5-HTP
5-Hydroxytryptophan - direct precursor to serotonin. Produced from tryptophan via tryptophan hydroxylase.
5-Hydroxytryptophan (5-HTP) is an amino acid intermediate in the conversion of tryptophan to serotonin.
Unlike tryptophan, 5-HTP readily crosses the blood-brain barrier and is directly converted to serotonin by aromatic L-amino acid decarboxylase (AADC), requiring vitamin B6 (P5P) as a cofactor.
The conversion of tryptophan to 5-HTP is the rate-limiting step in serotonin synthesis and requires the enzyme tryptophan hydroxylase plus the cofactor tetrahydrobiopterin (BH4) and iron. When BH4 is deficient, this conversion is impaired. 5-HTP supplementation can increase serotonin levels and is used for depression, anxiety, insomnia, and fibromyalgia.
However, long-term 5-HTP use without adequate dopamine precursors can deplete dopamine, as AADC is shared between serotonin and dopamine pathways.
Serotonin produced peripherally (90% is made in the gut) cannot cross the blood-brain barrier, so central serotonin must be synthesized in the brain from precursors that can cross.
5-HTP is derived commercially from the seeds of Griffonia simplicifolia.
Metabolic Connections
5-HTP connects to 5 other pathways.
Neurotransmitters
Serotonin
5-HTP is the direct precursor to serotonin, converted by aromatic amino acid decarboxylase with B6 as cofactor
Neurotransmitter regulating mood, sleep, appetite, and gut motility. 90% is made in the gut; brain serotonin is made locally.
Serotonin
5-HTP is the direct precursor to serotonin, one step away in the synthesis pathway
Neurotransmitter regulating mood, sleep, appetite, and gut motility. 90% is made in the gut; brain serotonin is made locally.
Amino Acids
Tryptophan
5-HTP is produced from tryptophan via tryptophan hydroxylase in the rate-limiting step of serotonin synthesis
Essential amino acid precursor to serotonin, melatonin, and NAD+. Most is metabolized via the kynurenine pathway.
Tryptophan
Tryptophan is converted to 5-HTP by tryptophan hydroxylase (rate-limiting step)
Essential amino acid precursor to serotonin, melatonin, and NAD+. Most is metabolized via the kynurenine pathway.