Iodine

Are you a health professional?

This section does not replicate the other information on this topic but provides additional details or context most relevant to professionals.

Modes of action

Dietary iodide deficiency and intracellular iodide deficiency caused by mislocalization of the sodium/iodine symporter (NIS) may play a role in the carcinogenesis of thyroid cancer and breast cancer. Sex hormones may contribute to the disparities in thyroid cancer incidence between males and females.¹Dong L, Lu J, Zhao B, Wang W, Zhao Y. Review of the possible association between thyroid and breast carcinoma. World Journal of Surgical Oncology. 2018;16(1):130. Dietary iodine insufficiency also represents a plausible explanation for the increasing incidence of breast cancer in young women with distant metastasis.²Rappaport J. Changes in dietary iodine explains increasing incidence of breast cancer with distant involvement in young women. Journal of Cancer. 2017 Jan 13;8(2):174-177. Testing of Iodine levels may be an important aspect of medical management for young women of childbearing age.

Iodine is an antioxidant and antiproliferative agent contributing to the integrity of normal mammary gland. The review authors recommend consideration of iodine supplementation as an adjuvant therapy.³Aceves C, Anguiano B, Delgado G. Is iodine a gatekeeper of the integrity of the mammary gland? Journal of Mammary Gland Biology and Neoplasia. 2005;10(2):189–196. Molecular iodine’s inhibition of the growth of human breast cancer cells may be through formation of 6-IL.⁴Nuñez-Anita RE, Arroyo-Helguera O, Cajero-Juárez M, López-Bojorquez L, Aceves C. A complex between 6-iodolactone and the peroxisome proliferator-activated receptor type gamma may mediate the antineoplastic effect of iodine in mammary cancer. Prostaglandins & Other Lipid Mediators. 2009;89(1-2):34–42.

On the other hand, iodine acts as an ER-α agonist in stimulation of ER-α transcriptional activity and ER-α mediated growth of breast cancer cells.⁵He S, Wang B et al. Iodine stimulates estrogen receptor singling and its systemic level is increased in surgical patients due to topical absorption. Oncotarget. 2017 Sep 4;9(1):375-384.

Preclinical evidence

Notable preclinical evidence is presented here; clinical evidence is listed in How can iodine help you? What the research says ›

Improving treatment outcomes

Breast cancer

• Iodine and iodide show antiproliferative effects in some breast cancer cell lines and animal models.⁶Stoddard FR 2nd, Brooks AD, Eskin BA, Johannes GJ. Iodine alters gene expression in the MCF7 breast cancer cell line: evidence for an anti-estrogen effect of iodine. International Journal of Medical Sciences. 2008;5(4):189–196; Arroyo-Helguera O, Rojas E, Delgado G, Aceves C. Signaling pathways involved in the antiproliferative effect of molecular iodine in normal and tumoral breast cells: evidence that 6-iodolactone mediates apoptotic effects. Endocrine-Related Cancer. 2008;15(4):1003–1011; Arroyo-Helguera O, Anguiano B, Delgado G, Aceves C. Uptake and antiproliferative effect of molecular iodine in the MCF-7 breast cancer cell line. Endocrine-related Cancer. 2006 Dec;13(4):1147-58; García-Solís P, Alfaro Y et al. Inhibition of N-methyl-N-nitrosourea-induced mammary carcinogenesis by molecular iodine (I2) but not by iodide (I-) treatment Evidence that I2 prevents cancer promotion. Molecular and Cellular Endocrinology. 2005 May 31;236(1-2):49-57.
• Anticancer effects in a triple negative basal cancer cell line⁷Mendieta I, Nuñez-Anita RE et al. Molecular iodine exerts antineoplastic effects by diminishing proliferation and invasive potential and activating the immune response in mammary cancer xenografts. BMC Cancer. 2019;19(1):261.
• Molecular iodine (I₂) is able to reduce the drug resistance and invasive capacity of mammary cancer cells exposed to doxorubicin.⁸Bontempo A, Ugalde-Villanueva B, Delgado-González E, Rodríguez ÁL, Aceves C. Molecular iodine impairs chemoresistance mechanisms, enhances doxorubicin retention and induces downregulation of the CD44+/CD24+ and E-cadherin+/vimentin+ subpopulations in MCF-7 cells resistant to low doses of doxorubicin. Oncology Reports. 2017;38(5):2867–2876. 
• Zoledronate and molecular iodine used together have increased anticancer effects against triple negative breast cancer cells.⁹Tripathi R, Singh P et al. Zoledronate and molecular iodine cause synergistic cell death in triple negative breast cancer through endoplasmic reticulum stress. Nutrition and Cancer. 2016;68(4):679–688.
• Iodine (I₂) used with doxorubicin exerts antineoplastic, chemosensitivity, and cardioprotective effects in animal models of breast cancer.¹⁰Alfaro Y, Delgado G, Cárabez A, Anguiano B, Aceves C. Iodine and doxorubicin, a good combination for mammary cancer treatment: antineoplastic adjuvancy, chemoresistance inhibition, and cardioprotection. Molecular Cancer. 2013 May 24;12:45. 

Prostate cancer

• Both iodide (I−) and iodine (I₂) show anticancer effects in prostate cancer cells.¹¹Aranda N, Sosa S, Delgado G, Aceves C, Anguiano B. Uptake and antitumoral effects of iodine and 6-iodolactone in differentiated and undifferentiated human prostate cancer cell lines. Prostate. 2013;73(1):31–41.

Helpful links for professionals