Cystine (a dipeptide of cysteine) and theanine supplementation restores high-Intensity resistance exercise-induced atenuation of natural killer cell activity in well-trained men. - GreenMedInfo Summary

Kawada, S, Kobayashi, K, Ohtani, M, and Fukusaki, C. Cystine and theanine supplementation restores high-intensity resistance exercise-induced attenuation of natural killer cell activity in well-trained men. J Strength Cond Res 24(3): 846-851, 2010-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