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This article is an extract from my book Griffiths' Sport Supplement Review and is protected by copyright. Permission is given to copy this article on other websites as long as this statement is included with a link back to this site.

In summary the evidence that a post exercise reduction in plasma glutamine is due to increased consumption by immune cells and that glutamine supplementation can prevent the temporary immuno-suppression that occurs is weak.

In light of the above discussion it is not surprising to find that the (few) studies of glutamine on exercise performance have failed to find any benefit either on immediate performance when consumed immediately prior to exercise or over a period of 6 weeks.

One study of 6 resistance trained men consuming approximately 23g of glutamine one hour prior to exercise did not find any improvement in their performance on the leg press or bench press compared to placebo (18).
Another study composed of 31 young adults failed to find any improvement in strength or lean body mass after undergoing 6 weeks of glutamine supplementation and a resistance training program (19).

In conclusion there is little evidence for the use of glutamine for any of its claimed benefits to athletes or sports people.
 

Commonly used dosages

Glutamine is most commonly sold as a powder with recommendations to consume 5 - 20g per day.

Some timed release formulations of glutamine are also sold. In order to maintain a high plasma glutamine concentration it is necessary to supplement with glutamine every 30 minutes (15), so there is some logic to this. However the amounts released are likely to be too low to have any benefit.
 
The evidence shows that less glutamine is used by the intestines as the amount consumed increases. When 1.5g is consumed the amount used by the intestines is as high as 75% compared with 55% when doses of 9g are consumed (11).

This indicates that timed release formulas are likely to be far less effective at increasing blood levels of glutamine than consuming a large amount of standard glutamine in one go.

Safety

No adverse effects have been seen from short term supplementation with doses up to 60g/day in hospital patients (20).

There has been a report of two individuals developing mania after consuming 2g and 4g a day of glutamine (21). The condition disappeared on cessation of glutamine intake.
 
Interactions

None known
 
References

1)Haisch M, Fukagawa NK, Matthews DE. Oxidation of glutamine by the splanchnic bed in humans. Am J Physiol Endocrinol Metab. 2000;278(4):E593-602
2)Dechelotte P, Darmaun D, Rongier M, Hecketsweiler B, Rigal O, Desjeux JF. Absorption and metabolic effects of enterally administered glutamine in humans. Am J Physiol. 1991;260(5 Pt 1):G677-82
3)Boza JJ, Dangin M, Mo�nnoz D, Montigon F, Vuichoud J et al. Free and protein-bound glutamine have identical splanchnic extraction in healthy human volunteers. Am J Physiol Gastrointest Liver Physiol. 2001l;281(1):G267-74
4)Boza JJ, Maire J, Bovetto L, Ball�vre O. Plasma glutamine response to enteral administration of glutamine in human volunteers (free glutamine versus protein-bound glutamine). Nutrition. 2000;16(11-12):1037-42
5)MacLennan PA, Brown RA, Rennie MJ. A positive relationship between protein synthetic rate and intracellular glutamine concentration in perfused rat skeletal muscle. FEBS Lett. 1987 May 4;215(1):187-91
6)MacLennan PA, Smith K, Weryk B, Watt PW, Rennie MJ. Inhibition of protein breakdown by glutamine in perfused rat skeletal muscle. FEBS Lett. 1988 Sep 12;237(1-2):133-6
7)Wu GY, Thompson JR. The effect of glutamine on protein turnover in chick skeletal muscle in vitro. Biochem J. 1990;265(2):593-8
8)Wilmore DW. The effect of glutamine supplementation in patients following elective surgery and accidental injury. J Nutr. 2001;131(9 Suppl):2543S-9S; discussion 2550S-1S
9)Boelens PG, Nijveldt RJ, Houdijk AP, Meijer S, van Leeuwen PA. Glutamine alimentation in catabolic state. J Nutr. 2001;131(9 Suppl):2569S-77S; discussion 2590S
10)Svanberg E, M�ller-Loswick AC, Matthews DE, K�rner U, Lundholm K. The effect of glutamine on protein balance and amino acid flux across arm and leg tissues in healthy volunteers. Clin Physiol. 2001;21(4):478-89
11)Mittendorfer B, Volpi E, Wolfe RR. Whole body and skeletal muscle glutamine metabolism in healthy subjects. Am J Physiol Endocrinol Metab. 2001;280(2):E323-33
12)Bowtell JL, Gelly K, Jackman ML, Patel A, Simeoni M, Rennie MJ. Effect of oral glutamine on whole body carbohydrate storage during recovery from exhaustive exercise. J Appl Physiol. 1999;86(6):1770-7
13)Rennie MJ, Bowtell JL, Bruce M, Khogali SE. Interaction between glutamine availability and metabolism of glycogen, tricarboxylic acid cycle intermediates and glutathione. J Nutr. 2001;131(9 Suppl):2488S-90S; discussion 2496S-7S
14)Castell LM, Poortmans JR, Newsholme EA. Does glutamine have a role in reducing infections in athletes? Eur J Appl Physiol Occup Physiol. 1996;73(5):488-90
15)Hiscock N, Pedersen BK. Exercise-induced immunodepression- plasma glutamine is not the link. J Appl Physiol. 2002 Sep;93(3):813-22
16)Krzywkowski K, Petersen EW, Ostrowski K, Kristensen JH, Boza J, Pedersen BK. Effect of glutamine supplementation on exercise-induced changes in lymphocyte function. Am J Physiol Cell Physiol. 2001;281(4):C1259-65
17)Rohde T, MacLean DA, Pedersen BK. Effect of glutamine supplementation on changes in the immune system induced by repeated exercise. Med Sci Sports Exerc. 1998;30(6):856-62
18)Antonio J, Sanders MS, Kalman D, Woodgate D, Street C. The effects of high-dose glutamine ingestion on weightlifting performance. J Strength Cond Res. 2002;16(1):157-60
19)Candow DG, Chilibeck PD, Burke DG, Davison KS, Smith-Palmer T. Effect of glutamine supplementation combined with resistance training in young adults. Eur J Appl Physiol. 2001;86(2):142-9
20)Garlick PJ. Assessment of the safety of glutamine and other amino acids. J Nutr. 2001 Sep;131(9 Suppl):2556S-61S
21)Mebane AH. L-Glutamine and mania. Am J Psychiatry 1984;141(10):1302-3

 

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