Iodine

We’re busy updating our review of iodine and will provide a rating when that’s complete. While we’re working, we share a summary from our predecessor website, Beyond Conventional Cancer Therapies. The information we share here was last updated in November 2020.

Please consider supporting our update and revision to this information.

Iodine

Key Points

• Before using this therapy, consult your oncology team about interactions with other treatments and therapies. Also make sure this therapy is safe for use with any other medical conditions you may have.
• Iodine, a mineral found in some foods, is used by your body to make thyroid hormones.
• Some foods can inhibit your body’s use of iodine. Those diagnosed with thyroid cancer or at high risk of thyroid cancer should avoid soy, cassava, and cruciferous vegetables.
• Some clinical evidence shows usefulness in treating breast cancer, but no definitive studies support the use of iodine supplements to enhance the effectiveness of chemotherapy or decrease heart toxicity.
• Iodine deficiency is a risk factor in breast cancers and thyroid cancer. Excess iodine absorption may promote cancer cell growth in some types of breast cancer.
• Iodine is an antioxidant and antiproliferative agent and an immune response activator.
• Iodine can interact with many medications, and excessive iodine intake can cause health risks.

Iodine, a mineral found in some foods, is used by your body to make thyroid hormones. These hormones control your body’s metabolism and many other important functions. Getting enough iodine is important for everyone, especially infants and women who are pregnant.1

Forms of Iodine

Iodine in food, including iodized salt, has several chemical forms. The elemental form of iodine is rarely found, usually taking the form of iodide in a salt, such as potassium iodide or sodium iodide. Other forms include inorganic iodine and iodate.

Your gastrointestinal tract absorbs iodide from food and iodized salt, or it converts iodate into iodide and then absorbs it. The thyroid gland concentrates iodide to use in making thyroid hormones. Excess iodide is excreted in the urine. A small study found that potassium iodide is almost completely (96.4 percent) absorbed in humans.2

Food and Iodine

A diet without enough iodine and other key nutrients can contribute to illnesses associated with the thyroid, including cancer. The National Institutes of Health lists the following dietary sources of iodine:

• Fish (including cod and tuna), seaweed, shrimp and other seafood, which are generally rich in iodine
• Dairy products (such as milk, yogurt and cheese) and products made from grains (like breads and cereals), which are the major sources of iodine in American diets
• Fruits and vegetables which contain iodine, although the amount depends on the iodine in the soil where they grew and in any fertilizer that was used
• Iodized salt, which is readily available in the United States and many other countries; processed foods, however, such as canned soups, almost never contain iodized salt9

For a list of the quantity of iodine per serving and the Percent Daily Value, see Table 2: Selected Food Sources of Iodine.10

Foods high in zinc and vitamins A and E support the proper manufacture of thyroid hormones:11

• Some types of seafood (oysters, crab, lobster)
• Beef
• Chicken (dark meat)
• Pumpkin seeds
• Cashews
• Chickpeas
• Oats

Other foods can inhibit your body’s use of iodine. For those diagnosed with thyroid cancer or at high risk of thyroid cancer, these foods should be avoided:12

• Soy
• Cassava
• Cruciferous vegetables: cabbage, broccoli, cauliflower, kale, bok choy, Brussels sprouts, garden cress

Treating the Cancer

Working against cancer growth or spread, improving survival, or working with other treatments or therapies to improve their anticancer action

Clinical Evidence

Breast Cancer

• No definitive human studies support recommending iodine supplements for increasing sensitivity to chemotherapy drugs, decreasing resistance to chemotherapy drugs or decreasing heart toxicity with breast cancer.
• Increased five-year disease-free survival in patients treated with a molecular iodine supplement before and after surgery, compared to those receiving it only after surgery3
• Suppressed development and size of both benign and cancerous neoplasias (abnormal growths) in humans and animals4

Lab and Animal Evidence

Managing Side Effects and Promoting Wellness

Managing or relieving side effects or symptoms, reducing treatment toxicity, supporting quality of life or promoting general well-being

Clinical Evidence

• Reduced levels of heart distress enzymes during epirubicin chemotherapy for breast cancer13
• Reduced fibrocystic breast symptoms14

Lab and Animal Evidence

Reducing Risk

Reducing the risk of developing cancer or the risk of recurrence

Clinical Evidence

Breast Cancer

• Deficiency is a risk factor in breast cancers16
• Excess iodine absorption (such as from antiseptic use during breast surgery) may stimulate estrogen receptor signaling and promote cancer cell growth in some types of breast cancer.17
• No definitive human studies support recommending iodine supplements to prevent breast cancer

Thyroid Cancer

• Iodine deficiency increases risks of thyroid cancer18

Lab and Animal Evidence

Optimizing Your Terrain

Creating an environment within your body that does not support cancer development, growth or spread

• Antioxidant and antiproliferative agent20
• Immune response activator21

Access

Food sources of iodine and iodized salt are readily available. Many multivitamin/mineral supplements contain iodine in the forms of potassium iodide or sodium iodide. Dietary supplements of iodine or iodine-containing kelp (a seaweed) are also available.

Cautions

Iodine can interact with many medications. Before taking an iodine supplement, consult your physician regarding safe use. Consult your pharmacist to check if you are taking any medications or supplements that may interact with iodine.

Excessive iodine intake can cause health risks (hyperthyroidism, goiter, thyroiditis, thyroid cancer). Overdose can result in acute poisoning symptoms. People with autoimmune thyroid disease and iodine deficiency may have side effects when taking iodine doses considered safe for the general population.22

Some people are intolerant of, or sensitive to, iodine in chemical agents such as radiocontrast agents (for x-rays), in iodine-containing disinfectants like Betadine, or even in foods. If people suspect they have an iodine allergy, their doctor can run tests to confirm. An individual should make sure that all medical professionals are aware of an iodine allergy before medical treatment.23

Radioactive iodine (RAI) treatment for patients with thyroid cancer does not appear to increase the risk or recurrence of breast cancer.24

Dosing

CancerChoices does not recommend therapies or doses, but only provides information for patients and providers to consider as part of a complete treatment plan. Patients should discuss therapies with their physicians to evaluate contraindications, interactions and side effects.

Levels of active ingredients of natural products can vary widely between and even within products. See Quality and Sources of Herbs, Supplements and Other Natural Products.

Dosage recommendations for iodine deficiency are available from these sources:

• Web MD: Iodine
• National Institutes of Health Office of Dietary Supplements: Iodine Fact Sheet for Health Professionals 
• The ZRT Laboratory Blog: Guide: How to Treat Iodine Deficiency

Integrative Programs, Protocols and Medical Systems

Alschuler & Gazella complementary approaches25

McKinney protocols26

Commentary

From naturopathic oncologist and CancerChoices advisor Lise Alschuler, ND, FABNO: Iodine should be supplemented only when there is confirmed deficiency.

Resources

• American Thyroid Association: Iodine Deficiency
• National Institutes of Health Office of Dietary Supplements:
  • Iodine
  • Iodine Deficiency
• Livestrong: Difference between Iodine and Potassium Iodide
• DifferenceBetween.net: Difference between Iodine and Potassium Iodide
• Association for the Advancement of Restorative Medicine℠: Iodine or Iodide: What’s Really in Our Supplements?
• Gurdev Parmar and Tina Kaczor: Textbook of Naturopathic Oncology
• McKinney N. Naturopathic Oncology, Fourth Edition
• Lise Alschuler, ND, FABNO, and Karolyn Gazella: The Definitive Guide to Cancer, 3rd Edition
• Keith I. Block, MD: Life over Cancer: The Block Center Program for Integrative Cancer Treatment
• Gerald Lemole, MD; Pallav Mehta, MD; and Dwight McKee, MD: After Cancer Care

References

1. Office of Dietary Supplements. Iodine: Fact Sheet for Consumers. National Institutes of Health. May 1, 2020. Viewed May 6, 2020.
2. Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals. National Institutes of Health. May 1, 2020. Viewed May 6, 2020.
3. Moreno-Vega A, Vega-Riveroll L et al. Adjuvant effect of molecular iodine in conventional chemotherapy for breast cancer. randomized pilot study. Nutrients. 2019 Jul 17;11(7). pii: E1623.
4. Aceves 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.
5. 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; 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; Nuñez-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; Stoddard 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.
6. Aranda 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.
7. Bontempo 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; Alfaro 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;12:45.
8. Tripathi 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.
9. Office of Dietary Supplements. Iodine Fact Sheet for Consumers. National Institutes of Health. May 1, 2020. Viewed May 6, 2020.
10. Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals. National Institutes of Health. May 1, 2020. Viewed May 6, 2020.
11. Office of Dietary Supplements. Zinc: Fact Sheet for Health Professionals. National Institutes of Health. March 6, 2020. Viewed April 24, 2020.
12. Office of Dietary Supplements. Iodine: Fact Sheet for Health Professionals. National Institutes of Health. March 31, 2020. Viewed April 24, 2020.
13. Moreno-Vega A, Vega-Riveroll L et al. Adjuvant effect of molecular iodine in conventional chemotherapy for breast cancer. randomized pilot study. Nutrients. 2019 Jul 17;11(7). pii: E1623.
14. Patrick L Iodine: deficiency and therapeutic considerations. Alternative Medicine Review. 2008 Jun;13(2):116-27.
15. Alfaro 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;12:45.
16. Smyth PP. The thyroid, iodine and breast cancer. Breast Cancer Res. 2003;5(5):235-8; Rappaport 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.
17. He 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.
18. Dong 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.
19. 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.
20. Aceves 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; Mendieta 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.
21. Mendieta 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.
22. Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals. National Institutes of Health. May 1, 2020. Viewed May 6, 2020.
23. Cadman B.  What is an iodine intolerance? Medical News Today. April 3, 2018. Viewed May 6, 2020.
24. Ahn HY, Min HS et al. Radioactive iodine therapy did not significantly increase the incidence and recurrence of subsequent breast cancer. Journal of Clinical Endocrinology & Metabolism. 2015;100(9):3486–3493; Dong 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.
25. Alschuler LN, Gazella KA. The Definitive Guide to Cancer, 3rd Edition: An Integrative Approach to Prevention, Treatment, and Healing. Berkeley, California: Celestial Arts. 2010; Alschuler LN, Gazella KA. The Definitive Guide to Thriving after Cancer: A Five-Step Integrative Plan to Reduce the Risk of Recurrence and Build Lifelong Health. Berkeley, California: Ten Speed Press. 2013.
26. McKinney N. Naturopathic Oncology, 3rd Edition. Victoria, BC, Canada: Liaison Press. 2016.