Tumorigenicity and mutagenicity studies with capsaicin of hot peppers.

Capsaicin, the pungent principle of hot pepper, was administered at concentrations of 1, 0.5, 0.25, 0.125 and 0.0625% in powdered diet for 35 days to five groups of Swiss albino mice. In the capsaicin-treated groups 4 mice (10%) developed 4 adenocarcinomas of the duodenum (one tumor at each dose level, except for the highest dose), while no such tumor occurred in the untreated control mice. Capsaicin exhibited a low level of mutagenicity in the Ames assay with S. typhimurium strain TA98 in the presence of liver activating enzymes from Aroclor-induced rats.