Absence of Rapid Deterioration in Men Doing Hard Physical Work on a Restricted Intake of Vitamins of the B Complex

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Abstract
Eight normal young men were maintained on a rigidly controlled regime of diet, physical work and exhaustive tests for 40 days. Twenty-one days were devoted to standardization with an average intake of B vitamins approximating the National Research Council recommendations. For the next 14 days the basal diet was constant and provided an average, in milligrams per 1,000 Cal., of 0.16 of thiamine, 0.15 of riboflavin and 1.8 of niacin. During these 14 days of “restriction” all men received daily capsules. Five men received placebos; each of the other three men received abundant daily supplements of yeast concentrate and synthetic B vitamins. During the last 5 days the same basal diet was used but all eight men received these supplements. None of the men knew the contents of the capsules ingested. None of the observers knew which men were receiving supplements and which only placebos. All food was directly analyzed for B vitamins as eaten. The energy level was carefully standardized by a set regimen of fixed tasks, most of them on motor-driven treadmills. Balance was maintained at 3,560 Cal. daily for the first 15 days and at 4,430 Cal. for the next 6 days. Thereafter (19 days) the average intake was 4,640 Cal. and the energy expenditure about 4,800 Cal. daily. Comprehensive clinical examinations, including electrocardiography and special ophthalmological details, were made at the start and at the end. A fixed schedule of repeated carefully standardized tests was maintained throughout. These included twelve objective tests covering endurance, anerobic work, speed, coordination and muscle strength. Blood lactate and pyruvate were repeatedly measured at rest and at fixed intervals after standard exhausting anerobic work. The urinary excretions of thiamine and of riboflavin were measured every few days. Psychological questionnaires were filled out by each man every other day. All results were in conclusive agreement that the vitamin intake and limitation were without effect on all the functions measured. Of all the variables measured and observed only the vitamin excretion in the urine reflected the intake. Claims that normal men undergo physical deterioration in a few days of hard work on diets similarly restricted in B vitamins are seriously questioned. The results reported previously are explained on the basis of factors independent of the vitamin intake, namely, faulty experiments and lack of objective measurements and proper controls.