Inhibition of esophageal carcinogenesis in corn-fed rats by riboflavin, nicotinic acid, selenium, molybdenum, zinc, and magnesium.

The effect of individual vitamins and minerals on esophageal carcinogenesis was assessed by supplementing a diet (based on corn) that was marginally deficient in many micronutrients. The test diets were fed to weanling inbred BD IX rats for 45 days; they were then given five subcutaneous doses (3 mg/kg body wt) N-nitrosomethylbenzylamine (MBN) over two and one-half weeks. The diets were continued until termination: 150 days later; at that time all rats were still clinically normal. Marked reductions in the number of tumors and tumor-bearing rats were recorded in groups of rats given supplements of riboflavin, nicotinic acid, zinc, magnesium, selenium, and molybdenum. Various combinations of nutrients did not distinctly reduce the tumor yield further; however, tissue analyses suggest that individual supplements could enhance the status of other marginally deficient nutrients. When the experiment was repeated, but was varied by commencing the supplements only well after the cessation of MBN exposure, inhibitory effects on tumorigenesis were still exerted by most nutrients. We emphasized that these nutritional effects along with the epidemiological evidence in humans are relevant to early prevention; also, the treatment of premalignant esophageal changes by high doses of these nutrients may be unwise. The merits of food supplementation schemes are discussed.