The ‘medicine cabinet’ mineral that’s a surprising breast health hero

Are you old enough to remember when Mum put iodine on your cuts and bruises so you wouldn’t get infected? That’s just one of many things iodine (and its close cousin, iodide) can do. This month, we’ll focus on iodine and breast cancer prevention and treatment, and a bit more, too.

Iodine is a basic element of planet Earth and, as far as we know, the Universe. Chemically it’s a ‘halogen’, a family of elements that includes bromine, chlorine, and fluorine. In the periodic table it’s abbreviated as ‘I’, and has the ‘atomic number’ 53.

The word ‘iodine’ is derived from the Greek word for purple, and describes the purple vapour produced by the element. In 1811, Bernard Courtois, a French chemist, first observed this purple vapour while he was isolating saltpeter (used in gunpowder) from seaweed. While he was aware he’d discovered an unknown element, further research on iodine did not begin for a number of years.

Iodine 101

One of the things we all ‘know’ about iodine is that it’s recommended medically in small amounts to support the thyroid and prevent the development of goitre, a growth of the thyroid tissue from too little iodine in the diet. But as sometimes happens, what we ‘know’ isn’t always entirely accurate. What our thyroid glands actually prefer is ‘iodide’, which is one-half of the iodine molecule – the other half is a second ‘iodide’. In other words, ‘iodine,’ is actually two iodides stuck together, symbolised as I2, just as what we call ‘oxygen’ is actually two oxygen molecules stuck together and symbolised as O2.

Iodide is used as a treatment for hypothyroidism or too little thyroid hormone. And both iodine and iodide are used… frequently along with lithium for the best results… to treat hyperthyroidism or too much thyroid hormone.

Iodine is also used to treat a variety of other conditions including skin diseases, fibrocystic breast disease, heart diseases, stroke and diabetes. And, of course, iodide is frequently used as a disinfectant in medical procedures, and in water purification.

Our bodies can’t make I2 so instead we have to ingest it from outside sources. This is easy if we’re seacoast dwellers, but challenging the further we live from the ocean. The fact is there is very little iodine in foods other than those obtained from the sea such as kelp, fish and shellfish. It’s also found in very small amounts in egg yolks, and is sometimes added during food processing (albeit rarely now, in the form of ‘iodised’ salt).

Are you at risk for iodine deficiency?

Iodised salt was used more extensively as a flowing agent in processed grain products before the 1980s, but then the medical authorities thought they knew better, and ordered that bromine be used instead. (Many students of that situation point to the significant increase in breast cancer that occurred just a few years after bromine replaced iodine in processed grains.) Iodine can be found in soil, but once again it is generally found in higher amounts in those areas closest to the sea; inland areas are often deficient meaning those that live there are often deficient as well. In the early 20th century, iodide was added to salt to create ‘iodised salt’, because of the high incidence of goitre in the ‘goitre belt’ of the United States – which predictably enough was the Midwest and other states far away from the seacoasts. Unfortunately, iodised salt use is declining.

In recent years the National Health and Nutrition Study (NHANES) has found that iodine and iodide intake has been very low in the general population for years. But more recently it has been rising to slightly higher levels and is now stabilising. Intake in certain ‘at risk groups’, however, is still too low, particularly among pregnant women. An article in the Lancet noted: ‘According to the World Health Organisation, in 2007, nearly 2 billion individuals had insufficient iodine intake, a third being of school age. Thus iodine deficiency, as the single greatest preventable cause of mental retardation, is an important public-health problem’.1

Taking a hit to your health

Iodine deficiency can lead to many health problems, including (but certainly not limited to) autoimmune thyroiditis, amenorrhoea (lack of menses), and possibly the development of cancer, such as cancer of the prostate, ovaries, or endometrium. In addition, the likelihood that iodine deficiency raises the risk of breast cancer is overwhelming. Besides mental retardation, if intake is inadequate during pregnancy, it can lead to brain damage in the foetus, myelination deficits, increased infant mortality rates, and hearing loss.

Iodine deficiency is also a risk factor for thyroid carcinoma. When iodine levels are low in the thyroid gland, your body’s ability to take up radioactive iodine is increased, something that was noted to occur in I2-deficient individuals after the Russian Chernobyl reactor meltdown.2

Two forms of ‘iodine’ in general use

Iodine is not very soluble in water, but it can be made more soluble by combining it with the much more soluble potassium iodide.

In 1829, Jean Lugol, a French physician, created Lugol’s solution, containing a mixture of 5 per cent iodine and 10 per cent potassium iodide in water, which was very widely used in medical practice until the early to mid1900s. Supplementation with Lugol’s solution is typically one or two drops per day, 6.25mg or 12.5mg of iodine and iodide.

Lugol’s iodine is still commonly used during examinations for uterine cervical dysplasia (potentially a pre-cancerous condition), when it is used to paint the cervix (Schiller’s test). Despite its decline in popularity in the conventional world of medicine, Lugol’s iodine is still used extensively by doctors skilled and knowledgeable in nutritional and natural medicine for the treatment of hormone-related disorders and other conditions.

Potassium iodide alone also has many potential uses, a number of them the ‘do-it-yourself’ kind. One increasingly important use out of dozens is protecting the thyroid gland against the uptake of radioactive iodine.

More than just a ‘thyroid mineral’

The iodide form of iodine is important for the production of the thyroid hormones ‘T4’ (thyroxine) and ‘T3’ (tri-iodothyronine). In fact, iodide is important to every other thyroid hormone and compound produced by the thyroid gland. These mostly neglected, and almost never publicised hormones, include both forms of ‘T2’. The ‘active’ form of T2 (di-iodothyronine) has been found in one study to stimulate growth hormone, and according to DeGroot and Jameson’s textbook Endocrinology declines with age, which is an excellent reason to use whole thyroid when supplementing thyroid hormones – but that’s a discussion for another time. This same textbook lists a total of 12 iodide-containing hormones and other compounds found in the thyroid.

What’s also not well-known is that up to 70 per cent of iodine and iodide in the body is found in other glands, organs, and tissues, most notably  the salivary glands, the stomach lining (‘gastric mucosa’ for the technically inclined), lactating and non-lactating mammary glands (‘breasts’ for those not technically inclined), and the kidneys.3,4

While the ‘thyroid stimulating hormone’ (‘TSH’, made in the pituitary gland) is necessary for the thyroid to absorb iodine, TSH is not needed for the absorption of iodide or iodine in other tissues. By contrast, the same things that inhibit iodine and iodide uptake by the thyroid also inhibit their uptake by other tissues. Among other molecules that inhibit iodine and iodide uptake are thiocyanate and perchlorate, natural and synthetic contaminants found in ground water and food.5,6

Chlorine and the fluorosilicic acid form of fluoride are deliberately put into drinking water in most of the United States, and in some parts of the UK, and (by order of the US medical authorities) potassium bromate was substituted for iodide in commercial bakery and bread products over 20 years ago. (Bromate in bread was banned in the UK in 1990 and Canada in 1994.) Chlorine, fluorine, and bromine can all interfere with the action of iodine and iodide in the body.

The breast cancer connection

More than 50 years ago it was discovered that iodine accumulates in breast tissue.7 In the 1970s based on his extensive research, Dr. Bernard Eskin of Temple University Medical School suggested iodine might be helpful as a treatment for women with breast cancer and/or as a breast cancer preventer. Dr. Eskin found that iodine (not iodide) may help prevent hyperplasia and dysplasia, cellular changes that are early steps in the development of breast cancer and quite often influenced by oestrogen.8,9

Eskin found that breast tissue deficient in iodine was much more likely to show pre-cancerous changes, such as atypia, dysplasia, and the promotion of early breast lesions. His animal studies show that deficiency in the mineral affects the anatomy of breasts (for the technically inclined, ‘mammary glands’).10 Eskin and his fellow researchers found that mammary gland cell hyperplasia (remember, this is a pre-cancerous condition) in iodine-deficient rats could be improved with an amount of iodine equivalent to a 5mg daily dose for a 110 pound woman.11,12

Eskin also demonstrated that the active form of iodine in breast tissue, and the form most effective in treating breast conditions, is iodine, not iodide, which concentrates in breast tissue more effectively than in the thyroid.13

The possible relationship between iodine deficiency, goitre, geography  and reproductive cancers was noted by others conducting research at the same time, implicating iodine deficiency as a potential risk in the development of prostate, endometrial, ovarian and breast cancers.14 More recently, researchers showed that the iodine content of breast cancers was much lower than that found in other tissues, sometimes in the same breast or in non-cancerous breast lumps (for the technically inclined, ‘fibroadenomas’). This evidence suggests that iodine uptake may be inhibited in those most susceptible to breast cancer.

Much like the thyroid, which takes up radioactive iodine when non-radioactive iodine levels are low, it has been found that abnormal breast tissue and malignancy have increased radioactive iodine uptake. Some have suggested using ‘radioactive scintigraphy’ (for the non-technically inclined, a technique which detects accumulations of radioactive elements) to detect breast cancers.15,16

Seaweed is one of the richest – if not the richest – sources of iodine. A 2001 study looked at the benefits of seaweed for preventing breast cancer. In rats, the seaweed ‘mekabu’ significantly decreased the occurrence of mammary cancers without any toxicity noted with administration. When studied in vitro (in test tubes) with three different types of human breast cancer cells, the beneficial effect was actually greater than a commonly used chemotherapy agent. The researchers concluded that mekabu has potential benefit in the prevention and treatment of breast cancer.17,18

A number of studies have demonstrated that iodine itself – but not iodide – can induce cancer cell death (apoptosis) in several cancer cell lines without affecting normal cells.

In 2005, researchers from the Autonomic National University in Juriquilla, Mexico reviewed evidence showing that iodine is ‘an antioxidant and antiproliferative agent contributing to the integrity of normal mammary gland.’

They pointed out that ‘In animal and human studies, molecular iodine (I2) supplementation exerts a suppressive effect on the development and size of both benign and cancer neoplasias… Iodine, in addition to its incorporation into thyroid hormones, is bound into antiproliferative iodolipids in the thyroid called iodolactones, which may also play a role in the proliferative control of mammary gland. We propose that an I2 supplement should be considered as an adjuvant (additional aid) in breast cancer therapy.’19

In June 2006, a group from the Sanjay Ghandi Institute of Medical Sciences, Lucknow, India reported that iodine is cytotoxic (kills cancer cells) to several human breast cancer cell lines, including (for the technically inclined) ‘MCF7, MDA-MB-231, MDA-MB-453, ZR-75-1, and T-47D.’ By contrast, when applied to human blood cells (monocytes), iodine inhibited growth and proliferation, but didn’t kill the cells.20

In December 2006, the Mexican group reported that iodine (but not iodide), along with an iodinated fatty acid, inhibited the MCF-7 form of human breast cancer cells. (They did not try iodine against the other human breast cancer cell lines noted above.) Iodine neither harmed nor inhibited fibroblasts, a normal type of human connective tissue cell that helps to support breast tissue as well as tissues throughout the body. Other technical details led the researchers to suggest that it may become active against cancer cells when it is bound to certain normally present lipids or proteins in the breasts.21

In 2009, researchers from the same Mexican university reported that four weeks of iodine treatment given to previously carcinogen-treated rats significantly reduced the incidence and size of mammary cancers. They reported on ‘mechanisms of action’ for killing cancer. (For the technically inclined, those mechanisms included ‘6-iodolactone formation’ and ‘PPAR gamma induction’.)22 

This research was extended by other researchers from the University of Munich, who concluded: ‘delta-iodolactone seems to be the iodocompound [a compound containing iodine] which can inhibit growth and induce apoptosis [‘cell suicide’]  in B-CPAP cells [a type of human thyroid cancer cells] line as well as in MCF-7 breast cancer cells’. [For the record, delta-iodolactone failed to affect two other types of thyroid cancer cells.]23

Beyond breast cancer

Also in 2010, another German research group reported the results of their research about the effects of ‘molecular iodine’ and iodolactones in 12 different types of human cancer cells.24 With the exception of one type of colon cancer cell line (CCL122 colon cancer cells), the growth of the other 11 types of cancer cells was significantly decreased by the tiny quantity of 10 micromoles of iodine. ‘SH-SYSY’ neuroblastoma cells… usually a lethal brain tumour… were totally inhibited by iodine and by delta-iodolactone, followed by MCF-7 breast cancer cells, which were 77.7 per cent inhibited by delta-iodolactone and 60 per cent inhibited by iodine.

In 2012, the Mexican research group reported on the effects of iodine and 6-iodolactone on one normal and two cancerous prostate cancer cell lines.25 They concluded: ‘Normal and cancerous prostate cells can take up iodine, and depending on the chemical form, it exerts anti-proliferative effects [for the non-technically inclined, slows cancer cell development] and apoptotic effects (causing cell ‘suicide’) both in vitro and in vivo (in cell cultures and in live animals).

Iodine influences oestrogen metabolism

What you’ve read immediately above is about iodine only, how it can kill cancer cells directly and as a part of ‘iodolactone’. However, iodine and iodide both have a big role in preventing breast cancer, and prevention is always, always better than treatment. 

One of the pioneers in the understanding of the importance of iodine in breast health was Dr. Henry Lemon, Professor of Gynecologic Oncology at the University of Nebraska Medical School. Dr. Lemon developed a mathematical formula known as the ‘oestrogen [EQ] quotient’ as a tool for comparing the levels of three types of oestrogen (oestrone, oestradiol and ostriol) and determining the degree of breast cancer risk.

Lemon’s calculation divided the amount of oestriol… an anti-carcinogenic oestrogen… by the sum of the oestrone… a predominantly pro-carcinogenic oestrogen… and oestradiol… the most potent and often – but not exclusively – pro-carcinogenic oestrogen. (For the mathematically inclined, Dr. Lemon’s calculation is written ‘EQ=E3 / E2 + E1’). If the ‘EQ’ is below one, oestrogen-related cancer risk is high; the higher the ‘EQ’ is above one, the lower the oestrogen-related cancer risk.

In one piece of research concerning oestriol and breast cancer, Dr. Lemon reported that about two-thirds of women diagnosed with breast cancer had subnormal urinary EQs (less than 1.0).26

In another small study of 34 women with no signs of breast cancer and 26 women with breast cancer, Dr. Lemon found the EQ below 1.0 in 21 per cent of the healthy women as compared with 62 per cent of the women with cancer.27 In the ‘non-cancer’ group, the median EQ was 1.3 in the premenopausal women, and 1.2 in the post-menopausal women, while in the group with cancer, the premenopausal women had a median EQ of 0.5 and the pre-menopausal women a median EQ of 0.8.

Laboratory animal studies totalling more than 500 rat-years show that oestriol is the most active protective oestrogen ever tested against breast cancers induced by several potent carcinogenic agents, including radiation.28,29

In addition to lowering cancer risk, Dr. Lemon found that oestriol might even be a treatment for cancer in some women. In a small unpublished study of women whose breast cancer had metastasised to their bones, approximately 40 per cent of the women taking a relatively large quantity of oestriol experienced a remission.30

Iodine helps fibrocystic breast disease

Dr. John Myers was another mid-20th century pioneer in the use of iodine and other minerals in medicine. He developed a treatment for fibrocystic breast disease using vaginal applications of iodine which has eliminated this problem for every woman – at the very least, several hundred – treated at Tahoma Clinic since the 1970s.

After I learned this treatment from Dr. Myers, I also used what Dr. Lemon had taught about the oestrogen quotient (EQ) and asked women with fibrocystic breast disease who were concerned about breast cancer risk to have their EQ measured before and after treatment. Many more than expected had a low EQ (less than 1.0) before treatment, and all – 100 per cent – of this low EQ group had a significant improvement in EQ after treatment. All of them also had elimination of fibrocystic breast disease.

Since that time, whenever a woman’s hormone test shows an EQ below 1.0 (indicating higher cancer risk), I’ve asked her to take a relatively large amount of iodine until her EQ rises to well above 1.0, and then ‘taper off’ to the smallest amount that helps her to maintain her EQ significantly above 1.0. This has worked for all but two women since the late 1970s, helping all but these two women to significantly lower their oestrogen-related cancer risk and keep it lower. If you have either of these problems… fibrocystic breast disease or low EQ… please consult a  doctor skilled and knowledgeable in natural and nutritional medicine, as higher quantities of iodine (and iodide) can slow down (‘suppress’) thyroid function.

Seeking safe limits on iodine and iodide

One of the reasons that iodine is not presently used more extensively is fear of down-regulation of the thyroid. What is a safe amount to use?

There’s more iodine and iodide in the Japanese diet than anywhere else in the world. Many authorities believe this is the reason why the Japanese enjoy better overall health than we do. For example:

  • In Japan the average life expectancy of 83 years is five years longer than the US average life expectancy of 78 years.
  • The age-adjusted breast cancer mortality rate in 1999 was three times higher in the United States than in Japan.
  • The incidence of breast cancer among Japanese immigrants to the United States rises from 20 to 30 per 100,000 after 10 years.
  • The age-adjusted rate of prostate cancer in Japan was 12.6 per 100,000 in 2002, while the rate in the United States was almost 10 times as high.
  • Heart-related deaths in men and women aged 35-74 years are much higher in the US (1,415 per 100,000) than they are in Japan (897 per 100,000).
  • In 2004, infant deaths were over twice as high in the United States (6.8 per 1,000) as they were in Japan (2.8 per 1,000).31

Remember, all of these health statistics are related to the amount of iodine and iodide already in the Japanese diet, not to therapeutic quantities, which in certain instances – fibrocystic breast disease, for example – can be hundreds of milligrams per treatment until the problem is gone. So what is that amount?

One early estimate by an American expert was 12.5mg a day.32 The Japanese Ministry of Health (admittedly a government agency) states that 3mg daily is the safe upper limit.33 A recent publication states: ‘By combining information from dietary records, food surveys, urine iodine analysis (both spot and 24-hour samples) and seaweed iodine content, we estimate that the Japanese iodine intake – largely from seaweeds averages – 1,000-3,000 μg/day (13mg/day)’.31

While it’s possible to be allergic to iodine and food sources of iodine, it’s unusual, and not lethal (except – very, very rarely – iodine doses given intravenously during ‘medical imaging’).

So unless you have a thyroid problem – including Hashimoto’s disease or Graves’ disease – it’s very likely safe to include the amount of iodine and iodide found in the Japanese diet into your own diet and supplement programme. For advice about this, and especially for prolonged use of higher-than-dietary-amounts of iodine and iodide, make sure to check with a doctor skilled and knowledgeable in natural and nutritional medicine.

Wishing you the best of health,

Dr. Jonathan V. Wright
Nutrition & Healing

Volume 6, Issue 10 – October 2012

Full references and citations for this article are available in the downloadable PDF version of the monthly Nutrition and Healing issue in which this article appears.

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