Possible Interaction: Niacin and Tryptophan

“Two out of three patients, including the subject who improved following an oral load of tryptophan, improved with L-tryptophan combined with nicotinamide , a tryptophan pyrrolase inhibitor, when administered for 1-3 weeks.”

“ Nicotinamide was given to reduce peripheral breakdown of tryptophan.”

“This study shows that a dietary undersupply of tryptophan and vitamin B3 , the metabolic precursors of nicotinamide adenine dinucleotide (NAD), during pregnancy is a cause for frequent multiple birth defects and miscarriages in wild-type mice.”

“It has now been definitely established that there exists an interchangeability of nicotinic acid and tryptophan in the nutrition of some animals on diets deficient in the vitamin and containing only suboptimal amounts of the amino acid (1-S).”

“Pre-treatment with nicotinamide (0.5 g three times daily) resulted in considerable decreases in AUC in plasma, and in urinary excretion of KYN and 3-HK, indicating inhibition of liver tryptophan pyrrolase.”

“They increase hepatic tryptophan oxygenase activity resulting in a surplus of tryptophan further in the pathway to niacin.”

“These results seem to indicate a decreased formation of nicotinic acid from tryptophan.”

“In the brain of mature rats, the combination of tryptophan and nicotinic acid in normal and immobilization decreased the level of LP and increased the intensity of AOA.”

“The increased activity of antioxidant system in the brain of rats by complex of tryptophan and nicotinic acid demonstrated its protective antioxidant properties.”

“The simultaneous introduction of tryptophan and nicotinic acid reduced negative changes of LP and AOA in the brain of old rats caused by immobilization stress exposure.”

“Pretreatment with nicotinic acid (500 mg/kg), an inhibitor of lipolysis, almost completely prevented the increase in plasma free tryptophan and NEFAs, and attenuated the increase in brain tryptophan induced by CL 316243.”

“The altered metabolism of tryptophan with ageing can lead to a decreased biosynthesis of nicotinic acid , tryptophan being the major source of body stores of NAD coenzymes, which are involved in almost all biogenetic and biosynthetic pathways of the organism.”