dyaus
January 23rd, 2005, 10:11 PM
Research
by Paul Cribb, B.H.Sci HMS
AST Director of Research
While supplementing with glutamine will not enable you to pack on 40 pounds of muscle in six weeks or smash national weight lifting records, this should be commonsense to most bodybuilders. However, glutamine supplementation does have a subtle yet integral role in building a premium body that excels at athletic performance.
Don’t let anyone bluff you into neglecting glutamine supplementation in favor of some new fad supplement. For over a decade we’ve known muscle cell building mechanisms are absolutely governed by the amount of glutamine held with the cell.[1] Muscle glutamine levels govern protein synthesis rates, maintenance of a positive nitrogen balance and any accumulation of lean tissue.[2] When combined with steady insulin levels, this muscle building response is shown to double.
Glutamine is also the most potent substrate at increasing muscle cell volume.[3] When intracellular levels of glutamine increase, so does cell volume.[4] Volumizing a muscle cell switches on anabolic mechanisms and shuts off the mechanisms that cause muscle breakdown. The amount of glutamine retained in muscle appears to control not only cell volume, but also the entire growth process. Via direct and indirect mechanisms, glutamine supplementation will enhance the body’s capacity to synthesize lean tissue.[1-8]
Peptide vs Free Form – Which is superior?
There has always been debate among athletes and the medical community regarding the most effective form of glutamine supplementation. There are basically three types of glutamine sold as nutritional supplements; free form (L-glutamine), protein-bound, and glutamine peptides.
Previously, due to limitations in methodology, science has been unable to examine the fate of glutamine supplementation directly. Now recent advances, called isotope tracer infusions, allow us to follow and track the fate of an amino acid when administered orally. A recently completed study put an end to the debate on which form of glutamine supplementation is superior.[9]
This study was the first to use isotope-labeled probes to assess the metabolism of glutamine in response to glutamine supplementation via the free amino acid or a peptide-bound source. The main conclusion of this research was that both sources were absorbed in exactly the same manner, just as effectively as each other, with no differences between them.[9]
Both peptide-bound and free form glutamine supplementation increased plasma glutamine levels to a similar extent, and both types of supplementation suffered a 65% local utilization by the intestinal tract. The researchers concluded that glutamine is readily bioavailable when taken either in the free form or protein bound source.[9]
Closer examination of the methodology and the data obtained reveals that the isotope tracer technique used by the researchers did not take into account the de novo synthesis of glutamine from the BCAA content of the other peptides within the peptide-bound glutamine mixture.[9] Therefore, the researchers admit that the glutamine plasma appearance readings from protein-bound glutamine supplementation could be an over-estimation of the glutamine derived from the protein-bound glutamine supplement.[9] Subsequently, the free form glutamine supplement maybe slightly more effective at increasing plasma glutamine levels for up take by muscle.
The bottom line is that there appears to be very little difference between peptide bound and free form glutamine in terms of absorption and effectiveness. So don’t let any supplement marketer tell you otherwise. If one form has to be better than the other, then based on this latest research, free form glutamine is probably more effective at directly enhancing circulating levels of glutamine.
What to expect from glutamine supplementation . . .
Research shows quite clearly that the vast majority of the glutamine supplement you consume won’t even get to your muscles to exert its potent muscle building effects. However, this is not a bad thing!
When the pseudo “muscle building experts” slam glutamine supplementation as “a waste of time and money” they fail to understand that maintaining intramuscular glutamine stores is the key to muscle growth, and supplementation indirectly ensures this process.
Research demonstrates that external sources of glutamine follow such exclusive cellular transport mechanisms and demanding metabolism pathways, the glutamine supplement will always be utilized to fulfill whatever metabolic demand is greatest.[10] In doing so, supplementation relieves the burden on muscle having to meet these relentless demands and leaves muscle glutamine stores intact. This ensures muscle anabolic (building) mechanisms are uninterrupted and this aspect alone will accelerate the growth process from intense training.
Glutamine supplementation will help maintain high levels of glutathione (our premier antioxidant). [11] As I have reported previously, increases in glutathione concentrations within the body correlates directly with increases in lean mass.[8,12,13] However, probably even more important is the fact that supplementing with glutamine also increases the health of every type of cell within the intestinal tract.[2,5] This is another indirect way glutamine supplementation enhances muscle gains.
From your lips to your anus (including stomach) is merely one long tube. The health of this “tube” determines the degree of absorption of every nutrient you consume. Glutamine supplementation optimizes the health of this entire system, enhancing your ability to absorb vital nutrients and prevent bacterial translocation and infection.[2] Do not underestimate this component. No matter how excellent your nutrition, if your absorption capabilities are below par you’ll always be lacking and never reach your potential in health or sport.
Glutamine supplementation also keeps that all-important organ, the liver, in tip-top condition, and enhances all hepatic antioxidant enzymes.[14,15] Never forget, the condition of your liver controls your health and longevity, and a healthy liver is paramount to building and maintaining muscle throughout life. The liver is responsible for secreting large amounts of the potent anabolic growth factors that build muscle.[16]
Other recent research demonstrates that consuming 6–10 grams of glutamine after training will enhance muscle glycogen synthesis and recovery resulting in higher glycogen levels within muscle. Remember that glycogen is the storage form of the primary fuel (muscle glucose) of intense exercise, and that accumulation of glycogen in muscle after training is the initial anabolic process that sets the stage for gains in lean mass.
Simply because free form glutamine isn’t a new, super-hyped supplement with amazing before and after pictures does not mean for one second that it is not a damn effective supplement. It is a supplement that no hard training athlete should be without.
References:
1. Watford M. Does glutamine regulate skeletal muscle protein turnover? TIBS 14:1-4.1989.
2. vanAcker BA,.et al. Glutamine:the pivot of our nitrogen economy? JPEN, 23(5suppl):S45-8, 1999.
3. Haussinger D et al. Cellular hydration state: An important determinant of protein catabolism in health and disease. Lancet 341:1330-1332.1993.
4. Rennie MJ et al. Glutamine metabolism and transport in skeletal muscle and heart and their clinical relevance. J.Nutr. 126: p1142S-1149S, 1996.
5. Miller AL. Therapeutic considerations of L-glutamine: a review of the literature. Altern Med Rev. 4(4):239-48,1999.
6. Neu. J,. et al. Glutamine nutrition and metabolism: Where do we go from here? FASEB.J.10. p829-837. 1996.
7. Parry-Billings,.et al. A communicational link between skeletal muscle, brain and cells of the immune system. Int.J.Sports Med.1,Suppl 2:S122-S128,1990.
8. Kinscherf R,.et al. Low plasma glutamine in combination with high glutamate levels indicate risk for loss of body cell mass in healthy individuals: the effect of N-acetyl-cysteine. J.Mol.Med. vol 74:393-400 1996.
9. Julio J. Boza, Martial Dangin, Denis Moënnoz et al. 281, (1)G267-G274, 2001
10. Rowbottom, Keast D and Morton A. The emerging role of glutamine as an indicator of exercise stress and overtraining. Sports Med. 21.2. p80-97. 1996.
11. Amores-Sanchez MI, Medina MA. Glutamine: as a precursor of glutathione and oxidative stress. Mol.Genet Metab;67(2):100-5,1999.
12. Hack V,. et al. Cystine levels, cystine flux, and protein catabolism in cancer cachexia, HIV/SIV infection and senescence. FASEB J. 11:84-92 1997.
13. Lands et al. A cystine donor enhances anaerobic performance. J. Appl. Physiol. 1999.
14. Ito A, Higashiguchi. Effects of glutamine administration on liver regeneration following hepatectomy.Nutri.15(1):23-8,1999.
15. Matilla B,. et al. Effects of parenteral nutrition supplemented with glutamine or glutamine dipeptides on liver antioxidant and detoxication in rats. Nutri 16(2):125-8,2000.
16. Jackson NC,.et al. Effects of glutamine supplementation, GH, and IGF-1 on glutamine metabolism in critically ill patients. Am.J.Physiol. Endocrinol.Metab.278(2):E226-33,2000.
17. Supplementing with glutamine enhances muscle glycogen synthesis.
by Paul Cribb, B.H.Sci HMS
AST Director of Research
While supplementing with glutamine will not enable you to pack on 40 pounds of muscle in six weeks or smash national weight lifting records, this should be commonsense to most bodybuilders. However, glutamine supplementation does have a subtle yet integral role in building a premium body that excels at athletic performance.
Don’t let anyone bluff you into neglecting glutamine supplementation in favor of some new fad supplement. For over a decade we’ve known muscle cell building mechanisms are absolutely governed by the amount of glutamine held with the cell.[1] Muscle glutamine levels govern protein synthesis rates, maintenance of a positive nitrogen balance and any accumulation of lean tissue.[2] When combined with steady insulin levels, this muscle building response is shown to double.
Glutamine is also the most potent substrate at increasing muscle cell volume.[3] When intracellular levels of glutamine increase, so does cell volume.[4] Volumizing a muscle cell switches on anabolic mechanisms and shuts off the mechanisms that cause muscle breakdown. The amount of glutamine retained in muscle appears to control not only cell volume, but also the entire growth process. Via direct and indirect mechanisms, glutamine supplementation will enhance the body’s capacity to synthesize lean tissue.[1-8]
Peptide vs Free Form – Which is superior?
There has always been debate among athletes and the medical community regarding the most effective form of glutamine supplementation. There are basically three types of glutamine sold as nutritional supplements; free form (L-glutamine), protein-bound, and glutamine peptides.
Previously, due to limitations in methodology, science has been unable to examine the fate of glutamine supplementation directly. Now recent advances, called isotope tracer infusions, allow us to follow and track the fate of an amino acid when administered orally. A recently completed study put an end to the debate on which form of glutamine supplementation is superior.[9]
This study was the first to use isotope-labeled probes to assess the metabolism of glutamine in response to glutamine supplementation via the free amino acid or a peptide-bound source. The main conclusion of this research was that both sources were absorbed in exactly the same manner, just as effectively as each other, with no differences between them.[9]
Both peptide-bound and free form glutamine supplementation increased plasma glutamine levels to a similar extent, and both types of supplementation suffered a 65% local utilization by the intestinal tract. The researchers concluded that glutamine is readily bioavailable when taken either in the free form or protein bound source.[9]
Closer examination of the methodology and the data obtained reveals that the isotope tracer technique used by the researchers did not take into account the de novo synthesis of glutamine from the BCAA content of the other peptides within the peptide-bound glutamine mixture.[9] Therefore, the researchers admit that the glutamine plasma appearance readings from protein-bound glutamine supplementation could be an over-estimation of the glutamine derived from the protein-bound glutamine supplement.[9] Subsequently, the free form glutamine supplement maybe slightly more effective at increasing plasma glutamine levels for up take by muscle.
The bottom line is that there appears to be very little difference between peptide bound and free form glutamine in terms of absorption and effectiveness. So don’t let any supplement marketer tell you otherwise. If one form has to be better than the other, then based on this latest research, free form glutamine is probably more effective at directly enhancing circulating levels of glutamine.
What to expect from glutamine supplementation . . .
Research shows quite clearly that the vast majority of the glutamine supplement you consume won’t even get to your muscles to exert its potent muscle building effects. However, this is not a bad thing!
When the pseudo “muscle building experts” slam glutamine supplementation as “a waste of time and money” they fail to understand that maintaining intramuscular glutamine stores is the key to muscle growth, and supplementation indirectly ensures this process.
Research demonstrates that external sources of glutamine follow such exclusive cellular transport mechanisms and demanding metabolism pathways, the glutamine supplement will always be utilized to fulfill whatever metabolic demand is greatest.[10] In doing so, supplementation relieves the burden on muscle having to meet these relentless demands and leaves muscle glutamine stores intact. This ensures muscle anabolic (building) mechanisms are uninterrupted and this aspect alone will accelerate the growth process from intense training.
Glutamine supplementation will help maintain high levels of glutathione (our premier antioxidant). [11] As I have reported previously, increases in glutathione concentrations within the body correlates directly with increases in lean mass.[8,12,13] However, probably even more important is the fact that supplementing with glutamine also increases the health of every type of cell within the intestinal tract.[2,5] This is another indirect way glutamine supplementation enhances muscle gains.
From your lips to your anus (including stomach) is merely one long tube. The health of this “tube” determines the degree of absorption of every nutrient you consume. Glutamine supplementation optimizes the health of this entire system, enhancing your ability to absorb vital nutrients and prevent bacterial translocation and infection.[2] Do not underestimate this component. No matter how excellent your nutrition, if your absorption capabilities are below par you’ll always be lacking and never reach your potential in health or sport.
Glutamine supplementation also keeps that all-important organ, the liver, in tip-top condition, and enhances all hepatic antioxidant enzymes.[14,15] Never forget, the condition of your liver controls your health and longevity, and a healthy liver is paramount to building and maintaining muscle throughout life. The liver is responsible for secreting large amounts of the potent anabolic growth factors that build muscle.[16]
Other recent research demonstrates that consuming 6–10 grams of glutamine after training will enhance muscle glycogen synthesis and recovery resulting in higher glycogen levels within muscle. Remember that glycogen is the storage form of the primary fuel (muscle glucose) of intense exercise, and that accumulation of glycogen in muscle after training is the initial anabolic process that sets the stage for gains in lean mass.
Simply because free form glutamine isn’t a new, super-hyped supplement with amazing before and after pictures does not mean for one second that it is not a damn effective supplement. It is a supplement that no hard training athlete should be without.
References:
1. Watford M. Does glutamine regulate skeletal muscle protein turnover? TIBS 14:1-4.1989.
2. vanAcker BA,.et al. Glutamine:the pivot of our nitrogen economy? JPEN, 23(5suppl):S45-8, 1999.
3. Haussinger D et al. Cellular hydration state: An important determinant of protein catabolism in health and disease. Lancet 341:1330-1332.1993.
4. Rennie MJ et al. Glutamine metabolism and transport in skeletal muscle and heart and their clinical relevance. J.Nutr. 126: p1142S-1149S, 1996.
5. Miller AL. Therapeutic considerations of L-glutamine: a review of the literature. Altern Med Rev. 4(4):239-48,1999.
6. Neu. J,. et al. Glutamine nutrition and metabolism: Where do we go from here? FASEB.J.10. p829-837. 1996.
7. Parry-Billings,.et al. A communicational link between skeletal muscle, brain and cells of the immune system. Int.J.Sports Med.1,Suppl 2:S122-S128,1990.
8. Kinscherf R,.et al. Low plasma glutamine in combination with high glutamate levels indicate risk for loss of body cell mass in healthy individuals: the effect of N-acetyl-cysteine. J.Mol.Med. vol 74:393-400 1996.
9. Julio J. Boza, Martial Dangin, Denis Moënnoz et al. 281, (1)G267-G274, 2001
10. Rowbottom, Keast D and Morton A. The emerging role of glutamine as an indicator of exercise stress and overtraining. Sports Med. 21.2. p80-97. 1996.
11. Amores-Sanchez MI, Medina MA. Glutamine: as a precursor of glutathione and oxidative stress. Mol.Genet Metab;67(2):100-5,1999.
12. Hack V,. et al. Cystine levels, cystine flux, and protein catabolism in cancer cachexia, HIV/SIV infection and senescence. FASEB J. 11:84-92 1997.
13. Lands et al. A cystine donor enhances anaerobic performance. J. Appl. Physiol. 1999.
14. Ito A, Higashiguchi. Effects of glutamine administration on liver regeneration following hepatectomy.Nutri.15(1):23-8,1999.
15. Matilla B,. et al. Effects of parenteral nutrition supplemented with glutamine or glutamine dipeptides on liver antioxidant and detoxication in rats. Nutri 16(2):125-8,2000.
16. Jackson NC,.et al. Effects of glutamine supplementation, GH, and IGF-1 on glutamine metabolism in critically ill patients. Am.J.Physiol. Endocrinol.Metab.278(2):E226-33,2000.
17. Supplementing with glutamine enhances muscle glycogen synthesis.