Glutamine is a conditionally essential amino acid that supports both digestive and immune system health. The majority of glutamine uptake occurs in the small intestine, where glutamine acts as an important energy source for the intestinal mucosa. During periods of physical stress, glutamine levels can become depleted, increasing the permeability of the intestinal mucosa. Glutamine supplementation has been shown to support normal digestive function and prevent increased intestinal permeability during periods of physical stress. Glutamine levels also tend to decrease following prolonged physical exertion, which could impact immune function, as glutamine is a major energy source for certain immune cells.