What glutamine is
Glutamine is an amino acid, one of the building blocks of protein. The body makes its own, mostly in muscle, and it also comes from protein-rich foods. It is the most plentiful free amino acid in blood and muscle.
Because the body makes it, glutamine is not considered essential for healthy people. Much of the early interest came from hospital research, where severe illness or injury can increase the body's demand. Those findings, often using intravenous or tube-fed glutamine, do not transfer automatically to a healthy adult taking a scoop of powder.
What the athlete trials found
The review screened 47 studies and pooled 25 of them. Glutamine was compared with placebo across a range of doses and study designs, most of them small and short.
A few subgroup results moved in unexpected directions. At doses above 200 mg per kilogram of body weight, glutamine lowered neutrophil counts, a type of white blood cell, and one glutamine compound raised blood sugar after exercise. Neither finding shows harm on its own, but neither supports the popular idea that glutamine reliably helps athletes recover or stay well.
| Outcome | What the pooled trials showed |
|---|---|
| Aerobic performance | No significant effect |
| Body composition | No significant effect |
| Immune measures | No significant effect overall |
| Body weight | A small average reduction, about 1.4 kg |
Where the gut and immunity claims come from
Cells lining the intestine use glutamine as a fuel, and immune cells use it too. That biology is real, and it is why glutamine is studied in critical illness and certain digestive conditions.
Biology is not the same as a demonstrated benefit from a supplement. In healthy, active adults, the pooled trials did not find an overall effect on immune measures. We do not describe our product as supporting the gut, immunity or recovery.
Dose and safety
A 2001 review by Garlick found glutamine well tolerated in the adult studies available at the time, while noting limited data on long-term use. A 2008 risk assessment by Shao and Hathcock set an "observed safe level" of 14 g of supplemental glutamine a day. Both authors of that assessment worked for the Council for Responsible Nutrition, a supplement industry trade group, which is worth knowing when weighing it.
One scoop of our powder provides 3.15 g, well under 14 g. The label advises checking with a physician first if you are pregnant, nursing, under 18 or have a medical condition.
How we describe our own product
DECLARED L-Glutamine is unflavored powder: 3.15 g of L-glutamine per 3.3 g scoop, with silicon dioxide as the only other ingredient, 30 servings per container.
The batch document we reviewed (lot 426748) reports heavy-metal results only, with lead and arsenic at very low levels. It does not include an identity or microbial test, and it lists a 2,000 mg serving that does not match the 3.3 g scoop, so we do not rely on its per-serving figures. This article explains research findings; it does not diagnose, treat, or prescribe.
Sources
- Ramezani Ahmadi A, et al. The effect of glutamine supplementation on athletic performance, body composition, and immune function: a systematic review and meta-analysis of clinical trials. Clin Nutr, 2019
- Garlick PJ. Assessment of the safety of glutamine and other amino acids. J Nutr, 2001
- Shao A, Hathcock JN. Risk assessment for the amino acids taurine, L-glutamine and L-arginine. Regul Toxicol Pharmacol, 2008
This material is for general educational purposes only and is not medical advice. Consult a qualified healthcare professional about your individual circumstances.