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
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) . 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 . 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 . In preclinical studies, salmon and tuna oil are more effective in increasing DHA levels in the brain compared to krill oil .
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 .
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 . 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 . 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.
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 . 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 . Encapsulated products without flavor additives typically have lower levels of oxidation compared to bulk oils or flavored products .
Information on side effects, dosage, and drug interactions from Drugs.com
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.