Relation of Corn Products to the Requirement of the Rat for Dietary Nicotinic Acid

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Abstract
No evidence of a specific deleterious effect of corn products in nicotinic acid-deficient rations was obtained. Growth of rats was very poor on a 9%-casein diet either with or without the inclusion of 40% of corn meal or grits, when nicotinic acid was not added to the diet. Growth was greater with 86.7% than with 40% corn meal in a 9%-casein diet, either with or without nicotinic acid. Normal growth was produced by the addition of 1 or 2 mg % of nicotinic acid to a 9%-casein diet containing 40% corn meal or grits, or 86.7% corn meal. Three hundred mg % of dl-tryptophane was only slightly less effective than 1 mg % of nicotinic acid in stimulating growth on a 40%-corn meal, 9%-casein diet. A 25%-casein diet containing 40% corn grits produced normal growth without the addition of nicotinic acid. The inclusion of 15% lard in a 9%-casein diet containing 40% corn meal, but no added nicotinic acid, caused a significant increase in growth. Nicotinic acid was required for normal growth on this diet. When 30% lard was included in the diet containing 40% corn meal and the casein increased to 13.3%, growth was normal without the addition of nicotinic acid. Fat was again found to have a marked nicotinic acid-tryptophane-sparing effect, indicating that nicotinic acid functions primarily in carbohydrate metabolism. The inclusion of 40% corn meal or grits in a diet, containing nicotinic acid and 9% casein, increased growth by more than 200%, thus showing a marked supplementary value of corn in low-casein diets. The conditions relating to the requirement of the rat for dietary nicotinic acid are discussed.