The Thiamine Requirement of the Albino Rat as Influenced by the Substitution of Protein for Carbohydrate in the Diet

The average daily thiamine requirement of ten, adult, male albino rats of the Wistar Institute strain weighing nearly 400 gm. and maintained in approximate energy equilibrium at 26°–30°C. on a diet containing 64% sucrose, 20% casein, and 10% hydrogenated cottonseed oil (plus cellulose flour, salts, and pure vitamin supplements) has been found to be 33 μg. (coef. var.=8%). On a diet high in protein (64% casein, 19.6% sucrose, 10% hydrogenated cottonseed oil; and representing a 9% decrease in the energy intake), nine of the ten rats had an average requirement of 20 μg. (coef. var. = 9%). A comparison of the two values demonstrates a 39% reduction in the daily requirement. The increase in the urinary pyruvate excretion (determined by the method of Lu) which indicates a possible disturbance in intermediary carbohydrate metabolism has been used as the index of subacute thiamine deficiency.