Indole-3-Carbinol

What is it?

Indole-3-carbinol is one of the major anticancer substances found in cruciferous (cabbage family) vegetables. It is a member of the class of sulphur-containing chemicals called glucosinolates.¹ It is formed from parent compounds whenever cruciferous vegetables are crushed or cooked.² ³

Indole-3-carbinol and other glucosinolates (e.g., other indoles and isothiocyanates such as sulforaphane) are antioxidants and potent stimulators of natural detoxifying enzymes in the body.⁴ ⁵ Indole-3-carbinol and other glucosinolates are believed to be responsible for the lowered risk of cancer in humans that is associated with the consumption of broccoli and other cruciferous vegetables like cauliflower, cabbage, andkale.⁶ ⁷ ⁸ ⁹ ¹⁰ ¹¹ ¹²

Feeding indole-3-carbinol or broccoli extracts rich in indole-3-carbinol has dramatically reduced the frequency, size, and number of tumours in laboratory rats exposed to a carcinogen. It appears to be especially protective against breast¹³ ¹⁴ ¹⁵ ¹⁶ and cervical¹⁷ ¹⁸ cancers because of a number of actions, including an ability to increase the breakdown of oestrogen. However, while most animal studies report protective effects, a few indicate that indole-3-carbinol may actually promote cancer formation in certain situations, depending upon the chemical initiator of cancer, method of exposure, and species of animal studied.¹⁹ ²⁰

Until there is further research and more human clinical data to determine if indole-3-carbinol actually inhibits rather than stimulates cancer formation, some researchers have recommended proceeding with caution when using isolated indole-3-carbinol as a dietary supplement.²¹ The areas where its use has currently been documented in humans are only preliminary, but the results are promising. Indole-3-carbinol reduced or halted the formation of precancerous lesions (papillomas) in 12 out of 18 people with recurrent respiratory tract papillomas.²² In addition, in a small double-blind trial, supplementation with 200 or 400 mg of indole-3-carbinol per day for 12 weeks reversed early-stage cervical cancer in 8 of 17 women.²³ Preliminary studies have also shown indole-3-carbinol has significantly increased the conversion of oestrogen from cancer-producing forms to nontoxic breakdown products.²⁴ ²⁵

Where is it found?

Indole-3-carbinol is found in highest concentrations in broccoli, but is also found in other cruciferous vegetables, such as cauliflower, cabbage, and kale.

Indole-3-carbinol has been used in connection with the following conditions (refer to the individual health concern for complete information):

Science Ratings	Health Concerns
	Cancer prevention (cervical cancer)
Reliable and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit. For a herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

Who is likely to be deficient?

As indole-3-carbinol is not an essential nutrient, no deficiency state exists.

How much is usually taken?

Based upon preliminary studies it is estimated that the minimum amount required for the prevention of breast cancer is 300 to 400 mg daily.²⁶

Are there any side effects or interactions?

No side effects from indole-3-carbinol have been reported.

At the time of writing, there were no well-known drug interactions with indole-3-carbinol.

References
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1. Stoewsand GS. Bioactive organosulfur phytochemicals in Brassica oleracea vegetables—a review. Food Chem Toxicol 1995;33:537–43.

2. Broadbent TA, Broadbent HS. The chemistry and pharmacology of indole-3-carbinol (indole-3-methanol) and 3-(methoxymethyl)indole. [Part I]. Curr Med Chem 1998;5:337–52.

3. Broadbent TA, Broadbent HS. The chemistry and pharmacology of indole-3-carbinol (indole-3-methanol) and 3-(methoxymethyl)indole. [Part II]. Curr Med Chem 1998;5:469–91.

4. Broadbent TA, Broadbent HS. The chemistry and pharmacology of indole-3-carbinol (indole-3-methanol) and 3-(methoxymethyl)indole. [Part I]. Curr Med Chem 1998;5:337–52.

5. Broadbent TA, Broadbent HS. The chemistry and pharmacology of indole-3-carbinol (indole-3-methanol) and 3-(methoxymethyl)indole. [Part II]. Curr Med Chem 1998;5:469–91.

6. Hecht SS. Chemoprevention of cancer by isothiocyanates, modifiers of carcinogen metabolism. J Nutr 1999;129:768S–74S [review].

7. Verhoeven DT, Goldbohm RA, van Poppel G, et al. A review of mechanisms underlying anticarcinogenicity by brassica vegetables. Chem Biol Interact 1997;103:79–129 [review].

8. Verhoeven DT, Goldbohm RA, van Poppel G, et al. Epidemiological studies on brassica vegetables and cancer risk. Cancer Epidemiol Biomarkers Prev 1996;5:733–48 [review].

9. Talalay P, Zhang Y. Chemoprotection against cancer by isothiocyanates and glucosinolates. Biochem Soc Trans 1996;24:806–10.

10. Maheo K, Morel F, Langouet S, et al. Inhibition of cytochromes P-450 and induction of glutathione S- transferases by sulforaphane in primary human and rat hepatocytes. Cancer Res 1997;57:3649–52.

11. Barcelo S, Gardiner JM, Gescher A, Chipman JK. CYP2E1-mediated mechanism of anti-genotoxicity of the broccoli constituent sulforaphane. Carcinogenesis 1996;17:277–82.

12. Plumb GW, Lambert N, Chambers SJ, et al. Are whole extracts and purified glucosinolates from cruciferous vegetables antioxidants? Free Radic Res 1996;25:75–86.

13. Bradlow HL, Sepkovic DW, Telang NT, Osborne MP. Multifunctional aspects of the action of indole-3-carbinol as an antitumor agent. Ann N Y Acad Sci 1999;889:204–13.

14. Bradlow HL, Sepkovic DW, Telang NT, Osborne MP. Indole-3-carbinol. A novel approach to breast cancer prevention. Ann N Y Acad Sci 1995;768:180–200.

15. Bradlow HL, Sepkovic DW, Telang NT, Osborne MP. Multifunctional aspects of the action of indole-3-carbinol as an antitumor agent. Ann N Y Acad Sci 1999;889:204–13.

16. Meng Q, Qi M, Chen DZ, et al. Suppression of breast cancer invasion and migration by indole-3-carbinol: associated with up-regulation of BRCA1 and E-cadherin/catenin complexes. J Mol Med 2000;78:155–65.

17. Yuan F, Chen DZ, Liu K, et al. Anti-estrogenic activities of indole-3-carbinol in cervical cells: implication for prevention of cervical cancer. Anticancer Res 1999;19(3A):1673–80.

18. Jin L, Qi M, Chen DZ, et al. Indole-3-carbinol prevents cervical cancer in human papilloma virus type 16 (HPV16) transgenic mice. Cancer Res 1999;59:3991–7.

19. Oganesian A, Hendricks JD, Pereira CB, et al. Potency of dietary indole-3-carbinol as a promoter of aflatoxin B1-initiated hepatocarcinogenesis: results from a 9000 animal tumor study. Carcinogenesis 1999;20:453–8.

20. Kim DJ, Han BS, Ahn B, et al. Enhancement by indole-3-carbinol of liver and thyroid gland neoplastic development in a rat medium-term multiorgan carcinogenesis model. Carcinogenesis 1997;18:377–81.

21. Dashwood RH. Indole-3-carbinol: anticarcinogen or tumor promoter in brassica vegetables? Chem Biol Interact 1998;110:1–5 [review].

22. Rosen CA, Woodson GE, Thompson JW, et al. Preliminary results of the use of indole-3-carbinol for recurrent respiratory papillomatosis. Otolaryngol Head Neck Surg 1998;118:810–5.

23. Bell MC, Crowley-Nowick P, Bradlow HL, et al. Placebo-controlled trial of indole-3-carbinol in the treatment of CIN. Gynecol Oncol 2000;78:123–9.

24. Michnovicz JJ. Increased estrogen 2-hydroxylation in obese women using oral indole-3-carbinol. Int J Obes Relat Metab Disord 1998;22:227–9.

25. Bradlow HL, Michnovicz JJ, Halper M, et al. Long-term responses of women to indole-3-carbinol or a high fiber diet. Cancer Epidemiol Biomarkers Prev 1994;3:591–5.

26. Wong GY, Bradlow L, Sepkovic D, et al. Dose-ranging study of indole-3-carbinol for breast cancer prevention. J Cell Biochem Suppl 1997;28–29:111–6.

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires March 2007.

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