Dietary indole compounds exert a strong protective effect on tissues such as breast, cervix, and prostate that are most susceptible to the effects of undesirable estrogen metabolites, such as 16-alpha-hydroxyestrone. Indole compounds favorably influence steroid hormone metabolism and help rebalance estrogen in favor of 2-hydroxyestrone, a protective estrogen metabolite.
Dietary indoles also stimulate liver detoxification enzymes, inhibit DNA damage, and regulate cell cycle progression. Indole-3-carbinol (I3C), the most prominent dietary indole, readily breaks down in the presence of stomach acid into diindolylmethane (DIM) and other associated indole compounds that are subsequently absorbed. Increased indole intake may be especially important for women or men with estrogen-related health conditions.