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Glutamine Benefits

By: Dr. Bill Misner Ph.D.
 

The human body replenishes its glutamine needs from pre-glutamine amino acid substrates in the muscles and lungs. It also may be replenished by glutamine-rich foods or supplements when the body fails to keep up with the supply and demand process. Deficiencies in glutamine may occur as a result of trauma, cancer, and extreme endurance exercise training. Since it is the main fuel source for miles and miles of intestinal enterocytes, millions of specific immune cells such as lymphocytes, macrophages, and fibroblasts, it is scavenged from the blood stream circulating glutamine to “feed” these cells. Glutamine is recruited for the Krebs Cycle to produce energy [see figure 1]. How then is glutamine catabolized in the energy cycle? Mitochondria enzymatically manufactures glutamine from other amino acids [especially BCAA’s], for transfer of energy through ATP end product within the Krebs cycle.

GLUTAMINE DEPLETION CYCLE* [Figure 1]

GLUTAMINE
\/
GLUTAMINASE Þ NH4 [Nitrogen +]
\/
GLUTAMATE
\/
TRANSAMINASE Þ PYRUVATE + ALANINE
\/
ALPHA-KETOGLUTARATE
\/
ATP Þ KREBS CYCLE
\/
ENERGY!

* KEY: Enzymes colored in green.

Glutamine is the most abundant free amino acid in human muscle and plasma and is utilized at high rates by rapidly dividing cells, including leucocytes, to provide energy and optimal conditions for nucleotide biosynthesis. As such, it is considered to be essential for proper immune function. During various catabolic states including surgical trauma, infection, starvation and prolonged exercise, glutamine homeostasis is placed under stress. Heavy exercise from overtraining or over-reaching depletes both circulating and muscle stores of glutamine. Glutamine is also the most abundant free amino acid in muscles, generating over 50% of the muscle-bound free amino acids, with alanine a distant 2nd in providing 10% of the free muscle aminos. During and following exercise 60% of the aminos cannibalized during exercise are from glutamine and alanine muscle stores.

Generally, the Branched Chain Amino Acids[BCAA] are then selectively induced to replete losses of glutamine and alanine. This is why a number of energy products[such as Hammer Gel], formulate the ingredient BCAA’s[Leucine, Valine, Isoleucine] for replacing glutamine and alanine expenditures due to their loss in exercise and their dietary exogenous absence. High protein sources of Glutamine are Hammer Whey Pro[1000 milligrams glutamine/serving], fish, legumes, raw cabbage, raw beets, and other meats.

One of the problems with getting enough glutamine is that heating tends to destroy it. Repletion then may depend on our body’s capacity to replenish it from other amino acids or exogenous donation in supplemental form. Glutamine is the most abundant amino acid in the bloodstream; at levels as high as 35% amino acid nitrogen. The bloodstream’s circulating glutamine is tapped when intestinal enterocytes do not have enough glutamine as their primary source of energy.

When the intestinal epithelial cell requirements for glutamine are lacking, muscle glutamine depletion is an indirect result as observed in hospital settings when critically ill patients suffer from muscle-waisting syndrome [Cachexia]. The same syndrome may occur in ENDURANCE ATHLETES WHO OVERTRAIN. When plasma and/or intestinal glutamine levels fail or “get behind”, bacteria, fungus and other toxins may translocate across intestinal membranes causing the body to be predisposed to react allergically or to contract gastric stress, irritable bowel, and cold or flu-like illness. With overtraining, immune system failure is accurately measured proportionately to the athlete’s circulating glutamine levels.

Falls in the plasma glutamine level (normal range is 500 to 750 mumol/L after an overnight fast) are observed following endurance events and prolonged exercise. These levels remain unchanged or temporarily elevated after short term, high intensity exercise. Plasma glutamine has also been reported to fall in patients with untreated diabetes mellitus, in diet-induced metabolic acidosis and in the recovery period following high intensity intermittent exercise. Common factors among all these stress states are rises in the plasma concentrations of cortisol and glucagon and an increased tissue requirement for glutamine for gluconeogenesis.

It is suggested that increased gluconeogenesis and associated increases in hepatic, gut and renal glutamine uptake account for the depletion of plasma glutamine in catabolic stress states, including prolonged exercise. The short term effects of exercise on the plasma glutamine level may be CUMULATIVE, since heavy training has been shown to result in low plasma glutamine levels (CONCLUSION

Endurance athletes are predisposed to immune compromise by depressed gastric functions from prolonged aerobic exercise more than short-term sessions. A preventive resolution of this disorder suggests increasing specific glutamine-rich supplements or following dietary-exercise protocols:

A-Glutamine-enhanced whey protein concentrates may be taken post-exercise. [1.5 scoops Hammer Whey Pro per 100 lbs. body weight]

B-Fish, raw legumes, raw cabbage, raw cabbage juice may be ingested post-exercise.

C-Free-form Glutamine should be consumed post-exercise or 3 hours prior. [2000 mg]

D-Carbohydrates should be taken during exercises. [240-280 calories/hour]

E-Short-term “easy” aerobic exercise need to be alternated prior to and following prolonged exercise.

F-Periodic rest days should be imposed post-workout of over 1 hour or if morning resting heart rate exceeds 5 beats per minute above base rate.

G-Do not take Glutamine during exercise due to the initial increase in NH4- [Nitrogen release during glutamine metabolism].

REFERENCES

[1]-Walsh NP, Blannin AK, Robson PJ, Gleeson M., Glutamine, exercise and immune function. Links and possible mechanisms. Sports Med. 1998 Sep;26(3):177-91. Review.
[2]-Robson PJ, Blannin AK, Walsh NP, Castell LM, Gleeson M., Effects of exercise intensity, duration and recovery on in vitro neutrophil function in male athletes. Int J Sports Med. 1999 Feb; 20(2): 128-35.
[3]-Nick GL., Medicinal Properties in Whole Foods. Townsend Letter, April 2002:149.
[4]-Gleeson M, Bishop NC. Special feature for the Olympics: effects of exercise on the immune system: modification of immune responses to exercise by carbohydrate, glutamine and anti-oxidant supplements., Immunol Cell Biol. 2000 Oct;78(5):554-61. Review.

Dr. Bill Misner, Ph.D. is the Director of Research and Product Development for E-CAPS INC. & HAMMER NUTRITION LTD., supplement anufacturers specializing in fuels, substrates, and supplements for endurance athletes. Dr. Misner published NUTRITION FOR ENDURANCE:FINDING ANOTHER GEAR, Dolezal & Associates Publishing, Livermore, Calif. 1998.
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Dr. Bill Misner, Ph.D.
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