Factors Affecting the Dietary Niacin and Tryptophane Requirement of the Growing Rat: One Figure

Abstract

The addition of corn or corn grits to a nicotinic acid-low synthetic ration results in a profound growth retardation which can be completely counteracted by the inclusion of from 1–1.5 mg. of nicotinic acid or 50 mg. of tryptophane per 100 gm. of ration. Other cereals containing less nicotinic acid produce no such effect. The kind of carbohydrate and the level of tryptophane influence the extent of the undesirable effect of corn. Glucose, dextrin and lactose were beneficial in their action. Small amounts of milk were also helpful in counteracting the growth depression but further benefits resulted from the addition of nicotinic acid. A low level of vitamins accentuated the deleterious action of corn. Nicotinamide and ethyl nicotinate were as active as nicotinic acid on an equal molar basis while nicotinamidemethochloride, trigonelline, and N-phenylnicotinamide were inactive. Non-corn rations low in tryptophane and nicotinic acid also gave poor growth when sucrose was used as the carbohydrate. The addition of tryptophane or nicotinic acid or the use of a carbohydrate which produced a favorable intestinal flora gave growth results comparable to those obtained with corn supplemented rations. The factors affecting the dietary tryptophane requirement and the importance of a desirable intestinal flora in this relationship are discussed.