What is indole-3-carbinol?
Indole-3-carbinol (I3C) is a naturally occurring compound found in cruciferous vegetables such as broccoli, Brussels sprouts, cabbage, and kale. I3C is also available in supplement form.
I3C is sometimes promoted as an alternative cancer treatment or as a way to prevent cancer. However, there is no scientific evidence to support these claims.

Health Benefits
I3C supplements are sometimes promoted as a way to treat or prevent cancer. However, there is no scientific evidence to support these claims.
I3C is sometimes touted as a natural alternative to conventional cancer treatments such as chemotherapy. However, there is no scientific evidence to support this claim.
I3C supplements are sometimes promoted for their purported anti-estrogen effects. Some research suggests that I3C may help reduce the risk of certain hormone-sensitive cancers, such as breast cancer. However, more research is needed in this area.
I3C supplements are sometimes promoted as a way to boost detoxification and fight inflammation. However, there is no scientific evidence to support these claims.
Side Effects and Safety Concerns
I3C is generally considered safe when taken in supplement form. However, some people may experience side effects such as nausea, vomiting, and diarrhea. I3C may also interact with certain medications, so it’s important to speak to your doctor before taking I3C supplements.
Pregnant women and those who are breastfeeding should avoid taking I3C supplements. There is not enough scientific evidence to determine whether I3C is safe for pregnant women or their babies.
I3C supplements should not be taken by those who have a history of hormone-sensitive cancers, such as breast cancer. I3C may stimulate the growth of these types of tumors.
I3C supplements are not recommended for children. There is not enough scientific evidence to determine whether I3C is safe for children.
Mechanism of Action
I3C supplements are thought to work by inhibiting the growth of cancer cells and by inducing cell death (apoptosis). I3C may also help reduce the risk of certain hormone-sensitive cancers, such as breast cancer.
Dosage and Preparation
I3C supplements are available in capsule, tablet, and liquid form. There is no standard dose of I3C, so it’s important to follow the instructions on the supplement label.
Interactions
I3C may interact with certain medications, including:
Anticoagulants and antiplatelet drugs: I3C may increase the risk of bleeding.
Hormone therapies: I3C may decrease the efficacy of these treatments.
St. John’s wort: Taking I3C with this supplement may decrease the efficacy of I3C.
Tamoxifen: I3C may decrease the efficacy of this breast cancer medication.
Before taking I3C supplements, speak to your doctor about any potential drug interactions.
Pharmacokinetics
I3C is rapidly absorbed from the gut and metabolized in the liver. The half-life of I3C is about 2 hours.
Alternatives
There is no scientific evidence to support the use of I3C supplements for the prevention or treatment of cancer. If you’re interested in using natural substances to boost your health, speak to your doctor about safe and effective alternatives.
Long-term effects of I3C supplementation are unknown. More research is needed to determine whether I3C is safe for long-term use.
Some natural substances that have been studied for their anti-cancer effects include:
Curcumin: This compound is found in turmeric. Curcumin may help prevent the growth of cancer cells and promote cell death.
Green tea: Green tea contains compounds that may help inhibit the growth of cancer cells.
Resveratrol: This compound is found in grapes and red wine. Resveratrol may help prevent the growth of cancer cells.
Silymarin: This compound is found in milk thistle. Silymarin may help protect healthy cells from the damaging effects of chemotherapy.
Vitamin D: Vitamin D may help prevent the development of certain types of cancer.
Zinc: Zinc may help prevent the growth of cancer cells.