Plain language summary
Glutamine is an amino acid, one of the building blocks of protein, and is the most abundant free amino acid in the body. Research shows that glutamine plays an important role in digestive health and immunity by supporting the integrity of the intestinal lining and suppressing inflammation. This review looks at glutamine and its mechanism on gut microbiota; the commensal bacteria which populate the gastro-intestinal tract. Glutamine supplementation was shown to beneficially affect the composition of gut bacteria in obese and overweight subjects, reduce bacterial overgrowth and more specifically reduce harmful strains of Clostridium spp. and Helicobacter spp. The subsequent increase in intestinal-friendly microbiota after supplementation aided symptoms of constipation. This same mechanism may help prevent bacterial infections in chemotherapy cancer patients which is a common side effect of the treatment. Glutamine also supports immune cell activity. White blood cells were shown to use a four-fold amount of glutamine versus glucose. There are indications of glutamine-mediated crosstalk between intestinal microbes and the immune system and that glutamine appears to be helpful in patients with severe digestive disturbances as well as metabolic stress, trauma, infection, burns and muscle-wastage.
Abstract
The scientific literature has demonstrated that glutamine is one of the main beneficial amino acids. It plays an important role in gut microbiota and immunity. This paper provides a critical overview of experimental studies (in vitro, in vivo, and clinical) investigating the efficacy of glutamine and its effect on gut microbiota. As a result of this review, we have summarized that glutamine could affect gut microbiota via different mechanisms including the reduction in the ratio of Firmicutes to Bacteroidetes, with the activation of NF-κB and PI3K-Akt pathways, reducing the intestinal colonization (Eimeria lesions) and bacterial overgrowth or bacterial translocation, increasing the production of secretory immunoglobulin A (SIgA) and immunoglobulin A+ (IgA+) cells in the intestinal lumen, and decreasing asparagine levels. The potential applications of glutamine on gut microbiota include, but are not limited to, the management of obesity, bacterial translocation and community, cytokines profiles, and the management of side effects during post-chemotherapy and constipation periods. Further studies and reviews are needed regarding the effects of glutamine supplementation on other conditions in humans.
Methodological quality
Allocation concealment
:
Not applicable
