Supplementation and sports: krill oil boosts the immune system after exercise

Sports supplementation with krill oil for six weeks boosts the immune system in the phase following physical exertion by increasing the activity of particular cells called Natural Killer cells, which play an important role in the body's defense. Krill supplements, which are rich in omega 3 and antioxidants, can therefore protect the athlete's health immediately after intense physical activity, that is, just when the action of Natural killers and other immune components decreases for several hours.

These are some of the results obtained by researchers at the University of Glasgow (Scotland), who tested the effects of sports supplementation with oil extracted from krill, the collection of small crustaceans that live in the Atlantic Ocean. The data were published in the prestigious journal PloSOne.

Sports and immune defense, what is the relationship?

The immune system is a complex collection of cells and molecules capable of recognizing and reacting to the exposure of foreign and harmful substances to the body. Exercise can have both positive and negative effects on immune function. In particular, in those who engage in moderate physical activity, an enhancement of immune defenses occurs and consequently they are less prone to infections, compared to sedentary people. Other studies show that, on the other hand,intense and prolonged physical activity such as that exerted by marathon runners or cyclists depresses the immune system, thus making athletes more susceptible to infection. The decline in immune system activity after prolonged, high-intensity exercise is referred to as the "Open Window," lasting for several hours, and it is at this stage that the athlete is most susceptible to infections, particularly those of the airways. 

Going into detail, this lack of protection seems to be due to the deficiency of IgA antibodies in the airway mucosa, the decrease in type 1 T lymphocytes, and that of Natural Killer cells that play a crucial role in protecting the body against harmful microorganisms. The use of specially formulated dietary supplements is a good strategy to boost the body's natural defenses and thus protect the athlete, without compromising sports performance. Omega-3-rich fish oil supplements are recommended for athletes for their anti-inflammatory, antithrombotic, antiarrhythmic, and hypolipidemic abilities. Several studies have suggested that most athletes, even amateur athletes, should consume EPA and DHA to prevent joint inflammation. In addition, over time these substances could improve sports performance, as reported by some recently published studies(read here)

Krill omega-3s boost the immune system during the "Open Window"

Experiments conducted by Scottish researchers showed that, in both men and women, supplementation with krill oil causes important changes at the immune level in the recovery period following exercise. In particular, the scholars observed that in subjects who had followed the supplementation, both the production of IL-2, a signal molecule belonging to the cytokine family that regulates immune cell activity, and the activity of Natural Killer cells had increased. As study coordinator Dr. Stuart Gray explained, the latter finding is very important because under normal conditions Natural Killer activity can decrease by up to 60 percent, even for several hours after prolonged exercise. These results confirm those obtained in a previous study published by the same scientists, in which fish oil supplementation appeared to increase IL-2 and Natural Killer, over the same recovery period. In the current study, however, krill oil was administered to volunteers at a much lower dose, about one-fourth, than the fish oil in the previous research, suggesting greater potential in sports nutrition for krill oil to increase athlete protection after strenuous exercise.

Some details of the study

The researchers recruited 37 healthy male and female volunteers with an average age of about 26 years. Randomly, each subject took either two grams per day of krill oil or a placebo for six weeks. All participants performed a chrono-cycling simulation, before and after the treatment. Analyses on the volunteers, at the beginning and after the six weeks, showed that those who had received the supplement possessed increased levels of EPA and DHA in red blood cells by 75% and 21%, respectively, while the Omega-3 Index had risen by 27%. In contrast, concentrations of omega-6, arachidonic acid and docosatetraenoic acid, had decreased by 7% and 17%. 

Regarding the immune system, in the group that had taken krill oil, in addition to the significant increase in IL-2 production, no changes in the production of other cytokines were observed during the recovery period. In addition, there was no effect on physical performance, either on heart rate or oxygen consumption. As the scientists pointed out, this work is the first to study the effects of krill oil supplementation on cells and marker molecules of immune function, and it showed that this type of supplement can enhance some elements of the immune system about 3 hours after exercise, without changing physical performance. 

It now remains to be seen whether the action on the immune system may be sufficient to reduce respiratory tract infections by further study of the role of krill oil. 

Source: M. Da Boit, I. Mastalurova, G. Brazaite, N. McGovern, K. Thompson, S.R. Gray "The Effect of Krill Oil Supplementation on Exercise Performance and Markers of Immune Function" PLoS One ; 2015; Volume 10, Number 9: e0139174.