Modification of beet and cabbage diets of aflatoxin B1-induced rat plasma alpha-foetoprotein elevation, hepatic tumorigenesis, and mutagenicity of urine.

Weanling male Fischer rats were fed a purified diet or diets containing 25% (w/w) freeze-dried ground beets or cabbage with or without 1 ppm aflatoxin B1 (AFB1) for 26 wk. In 3-7 wk the cabbage diet diminished, while the beet diet enhanced AFB1-induced plasma alpha-foetoprotein (AFP) elevation. When the experiment was extended to 42 wk by maintaining the animals on the purified (basal) diet for a further 16 wk the rats that had consumed AFB1 in the beet diet had 72 +/- 14 tumours/liver (mean surface diameter of tumours, 6.13 +/0 4.69 mm); animals that had been given AFB1 in the control diet had 30 +/- 16 tumours/liver (mean surface diameter, 4.36 +/- 3.16 mm); rats that had been given AFB1 in the cabbage diet had 13 +/- 5 tumours/liver (mean surface diameter, 4.28 +/- 2.89 mm). In the Salmonella/mammalian microsomal test, urine from rats fed AFB1 with beets caused significantly (P less than 0.05) more revertants in Salmonella typhimurium strain TA98 than did urine from rats fed AFB1 with purified or cabbage diets. The beet- and cabbage-containing diets had no effect on the plasma AFP concentration, hepatic tumorigenesis, or the mutagenicity of urine in rats receiving no AFB1. The evidence suggests that non-nutrient components of common vegetables may influence the response to chemical carcinogens, and that AFP determinations are useful in the rapid identification of dietary factors that modify carcinogenesis.