Since you didn't read the last study I posted I will summarize a few abstracts. Still waiting on your sources which discredit niacinamide.
"patientwith anorexia nervosa an insufficient sup-ply of vitamin B3 or protein resulted in re-duced urinary levels of the serotonin break-down product, 5-hydroxy-indolacetic acid(5-HIAA).32 The authors of this report pos-tulated that a deficiency of vitamin B3 re-duced the feedback inhibition upon thekynurenine pathway, resulting in more tryp-tophan being diverted to the kynureninepathway, making less substrate available forthe synthesis of serotonin. By contrast, theuse of pharmacological doses of vitamin B3can increase the production of serotonin.33In a rat study, the administration of 20 mgof niacin resulted in increased levels of 5-HIAA and decreased levels of xanthurenicacid via the kynurenine pathway.34 Taki ngpharmacological doses of niacinamide (orany other form of vitamin B3) would increasethe production of serotonin, by divertingmore tryptophan to become substrate forserotonin synthesis"2. Judd LE, Poskitt BL: Pellagra in a patient with aneating disorder. Br J Dermatol, 1991;125:71-72.
33. Gedye A: Hypothesized treatment for migraineusing low doses of tryptophan, niacin, calcium,caffeine, and acetylsalicylic acid. Med Hypoth-eses, 2001;56:91-94.
34. Shibata Y, Nishimoto Y, Takeuchi F, Tatsuma Y:Tryptophan metabolism in various nutritive con-ditions. Acta Vitamin Enzymol, 1973; 29: 190
"Niacinamide modulated spinal cord activity, and had anticonflict, an-ticonvulsant, muscle relaxing and hypnotic effects. The potency of ni-acinamide was found to be equivalent to a highly potent benzodiazepine.Niacinamide had a low affinity to the benzodiazepine-binding site inthe mammalian brain. This low affinity may have been the result of thebinding assay used, or it may have been a reflection that more than onebinding-site existed by which niacinamide exerted its benzodiazepine-like properties."
. Möhler H, Polc C, Cumin R, Pieri L, Kettler R:Nicotinamide is a brain constituent withbenzodiazepine-like actions. Nature, 1979; 278:563-565.
"Niacinamide antagonized the effects of diazepam, therefore interactingwith the benzodiazepine receptor in vivo. However, niacinamide did notmimic the benzodiazepine properties of diazepam when tested withthe rat head-turning model. Niacinamide probably does havebenzodiazepine-like properties at different benzodiazepine receptor sitesin the CNS, but its effects are unrelated to the actions of gamma-aminobutyric acid (GABA)."Slater P, Longman DA: Effects of diazepam andmuscimol on GABA-mediated neurotrans-mission: interactions with inosine and nicoti-namide. Life Sci, 1979; 25: 1963-1967.
"Niacinamide had a qualitatively similar effect to that of diazepam. It wasconcluded that niacinamide exerted its effects by influencing the turnoverof serotonin, noradrenaline (norepinephrine), dopamine and GABA in thoseareas of the brain thought to be unbalanced in anxiety." Kennedy B, Leonard BE: Similarity between theaction of nicotinamide and diazepam on neu-rotransmitter metabolism in the rat. BiochemSoc Trans, 1980; 8: 59-60.
"Niacinamide could possibly be a competitive antagonist for thebenzodiazepine receptor since it prevented the binding of kynurenineto the benzodiazepine receptor. It was further postulated that this ac-tion was more likely of central origin than peripheral origin. It couldnot be determined if niacinamide’s action was indeed related to itsoccupation of the benzodiazepine receptor."
28. Lapin IP: Nicotinamide, inosine and hypoxan-thine, putative endogenous ligands of thebenzodiazepine receptor, opposite to diazepamare much more effective against kynurenine-induced seizures than against pentylenetetra-zol-induced seizures. Pharmacol BiochemBehav, 1981; 14: 589-593.
"Niacinamide was structurally dissimilar to the benzodiazepine receptors.Niacinamide did not act as a specific ligand for the benzodiazepinereceptor, but instead had a weak binding affinity for the receptor."
Markin RS, Murray WJ: Searching for the en-dogenous benzodiazepine using the graph theo-retical approach. Pharm Res, 1988;5:408-412.
Niacinamide and its analogs possessed properties similar tobenzodiazepines at various zones of the cerebral cortex by influencingthe GABA-ergic system."
"30. Akhundov RA, Dzhafarova SA, Aliev AN: Thesearch for new anticonvulsant agents based onnicotinamide. Eksp Klin Farmakol, 1992;55:27-29.