The Study
Supplementation of L-glutamine enhanced mucosal immunity and improved hormonal status of combat-sport athletes
This study gave some athletes a supplement and others a placebo, then saw what happened. It found that the supplement group got fewer colds and felt better, but it’s not proof the supplement caused it — maybe they just got lucky or felt better because they knew they were taking something special.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Athletes who took a daily amino acid supplement (glutamine) for 3 weeks got fewer colds, felt better emotionally, and their bodies showed signs of better immune and hormone balance compared to those who took a placebo.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 554 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — fewer colds and better mood during intense training can mean fewer missed practices and better performance.
- 2Glutamine group: IgA and NO increased, URTI cases dropped significantly, testosterone stayed stable (while placebo group dropped), testosterone/cortisol ratio improved by 85%, mood improved.
- 3No change in cortisol, soreness, sleep, or stress.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of the International Society of Sports Nutrition
Year
2024
Authors
Tung-Lin Lu, Ai-Chi Zheng, Katsuhiko Suzuki, Chi-Cheng Lu, Chung-Yuan Wang, Shih-Hua Fang
Related Content
Claims (6)
In combat-sport athletes, taking L-glutamine daily at 0.3 grams per kilogram of body weight for three weeks reduces the drop in salivary testosterone and maintains the testosterone-to-cortisol ratio after intense training.
Taking L-glutamine at a dose of 0.3 grams per kilogram of body weight daily for three weeks increases the concentration of nitric oxide in saliva among combat-sport athletes.
In combat-sport athletes, taking 0.3 grams of L-glutamine per kilogram of body weight daily for three weeks increases levels of salivary immunoglobulin A and nitric oxide and lowers the rate of upper respiratory tract infections.
In combat-sport athletes taking 0.3 grams of L-glutamine per kilogram of body weight daily for three weeks, salivary cortisol levels remain unchanged, while the testosterone-to-cortisol ratio increases due to stable testosterone levels.
Taking glutamine supplements lowers the rate of respiratory tract infections in people who engage in intense physical training.
In combat-sport athletes taking 0.3 grams of L-glutamine per kilogram of body weight daily for three weeks, subjective mood scores improve, while muscle soreness, sleep quality, and perceived stress remain unchanged.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.