Glutamine for Sports & Fitness
What is it?
Glutamine is the most abundant amino acid
(protein building block) in the body and is involved in more metabolic processes than any
other amino acid. Glutamine is converted to glucose when more glucose is required by the body
as an energy source. It serves as a source of fuel for cells lining the intestines. Without
it, these cells waste away. It is also used by white blood cells and is important for immune function.
Why do athletes use it?*
Some athletes say that glutamine
- helps boost the immune system.
What do the advocates say?*
Glutamine is the most utilized amino acid in the body. Based on its biochemistry, glutamine
is a good supplement for athletes. Glutamine is best taken consistently, on a daily basis,
rather than just before or after a hard workout, to build up tissue levels.
Although glutamine is inexpensive and non-toxic, realize that you run the risk of upsetting
the balance of the body’s amino acids (as is the case with supplementing with only one
of any of the amino acids.
How much is usually taken by athletes?
The amino acid glutamine appears to play a role in several aspects of human physiology that
might benefit athletes, including their muscle function and immune system.1 Intense
exercise lowers blood levels of glutamine, which can remain persistently low with
overtraining.2 Glutamine supplementation raises levels of growth hormone at an
intake of 2 grams per day,3 an effect of interest to some athletes because of the
role of growth hormone in stimulating muscle growth,4 and glutamine, given
intravenously, was found to be more effective than other amino acids at helping replenish
muscle glycogen after exercise.5 However, glutamine supplementation (30 mg per 2.2
pounds body weight) has not improved performance of short-term, high-intensity exercise such
as weightlifting or sprint cycling by trained athletes,6 7 and no
studies on endurance performance or muscle growth have been conducted. Although the effects of
glutamine supplementation on immune function after exercise have been
inconsistent,8 9 double-blind trials giving athletes glutamine (5 grams
after intense, prolonged exercise, then again two hours later) reported 81% having no
subsequent infection compared with 49% in the placebo group.10
Are there any side effects or interactions?
No significant side effects have been reported in glutamine studies.
Are there any drug
interactions?
Certain medicines may interact with glutamine. Refer to drug interactions for a list of those medicines.
*Athletes and fitness advocates may claim benefits for glutamine
based on their personal or professional experience. These are individual opinions and
testimonials that may or may not be supported by controlled clinical studies or published
scientific articles on glutamine. For more complete and detailed information, including
references and safety information, see Glutamine
as a nutritional supplement.
References:1. Antonio J, Street C. Glutamine: a potentially useful supplement for
athletes. Can J Appl Physiol 1999;24:1–14 [review].
2. Rowbottom DG, Keast D, Morton AR. The emerging role of glutamine as an
indicator of exercise stress and overtraining. Sports Med 1996;21:80–97
[review].
3. Welbourne TC. Increased plasma bicarbonate and growth hormone after an
oral glutamine load. Am J Clin Nutr 1995;61:1058–61.
4. Macintyre JG. Growth hormone and athletes. Sports Med
1987;4:129–42 [review].
5. Varnier M, Leese GP, Thompson J, et al. Stimulatory effect of
glutamine on glycogen accumulation in human skeletal muscle. Am J Physiol
1995;269:E309–15.
6. Antonio J, Sanders MS, Kalman D, et al. The effects of high-dose
glutamine ingestion on weightlifting performance. J Strength Cond Res
2002;16:157–60.
7. Haub MD, Potteiger JA, Nau KL, et al. Acute L-glutamine ingestion does
not improve maximal effort exercise. J Sports Med Phys Fitness
1998;38:240–4.
8. 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;30:856–62.
9. Castell LM, Newsholme EA. Glutamine and the effects of exhaustive
exercise upon the immune response. Can J Physiol Pharmacol 1998;76:524–32
[review].
10. Castell LM, Poortmans JR, Newsholme EA. Does glutamine have a role in
reducing infections in athletes? Eur J Appl Physiol 1996;73:488–90.