Indole-3-Carbinol I3C by NSI - Nutraceutical Sciences Institute

POSSIBLY EFFECTIVE

• Colorectal cancer. Consumption of cruciferous vegetables, including broccoli, seems to reduce the risk of developing colorectal cancer. Details: Epidemiological research has found that the highest intakes of cruciferous vegetables, including broccoli, are associated with an 18% to 20% reduced risk of developing colorectal neoplasms when compared with the lowest intakes (14148,96187,96189).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Bladder cancer. It is unclear if consumption of broccoli reduces the risk of developing bladder cancer. Details: Epidemiologic research has found that eating about 1.75 cups daily of cruciferous vegetables, such as broccoli or cabbage, is associated with a 30% reduced risk of developing bladder cancer (14864).
• Breast cancer. It is unclear if consumption of broccoli reduces the risk of developing breast cancer. Details: Epidemiological research has found that consumption of broccoli is associated with a modestly reduced risk of developing breast cancer in premenopausal adults. However, broccoli consumption does not seem to be associated with breast cancer risk in postmenopausal adults (14146).
• Fibromyalgia. Broccoli has only been evaluated in combination with ascorbigen; its effect when used alone is unclear. Details: A small clinical study in females with fibromyalgia shows that taking one capsule containing ascorbigen 100 mg and broccoli powder 400 mg once daily for one month improves pain by 18% and reduces physical impairment by 20% when compared with baseline (19605). It is unclear if this effect is due to broccoli, ascorbigen, or the combination. The validity of these findings is limited by the lack of a comparator group.
• Gastric cancer. It is unclear if consumption of broccoli reduces the risk of developing gastric cancer. Details: A small epidemiological study has found that higher consumption of broccoli is associated with a reduced risk of developing gastric cancer when compared with lower consumption (14148).
• Hypercholesterolemia. Broccoli has only been evaluated in combination with cabbage; its effect when used alone is unclear. Details: A small clinical study in patients with mild to moderate hypercholesterolemia shows that consuming 160 grams of a beverage containing broccoli, cabbage, and fruit twice daily for 12 weeks reduces levels of low-density lipoprotein (LDL) cholesterol by 8.5% when compared with baseline. It is unclear if the improvement from baseline differed when compared with those consuming a similar beverage without broccoli and cabbage (19607). It is unclear if this effect is due to broccoli, cabbage, or the combination.
• Prostate cancer. It is unclear if consumption of broccoli reduces the risk of developing prostate cancer; the available research is conflicting. In patients with prostate cancer, broccoli has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Some epidemiological research has found that consumption of Brassica vegetables, such as broccoli, Brussels sprouts, cauliflower, and cabbage, is associated with a reduced risk of developing prostate cancer (14145). However, other epidemiological research has found no association (14147,15172). Clinical research in adults with prostate cancer shows that taking a whole food formulation containing broccoli powder 100 mg, turmeric powder 100 mg, pomegranate whole fruit powder 100 mg, and green tea extract 20 mg three times daily for 6 months prevents an increase in prostate specific antigen (PSA) levels. Mean PSA levels increased by 15% in the whole food formulation group, compared with 79% in the placebo group. Also, 46% of those taking the whole food formulation showed final PSA levels that were the same or lower than initial PSA levels, compared with 14% of those in the placebo group (89730). However, it is not yet known whether the whole food formulation reduces the risk of prostate cancer progression or recurrence. It is unclear if these effects are due to broccoli, other ingredients, or the combination. More evidence is needed to rate broccoli for these uses.

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INSUFFICIENT RELIABLE EVIDENCE to RATE

• Breast cancer. Although there has been interest in using oral indole-3-carbinol for breast cancer, there is insufficient reliable information about the clinical effects of indole-3-carbinol for this purpose.
• Cervical dysplasia. It is unclear if oral indole-3-carbinol is beneficial in patients with cervical dysplasia. Details: Preliminary clinical research shows that taking indole-3-carbinol 200-400 mg orally daily for 12 weeks is associated with complete regression of precancerous lesions in 45% to 50% of women with grade II or III, biopsy-proven cervical intraepithelial neoplasia (CIN, cervical dysplasia), the majority of whom are positive for human papilloma virus (HPV) infection (7173).
• Colorectal cancer. Although there has been interest in using oral indole-3-carbinol for colorectal cancer, there is insufficient reliable information about the clinical effects of indole-3-carbinol for this purpose.
• Fibromyalgia. Although there has been interest in using oral indole-3-carbinol for fibromyalgia, there is insufficient reliable information about the clinical effects of indole-3-carbinol for this purpose.
• Liver disease. Although there has been interest in using oral indole-3-carbinol for liver disease, there is insufficient reliable information about the clinical effects of indole-3-carbinol for this purpose.
• Nonmelanoma skin cancer. It is unclear if oral indole-3-carbinol is beneficial in patients with nonmelanoma skin cancer. Details: Preliminary clinical research in patients with vulvar intraepithelial neoplasia (VIN), a precancerous condition that can progress to squamous cell carcinoma, shows that taking indole-3-carbinol 200 mg or 400 mg daily for 6 months improves symptoms and reduces lesion size and severity when compared with baseline. However, tissue biopsies taken from the women with the most severely affected areas did not show any improvement in grade of VIN (93241). The validity of this finding is limited by the small study size and lack of a comparator group. Additionally, it is unclear if treatment with indole-3-carbinol reduces the risk of progression to cancer.
• Ovarian cancer. It is unclear if oral indole-3-carbinol is beneficial in patients with ovarian cancer. Details: Preliminary clinical research in patients with previously untreated stage III-IV ovarian cancer shows that taking indole-3-carbinol 200 mg orally twice daily with or without epigallocatechechin-3-gallate (EGCG) 200 mg twice daily, in conjunction with neoadjuvant chemotherapy and surgery, increases median overall survival and progression-free survival by 16 and 18 months, respectively, when compared with chemotherapy and surgery alone. The addition of indole-3-carbonol with or without EGCG also reduced the tumor recurrence rate by about 16% when compared with chemotherapy and surgery alone (98610).
• Recurrent respiratory papillomatosis. It is unclear if oral indole-3-carbinol is beneficial in patients with recurrent respiratory papillomatosis. Details: Preliminary clinical evidence shows that taking indole-3-carbinol 200 mg twice daily for a mean of 57.6 months (range 31 months to 76 months) after complete surgical removal of respiratory papillomas stops regrowth in about a third of patients and slows regrowth, reducing the need for repeated surgery, in another third (7172,47645,93239).
• Systemic lupus erythematosus (SLE). It is unclear if oral indole-3-carbinol is beneficial in patients with SLE. Details: Preliminary clinical research shows that taking indole-3-carbinol 125 mg orally three times daily for 3 months does not significantly decrease disease activity when compared with baseline in women aged 20-49 years with SLE (93240). More evidence is needed to rate indole-3-carbinol for these uses.

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LIKELY SAFE ...when used orally in food amounts (14145). There is insufficient reliable information available about the safety of broccoli when used in medicinal amounts.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in food amounts (14145). There is insufficient reliable information available about the safety of broccoli when used in medicinal amounts during pregnancy and lactation; avoid using.

(Read more about BROCCOLI)

POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts. Doses up to 400 mg daily have been used safely for 3-76 months (7173,93239,93240,93241). There is also some evidence that 400 mg twice daily can be used safely for 4 weeks (93242).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately in medicinal amounts. There is limited evidence from 9 children with recurrent respiratory papillomatosis that indole-3-carbinol can be safely used in children ages 1.2-16 years for 12-76 months at doses of 6-17 mg/kg of body weight daily (7172,93239).

PREGNANCY AND LACTATION:
There is insufficient reliable information available about the safety of indole-3-carbinol when used during pregnancy and lactation; avoid using.

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CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, broccoli might reduce the levels and effects of drugs metabolized by CYP1A2.  Details Pharmacokinetic research in humans shows that eating 500 grams of fresh broccoli daily for 6-12 days can increase CYP1A2 activity by 10% to 200% (19608,95722). Induction of CYP1A2 activity by broccoli is attributed to its glucosinolate constituents (19608).

CYTOCHROME P450 2A6 (CYP2A6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, broccoli might reduce the levels and effects of drugs metabolized by CYP2A6.  Details Pharmacokinetic research in humans shows that eating 500 grams of broccoli daily for 6 days increases CYP2A6 activity by 135% to 550%. Induction of CYP2A6 activity is attributed to its glucosinolate constituents (19608).

(Read more about BROCCOLI)

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, indole-3-carbinol might increase the risk of bleeding when used with antiplatelet or anticoagulant drugs.  Details In vitro research shows that indole-3-carbinol inhibits platelet aggregation (98611).

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, indole-3-carbinol might increase the metabolism of CYP1A2 substrates and lower serum concentrations.  Details Animal research shows that indole-3-carbinol induces CYP1A2 enzymes (7187).

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Indole-3-carbinol might interfere with the effects of estrogen therapy.  Details Preliminary clinical and in vitro evidence shows that indole-3-carbinol has antiestrogenic activity (7173,47621,93238,93240).

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General ...Broccoli is well tolerated when consumed as food. A thorough evaluation of safety outcomes when broccoli is taken as medicine has not been conducted.

Dermatologic ...Topically, allergic reactions to broccoli have caused contact dermatitis (14158).

Hepatic ...In one case report, a 56-year-old adult developed elevated transaminases, with alanine aminotransferase (ALT) 5. 8 times above normal, aspartate aminotransferase (AST) 2.4 times above normal, and gamma-glutamyl transpeptidase (GGT) 5.1 times above normal. This was thought to be related to the consumption of 800 mL of broccoli juice daily over a 4-week period. Values returned to normal 15 days after cessation of juice consumption (96191).

Immunologic ...Topically, allergic reactions to broccoli have caused contact dermatitis (14158).

(Read more about BROCCOLI)

General ...Orally, indole-3-carbinol seems to be well tolerated.
Most Common Adverse Effects:
Orally: Diarrhea, imbalance, nausea, rash, tremor, unsteadiness.

Dermatologic ...Orally, indole-3-carbinol has been associated with reports of rash (93242). A woman taking indole-3-carbinol 375 mg daily for treatment of systemic lupus erythematosus (SLE) developed a generalized maculopapular rash which resolved when indole-3-carbinol was discontinued and recurred when it was restarted (93240).

Gastrointestinal ...Orally, indole-3-carbinol increases gastrointestinal motility and has been associated with diarrhea (93242,93243).

Neurologic/CNS ...Indole-3-carbinol has been associated with reports of unsteadiness and imbalance, especially at higher doses (7172). An adult male taking 400 mg twice daily for treatment of recurrent respiratory papillomatosis developed imbalance and tremor after 10 days of treatment. This resolved when the dose was halved (93238). Two children who took 3 times the intended weight-based dose of indole-3-carbinol in one day developed unsteadiness and nausea (93238).

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