Yes, this blog was a long time coming! I will plead the usual excuses of being overwhelmingly busy… Anyway, I wrote a research paper this semester looking the relationships between thyroid function, breast pathologies, and the role of iodine supplementation. This blog is a summary of what I learned. References are listed at the end and can be found on PubMed.
First, thyroid. There is an observed correlation between thyroid dysfunction and breast cancer (1,2,3), particularly hypothyroidism (3,4). Decreased function of the thyroid gland and rising TSH are also associated with a doubling in the risk of development of fibrocystic breast disease (5).
Next, iodine and breasts. Both breast tissue and thyroid tissue concentrate iodine (6) and deficiency of iodine causes “atypical tissue and physiologic changes in both” (7). One researcher noted that “geographic differences in the rates of breast, endometrial, and ovarian cancer appear to be inversely correlated with dietary iodine intake” (8). For example, in Japan seaweed (high in both iodine and selenium) is a major part of the diet and may play a role in the low incidence of both benign and malignant breast disease in that country (9).
A study on rats demonstrated a reduction in breast cancer incidence with iodine treatment (10). With regard to fibrocystic breast disease, randomized, double-blind, placebo-controlled, multicenter clinical trials (the gold-standard of conventional medicine!) have demonstrated that supplementation with iodide/iodine significantly reduced breast pain, tenderness, and nodularity (11,12).
So how does this work? One theory is that iodine deficiency leads to a state of excess estrogen (13), increasing the risk of a whole host of cancers. Iodine is also believed to suppress tumour growth (14), induce tumour cell death (15), and regulate genes that influence hormone metabolism, cell cycle, growth, and differentiation (16).
So why is this useful information? Everything in the body is connected, particularly the endocrine system. So, when something is going wrong in one area, like thyroid function, there are likely also going to be issues either immediately or down the road with another area, particularly reproductive organs. The causal mechanisms are not clear yet, but it is prudent to assess breast health when patients present with thyroid dysfunction and vice versa. There is evidence to suggest that iodine is effective nutritional treatment for fibrocystic breast disease and it may also be useful in reproductive cancers. Molecular iodine, rather than iodide, was found to be most effective and have the least adverse effects on the thyroid (12).
There is lots of other interesting information that I was not able to get to, such as a deeper look at the interaction of sex hormones with thyroid function and other influences on hormonal balance, such as sleep. Maybe one day I’ll have time to do more research and I’ll post an update!
1. Turken O, NarIn Y, DemIrbas S, Onde ME, Sayan O, KandemIr EG, YaylacI M, Ozturk A. Breast cancer in association with thyroid disorders. Breast Cancer Res. 2003;5(5):R110-3. Epub 2003 Jun 5.
2. Saraiva PP, Figueiredo NB, Padovani CR, Brentani MM, Nogueira CR. Profile of thyroid hormones in breast cancer patients. Braz J Med Biol Res. 2005 May;38(5):761-5. Epub 2005 May 25.
3. Giani C, Fierabracci P, Bonacci R, Gigliotti A, Campani D, De Negri F, Cecchetti D, Martino E, Pinchera A. Relationship between breast cancer and thyroid disease: relevance of autoimmune thyroid disorders in breast malignancy. J Clin Endocrinol Metab. 1996 Mar;81(3):990-4.
4. Kuijpens JL, Nyklíctek I, Louwman MW, Weetman TA, Pop VJ, Coebergh JW. Hypothyroidism might be related to breast cancer in post-menopausal women. Thyroid. 2005 Nov;15(11):1253-9.
5. Mardaleishvili KG, Nemsadze GG, Metreveli DS, Roinishvili TL. [About correlation of dysfunction of the thyroid gland with fibrocystic diseases in women] Georgian Med News. 2006 Nov;(140):30-2. Russian.
6. Patrick L. Iodine: deficiency and therapeutic considerations. Altern Med Rev. 2008 Jun;13(2):116-27. Review.
7. Eskin BA, Grotkowski CE, Connolly CP, Ghent WR. Different tissue responses for iodine and iodide in rat thyroid and mammary glands. Biol Trace Elem Res. 1995 Jul;49(1):9-19.
8. Stadel BV. Dietary iodine and risk of breast, endometrial, and ovarian cancer. Lancet. 1976 Apr 24;1(7965):890-1.
9. Cann SA, van Netten JP, van Netten C. Hypothesis: iodine, selenium and the development of breast cancer. Cancer Causes Control. 2000 Feb;11(2):121-7. Review.
10. García-Solís P, Alfaro Y, Anguiano B, Delgado G, Guzman RC, Nandi S, Díaz-Muñoz M, Vázquez-Martínez O, Aceves C. 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. Mol Cell Endocrinol. 2005 May 31;236(1-2):49-57. Epub 2005 Apr 13.
11. Kessler JH. The effect of supraphysiologic levels of iodine on patients with cyclic mastalgia. Breast J. 2004 Jul-Aug;10(4):328-36.
12. Ghent WR, Eskin BA, Low DA, Hill LP. Iodine replacement in fibrocystic disease of the breast. Can J Surg. 1993 Oct;36(5):453-60.
13. Stadel BV. Dietary iodine and risk of breast, endometrial, and ovarian cancer. Lancet. 1976 Apr 24;1(7965):890-1.
14. Funahashi H, Imai T, Tanaka Y, Tobinaga J, Wada M, Morita T, Yamada F, Tsukamura K, Oiwa M, Kikumori T, Narita T, Takagi H. Suppressive effect of iodine on DMBA-induced breast tumor growth in the rat. J Surg Oncol. 1996 Mar;61(3):209-13.
15. Shrivastava A, Tiwari M, Sinha RA, Kumar A, Balapure AK, Bajpai VK, Sharma R, Mitra K, Tandon A, Godbole MM. Molecular iodine induces caspase-independent apoptosis in human breast carcinoma cells involving the mitochondria-mediated pathway. J Biol Chem. 2006 Jul 14;281(28):19762-71. Epub 2006 May 5.
16. 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. Int J Med Sci. 2008 Jul 8;5(4):189-96.
A quote from a few days ago, courtesy of iGoogle:
Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for - in order to get to the job you need to pay for the clothes and the car, and the house you leave vacant all day so you can afford to live in it. - Ellen Goodman
In other news, since I am generally constantly swamped with schoolwork, I am going to write some blogs on subjects I am learning in school or have written papers about (for school!) lately. Stay tuned! The first topic will be "Iodine, Thyroid, and Breast Health".
Great quote of the day from iGoogle today:
Too many people are thinking of security instead of opportunity. They seem more afraid of life than death. - James F. Byrnes
A few pieces of news:
In June, I first started seeing an osteopath and I have had a total of two visits with her. Yesterday I ran for 53 minutes pain-free, which is the longest I’ve ever been able to run in my life. I am amazed. I am hoping to make that 60 minutes later this week...
Thanks to discussion on the forums re: Ron’s rebirth as a type A, I blood-typed myself this morning and confirmed that I am indeed type O positive. I would be quite disappointed to find out otherwise! I know you were all on the edge of yours seats… And yes, I have measured myself many, many times and I am definitely a Gatherer.
I am writing my first set of naturopathic licensing exams on Tuesday (NPLEX Part I)! One day, five subjects, five exams… And then relative freedom until September!
While studying for the past six weeks I have discovered how effective good nutrition, exercise, power-napping, and meditation can be in learning and concentration. Most recently I added L-theanine to my supplement pile on the recommendation of a co-worker and have found it very effective at reducing anxiety and increasing my focus!
The month of July for me means studying. On August 5th I am writing 5 exams in basic sciences (anatomy, physiology, biochemistry, microbiology, and pathology) as part of licensing to eventually become a naturopathic doctor. All naturopathic students finished 2nd year write these exams on the same day across North America! Needless to say, there is a lot of material (2 years’ worth) to review, so my body and brain needs support. A smoothie is a great way to add a lot of extra nutrients to your diet, so I thought I’d share my morning smoothie recipe which is made up (almost) entirely of Gatherer superfoods:
Frozen pineapple chunks
Frozen mango chunks
1 Tbsp lecithin
1 Tbsp ground flax
½ scoop Protein Blend O
½ scoop Harmonia sprouted greens powder
1. Fill 2 cup smoothie cup with fruit, lecithin, flax, protein powder, and greens powder.
2. Add a splash of cranberry juice, a slightly larger splash of pineapple juice and fill rest of cup to cover fruit with water.
3. Let sit for approximately 15-20 minutes (while you shower, get ready for the day, whatever).
4. Blend together and drink.
I usually drink half of this mixture before eating the rest of my breakfast (usually an egg and some kind of vegetable) and then the other half as a snack later in the day.
In addition to the above, I am also taking fish oil and Catechol twice per day, as I find these supplements help with focus and concentration, as well as supporting my body through stress. I also make sure to have at least one cup (but not more than two) of green tea in the morning to energize me.