Effect of corn and sorghum diets in N1 methylnicotinamide excretion and hepatic enzymes in rats.

This study was carried out to compare the effects of corn (Zea mays) and sorghum (Sorghum vulgare) diets on urinary N1 methylnicotinamide (N'MN) excretion and on the activity of hepatic enzyme in young adult rats. Thirty rats, weighing an average of 174.3 g at the beginning of the experiments, were divided into three groups and studied for 13 weeks. The two experimental diets supplied 7% protein, and a casein diet was used as control. Niacin was excluded from the vitamin mixture used in the corn and sorghum diets. The activities of the following enzymes were studied: betaHOB-D, G6P-D, NADH2-TR, NADPH2-TR, and 3 HOA-0. Urinary excretion of N'MN was statistically different among the three groups, the corn group having the lowest level. The corn-fed animals appeared to have more obvious alterations in liver enzyme activity. The changes found in corn and sorghum-fed animals are different and cannot be explained as due to niacin deficiency. The different amino acid compositions of the two grains and their relationship with the discrepancies in the result are also discussed.