Glutamine is involved in maintaining a positive nitrogen balance (an anabolic state) and also aids rapidly growing cells (immune system lymphocytes and intestinal cell enterocytes). Glutamine has recently been the focus of much scientific interest. A growing body of evidence suggests that during certain stressful times, the body may require more glutamine than it can produce. Under these circumstances, glutamine may be considered a "conditionally essential" amino acid. In addition, glutamine is a regulator of acid-base balance and a nitrogen transporter.