I3C (Indole-3-Carbinol): What it does and why people take it

Heard of I3C and wondered if it’s worth trying? I3C, short for indole-3-carbinol, is a compound your body makes when you eat cruciferous vegetables like broccoli, cabbage, Brussels sprouts, and cauliflower. People take it as a supplement mainly to support healthy estrogen metabolism and for its potential protective effects seen in lab studies. That doesn’t mean it’s a cure-all, but it’s useful to know what it can — and can’t — do.

Benefits and what the research says

Lab studies and small human trials show I3C may shift how the body processes estrogen toward less reactive forms. That’s why some use it for conditions linked to estrogen balance. Early clinical work suggests possible benefits in hormone-related issues and as a complementary approach in certain prevention strategies, but large, conclusive trials are still missing. If you’re considering I3C for any health condition, treat it as a supportive option, not a replacement for proven medical therapy.

A quick practical point: I3C breaks down into several compounds in the stomach, including DIM (diindolylmethane). DIM is more stable and is sold as its own supplement. Some people prefer DIM because it’s easier to dose and study, while others choose I3C because it’s closer to the natural plant compound.

Dosage, safety, and side effects

Typical supplement doses range around 200–400 mg per day, often split into two doses. Some clinical reports use higher amounts, but higher does not always mean safer. Common side effects are mild and include stomach upset, nausea, and headaches. Less commonly, people report skin rash or temporary changes in liver enzyme tests.

Important safety note: I3C can change how the liver handles certain drugs and may influence hormone-sensitive conditions. That means it can alter levels of medications processed by liver enzymes or affect hormonal therapies. If you’re on prescription medicine, hormone therapy, anticoagulants, or have a hormone-sensitive cancer history, check with your doctor before starting I3C.

Avoid I3C if you are pregnant or breastfeeding — we don’t have enough safety data. Children should not take high-dose supplements unless a pediatrician approves.

Want to use food first? Eating several servings of cruciferous vegetables each week gives you natural exposure to I3C precursors without supplement risks. If you choose a supplement, pick brands with third-party testing and clear labeling.

Questions? Try asking your pharmacist or clinician about interactions with your current meds. If you decide to try I3C, start at the lower end of the dose range and watch for side effects. For more detailed reads on supplements, drug interactions, and safe online purchasing, check the related posts tagged I3C on Evo-Pharmacy.com below.