Indole-3-Carbinol (I3C) Uses, Research and Safety

Indole-3-carbinol (I3C) is a sulphur-containing phytonutrient found in cruciferous vegetables, such as broccoli, cabbage, kale, Brussels sprouts and cauliflower.

The average person consumes between 20 and 120 mg of I3C per day in their diet.

The phytonutrient can also be synthesized and is being researched for its effects on certain cancers. Researchers have observed that people with a diet high in fruits and vegetables are less likely to develop some cancers.

They are looking into vegetable constituents – like I3C – as a possible explanation. I3C is a glucosinolate that is synthesized via the enzymatic breakdown (hydrolysis) of glucobrassicin (indole glucosinolate).

It is a precursor of diindolylmethane (DIM), and, like DIM, it has been observed to exhibit effects that may be useful in cancer prevention and treatment.

Besides its potential anticancer actions, indole-3-carbinol has been observed to exhibit antioxidant, hepatoprotective and immunomodulatory effects.

Taken orally, I3C is used for the prevention of various cancers, fibromyalgia, systemic lupus, laryngeal papillomatosis, hormonal imbalances, cervical dysplasia and more. It may help detoxify the liver and kidneys and help improve immune system function.

More randomized, double-blind human studies are required to discern the precise therapeutic benefits of I3C. The National Institutes of Health in the United States is currently sponsoring research programs to explore the therapeutic potential of I3C.

I3C (Indole-3-Carbinol)

Hormone Supplement

Hormone Balance

Weight Loss

Liver Health

How It Works:

• Supports healthy estrogen metabolism
• Improve hormone balance & fat burning
• Promotes liver detoxification

Dosage:

Between 200 - 400 mg per day

Safety:

Rated Possibly Safe

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What is Indole-3-Carbinol?

I3C is ingested through the diet, but it is not this molecule itself that brings about the possible health benefits.

During the process of digestion, individual I3C molecules may bind together to form acid condensation products that are biologically active.

The most important of these condensation products is called diindolylmethane (DIM).

In animal tests, both DIM and I3C have inhibited the onset of cancer when administered prior to, or at the same time as, carcinogens were introduced.

Clinical results concerning the antitumor and chemopreventive effects of I3C are somewhat contradictory.

Although some results are promising, supplementing with I3C to prevent or cure cancer is not approved by the FDA. Research is ongoing to establish both the possible benefits and risks of I3C supplementation.

Other Uses of I3C and DIM

I3C and DIM are also used to support weight loss and as bodybuilding supplements. These compounds have been observed to improve hormone balance. They are reported to work by preventing estrogen levels from becoming too high or too low.

I3C may also support higher testosterone levels in some cases. This could promote fat loss and muscle building as a component in the appropriate diet and workout regimen.

DIM and/or I3C have been observed to alter estrogen metabolite concentrations in female urine samples. Researchers hypothesize that by affecting estrogen balance, indole-3-carbinol and diindolylmethane may be useful in preventing and/or curing various hormone-sensitive conditions.

Results from small-scale, preliminary human trials suggest that supplementation with I3C is useful for conditions associated with HPV (human papillomavirus) infections, including RRP (recurrent respiratory papillomatosis) and CIN (cervical intraepithelial neoplasia). It is also used to alleviate some symptoms of PMS and menopause in women.

More research is required before any definitive claims can be made.

Clinical Proof for Indole-3-Carbinol

In most cases, the therapeutic effects of I3C are unsubstantiated and under active investigation. The only available clinical evidence for the effectiveness of I3C as a therapeutic agent concerns the treatment of cervical intraepithelial neoplasia (CIN).

When used daily for periods up to 12 weeks, I3C supplementation has been observed to cause complete regression of CIN in roughly 50 percent of subjects diagnosed with either stage-II or stage-III CIN.

Research suggests that doses of 200 mg per day may be as effective as doses of 400 mg per day.

For the prevention of breast cancer, 300 mg of I3C taken orally each day has been used. For treating recurrent respiratory papillomatosis, twice-daily doses of 200 mg have been used.

Again, although these doses have been used, there is insufficient evidence to connect I3C consumption with the prevention or treatment of any disease.

Safety and Side Effects of I3C Supplementation

Natural Medicines describes indole-3-carbinol as likely safe when taken orally in amounts between 20 mg and 120 mg daily, the amount commonly consumed in one’s daily diet.

Some evidence suggests that daily doses between 100 mg and 200 mg are safe for up to 15 consecutive months.

I3C doses between 200 and 400 mg per day have been used for up to three months without severe side effects.

In children aged two to twelve, indole-3-carbinol supplementation may be safe in daily doses of up to 200 mg, depending on the child’s weight. These dose levels have been monitored for up to 15 months.

Natural Medicines notes that I3C is likely safe for women who are pregnant and/or nursing, provided consumption does not exceed what is commonly consumed in one’s diet.

Indole-3-carbinol is generally well tolerated, especially at levels commonly consumed in the diet. At medicinal levels, I3C may cause temporary and mild skin rashes. Also, small increases of alanine aminotransferase (a liver enzyme) may occur.

With doses exceeding 400 mg daily, nausea, tremors and symptoms of disequilibrium may occur.

Also, there is some concern that I3C may promote tumorigenesis in patients who are exposed to certain carcinogenic agents during tumor induction initiation phases. This has not been observed in any human subjects.

To date, no negative interactions between indole-3-carbinol and pharmaceutical drugs have been observed. Also, no interactions have been noted between I3C and herbals products or other foodstuffs. However, it is possible for I3C to increase the activity of the CYP1A2 liver enzyme.

This may in alter the metabolism of medications and herbal products that are broken down by this enzyme. Also, I3C and DIM have both been observed to affect the levels of the enzyme CYP3A4 in the liver. CYP3A4 is necessary for the metabolism of approximately half of all prescribed medications.

Be sure to speak with your doctor before taking I3C to make sure the supplement is safe for you, given your unique medical history.

Conclusions about Indole-3-Carbinol

DIM and its precursor, I3C, are both under clinical investigation as possible anticancer agents. They have shown action against various cancer cell lines in laboratory experiments.

Also, they are known to improve some conditions associated with the imbalance of estrogen. Indole-3-carbinol, like DIM, is under active investigation to better understand what, if any, therapeutic benefits it can confer.

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