Data published in PLoS One indicated that six weeks of krill oil supplementation resulted in significant increases in the production of IL-2 (a signaling molecule regulating the activity of immune cells) and the activity of natural killer (NK) cells in the recovery period after exercise.
“NK cells are the first line of defense, reacting quickly to threats such as bacteria and viruses to keep them under control until the antigen-specific immune system responds,” explained study coordinator Dr Stuart Gray, a lecturer in exercise and metabolic health at the University of Glasgow in Scotland. “Their activity can be decreased by up to 60% for several hours after extended exercise. Krill oil might therefore help to increase host protection after intense exercise."
The study was funded by Aker Biomarine AS, and the company welcomed the results. Torbjorn Furuseth, EVP Innovation, Aker BioMarine Antarctic AS, said: “This study is in line with previous work on fish oil, where similar results were observed. However, the krill oil EPA and DHA dose used was only a quarter of the dose given in the earlier fish oil study to the same group. This demonstrates that krill oil has great potential in the sports nutrition sector.”
Study details
Dr Gray and his co-workers recruited 37 healthy men and women with an average age of 25.8 and randomly assigned them to receive either placebo or two grams per day of krill oil for 6 weeks. All of the participants performed a simulated cycling time trial before and after the six week intervention period.
The results showed that the krill oil supplementation produced 75% and 21% increases in erythrocyte EPA and DHA levels, respectively, while the Omega-3 Index increased by 27%. These increases coincided with decreases in arachidonic and docosatetraenoic acid of 7% and 17%, respectively.
In addition, significant increase in the production of PBMC IL-2 and the activity of NK cells in the recovery period after exercise were also observed for the krill oil group, but other cytokines were unaffected.
No effects were observed for time trial performance, nor did the researchers observed any effects on heart rate or oxygen consumption.
“[T]he current study is the first study to investigate the effects of 6-weeks of krill oil supplementation on exercise performance, markers of immune function and lipid peroxidation, and has shown that krill oil can increase PBMC IL-2 production and NK cell cytotoxic activity 3h post-exercise in both healthy young males and females without modifying performance,” wrote the researchers.
“It is worth noting at this point that ideally we would have taking blood samples not only during the final time trial but also during the initial time trial, allowing a more direct comparison of responses in immune measures after the supplementation period in the same individuals, this is a limitation of the current study.
“It also remains to be established whether these alterations in immune function can ultimately reduce the burden of upper respiratory tract infections which are elevated in those with high training loads.”
Source: PLoS One
2015; Volume 10, Number 9:e0139174, doi: 10.1371/journal.pone.0139174
“The Effect of Krill Oil Supplementation on Exercise Performance and Markers of Immune Function”
Authors: M. Da Boit, I. Mastalurova, G. Brazaite, N. McGovern, K. Thompson, S.R. Gray