (DHA) and eicosapentanoic acid (EPA), omega-3 fatty acids that are building blocks of the brain. While the omega-3s in krill oil may be slightly more absorbable than those in fish oil, the overall amount in krill oil is significantly lower. No studies have tested whether krill oil can prevent cognitive decline or dementia, or how its effects on brain health compare to fish oil or other DHA/EPA supplements.


No clinical trials have evaluated whether krill oil may slow cognitive decline or prevent dementia, though many studies have examined the relationship between DHA/EPA and cognitive functions.

Our search identified:

• 1 randomized clinical trial in healthy elderly
• 5 studies in healthy adults that measured levels of DHA and EPA in the body after krill oil ingestion
• Numerous preclinical studies on possible mechanisms of action

Potential Benefit

No studies have specifically tested whether krill oil can prevent cognitive decline or dementia. In a double-blind randomized controlled trial of 45 healthy elderly men, brain activity in the prefrontal cortex was increased more during working memory tasks after 12 weeks of krill oil supplementation compared to placebo (medium chain triglycerides) [1]. However, no results were reported on the effect of krill oil on cognitive performance. Although sardine oil contained higher amounts of DHA and EPA, it did not increase brain activity more than placebo. Larger studies that also include cognitive outcomes are needed to evaluate the effects of krill oil on cognitive health.

Studies in humans comparing DHA and EPA bioavailability from krill versus fish oil have shown mixed results. When controlling for the amounts of DHA and EPA, their bioavailability? from krill oil is similar to or slightly higher than that of fish oil [2][3]. When krill and fish oil supplements are compared directly, fish oil is more effective in raising blood levels of omega-3 in healthy subjects because it contains much higher levels of DHA and EPA [4]. In preclinical studies, salmon and tuna oil are more effective in increasing DHA levels in the brain compared to krill oil [5].

For Dementia Patients

No clinical studies have tested whether krill oil benefits patients with dementia. Randomized clinical trials have reported that Alzheimer's patients are not likely to benefit from DHA supplements, although some modest benefits may be seen in people at early stages of cognitive decline [6][7].


Side effects with krill oil are typically mild and include "fishy burps," mild gastrointestinal symptoms, increased bowel frequency, soft stool, flatulence, mild hypertension, taste change, heart burn, and localized pimples [8][9][10]. Krill oil may interact with some drugs, such as estrogens (birth control pills or hormone replacement), blood thinners (e.g., warfarin), aspirin and other NSAIDs, beta-blockers (e.g., atenolol, carvedilol, etc.), diuretics (e.g., chlorothiazide), and orlistat for weight loss [11]. Krill oil should not be used if you are allergic to fish, shrimp, or any other type of seafood.

NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.

How to Use

Krill oil is commercially available as dietary supplements. Clinical trials examining the effects of krill oil have used doses ranging from 300–3000 mg per day [2][3][12]. Even though the DHA and EPA in krill oil may be slightly better absorbed than those in fish oil, krill oil has significantly lower levels of DHA and EPA per unit volume [2][3][4]. Encapsulated products without flavor additives typically have lower levels of oxidation compared to bulk oils or flavored products [13].

Learn More

Information on side effects, dosage, and drug interactions from

An analysis of commercially available fish and krill oil supplements at Labdoor

Quality Control of Sources: United States Pharmacopeial Convention (USP) and FDA Information on Dietary Supplements offer information on the quality of specific supplements and can assist in finding a trusted brand.


  1. Konagai C, Yanagimoto K, Hayamizu K et al. (2013) Effects of krill oil containing n-3 polyunsaturated fatty acids in phospholipid form on human brain function: a randomized controlled trial in healthy elderly volunteers. Clin Interv Aging 8, 1247-1257.
  2. Schuchardt JP, Schneider I, Meyer H et al. (2011) Incorporation of EPA and DHA into plasma phospholipids in response to different omega-3 fatty acid formulations--a comparative bioavailability study of fish oil vs. krill oil. Lipids Health Dis 10, 145.
  3. Yurko-Mauro K, Kralovec J, Bailey-Hall E et al. (2015) Similar eicosapentaenoic acid and docosahexaenoic acid plasma levels achieved with fish oil or krill oil in a randomized double-blind four-week bioavailability study. Lipids Health Dis 14, 99.
  4. Laidlaw M, Cockerline CA, Rowe WJ (2014) A randomized clinical trial to determine the efficacy of manufacturers' recommended doses of omega-3 fatty acids from different sources in facilitating cardiovascular disease risk reduction. Lipids Health Dis 13, 99.
  5. Tou JC, Altman SN, Gigliotti JC et al. (2011) Different sources of omega-3 polyunsaturated fatty acids affects apparent digestibility, tissue deposition, and tissue oxidative stability in growing female rats. Lipids Health Dis 10, 179.
  6. de Souza Fernandes DP, Canaan Rezende FA, Pereira Rocha G et al. (2015) Effect of Eicosapentaenoic Acid and Docosahexaenoic Acid Supplementations to Control Cognitive Decline in Dementia and Alzheimer's Disease: A Systematic Review. Nutr Hosp 32, 528-533.
  7. Mazereeuw G, Lanctot KL, Chau SA et al. (2012) Effects of omega-3 fatty acids on cognitive performance: a meta-analysis. Neurobiol Aging 33, 1482 e1417-1429.
  8. Albert BB, Derraik JG, Brennan CM et al. (2015) Supplementation with a blend of krill and salmon oil is associated with increased metabolic risk in overweight men. Am J Clin Nutr 102, 49-57.
  9. Berge K, Musa-Veloso K, Harwood M et al. (2014) Krill oil supplementation lowers serum triglycerides without increasing low-density lipoprotein cholesterol in adults with borderline high or high triglyceride levels. Nutr Res 34, 126-133.
  10. Ramprasath VR, Eyal I, Zchut S et al. (2013) Enhanced increase of omega-3 index in healthy individuals with response to 4-week n-3 fatty acid supplementation from krill oil versus fish oil. Lipids Health Dis 12, 178.
  11. (2016) Krill Oil. Drugscom.
  12. Bunea R, El Farrah K, Deutsch L (2004) Evaluation of the effects of Neptune Krill Oil on the clinical course of hyperlipidemia. Altern Med Rev 9, 420-428.
  13. Jackowski SA, Alvi AZ, Mirajkar A et al. (2015) Oxidation levels of North American over-the-counter n-3 (omega-3) supplements and the influence of supplement formulation and delivery form on evaluating oxidative safety. J Nutr Sci 4, e30.