Can You Take L-Lysine and L-Ornithine Together?

May affect absorption

The short answer

L-Ornithine and L-Lysine are both dibasic amino acids that compete for the same cationic amino acid transporters (CAT family/System y+). Taking them simultaneously reduces absorption efficiency of both.

How to arrange timing

Separate L-Ornithine and L-Lysine by at least 1 hour for optimal absorption of both cationic amino acids.

Reference

Reference noted for this combination: Closs EI, et al. Plasma membrane transporters for arginine. J Nutr. 2004;134(10 Suppl):2752S-2759S.

Important context

Whether supplements suit you together also depends on dose, product formulation, health conditions, and medication use. Ask a doctor or pharmacist first if you take medication, are pregnant or breastfeeding, or have a chronic condition.