Cystine and Theanine Supplementation Restores High-Intensity Resistance Exercise-Induced Attenuation of Natural Killer Cell Activity in Well-Trained Men

Abstract

We investigated the effects of supplementation with cystine, a dipeptide of cysteine, and theanine (CT), a precursor of glutamate, on immune variables during high-intensity resistance exercise. Cysteine and glutamate are involved in the formation of glutathione, which modulates the activity of natural killer (NK) cells. In this double-blinded clinical trial, 15 well-trained men (aged 22.8 +/- 4.0 years) were divided into 2 groups: placebo (n = 7) and CT (n = 8). The placebo group was administered a powder containing cellulose (950 mg) and glutamate (30 mg), whereas the CT group was administered a powder containing cystine (700 mg) and theanine (280 mg), once daily for 2 weeks. The subjects trained according to their normal schedule (3 times per week) in the first week and trained at double the frequency (6 times per week) in the second week. Concentrations of immunoglobulin (Ig)M, interleukin (IL)-6, IL-8, and salivary IgA and the leukocyte count did not change significantly in either group. There was a significant decrease (p < or = 0.05) in the NK cell activity (NKCA) in the placebo group after the second week compared with that in the CT group (placebo: 69.2 +/- 16.1% vs. CT: 101.7 +/- 38.7%). Phytohemagglutinin-induced lymphocyte blastoid transformation did not change significantly in either group. These results suggest that NKCA is not affected in a normal training schedule with or without CT supplementation. However, high-intensity and high-frequency resistance exercises cause attenuation of NKCA, which CT supplementation appears to restore. Therefore, in practical application, CT supplementation would be useful for athletes to restore the attenuation of NKCA during high-intensity and high-frequency training.

Suppression of exercise-induced neutrophilia and lymphopenia in athletes by cystine/theanine intake: a randomized, double-blind, placebo-controlled trial

“…P was also in granular form and contained 930 mg of crystalline cellulose and 50 mg of monosodium glutamate. In previous human trials of CT supplementation, CT was supplemented for 14 days before Flu vaccination [6], seven days before high-intensity resistance exercise [20] and 10 days before the endurance training camp in our previous study [16]. All of these trials reported starting CT supplementation at least 7 days before the vaccination or exercise stress.…”

Amino acid and vitamin supplementation improved health conditions in elderly participants

“…It has been shown that NK cell activity is impaired due to various stressors, such as chronic heart failure (40) and high-intensity physical exercise. (41) Moreover, it has been understood that NK cell activity is mediated, at least partially, by nitric oxide-mediated pathways. (42,43) Therefore, it is thought that arginine has a positive effect on NK cell activity because it is the only biosynthetic substrate for nitric oxide.…”

Completing an Ironman Triathlon with Pneumonia: a Case Report

“…A number of nutritional supplements, such as magnesium [11] , cystine, theanine (precursor of glutamate) [12] or glutamine [13] have been studied to see whether they can restore the impaired immune function after training. However, further research is needed in this field.…”