Product Information

Synonyms: I3C; 3-(Hydroxymethyl)indole; 3-indolylcarbinol; 3-indolylmethanol

Keywords: cancer, cervical dysplasia, leukemia, melanoma, herpes, Alzheimer’s, pregnancy


This article is a condensed version of Dr. Zarkov’s summary of medical research into I3C supplementation on the LifeLink website.

Indole-3-carbinol (I3C) is a substance that results from cooking or crushing certain plant foods — especially ‘cruciferous vegetables’, which include broccoli, brussels sprouts, and cauliflower. Enzymes in the plants convert certain biochemicals into I3C. Stomach acid converts I3C into other compounds (such as ‘DIM’), some of which have anti-cancer activity.

What we can’t tell you

In the U.S. and some other industrialized countries, government agencies like the U.S. Food and Drug Administration have adopted censorship as a method for intensifying their control over the supplement industry and its customers. Thus, FDA regulations prohibit us from telling you that any of our products are effective as medical treatments, even if they are, in fact, effective.

Accordingly, we will limit our discussion of Indole-3-carbinol to a brief summary of relevant research, and let you draw your own conclusions about what medical conditions it may be effective in treating.


For general information about I3C, we recommend the reviews by Rogan1, Thorne2, Stoewsand3, and Broadbent4,5. More specialized reviews are those by Aggarwal6, Shertzer7, and Kim8.


Interest in I3C as an anti-cancer agent dates back at least to the 1970s when it was shown that I3C inhibits the formation of breast cancer tumors in rats.11 Ethnic food studies soon showed that diets high in cruciferous vegetables are correlated with lower rates of breast cancer.10 Despite this promising beginning, the medical research community did not take a serious interest in I3C until the 1990s, when it became available as a nutritional supplement and women began to use it successfully to treat cervical dysplasia.

Other potential applications of I3C include the prevention or treatment of: • prostate cancer • melanoma • non-melanoma skin cancer • lung cancer • colon cancer • recurrent respiratory papillomatosis • herpes simplex • fetal cancer • Alzheimer’s • ovulation.

Cervical dysplasia, papillomatosis

Cervical dysplasia (CIN) is a precancerous condition caused by the Human Papilloma Virus. In 2000 a clinical trial revealed that 50% of patients who used I3C at 200 mg/day had a complete regression of CIN in 12 weeks or less.12

Recurrent respiratory papillomatosis (RRP) is the repeated growth of papillomas in the larynx and trachea. In a 1998 clinical trial of I3C, one-third of RRP patients saw their papillomas stop growing; another third experienced a reduction in growth rate.13

I3C and cancer

In the body, I3C and its metabolites regulate cell-signalling pathways, particularly those involving estrogens. Some of these pathways are involved in the development of tumors from precancerous cells.6 By disrupting the biochemistry of precancerous cells, I3C causes them to die before they can form tumors — and it does this without harming normal cells.14 I3C-sensitive cancers include those of the breast,15,9,11 prostate,16,17,18,19 cervix,20 endometrium,21 colon,22 ovaries,3 lung,23 white blood cells (leukemia),6 and skin (melanoma24, and UV-induced non-melanoma skin cancer25).

It was reported in 2001 that I3C inhibits the basic processes used by cancer cells to form new tumors by metastasis.27

Evidence from tissue culture experiments suggests that genistein (a nutritional supplement extracted from soybeans) works synergistically with I3C to kill cancer cells.21

Carcinogenic substances in the diet or environment during pregnancy can predispose the fetus to develop cancer many years later. Experiments in rats have shown that I3C, taken during pregnancy, provides substantial protection against such malignancies.28

Does I3C shrink existing tumors? Several experiments with high-dose I3C in fish and in rats led some researchers to believe that if I3C supplementation were delayed until after a tumor had already developed, the growth of that tumor might actually be accelerated by I3C.10,34,35,36,37 Other experiments, however, have shown that I3C can kill tumor cells, at least in certain tissues.14,26,37 Since no appropriate experiments have been done on real tumors in humans, the issue has not yet been resolved.

In summary, the available evidence suggests that an I3C supplement may:

  • eliminate a precancerous condition and prevent progression to cancer;2
  • inhibit the spread of existing tumors to other parts of the body;27
  • shrink existing tumors in some tissues (e.g. breast, cervix)14,26,37;
  • enlarge existing tumors in other tissues (especially the liver)37.
I3C and Herpes simplex (lip and genital herpes)

A tissue culture experiment in 2003 showed that I3C can cause a 100% inhibition of the Herpes simplex virus.29,2

I3C prevents ovulation

I3C has anti-ovulatory properties, as was shown in rats in 2002.30 Regular I3C supplementation could be a useful back-up for one’s regular anti-pregnancy method.

Protection against toxic substances

The body produces many enzymes that inactivate substances that would be toxic if their concentrations became too high. I3C induces the production of such enzymes.31

I3C and Alzheimer’s Disease

A hallmark of Alzheimer’s Disease is the formation of protein tangles called ‘amyloid fibrils’ in nerve cells of the brain. These tangles disrupt the structure of the nerve cells and also collect metal ions which, in turn, promote the production of free radicals that damage and kill nerve cells. Recent Alzheimer’s research has identified I3C as a substance that inhibits the formation of amyloid fibrils.32


Most clinical work with I3C uses dosages from 200 mg/day to 400 mg/day.2 The optimum dosage for breast cancer effects is thought to be 400 mg/day.33

Why take I3C as a supplement when you could instead just eat lots of broccoli or other cruciferous vegetables? There are two reasons: first, the vegetables contain many alkaloidal substances, some of them harmful; second, you have no way of knowing whether a given serving of a vegetable has a lot or only a little of the I3C-related substances you are trying to consume. Supplement capsules solve both of these problems.


Are Indole-3-carbinol supplements useful for the conditions and purposes mentioned above? We aren’t allowed to tell you, so you should take a look at some of the references cited here, and then decide for yourself.

30050 200 mg 60 capsules 1-2 capsules $30.95
(12% off!)

Pronunciation: indole ınʹ·dol, carbinol kărʹ·bē·nol

— RM

Last modified 2010.09.01