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Glutamine

Supplement amino acid fitnessgut
Aka: L-glutamine
Brands seen in Singapore: California Gold Nutrition, NOW Foods, Doctor's Best, Thorne, Nutricost
Third-party tested: Thorne lists a certified glutamine product with NSF Certified for Sport.Certification is granted per product, so check the tub you actually own. Not being listed is not the same as failing.
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Little gain in training · one small trial in IBS
Take with
In the IBS trial, alongside a low-fodmap diet
Studied for
Recovery study used four 0.3 g/kg doses over 3 days
Pros & cons
Pros
  • 15–30 g a day showed no evidence of toxicity
  • No side effects reported in the exercise studies
  • One small trial: less soreness, faster recovery
Cons
  • NIH: research does not support it for performance
  • 45 g a day for 6 weeks changed nothing in lifters
  • Gut evidence is one small 6-week IBS trial
Sources
  1. NIH ODS — Dietary Supplements for Exercise and Athletic Performance (Health Professional), glutamine background · read 2026-08-27
    what it says
    “Glutamine is the most abundant amino acid in muscle, blood, and the body's free-amino-acid pool … an adult consumes about 3–6 g/day in protein-containing foods … It is an EAA for critically ill patients”
  2. NIH ODS — Exercise and Athletic Performance, glutamine and strength training · read 2026-08-27
    what it says
    “There were no significant differences between the two groups in measures of strength, torque, or lean tissue mass, demonstrating that glutamine had no effect on muscle performance, body composition, or muscle-protein degradation”
  3. NIH ODS — Exercise and Athletic Performance, glutamine and recovery from eccentric exercise · read 2026-08-27
    what it says
    “glutamine (four doses of 0.3 g/kg body weight over 3 days) … Supplementation with glutamine reduced the magnitude of strength loss, accelerated strength recovery, and diminished muscle soreness more quickly than placebo; these effects were more pronounced in the men”
  4. NIH ODS — Exercise and Athletic Performance, glutamine and immune function · read 2026-08-27
    what it says
    “Some athletes use glutamine supplements in the hope that they will attenuate exercise-induced immune impairment and reduce their risk of developing upper respiratory tract infections. However, there is little research-based support for this benefit”
  5. NIH ODS — Exercise and Athletic Performance, glutamine safety · read 2026-08-27
    what it says
    “the glutamine had no reported side effects … Daily oral doses ranging from 0.21 to 0.42 g/kg body weight glutamine (equivalent to 15–30 g/day in a person weighing 154 pounds) have provided no biochemical or clinical evidence of toxicity”
  6. NIH ODS — Exercise and Athletic Performance, glutamine implications for use · read 2026-08-27
    what it says
    “The research to date does not support taking glutamine alone to improve exercise and athletic performance”
  7. Glutamine Supplementation Enhances the Effects of a Low FODMAP Diet in Irritable Bowel Syndrome Management (Frontiers in Nutrition 2021, PMC8716871) · read 2026-08-27
    what it says
    “randomized to receive a low FODMAP diet either with glutamine (15 g/day) or a placebo for 6 weeks … the superiority of adding glutamine supplementation to a low FODMAP diet in amelioration of IBS symptoms”
  8. HSA Health Supplements Guidelines (GL-CHPB-3-001 Rev. 020, January 2026), Tables 4–5 · read 2026-08-27
    what it says
    “HS for use by the general adult population should not contain vitamins and minerals exceeding the stipulated limits stated in Tables 4 and 5”
  9. HSA Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines (Oct 2025), Annexes A/B · read 2026-08-27
    what it says
    “The objective of this guideline is to highlight the substances of concern when used in HS and TM and is not meant to be an exhaustive list”
  10. iHerb Singapore — L-Glutamine category page (default sort, 110 results) · read 2026-08-27
    what it says
    “L-Glutamine … 1 - 48 of 110 results”
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Updated 2026-08-30. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.