It is believed that the consumption of cruciferous vegetables such as broccoli, cabbage, cauliflower, kale and Brussels sprouts can reduce the risk of several cancers. This anti-cancer property of cruciferous vegetables has been linked to the glucosinolate derivates, mainly indole-3-carbinol
and crambene. These phytochemicals seem to act as detoxification agents for carcinogens by enhancing the detoxification enzymes. Indole-3-carbinol is bifunctional enhancer of detoxification enzymes because it stimulates both phase I and phase II enzymes. Crambene is mainly a stimulator of phase II enzymes. Test with rats have showed that indole-3-carbinol and crambene act synergistically on stimulation of phase II enzymes.
This study was carried out on male rats which were fed with the carcinogen aflatoxin B1. The rats were divided in groups:
- control group (without aflatoxin B1)
- positive control group (with aflatoxin B1)
- crambene group
- indole-3-carbinol group
- high dose group (crambene and indole-3-carbinol)
- low dose group (crambene and indole-3-carbinol)
The anti-cancer effect was measured by the level of glutathione S-transferase. The researchers found that crambene group, the indole-3carbinol group and the high dose group protected against the carcinogenic effect of aflatoxin B1. The low dose group showed no protection. This was the first in vivo study to demonstrate the chemoprotective action of crambene. The study mainly investigated the potential of crambene and indole-3-carbinol to block initiation of carcinogenesis rather than to suppress initiated cancer cells.
The study concluded that high concentrations of the phytochemicals crambene and indole-3-carbinol reduced the initiation of carcinogenesis by aflatoxin B1, but that low concentrations, which correspond to realistic consumption, showed no effects. More in vivo studies are necessary to investigate the synergistic effect of crambene and indole-3-carbinol on overall carcinogenesis.
Source: Matthew A. Wallig, Kathleen M. Heinz-Taheny, Donna L. Epps and Tamara Gossman. Synergy among Phytochemicals within Crucifers: Does It Translate into Chemoprotection?. Journal of Nutrition 135:2972S-2977S, December 2005