Now Foods, L-Citrulline, 4 OzProduct Description Citrulline is a non essential amino acid that is an important intermediate in the urea cycle, functioning along with other amino acids to rid the body of ammonia, a byproduct of protein metabolism.* Citrulline also plays an important role in the healing process and in the maintenance of a healthy immune system.* Product Benefits A Dietary Supplement Healthy Immune System Function* Support Protein Metabolism* Ingredients Supplement