Four nutraceuticals,
sugar beet roots, cucumber fruits, New Zealand spinach leaves, and turmeric rhizomes, were evaluated for their comparative effectiveness against dimethylbenz[a]
anthracene (DMBA)-initiated and
croton oil-promoted skin
tumors. Three different protocols were used. The most effective protocol (Protocol 2) is the topical application of the nutraceuticals 1 h before
croton oil. There was a decrease in the percent skin
tumor incidence, a decrease in multiplicity of skin
tumors, and a later onset of skin
tumors compared with the positive control for all the nutraceuticals tested, with turmeric being the most potent, as evidenced by 30% skin
tumor incidence, 87.2% decrease in skin
tumors, and a 5-wk delay in skin
tumor formation compared with the positive control. Topical application of the nutraceuticals daily for 5 days before DMBA and 1 h before
croton oil (Protocol 1) and immediately after
croton oil (Protocol 3) did not have an additional protective effect against skin
tumors compared with Protocol 2. Kruskal-Wallis analysis of variance by ranks showed that Protocol 2 is the most effective, with the treatment groups belonging to different populations at the 0.05 level of significance compared with alpha = 0.20 for Protocols 1 and 3. Turmeric is the most potent nutraceutical, because the average number of
tumors formed after application of tumeric is statistically different from the positive control at alpha = 0.01.