Indole-3-Carbinol (I3C) is a compound produced from the breakdown of glucobrassicin, a substance found in cruciferous vegetables such as broccoli, cabbage, and Brussels sprouts. Its use to support the female reproductive system, particularly for hormone balance and cervical health, is primarily based on scientific evidence from preclinical and clinical studies. I3C is known to modulate estrogen metabolism, favoring the production of less potent estrogen metabolites, which may reduce the risk of estrogen-dependent conditions such as cervical dysplasia and possibly endometriosis.

Several clinical trials have investigated the effects of I3C on cervical intraepithelial neoplasia (CIN), a precancerous condition of the cervix. For example, a randomized clinical trial published in Gynecologic Oncology (1998) demonstrated that oral I3C supplementation led to regression of CIN in a significant proportion of women compared to placebo. Additional research has shown that I3C and its metabolite, diindolylmethane (DIM), can influence estrogen metabolism and may have protective effects against hormone-driven cancers.

However, while the evidence supports a role for I3C in specific conditions related to the female reproductive system, such as cervical dysplasia, the breadth and long-term safety of its use for general reproductive health are less well established. More large-scale human studies are needed to confirm efficacy and safety. Thus, the evidence rating is moderate (3/5).