I posted this in a previous thread.
This is taken form an old study done in mice.
The concentration of L-5-hydroxytryptophan (5-HTP) was measured in plasma and whole brain tissue from mice by use of high pressure liquid chromatography with fluorimetric detection after reaction with phthaldialdehyde. 5-HTP was injected intraperitoneally and the rise in plasma and brain 5-HTP concentrations was found directly related to the size of amino acid dose. Carbidopa, an extracerebral inhibitor of L-aromatic amino acid decarboxylation, increased dose dependently the brain bioavailability of systemically administered 5-HTP not only by peripheral enzyme inhibition, but also by inhibition of the decarboxylase activity within the blood-brain barrier as indicated by a rise in the calculated brain/plasma 5-HTP concentration ratio.
Magnussen I. Effects of carbidopa on the cerebral accumulation of exogenous L-5-hydroxytryptophan in mice. Acta Pharmacol Toxicol (Copenh). 1984 Sep;55(3):199-202
And this.
5-Hydroxytryptophan (5-HTP) is the intermediate metabolite of the essential amino acid L-tryptophan (LT) in the biosynthesis of serotonin. Intestinal absorption of 5-HTP does not require the presence of a transport molecule, and is not affected by the presence of other amino acids; therefore it may be taken with meals without reducing its effectiveness. Unlike LT, 5-HTP cannot be shunted into niacin or protein production. Therapeutic use of 5-HTP bypasses the conversion of LT into 5-HTP by the enzyme tryptophan hydroxylase, which is the rate-limiting step in the synthesis of serotonin. 5-HTP is well absorbed from an oral dose, with about 70 percent ending up in the bloodstream. It easily crosses the blood-brain barrier and effectively increases central nervous system (CNS) synthesis of serotonin. In the CNS, serotonin levels have been implicated in the regulation of sleep, depression, anxiety, aggression, appetite, temperature, sexual behaviour, and pain sensation. Therapeutic administration of 5-HTP has been shown to be effective in treating a wide variety of conditions, including depression, fibromyalgia, binge eating associated with obesity, chronic headaches, and insomnia.
Birdsall TC. 5-Hydroxytryptophan: a clinically-effective serotonin precursor. Altern Med Rev. 1998 Aug;3(4):271-80
You make up your mind but i'm sticking with the 5-HTP
Laura if you have some evidence to back up your statements that would be much appreciated. But i prefer to believe peer reviewed journal articles rather than a post on a bulletin board.