Fish oil helps athletes’ immune system to fight cancer cells


Intensive training reduces the activity of immune cells that destroy pathogens and cancer cells. That’s why athletes are more likely to fall prey to nasty viruses after a heavy workout or training session. Fish oil supplements probably offer protection, researchers at the University of Aberdeen discovered.

Immune system
You’ll find regular postings on this website about substances that are supposed to give the immune system a boost. Potential candidates include oatmeal fibre, Chlorella, Echinacea, garlic, and – believe it or not – near beer.

The Brits decided to go in a different direction and examined the effect of fish-oil capsules. They were inspired by a study done in 2007 at the Universidade Federal do Rio de Janeiro, which showed that post-training fish-oil supplementation improved the functioning the immune system of swimmers. [Prostaglandins Leukot Essent Fatty Acids. 2007 Oct-Nov; 77(3-4): 139-45.]

The Brits did an experiment with 17 male subjects, all of whom were in their mid-twenties. The researchers got their subjects to cycle for an hour at 70 percent of their VO2max.

Half of the men had taken 3 g olive oil in capsule form [Control] for a period of six weeks up to the cycling session; the other half took 3 g fish oil [Fish Oil] daily. The 3 g fish oil contained 1.3 g EPA and 0.3 g DHA.

After the session the researchers analysed the men’s blood. They discovered that the immune cells of the men who had been given fish oil three hours after the workout produced more interleukin-2. Interleukin-2 inhibits the immune system’s activities against healthy cells, as happens in people suffering from arthritis and diabetes. Interleukin-2 also activates Natural Killer cells, the immune system’s primitive but effective storm troopers, which spring to action immediately a pathogen enters the body and decimate cells that develop abnormally.


The researchers added immune cells to human cancer cells in test tubes and then counted how many cancer cells the immune cells destroyed. The figure above shows that the immune cells killed more cancer cells three hours after the session if the men had taken fish oil.

“The findings in the current study demonstrate that supplementation with fish oil rich in omega-3 polyunsaturated fatty acids can enhance aspects of the innate and acquired immune system after exercise and it would be of clear interest, therefore, to determine whether over the longer term fish oil could decrease the incidence of upper respiratory tract infections associated with intense exercise training”, the researchers write.

Fish oil supplementation augments post-exercise immune function in young males.


Fish oils and related fatty acid components have anti-inflammatory properties, with beneficial effects against various disorders such as cardiovascular disease. A single bout of exercise can alter immune function. However, the effects of fish oil on immune function after a single bout of exercise are currently unknown. This study investigated the effect of supplementation with fish oil on the immune response to an acute bout of endurance exercise.

Sixteen male subjects underwent a six week double blind randomised placebo controlled supplementation trial involving two groups (fish oil or placebo oil, 3g/day). They attended for two visits, the first involving a maximal exercise test and the second involving a 1-h bout of endurance exercise on a cycle ergometer at 70% (V)O(2peak). Blood samples were taken pre-supplementation, pre-exercise (post-supplementation), immediately, 1 and 3h post-exercise. Samples were analysed for plasma IL-6, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and cortisol; peripheral blood mononuclear cell (PBMC) IL-2, IL-4 and IFN-? production; neutrophil phagocytosis/oxidative burst; and natural killer (NK) cell cytotoxic activity.

Post-supplementation EPA concentration was increased (P=0.0127) in the fish oil group. At 3h post-exercise PBMC IL-2 (P=0.0067) and NK cell activity (P=0.0163) was greater in the fish oil compared with the control group. However, PBMC IL-4 and IFN-? productions, plasma IL-6 and cortisol concentrations, as well as neutrophil activity were unaffected by fish oil supplementation.

The current study demonstrates that fish oil supplementation reduces increases PBMC IL-2 production and NK cell cytotoxic activity in the recovery period after exercise.
Copyright © 2012 Elsevier Inc. All rights reserved.

PMID: 22902522 [PubMed – indexed for MEDLINE]