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Glutamine

A conditionally essential amino acid which only appears to benefit the body as supplementation when otherwise deficient (vegans, vegetarians with low dairy intake) or during prolonged endurance exercise. Anecdotally reported to reduce sugar cravings.

Our evidence-based analysis on glutamine features 111 unique references to scientific papers.

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Summary of Glutamine

Primary information, health benefits, side effects, usage, and other important details

Glutamine is one of the 20 naturally occurring amino acids in dietary protein, specifically it is a conditionally essential amino acid (being elevated to essential during periods of disease and muscle wasting typical of physical trauma). It is sold as an isolated amino acids as well as being found in high levels in dietary meats and eggs. It is found in very high levels in both whey and casein protein.

Glutamine is a very effective intestinal and immune system health compound, as these cells use glutamine as the preferred fuel source rather than glucose.

It is generally touted as a muscle builder, but has not been proven to enhance muscle building in healthy individuals; only those suffering from physical trauma such as burns or muscular wounds (knife wounds) or in disease states in which muscle wasting occurs, such as AIDS. In these individuals, however, glutamine is effective at building muscle and alleviating a decrease in muscle mass typical of the ailment.

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How to Take

Medical Disclaimer

Recommended dosage, active amounts, other details

Supplementation of L-glutamine tends to be dosed at 5 g or above, with higher doses being advised against due to excessive ammonia in serum. The lowest dose found to increase ammonia in serum has been 0.75 g/kg, or approximately 51 g for a 150 lb individual.

Due to the relative inefficacy of glutamine supplementation for increasing muscle mass, the optimal dosage is not known. The above recommended doses are sufficient for intestinal health reasons and for attenuating a possible relative glutamine deficiency (seen in instances of low protein intake or veganism).

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Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects glutamine has on your body, and how strong these effects are.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Notes
grade-b
Minor
Low See all 3 studies
Differential effects on ammonia, with decreases being present when glutamine is taken as part of a daily supplement routine and measured during prolonged exercise with a possible increase with high acute doses (which fades with time)
grade-c Minor Very High See 2 studies
An increase in blood glucose may occur from direct conversion of glutamine into glucose following oral ingestion
grade-c Minor - See study
An increase in serum creatinine has been noted, but thought to be due to a reduction in glomerular filtration rate acutely rather than due to alterations in muscle damage
grade-c Minor Moderate See 2 studies
Although a failure has been noted in persons with COPD, one study has noted acute benefits in chronic stable angina with 80mg/kg oral glutamine supplementation.
grade-c Minor - See study
A decrease has been noted in elderly persons given 0.5g/kg glutamine to a level where although the authors were not concerned but some serum biomarkers were adversely affected; long-term significance of this unknown
grade-c Minor Very High See 2 studies
An increase in insulin occurs following ingestion of glutamine supplementation, which is thought to be secondary to the increase in blood glucose seen with glutamine ingestion
grade-c Minor - See study
An increase in urea has been noted with glutamine supplementation
grade-c Minor - See study
An increase in serum urate has been noted in the range of 10-20% acutely, but attenuates with time and is likely not a concern within a week. Practical significance of this increase unknown.
grade-c - - See study
No significant alterations in C-Reactive Protein levels
grade-c - - See study
No significant alterations in cortisol noted
grade-c - - See study
The addition of glutamine supplementation to an exercise regiment has failed to outperform placebo in reducing fat mass.
grade-c - - See study
No significant alterations in hematocrit noted
grade-c - - See study
No significant influence on immunity per se
grade-c - - See study
No significant influence on inflammatory cytokines except perhaps IL-6 seen with glutamine supplementation
grade-c - - See study
Supplemental glutamine does not appear capable of increasing lean mass when paired with a weightlifting routine.
grade-c - - See study
In safety testing, there does not appear to be an adverse effect of glutamine supplementation on liver enzymes in serum
grade-c - - See study
Serum creatinine (increased during exercise and thought to be indicative of muscle damage) does not appear to be significantly altered with glutamine supplementation
grade-c - - See study
No significant influence on power output and strength associated with glutamine supplementation over placebo.
grade-c - - See study
Glutamine has failed to be of benefit to symptoms associated with Duchenne muscle dystrophy
grade-c - - See study
No significant alterations in testosterone noted
grade-c - - See study
In safety testing, no significant alterations in white blood cell count is noted.
grade-d Minor Low See all 3 studies
A possible reduction of symptoms associated with Crohn's disease may occur, but this appears to be unreliable

Studies Excluded from Consideration

  • Confounded with the inclusion of other nutrients[1][2]

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Frequently Asked Questions and Articles on Glutamine

Fact check: does glutamine build muscle?
Glutamine supplementation does not affect body composition, but it may accelerate strength recovery from resistance-training sessions and reduce the occurrence of infections in hard-training endurance athletes.

Things to Note

Is a Form Of

Other Functions:

Primary Function:

Also Known As

L-Glutamine

Do Not Confuse With

Glutamate, Alanylglutamine (Sustamine)

  • Glutamine is non-stimulatory

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Click here to see all 111 references.