The functional capacity of the tryptophan-niacin pathway in pellagrous children

The aim of this work was to study the functional capacity of the tryptophan-niacin pathway in pellagrous children by analysis of several interrelated metabolites excreted in their urine. 2 groups of these patients were studied and compared with appropriate controls; patients with pure pellagra and patients with pellagra associated with parasitic infection. It was found that niacin deficiency led, at least in part, to an inhibition of the NADPH-dependent kynurenine hydroxylase enzyme in patients with pure pellagra. Niacin supplementation (120 mg.) daily for one month did not completely restore the activity of this enzyme in a patient with pure pellagra. The reason for this is still obscure. In contrast, niacin deficiency in pellagra associated with certain parasites, seems to be due to the impairment in the further degradation of 3-hydroxykynurenine to niacin. 1 patient of this group responded clinically and biochemically to treatment with adequate quantities of niacin, B vitamins and balanced diet. The disappearance of the clinical manifestations of pellagra does not necesasrily mean that the patient is biochemically cured. This may imply that under such conditions recurrences of pellagra are possible.