Abstract

Different levels of ß‐carotene (0, 5, 25, 125, and 250 mg/kg diet) were tested for their chemoprevention effects using 9,10‐dimethyl‐1,2‐benzanthracene‐induced salivary gland tumor model in rats. Tumor incidence and tumor weights were slightly lower in rats fed diets supplemented with 25 mg or more ß‐carotene/kg diet. Hepatic vitamin A and ß‐carotene levels were increased in a dose‐dependent fashion, reaching a plateau at 125 mg ß‐carotene/kg diet. In plasma, ß‐carotene concentrations were also increased with an increase in dietary ß‐carotene. Vitamin A levels in plasma were not affected. The normal salivary glands had higher concentrations of ß‐carotene than did the tumors. The results suggest that the decreases in tumor incidence and tumor weight may be related to the increase in plasma and tissue levels of ß‐carotene as a result of feeding high levels of ß‐carotene.