The Performance of Normal Young Men on Controlled Thiamine Intakes

Abstract

Thiamine intake was limited and measured in four series of experiments. Each experiment lasted 10 to 12 weeks and involved four normal young men subjects. The diet was adequate except for thiamine and balance was maintained at 3050 ± 200 Cal. per day. Two control series were run in which all conditions and tests were applied identically but the subjects received in addition 1 mg. of thiamine daily. Average thiamine intakes studied were, in milligram per 1,000 Cal., 0.63, 0.53, 0.33, and 0.23 as determined by thiochrome analyses on all food. Calculated values were 10.3%, c = ± 6.7%, less than the thiochrome analyses. Excretion of thiamine in the urine averaged, after a few weeks, about 10% of the dietary thiamine on an intake of 0.33 mg. per 1,000 Cal., and about 7% on 0.23 mg. Saturation tests gave similar results. All subjects adhered to a fixed regime of weekly work performance. Blood and other examinations were made at regular intervals. All conditions and experiments were rigidly standardized. Tests covered simple strength, responses during brief exhausting work, prolonged severe work, and in recovery, psychomotor tests of speed and coordination, and glucose tolerance. General and clinical observations and subjective reports were analyzed. Electrocardiographic and roentgenographic studies were made. Variables measured in rest, work, and recovery included heart rates, blood pyruvate, lactate, glucose and hemoglobin, and the psychomotor performances. All results are in agreement that, for the periods studied, no benefit of any kind was observed to be produced by an intake of more than 0.23 mg. of thiamine per 1,000 Cal. At this level of intake muscular, neuromuscular, cardiovascular, psychomotor and metabolic functions were in no way limited by the thiamine restriction. Clinical signs, subjective sensations and state of mind, and behavior were likewise apparently unaffected by thiamine intakes from 0.96 to 0.23 mg. per 1,000 Cal. From the present work no conclusions are drawn as to requirements for men during more prolonged periods, or for women, children, the aged, or for states of disease or injury.