Indole-3-carbinol

Indole-3-carbinol (C9H9NO) is a naturally occurring phytochemical found at relatively high levels in cruciferous vegetables. Indole-3-carbinol is the subject of on-going biomedical research into its possible anticarcinogenic, antioxidant, and anti-atherogenic effects. Research on indole-3-carbinol has been conducted primarily using laboratory animals and cultured cells. Limited and inconclusive human studies have been reported. A recent review of the biomedical research literature found that, "evidence of an inverse association between cruciferous vegetable intake and breast or prostate cancer in humans is limited and inconsistent" and "larger randomized controlled trials are needed" to determine if supplemental indole-3-carbinol has health benefits.

Indole-3-carbinol and cancer
Investigation of mechanisms by which consumption of indole-3-carbinol might influence cancer incidence focus on its ability to alter estrogen metabolism and other cellular effects. Controlled studies have been performed on such animals as rats, mice, and rainbow trout, introducing various controlled levels of carcinogens, and levels of Indole-3-carbinol into their daily diet. Results showed dose-related decreases in tumor susceptibility due to Indole-3-carbinol (inferred by decreases in aflatoxin-DNA binding). The first direct evidence of pure anti-initiating activity by a natural anticarcinogen (indole-3-carbinol) found in human diet was claimed by Dashwood, et al, in 1989.

In 2006, Hsu et al proved that indole-3-carbinol induces a G1 growth arrest of human reproductive cancer cells. This is significant in the prevention and treatment of cancer, as the G1 phase of cell growth occurs early in the cell lifecycle, and for most cells is the major period of cell cycle during its lifespan. The G1 phase is marked by synthesis of various enzymes that are required in the next ("S") phase, including those needed for DNA replication.

It should be noted that indiscriminant overuse of indole-3-carbinol supplements in hopes of preventing cancer may be unwise, as hormone balance should be tested (via simple blood test) before regular consumption. Such caution is advised due to its effect on estrogen levels (estrogen has a significant impact on brain function).

Dietary sources
Indole-3-carbinol occurs naturally in cruciferous vegetables such as cabbage, broccoli, brussels sprouts, and kale. It is also widely available in supplement form.