Without iodine, thyroid hormone cannot be formed. Without thyroid hormone we are not born. Low levels of thyroid due to iodine deficiency are the leading cause of preventable mental retardation in the world, called cretinism. Because of the prevalence of iodine deficiency, iodine deserves significant attention.

In addition, thyroid is the only hormone to require a trace element to function! This makes thyroid unique among hormones. In my experience, an undiscovered iodine deficiency is the leading cause of a poorly functioning thyroid, either with or without lab evidence of hypothyroidism. Entire books have been written on iodine deficiency. (Iodine, Why You Need It, Why You Can’t Live Without It, by Dr. David Brownstein; The Iodine Crisis, by Lynne Farrow; What Doctors Fail to Tell You About Iodine and Your Thyroid, by Dr. Robert Thompson, Breast Cancer and Iodine, by David Derry, MD). In addition, Dr. Guy Abrahams has written numerous professional articles about iodine.

Dr. Jerry Tennant states that every organ that secretes something requires iodine. He lists those organs as follows: Thyroid, salivary glands, choroid plexus, CSF and brain, intestinal mucosa, breasts, ovaries, vagina and uterus, prostate, eye ciliary body and conjunctiva, nose, sinus and mouth, substantia nigra (the part of the hypothalamus that when damaged leads to Parkinson’s), stomach (required for making stomach acid), pancreas (for making digestive enzymes), liver and gall bladder, skin, bone marrow, adrenal glands, kidneys, and lungs.

He also notes that these organs are the ones that tend to get cancer; and that the Japanese who have a very low rate of cancer, also consume the highest level of iodine. He goes on to point out that iodine kills all single cell organisms and that tissues exposed to the outside environment contain much higher levels of iodine than the blood (which is one reason why measuring levels if iodine in the blood does not reflect tissue levels).

David M. Derry, MD, PhD has written a fascinating book titled “Breast Cancer and Iodine”. He notes that iodine plays many roles in the body other than as an integral part of thyroid hormone, including: protecting the stomach against the pathogenic bacteria H. pylori, coating incoming allergens (antigens) making them non- allergenic, binding to polyunsaturated fats, stabilizing and protecting them against oxidation, deactivates most biological and chemical toxins in the stomach, kills all single cell organisms in very low doses and induces programmed cell death (apoptosis), thereby protecting against induction of cancer.

Dr. Derry goes on to point out that thyroid was the first hormone to evolve, and that this required iodine. He notes that iodine was the first single cure discovered for a specific disease, goiter, which was discovered in the early 1800’s! He tells us how iodine, deposited in rocks and soil is removed by rain and erosion. Ice ages stripped topsoil away as glaciers formed and retreated. Modern farming practices further deplete iodine from the soil, as it is never replaced.

Dr. Derry further describes how single cell organisms evolved without iodine (which is probably why they are so susceptible to it). With further evolution seaweed developed, which has the ability to concentrate iodine up to 20,000 times that of seawater; using a mechanism similar to the Sodium/Iodide Symporter used by many tissues in the human body. He relates how iodine binds selectively to Histadine and Tyrosine amino acids. Binding to Tyrosine creates thyroid hormone, which would have been found in many proteins within each cell. At some point in evolution, nuclear thyroid receptors formed and thyroid became the regulator of DNA function. Similarly, mitochondrial DNA also formed thyroid receptors, bringing it under the control of thyroid hormone. We can see then how every cell in the body is dependent upon the first hormone and how crucial iodine is to that process.

Doctors seem to have forgotten that the primary cause of goiter is an iodine deficiency. Iodine deficiency is the most common essential nutrient deficiency in the world. About 1/3 of the world’s population lives in iodine deficient areas, including people living in large parts of the United States. The farther from the ocean one is, the more likely the area is to be deficient.

Formerly in the Midwest, also known as the goiter belt, up to 50% of the population was iodine deficient to the point where they had goiters. In the 1920’s iodine was added to salt in very small quantities, just sufficient to prevent most goiters. However in the past forty years iodine intake has declined by 50%, largely due to the (weak) association between salt intake and high blood pressure, leading to many subclinical iodine deficiencies. Interestingly, this parallels a huge increase in the incidence of thyroid cancer. Thyroid nodules often follow goiter and can occasionally progress to become malignant.

I have had several patients who have had their thyroid removed because they had a goiter! There was no cancer or other thyroid disease present, just an enlarged thyroid. Unbelievably, none of them had their iodine levels checked. I would strongly urge anyone who has a goiter to have his or her iodine levels checked, especially if your doctor is recommending having your thyroid removed. The appropriate test is the Iodine Loading Test.

Just as thyroid hormone is necessary for every cell of the body, so is iodine. In fact there are a number of cell types in the body that concentrate iodine against a gradient. When sufficient, the thyroid may contain up to 50 times as much iodine as the blood. This requires an active transport system called the sodium/iodide symporter (NIS), which is also present in breast tissue, salivary glands, ovaries and GI tract. This would imply that iodine is especially critical to these tissues, otherwise they would have no need to spend energy moving iodine inside the cell, nor would they need to store it.

Our illustrious FDA has set the Recommended Dietary Allowance (RDA) for iodine at 150 micrograms per day. The RDA is basically the amount of a nutrient necessary to prevent overt disease. It is vastly different than optimal levels. Would you prefer minimal or optimal health?

An intake of 150mcg/day may prevent overt goiter, but it is insufficient to optimize tissue levels. For example, there is a biological molecule called delta-iodolactone, which is made from the omega-6 essential fatty acid called arachadonic acid, to which iodine has been attached. This molecule has been shown to regulate growth of thyroid cells. It causes a reduction in cellular proliferation and death of damaged cells (apoptosis), which is a critical step in prevention of cancer. It is present in other tissues as well, including breast, prostate, colon and nervous system.

Studies have shown that moderately high levels of iodine are protective against breast cancer. It appears that iodine is not acting directly to reduce cell growth and induce cell death. Rather it acts through delta-iodolactone. Dr. David Brownstein, in his book “Overcoming Thyroid Disorders” states that the amount of iodine needed to produce delta-iodolactone is 100 times the RDA. This would be the equivalent of 15 mg/day, or about what the typical Japanese diet provides. Without adequate iodine, delta-iodolactone is not made. Without it, proper control of thyroid cells does not occur and they proliferate. This could be the mechanism by which a goiter occurs. Without delta-iodolactone, thyroid (and other cell types) do not undergo programmed cell death or apoptosis, potentially leading to cancer.

Again referring to Dr. Derry, he notes that formerly Iceland, along with Japan, had the highest intakes of iodine. Both of these countries also had the smallest thyroid glands of any nations on Earth. (Remember that iodine deficiency causes the thyroid to grow in an attempt to capture more iodine. Enlarged thyroid glands are called goiters). The third thing both Iceland and Japan had in common were very low rates of breast cancer (The breast is one tissue that concentrates iodine). Whereas Japanese got their iodine mostly from seaweed, Icelanders got theirs from fish. In the early 1900’s all the leftover fish parts were fed to cows.

Like human’s cow’s milk can concentrate iodine, meaning that Icelandic cow’s milk was very high in iodine. Then fishing practices changed and between 1940-1960’s the amount of iodine ingested by Icelanders dramatically decreased. This was accompanied by a 10-fold increase in the rate of breast cancer to equal that of the USA. A similar increase is seen in Japanese women who migrate to the United States and change their diet to the typical Western diet deficient in iodine.

Dr. Derry, referencing the work of several other physicians, postulates that cancer cannot spread unless the connective tissue of the tissue or organ in which the cancer arises, is damaged. He notes that thyroid hormone is the controlling hormone for connective tissue integrity. In the hypothyroid state, tissue develops myxedema, swelling caused by the deposition of mucin. This damages the connective tissue and allows for cancer to spread.

So what is the correct amount of iodine to take? There is no one right answer for everyone, as each individual need varies. What is appropriate for one person may be too low or too high for another. Someone with Hashimoto’s or Grave’s Disease may not initially be able to take a larger dose due to temporary side effects. In addition, the adequacy of the trace element selenium affects iodine and thyroid levels. Both iodine and selenium are necessary for appropriate production, transport, conversion from T4 to T3, and metabolism of thyroid hormone.

In addition, results of a study showed that high iodine intake in the presence of selenium deficiency, may cause thyroid tissue damage as a result of low thyroid glutathione peroxidase activity. Glutathione is the major antioxidant produced within the body to protect against oxidative damage caused by free radicals. Selenium is a necessary component of the glutathione peroxidase enzyme.

The same study also found that selenium could increase T4 levels in the presence of an iodine deficiency. Another study showed that a selenium, but not an iodine deficiency significantly decreased Type 1 deiodinase activity to only 6-13% that of controls, meaning a significant reduction in the conversion of T4 to T3. At the same time, Type II deiodinase, found in the brain and pituitary gland was not significantly affected, indicating that it may possibly not be dependent on selenium. The importance of this is that with a selenium deficiency, peripheral conversion of T4 into T3 will be affected, but conversion in the pituitary will continue as normal. This would then mean that despite reduced peripheral T3, that TSH levels would not increase, as TSH is sensitive to the levels of T3 within the pituitary.

It is important to note that that there is no mechanism for the kidneys to resorb iodine lost in the urine. Many other essential minerals and electrolytes do have a means by which the kidneys can extract them from the urine to preserve their levels. This means that a constant supply of iodine is needed to maintain optimal levels.

What type of iodine and how much iodine should one take? I strongly recommend that prior to taking iodine, that one have an Iodine Loading Test performed. This will assist in determining the necessity of taking iodine and the initial amount one should take. A word of warning: if you are taking Amiodarone or any other iodine containing drug, or already have a diet rich in seaweed or other iodine sources, taking additional iodine may have an adverse effect on thyroid hormone production. (This is called the Wolff-Chaikoff effect). Excess iodine may damage the thyroid gland. Also, if you have recently had any type of medical test that uses iodine as a dye (MRI, CT scan, radioactive iodine), I do not recommend taking iodine until you have had an Essential Thyroid Panel and Iodine Loading Test done. I also strongly urge anyone taking iodine to also take 200- 400 micrograms of selenium as selenomethionine, to avoid a selenium deficiency.

If one is taking iodine, Lugol’s solution or another similar formula should be used. This contains both potassium iodide (formula: KI) and elemental iodine (Formula I2). There are other forms of iodine but research has shown the superiority of I2 and KI. A 2-year study on women with fibrocystic breast disease showed that I2 yielded superior results with fewer side effects than either sodium iodide or protein-bound iodide.

Another study compared KI to potassium iodate (KIO3) in preventing oxidative damage to the thyroid gland. They concluded that KI decreased oxidative damage at generally recommended prophylactic levels while KIO3 actually increased damage. In both animal and human studies, I2 suppresses the development and size of benign and cancerous growths through several different pathways. A 2013 paper in the journal Thyroid recommends an increased iodine intake to at least 3mg./day of I2.

Guy Abraham, MD was one of the leading iodine and thyroid experts. He coined the term “Orthoiodosupplementation” meaning right or correct iodine supplementation. Based on a variety of studies, he concluded that 12.5mg. of iodine as found in Lugol’s formula, per day was needed for whole body adequacy. This was to be done under doctor supervision.



About the Author: Dr. Douglas L. Weed

Dr. Weed practices Functional Nutrition, Chiropractic care, and offers weight loss solutions in Napa, CA at Heun Chiropractic, Inc. He has a doctorate in Chiropractic care and he has received certifications in physical rehabilitation and as a Qualified Medical Examiner. With a post-graduate certification in Functional Medicine, focusing on functional endocrinology, digestive disorders and Peripheral Neuropathy, he is committed to lifelong education and helping patience transform their health.