Plain language summary
According to previous studies, strenuous exercise may contribute towards an imbalance in Th1/Th2 cytokines that are secreted by the immune system, resulting in an impairment of the immune system. The main aim of this study was to analyse the effect of L-theanine on cytokines of the immune system and establish the role of L-Theanine as immunomodulatory. This double blind randomised study recruited 20 men from the Polish rowing team. The subjects were randomised to the supplemented group and placebo group. The supplemented group received gelatine capsules with 150 mg L-theanine extract whilst the placebo group received visually identical capsules with corn starch. The participants in the study were asked to take two capsules per day for 6 weeks. Athletes from both the groups did not differ significantly in terms of their mean age, body height, body weight and years of training. After 24 hour recovery, the athletes in the supplemented group showed lower amount of cytotoxic cell. The authors concluded based on the study that supplementation with L- theanine in athletes exposed to strenuous exercise had beneficial effect.
Abstract
BACKGROUND The aim of this study was to analyze the response of selected components of the immune system in rowers to maximal physical exercise, and to verify if this response could be modulated by supplementation with L-theanine. METHOD The double-blind study included 20 members of the Polish Rowing Team. The subjects were randomly assigned to the supplemented group (n = 10), receiving 150 mg of L-theanine extract for 6 weeks, or to the placebo group (n = 10). The participants performed a 2000-m test on a rowing ergometer at the beginning (1st examination) and at the end of the supplementation period (2nd examination). Blood samples were obtained from the antecubital vein before each exercise test, 1 min after completing the test, and after a 24-h recovery. Subpopulations of T regulatory lymphocytes (Tregs) (CD4+/CD25+/CD127-), cytotoxic lymphocytes (CTLs) (CD8+/TCRαβ+), natural killer (NK) cells (CD3-/CD16+/CD56+) and TCRδγ-positive (Tδγ) cells were determined by means of flow cytometry. The levels of interleukin 2 (IL-2), interleukin 4 (IL-4), interleukin 10 (IL-10), interferon gamma (INF-ɤ) and total antioxidant capacity (TAC) were determined with commercially available diagnostic kits. RESULTS Supplementation with L-theanine contributed to a significant post-exercise decrease in IL-10 concentration, which was reflected by higher values of IL-2 to IL-10 and IFN-γ to IL-10 ratios. Moreover, a significant post-recovery decrease in CTL count, Treg to NK and Treg to CTL ratios was observed in the supplemented group. CONCLUSION Despite the decrease in the number of some cytotoxic cells (CTLs) and an increase in the proportion of Tregs to CTLs, supplementation with LTE seems to exert a beneficial effect on a disrupted Th1/Th2 balance in elite athletes, as shown by the decrease in IL-10 concentration.
Methodological quality
Jadad score
:
2
Allocation concealment
:
Yes
