Can You Take L-Tryptophan and L-Tyrosine Together?

Dose or timing may matter

The short answer

L-tyrosine and L-tryptophan compete for the same large neutral amino acid transporter (LAT1) at the blood-brain barrier. High-dose tyrosine may reduce tryptophan brain uptake, lowering serotonin synthesis.

How to arrange timing

Take L-tyrosine and L-tryptophan at different times of day to minimize transport competition.

Reference

Reference noted for this combination: Fernstrom JD, Fernstrom MH. Tyrosine, phenylalanine, and catecholamine synthesis and function in the brain. J Nutr. 2007;137(6 Suppl 1):1539S-1547S

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.