Overview of the role of vitamins and minerals on the kynurenine pathway in health and disease

The kynurenine pathway (kp) of l-tryptophan metabolism produces several neuroactive metabolites with an amino acidstructure. these metabolites may play an important role in the pathophysiology of irritable bowel syndrome,alzheimer'sdisease,parkinson's disease,huntington's disease,schizophrenia,aids-dementia complex,depression,epilepsy and theaging process. modulation of the kp through inhibition or stimulation of enzyme synthesis and activity can be an alternativeapproach to traditional therapy. furthermore,it may be responsible for the altered functioning of the enteric nervous systemand the central nervous system. there is evidence that the kp is sensitive to changes in the concentration of many vitaminsand minerals that play a crucial role as coenzymes and cofactors in the de novo synthesis of nicotinamide adeninedinucleotide coenzyme. a reduction in the availability of the active form of vitamin b6 (pyridoxal 5'-phosphate,plp) isknown to affect tryptophan hydroxylase,kynurenine aminotransferase and kynureninase (kynu). vitamin b2 deficienciesresult in a reduction in the activity of the flavin adenine dinucleotide dependent enzyme,kynurenine 3-monooxygenase.minerals are also responsible for the proper functioning of enzymes engaged in l-tryptophan metabolism. mn2+,zn2+,co2+and cu2+ influence kynu activity,and mg2+ regulates quinolinate phosphoribosyl transferase. fe2+ is responsible for theproper functioning of both indoleamine 2,3-dioxygenase and 3-hydroxy-anthranilic acid dioxygenase. changes in theconcentration of kp metabolites and in enzymatic activity have been found in many pathological states. therefore,it isjustifiable to regulate the concentration of certain kynurenines or enzymes in the kp which may provide a potentialtherapeutic target for the treatment of various health impairments. this review demonstrates the role of vitamin and mineralactivity on the kp,which may have an effect on the proper functioning of the human organism. surplus administration ofvitamins did not elicit any beneficial effects on l-tryptophan metabolism. whether a mineral surplus influences l-tryptophanmetabolism is still not established. it seems that cofactor deficiencies influence the kp far more than surpluses. © 2016,polish physiological society. all rights reserved.