Safety of glutamine-enriched parenteral nutrient solutions in humans

Glutamine is a nonessential amino acid that acts as a nitrogen source for many biosynthetic pathways. In animal studies, glutamine has been shown to aid in intestinal mucosal growth, reduce gastrointestinal toxicity after chemotherapy, prevent atrophy (shrinkage) of the pancreas, and reduce the development of fatty liver associated with intravenous feeding. Therefore, glutamine-enriched solutions may be useful in the parenteral (intravenous) feeding of patients. The safety of glutamine-enriched parenteral nutrition was evaluated in seven volunteers who received infusions of parenteral nutrients containing glutamine (20 and 40 grams per day) for six days. Plasma glutamine levels increased during the glutamine diet therapy. However, blood levels of ammonia and glutamate, toxic metabolites of glutamine, were not significantly increased following glutamine-enriched parenteral feeding. Serum enzyme levels, indicative of normal liver and kidney function, were not altered by the glutamine diet. Blood concentrations of insulin, growth hormone, glucagon and cortisol remained within the normal range. The results suggest that glutamine-enriched parenteral solutions, at 40 grams of glutamine daily, are safe and nontoxic when provided in a five-day therapy program. (Consumer Summary produced by Reliance Medical Information, Inc.)