The most prevalent amino acid in human blood is glutamine. Glutamine may become conditionally required in some situations, such as intense physical training, when the body is unable to meet its needs through glutamine synthesis. This conditionally necessary amino acid can be obtained through diet, including food supplements.

Glutamine is the most abundant amino acid in the human blood. Glutamine may become conditionally essential in certain situations, including intensive physical training, when the body cannot meet its needs by synthesizing glutamine. This conditionally essential amino acid can be provided by dietary protein intake, including by food supplements.