Impact of Enteral Arginine Supplementation on Lysine Metabolism in Humans: A Proof-of-Concept for Lysine-related Inborn Errors of Metabolism

Schmidt, Z.; Murthy, G.; Ennis, M.; et al.

Standard treatments for inborn errors of metabolism affecting catabolic pathways of essential amino acids involve dietary restriction or modification with supplements. This is the case for pyridoxine dependent epilepsy (PDE) where Lys is restricted in the diet. Arginine has been suggested as a supplement, because it competes with Lys for transport across tissues. To investigate the impact of Arg supplements on Lys metabolism, a proof-of-concept study with healthy humans was performed. This involved an oral dosing strategy with unlabeled Arg·HCl and the tracer 1-¹³C L-Lys, being oxidized to ¹³CO₂. While the isotope ratio MS results suggested, for the first time, a potential range of L-Arg·HCl for oral supplements, follow-up studies in PDE patients are required.