This means that 5-HTP absorption is limited by the same competitive transport dynamics as tryptophan. This has, indeed, been noted by clinicians. Although I remain open to the possibility that there may be some kind of passive transport mechanism for 5-HTP in addition to active transport, I have been unable to find a reference that documents such a possibility. Anybody interested in using 5-HTP would be well served to read it and add it to their personal library. References G Huether and P Schuff-Werner .
Platelet serotonin acts as a local releasable antioxidant.