Pyridoxine Deficiency and Tryptophan Metabolism in Chronic Alcoholics

Abstract

T-Tryptophan oral load tests were administered to twenty-one chronic alcoholic patients and fasting plasma pyridoxal-5-phosphate levels were estimated. Three patients (14 per cent) were thought to be pyridoxine deficient and the data indicated that tryptophan load tests were abnormal with plasma pyridoxal-5-phosphate levels of less than 40 per cent of normal. Nine subjects were considered normal and nine had subnormal urinary excretion of tryptophan-nicotinic acid intermediate metabolites, although plasma pyridoxal-5-phosphate levels in both these groups were more than 40 per cent of normal. Possible explanations of subnormal metabolite excretion are discussed and it is proposed that there may be facilitated tryptophan-nicotinic acid conversion in chronic alcoholism because of increased metabolic requirements for nicotine-adenine dinucleotide (NAD). There was no confirmation of previous reports of reduced 5-hydroxyindole-acetic acid excretion in chronic alcoholic subjects.