In this Indole-3-Carbinol review, we will give you an overview of what this supplement is, how it works, some of the purported health benefits associated with its use and possible dangers.
Clinical and scientific research into indole-3-carbinol (I3C) has increased as the plant nutrient is being investigated for its possible anti-cancer properties.
I3C is a phytonutrient contained in cruciferous vegetables from the Brassica botanical genus. Examples of these vegetables include kale, watercress, kohlrabi, rapeseed, mustard greens, cabbage, broccoli and Brussels sprouts.
In addition to crucifers, some root vegetables like horseradish and turnip also contain high levels of I3C. The average human diet contains up to 120 mg of I3C per day, but these levels vary widely according to culture and individual diet.
I3C supplements are also available for those who wish to increase their intake of this supplement. According to user reviews, Indole-3-carbinol supplements are commonly taken for weight loss, hormone balance, hot flashes, acne, PMS symptoms, bodybuilding, post-cycle therapy for steroid users and more.
This supplement is also being reviewed by researchers for its potential to reduce the risk of developing certain cancers.
It may also have therapeutic value for other conditions, such as recurrent respiratory papillomatosis, herpes, HPV and lupus.
Although research is ongoing, I3C has not been proven to treat, cure or prevent any disease. While it exhibits beneficial effects, it has not been approved by the FDA for the treatment of any health condition.



- Supports healthy estrogen metabolism
- Improve hormone balance & fat burning
- Promotes liver detoxification
Indole-3-Carbinol Review
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On its own, indole-3-carbinol does not exhibit therapeutic effects.
When the molecule is consumed and comes in contact with stomach acid, it gets converted into diindolylmethane (DIM).
This is the active compound which is being investigated for its capacity to combat various cancer cell lines.
As a constituent of plant cells, I3C remains in the form of 3-indolylmethyl glucosinolate.
When the cells of the plant are broken apart by chewing or cutting, an enzyme called myrosinase is released.
This enzyme converts 3-indolylmethyl glucosinolate into indole-3-carbinol.
In this form, it is still an inactive substance. However, when it reaches the stomach, digestive enzymes convert I3C into the metabolites DIM or indolylcarbazole.
Because I3C needs to be exposed to the stomach’s digestive enzymes to form active metabolites, I3C produces no effects when taken intravenously or via any other method that does not involve it passing through the digestive tract.
Review of I3C Effects
Researchers are looking into indole-3-carbinol as a preventative agent for breast, colon, cervical, endometrial and other cancers. This interest stems from the observation that individuals who consume a diet high in cruciferous vegetables are less likely to develop certain cancers, particularly estrogen-sensitive cancers.
Research indicates that I3C affects the liver’s metabolism of some substances, including estrogens.
Estradiol is an estrogen sex hormone found in both women and men, with significantly higher level in women. In the liver, it gets metabolized into either 16-alpha-hydroxysestrone or 2-alpha-hydroxyestrone.
These are two types of “estrogen metabolites”, but they exhibit very different effects in the body. 16-alpha-hydroxysestrone is the more active metabolite and is sometimes called “bad estrogen”. Its presence in the body is linked to an increased risk of hormone-sensitive conditions and cancers, including breast cancer.
2-alpha-hydroxyestrone is the less active metabolite and is sometimes called “good estrogen.” It is not linked to the development of cancer.
Because it competes with “bad estrogen” for the same receptor binding sites in the body, it can exhibit a protective effect against hormone-sensitive conditions.
Research reviews of I3C show that this supplement increases the production of “good estrogen” and lowers the production of “bad estrogen” within the liver. This molecule has been observed to increase certain liver enzymes, particularly the P450 cytochrome enzymes.
By increasing these enzymes, I3C causes the liver to convert more Estradiol into 2-alpha-hydroxyestrone than 16-alpha-hydroxysestrone.
Top I3C Uses
Due to its regulatory effects on estrogen levels, I3C is a popular supplement for women. But it can also offer benefits for men.
User reviews show that this supplement is commonly taken for acne, weight loss, bodybuilding, PMS, menopause and a number of other diverse uses.
All of these areas of human health can be affected by hormone balance in the body.
In women, excess estrogen is linked to weight gain, acne and painful periods. Using an I3C supplement may normalize estrogen levels and alleviate some of these conditions.
In men, estrogen is also linked to weight gain, low energy, low libido and possibly gynecomastia (or male breast formation). According to I3C and DIM reviews, these supplements are often used by men who want to improve their testosterone to estrogen balance in the body.
I3C has been shown to inhibit the aromatase enzyme which converts testosterone into estrogen in both men and women. By inhibiting this enzyme, this supplement may allow for naturally higher levels of testosterone and lower estrogen levels in some men.
This increase in testosterone can support improved energy levels, sex drive and sexual function, muscle building and strength. Some male bodybuilders also take I3C and DIM as part of a “Post-Cycle Therapy” following steroid use or testosterone therapy.
Additional Uses of I3C
Another areas of interest for I3C users is as a detoxification aid. According to research reviews, I3C induces Phase II enzymatic reactions in the liver.
This is part of how your body detoxifies itself and clears toxins out of the liver. Phase II metabolism in the liver involves increasing the water solubility of toxins and excreting these compounds from the body.
There is also some indication that I3C increases apoptosis (cell death) and cell cycle arrest in tumor cells. Evidence suggests that I3C may be an effective anti-cancer agent. However, there is a small amount of data that correlates I3C with increases in carcinogenicity.
Research also suggests this molecule may help support cardiovascular function. I3C has been observed to lower LDL (bad) cholesterol, raise HDL (good) cholesterol, lower triglycerides (stored fats) and improve glucose uptake.
Because of these characteristics, I3C may help lower the risk of developing some health conditions. However, these observations have been made in laboratory and animal experiments and it is unclear if the same effect will occur in humans.
I3C Dose Guide
Natural Medicines notes that I3C is likely safe for healthy individuals in amounts commonly consumed through the diet, which range between 20 and 120 mg per day.
Natural Medicines has rated doses between 120 and 200 mg per day as possibly safe for periods of up to 15 months.
Higher doses, between 200 and 400 mg per day, have been used for periods of up to three months. Daily doses above 400 mg have been associated with tremors, disequilibrium and other serious side effects.
Because I3C affects how the liver metabolizes (breaks down) certain medicines and herbal products, there may be drug interactions. The effects and side effects of these substances may be either intensified or weakened.
For this reason, it is very important to speak with your doctor before starting to supplement your diet with I3C. Although reviews of I3C show that it is generally well tolerated, it may cause adverse effects in some individuals.
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Article last updated on: April 8th, 2018 by Nootriment