Often referred to as the “multitasker,” glutamine is a nutrient with
an impressive range of health benefits. It helps balance blood sugar, build lean muscle, and strengthen the body’s defenses. In the gut,
it promotes the health and function of the mucosal cells for normal healing and repair. Furthermore, glutamine distributes nitrogen freely to the cells which need it most, such as the immune, gut, and muscle cells.3 Glutamine is also fuel for brain cells which helps keep mental energy up and stress and mental fatigue down.4
Nearly 80% of total body glutamine is found in skeletal muscle. For individuals who often skip meals or do not consume enough protein, such as the critically-ill, glutamine supplementation may be beneficial for helping maintain muscle mass (skeletal muscle is the major supplier of glutamine in cases of severe illness).1 The body requires a steady supply of protein or it will eventually break muscle down for energy, i.e., during the overnight 12-hour fasting period. This catabolic state is halted by protein consumption or by supplementing with glutamine in order for the body to receive the nitrogen it needs to build and maintain muscle.1
Prolonged exercise lowers glutamine levels in the body, and has been shown to decrease mucosal immunity. Glutamine supplementation has been shown to promote the production of IgA antibodies and maintain pro- and anti- inflammatory cytokine balance in athletes with damaged mucosal immunity caused by strenuous exercise.5 Glutamine helps the body store more glycogen (the energy reserve in muscles and liver to fuel exercise) and enhances growth hormone secretion, which increases muscle growth and improves overall health.1 A randomized, double-blind placebo- controlled human crossover study showed glutamine supplementation to diminish muscle soreness and speed up recovery following eccentric exercise.6 Supplementing before and after exercise may help attain maximum results and replete lost stores.
Intestinal cells utilize approximately 30% of total glutamine in the body, competing with other tissues for utilization. Glutamine promotes proliferation of enterocytes, helps regulate tight junction proteins, suppresses pro-inflammatory cytokine expression and signaling pathways, and protects against cellular stress and apoptosis. It is considered “the intestinal permeability factor” because of its ability to maintain the integrity of the intestinal wall.
If the intestinal lining becomes permeable or “leaky,” large food molecules enter the bloodstream, which can lead to a host of conditions such as disrupted immune function, autoimmune diseases, food allergies, and even mood disorders.8 Glutamine stores are depleted during severe metabolic stress including inflammatory bowel diseases such as Crohn’s disease (CD), and in clinical studies supplementation has been shown to protect the intestinal mucosa and reduce colonic inflammatory cytokine production.
Clinical trials determined that 21 g glutamine for 28 days resulted in improved clinical outcomes in patients with CD, and in patients in remission phase of CD, 0.5 g/kg body weight glutamine for 2 months reduced intestinal permeability and morphology.
Results from various in vivo and in vitro studies suggest glutamine a promising therapeutic treatment for intestinal inflammatory disorders via inhibition of NF- κβ and STAT pathways, ultimately suppressing IL-6, TNF-α , IL-8, and iNOS.7 Moreover, a pilot study of obese humans found that 14 days of glutamine (30 g) treatment significantly altered gut microbiota, reducing Firmicutes to Bacteroidetes ratio.