AbstractThe anticarcinogenic effect of dietary turmeric on benzo[a]pyrene‐(BP) induced fore‐stomach neoplasia and 7,12‐dimethylbenz[a]anthracene (DMBA)‐induced skin tumorigenesis in female Swiss mice was evaluated. To further elucidate the mechanism of antineoplastic action of turmeric, its effect on the hepatic cytochrome b5, cytochrome P‐450, glutathione, and glutathioneS‐transferase activities was studied in female Swiss mice. Turmeric (2% or 5%) in the diet significantly inhibited the BP‐induced forestomach tumors, and this response was dose and time dependent. The 2% turmeric diet significantly suppressed DMBA‐induced skin tumors in mice. The 5% turmeric diet for seven consecutive days resulted in a 38% decrease in the hepatic cytochrome b5 and cytochromeP‐450 levels. Glutathione content was increased by 12%, and the glutathioneS‐transferase activity was enhanced by 32% in the liver. Our results document a protective effect of turmeric on BP‐induced forestomach and DMBA‐induced skin tumors in mice.