A Study of Test Dose Excretion of Five B Complex Vitamins in Man

Abstract

An oral test dose of thiamine, riboflavin, nicotinamide, folic acid and pyridoxal was administered to 115 subjects of varying nutritional status, and the urinary excretion of these vitamins or their metabolites in the subsequent 4 hours was determined. Findings were evaulated in relation to clinical status and dietary histories for the following groups of subjects: (1) controls (essentially normal persons); (2) miscellaneous hospital patients; (3) subjects on weighed diets low in B complex vitamins; (4) patients with signs of vitamin B complex deficiency; (5) patients with clincal evidence of thiamine deficiency; and (6) patients with diabetes mellitus. The diets of the control subjects and of subjects with diabetes mellitus were much more satisfactory as to content of B vitamins that those of the other groups. The mean thiamine excretion after the test dose was found to be significantly lower in patients with thiamine deficiency and in subjects who had been maintained on weighed diets low in B vitamins than in control subjects. Riboflavin excretion was significantly decreased only in the group of subjects on weighed diets low in B vitamins. Neither thiamine nor riboflavin excretion was significantly diminished in patients with clinical evidence of vitamin B complex deficiency. The excretion of N¹-methylnicotinamide was less than that of the control subjects in all groups tested. The difference was statistically significant in the miscellaneous hospital patients, in patients with signs of thiamine or vitamin B complex deficiency, and in subjects with diabetes mellitus. Folic acid excretion was significantly lower in subjects with evidence of thiamine or vitamin B complex deficiency than in control subjects. In contrast to this, folic acid excretion in 5 subjects maintained on weighed diets low in B vitamins was significantly higher than that found in the controls. The excretion of 4-pyridoxic acid was essentially the same in all of the groups tested. In subjects with diabetes mellitus, the mean excretion of thiamine and riboflavin was significantly higher than that found in control subjects, while that of N¹-methylnicotinamide was significantly lower. These findings suggest a possible abnormality in the utilization of thiamine and riboflavin in patients with diabetes mellitus. The test dose procedure described in this study appears to be useful in evaluating the nutriture of groups of individuals in regard to thiamine and niacin and to be of less value with respect to riboflavin, folic acid and pyridoxal.