Glutamine ? For healing the gut..

7. Interactions with Intestinal Health

7.1. Protein Synthesis

Glutamine supplementation has been shown to stimulate protein synthesis in the gut of healthy humans to a similar potency as mixed amino acids.[55]


7.2. Intestinal Integrity/Permeability

Glutamine is investigated to aiding a 'leaky gut' as it is a regulator of intestinal tight junction barriers.[56] Intentional depletion of intracellular glutamine and inhibition of glutamine synthesis in vitro leads to rapid increases in gut permeability.[57][58][59] In the absence of dietary glutamine, de novo synthesis via glutamine synthetase is the main soruce of glutamine.[56]

Glutamine has been implicated in also alleviating the increased permeability done to the gut by acetaldehyde, the metabolite of Alcohol[60] as well as chemotherapy[61] and radiation therapy.[62] Glutamine can alleviate the increase in permeability associated with sepsis in vivo, but not prevent it.[63]

In an intervention study on preterm infants, it was demonstrated that glutamine supplementation at 0.3g/kg could aid in intestinal integrity and reduce the occurrence of septicemia and increase recovery;[64] and these results have been replicated with both positive[65] and negative results.[66]

A study with 15g oral glutamine on critically ill patients did not find significant decreases in intestinal permeability.[67]

At least one study has shown glutamine, in adults, to confer protection from adverse chemotherapy induced changes in intestinal permeability.[68]


7.3. Crohn's Disease

Crohn's disease is a disease characterized by increased intestinal permeability as well as an inflammatory response in the intestinal membrane.

One study using 21g oral glutamine daily in a small sample size noted that glutamine was not effective in reducing intestinal permeability associated with Crohn's Disease.[69] A response to this study concurred with reports of a study done on children with Crohn's having the same results[70] and hypothesized that the benefits of glutamine on the intestinal wall could be getting negated by glutamine enhancing T-cell and Nitric Oxide function,[71] of which are adverse pathology associated with Crohn's disease.[70] These results are supported by one study using intravenous glutamine at 0.3g/kg finding no apparent benefit.[72]

In contrast to the null effects, a more recent study found improvements in intestinal permeability associated with both glutamine and the active control of Whey Protein protein, both at 0.5g/kg bodyweight daily for 2 months,[73] and one intravenous study has noted improvements in intestinal permeability.[74] It is hypothesized that this may be due to the higher dosage of glutamine used.[73]


7.4. Water absorption

Glutamine has also been shown to aid in the uptake of water from the gut, potentially leading it to be a rehydration aid. However, the increase seen, when compared to other methods such as glucose or sodium is neglibible.[75]