Krill oil makes you more intelligent and prevents depression

Supplements containing krill oil improve mental health, neurologists at the University of Bergen in Norway discovered when they did experiments with rats. The krill oil improved learning processes and also had an anti-depressive effect.
Supplements containing krill oil improve mental health, neurologists at the University of Bergen in Norway discovered when they did experiments with rats. The krill oil improved learning processes and also had an anti-depressive effect.

At first glance krill oil resembles fish oil. The difference however is that manufacturers make fish oil from fish, while krill oil is made from a tiny shrimp called Euphausia superb. The oil in Euphausia superb contains no triglycerides (which fish oil contains); instead it contains phospholipids. On top of this krill oil contains relatively large amounts of the carotenoid astaxanthin.

Some scientists think that krill oil has a greater effect on the brain than regular fish oil does. The brain not only contains relatively large amounts of fish fatty acids, these are contained in phospholipids, as they are in krill oil.

The researchers gave some of their lab animals 0.2 g krill oil daily in oral form for a period of seven weeks. The human equivalent of this dose is extremely high: over 10 g krill oil per day.

This doesn’t mean that the experiment is irrelevant when it comes to the effects of krill oil in humans. Researchers think that fish fatty acids accumulate in the cells, and that long-term exposure to small amounts of fish fatty acids may have the same effect as short-term exposure to large amounts of them.

Another group of the lab animals was given the anti-depressant imipramine daily. The rats in the control group got no krill oil and no imipramine.

At the end of 43 days the researchers put the animals in a cage under irritatingly bright lights. There was a switch in the cage that the animals could operate and enabled them to turn off the light [ALP]. There was also a switch in the cage which had no effect on the light [ILP].

The figure below shows that both male [first figure below] and female [second figure below] rats that had been given krill oil pressed the good switch more often than the animals in the other groups. The researchers conclude that the krill oil had boosted the rats’ ability to perform new tasks.


In another test the researchers put the rats in a container of water. Rats can’t stand water and will swim until they find a way of getting out of the water. The researchers timed the rats until they gave up trying to get out of the water.

Scientists regard this test as a way of imitating the development of depressions in humans. Humans develop depression when they are in a difficult situation where each attempt to escape from this results in a negative stimulus. At some point people give up and depression ensues.

The figure below shows that both male [left] and female rats [right] that had been given krill oil floated around without moving in the water for a shorter amount of time than the rats in the control group. This suggests that krill oil protects against depression.


Imipramine protected slightly better against depression than krill oil.

When the researchers examined the brains of the lab animals they noticed that imipramine boosted the activity of the neural growth factor BDNF. Krill oil did not have this effect. The researchers admit that they don’t know exactly how krill oil works.

Aker BioMarine [], a Norwegian producer of krill oil, co-funded the study.

Enhanced cognitive function and antidepressant-like effects after krill oil supplementation in rats.

Wibrand K, Berge K, Messaoudi M, Duffaud A, Panja D, Bramham CR, Burri L.



The purpose of the study was to evaluate the effects of krill oil (KO) on cognition and depression-like behaviour in rats.


Cognition was assessed using the Aversive Light Stimulus Avoidance Test (ALSAT). The Unavoidable Aversive Light Stimulus (UALST) and the Forced Swimming Test (FST) were used to evaluate the antidepressant-like effects of KO. Imipramine (IMIP) was used as the antidepressant reference substance.


After 7?weeks of KO intake, both males and females treated with KO were significantly better in discriminating between the active and the inactive levers in the ALSAT from day 1 of training (p<0.01). Both KO and IMIP prevented resignation/depression on the third day in the UALST. Similarly, a shorter immobility time was observed for the KO and IMIP groups compared to the control in the FST (p<0.001). These data support a robust antidepressant-like potential and beneficial cognitive effect of KO. Changes in expression of synaptic plasticity-related genes in the prefrontal cortex and hippocampus were also investigated. mRNA for brain-derived neurotrophic factor (Bdnf) was specifically upregulated in the hippocampus of female rats receiving 7?weeks of KO supplementation (p=0.04) and a similar trend was observed in males (p=0.08). Males also exhibited an increase in prefrontal cortex expression of Arc mRNA, a key protein in long-term synaptic plasticity (p=0.05). IMIP induced clear effects on several plasticity related genes including Bdnf and Arc.


These results indicate that active components (eicosapentaenoic acid, docosahexaenoic acid and astaxanthin) in KO facilitate learning processes and provide antidepressant-like effects. Our findings also suggest that KO might work through different physiological mechanisms than IMIP.

PMID: 23351783 [PubMed – indexed for MEDLINE] PMCID: PMC3618203