Iodine and the Thyroid: Why Your Body Needs More Than You Think
We’ve talked at length about the importance of the thyroid for overall health and wellness. Remember that the thyroid is a butterfly-shaped gland located in the lower front of the neck. Its responsibilities are numerous, including:
Regulating metabolism
Heart function
Digestion
Muscle control
Bone maintenance
Mood regulation
Brain development
The thyroid produces hormones that regulate all of the above functions. Sufficient thyroid hormone is incredibly important, as all cells, muscles, and organs in the body depend on thyroid hormone levels to function properly. The thyroid is the main metabolic regulator of the body. As a reminder, hypothyroidism is when the thyroid gland is not releasing enough thyroid hormone for metabolic demands. Hyperthyroidism is when the thyroid gland is producing too much thyroid hormone, and the body takes on a hyper metabolic state. Those who have an autoimmune thyroid condition can fluctuate between overactive and underactive thyroid symptoms.
Thyroid hormones are T4 (thyroxine) and T3 (triiodothyronine). The thyroid is unable to make T4 and T3 in adequate amounts without one major essential mineral: iodine. T4 has four iodine atoms, and T3 has three iodine atoms, so the thyroid requires sufficient intake of iodine to produce them appropriately (1).
Iodine deficiency consequences
People at the highest risk for iodine deficiency include (2):
Pregnant women
Those who live in countries with iodine-deficient soil (including South Asia, Southeast Asia, New Zealand, and European countries )
Those who don’t use iodized salt (or take iodine supplements- we’ll talk about the issues with iodized salt soon)
Those who are vegans or vegetarians
Consequences of an iodine deficiency include (1):
Goiter formation
Hypothyroidism
Autoimmune thyroid diseases (Graves’ and Hashimoto’s)
Thyroid cancer
The American Thyroid Association estimates that more than 12 percent of the United States population will develop a thyroid condition at some point in their lifetime. It’s estimated that 20 million Americans have a thyroid condition with up to 60 percent of those people being unaware that they have a thyroid issue (3). Some experts estimate that the numbers of those with a thyroid condition are much higher.
Additionally, thyroid hormone, and therefore, iodine, is extremely important for a baby’s brain development. Consequences of an iodine deficiency for newborns include intellectual disability, goiter, lowered IQ, ADHD, and autism. Iodine deficiencies in utero are associated with increased rates of stillbirth and congenital abnormalities (1).
Iodine-containing foods and why you need more than the RDA
There are a few sources of food that contain iodine. These include:
Seaweed, including kombu kelp, wakami, and nori
Cod fish
Cow’s milk
Cow’s yogurt
Cottage cheese
Shrimp
Tuna
Eggs
Prunes
Lima beans
Iodized salt
Iodine, in the form of potassium iodine, was added to salt beginning in the 1920s in order to prevent goiter, intellectual disability, and stunted growth. This movement was largely successful. However, the current recommendations for daily iodine intake may be inadequate for preventing other thyroid disorders, like Graves’ disease, Hashimoto’s disease, hypothyroidism, and thyroid cancer. Additionally, salt that is iodized may be far less bioavailable than iodine from other iodine sources. Salt that is iodized is also usually refined salt, which has been exposed to toxic chemicals in order to give it its white color (1). It is best to rely on iodine from other food sources and high-quality supplements.
The following recommended dietary allowances for iodine are as follows:
Once again, while these RDA levels are effective in preventing goiter, these RDA levels may not be sufficient to support optimal thyroid, endocrine, and immune system function. Some experts argue that iodine intake should be 100 times the RDA recommendation in order to have proper oxidation and organification for optimal function (1). To compound this issue, our exposure to detrimental halogens like fluoride, bromide, and chlorine has increased. These toxic halogens can do damage to the thyroid and body, interfere with iodine uptake, and exacerbate iodine deficiency (4, 5, 6).
Instead of the RDA, most people need 12-50 mg/day of a combination of iodine and iodide for optimal thyroid functioning and overall wellness.
Iodine also maintains the regular architecture of various glands, including the thyroid, ovaries, uterus, breast, and prostate. As long as the tissues in the glands have enough iodine, the tissues maintain their structure. However, when iodine is deficient, the tissues start to become cystic. If the deficiency continues, the cysts then become nodular and eventually become hyperplastic. When this happens, cells begin multiplying rapidly. If not addressed, the state of the glandular tissue turns into cancer. However, iodine supplementation can dramatically improve and/or completely resolve the compromised architecture of these important glands (1).
Iodine supplementation in combination with thyroid hormone
When a thyroid issue is suspected, it’s extremely important to assess iodine levels in the body. If they are not sufficient, it’s also important to use the correct form of iodine to treat the deficiency. We use both iodine and iodide-containing products, which help to correct iodine deficiencies and reduce the amount of thyroid hormone that is needed. Ideally, it’s also a good idea to first address iodine levels and then begin thyroid hormone dosing. If you are already taking a thyroid hormone, work with a skilled functional medicine practitioner to address iodine levels and closely monitor thyroid hormone levels. Taking thyroid hormone without addressing iodine levels can exacerbate a thyroid condition.
When iodine supplementation first begins, it’s not uncommon for TSH levels to rise. This is the body’s response to an increased supply of iodine - it increases TSH in order to stimulate more NIS transporters, which are plasma membrane glycoproteins that mediate the uptake of iodine into the thyroid. The more iodine the body has to process, the more NIS needed. Raised TSH levels are an appropriate response, and these TSH levels may stay elevated until the body adapts to its new normal of iodine. It is extremely rare to have iodine-induced hypothyroidism or hyperthyroidism, and there are usually underlying reasons for this. Once again, it’s important to work with a skilled functional medicine practitioner to find the right supplementation for you.
Oxidation and organification of iodine
When iodide, which is the reduced form of iodine, enters the thyroid gland, it undergoes oxidation, where it is then turned into iodine. In order for this process to occur, the body needs hydrogen peroxide and thyroperoxidase (TPO) to interact. Taking appropriate amounts of B2 and B3 will help the body have the right amount of hydrogen peroxide to have proper oxidation of iodine. It’s important that the hydrogen peroxide is then reduced to H2O after completing this task. Otherwise, it can cause damage to thyroid tissues and induce Hashimoto’s. Glutathione peroxidase, which has selenium, is needed to keep this process in check (1).
If oxidation properly occurs then the iodine goes through organification and becomes part of cholesterol, lipids, and proteins. Organification of iodine means that the iodine is bound to an organic molecule. This is where experts, like Dr. David Browstein, recommend that we need at least 100x the RDA in order to produce important iodo-lipids like delta-iodolactone (1). While the RDA will prevent goiter and perhaps produce thyroid hormones, there’s evidence that delta-iodolactone will help to prevent thyroid and breast cancers by causing apoptosis (cell death) of malignant cells (7).
As you can see, there’s much more to preventing and/or treating a thyroid condition than simply taking thyroid hormones. Iodine plays an essential role in optimal thyroid function and also requires other vitamins and minerals, such as selenium, B2, and B3 to support its vital role. It is extremely important to work with a skilled functional medicine practitioner to find the right balance for your body and optimal thyroid function. Please call our office if you would like us to support you on your health journey.
Works cited:
Brownstein, D. (2014). Iodine: Why you need it, why you can’t live without it (5th ed.). Medical Alternatives Press.
https://www.sciencedirect.com/sdfe/pdf/download/eid/1-s2.0-0002914961903745/first-page-pdf