The Most Important Thyroid Nutrient - Are You Getting Enough?

One thing often not discussed or tested when assessing thyroid health is iodine.  Iodine is an essential trace element required to create thyroid hormone.  In fact, that’s pretty much its only purpose in the body.  About 80% of iodine is located in the thyroid gland.  We excrete approximately 200mcg of iodine on a daily basis, through the kidneys, bile, stool, saliva and sweat.  The recommended daily intake (RDI) of iodine, to avoid disease in the population, is 150mcg.  Iodine binds with a little amino acid you may have heard of before, tyrosine, to create thyroid hormone.  We get tyrosine (like many amino acids) from food with significant ease as it is a component of proteins.  Iodine, however, is not as guaranteed to be plentiful in the diet and this is commonly why deficiency occurs. 

The major sources of iodine come from sea life, such as oysters (containing 160mcg iodine), saltwater fish, kelp (90mcg) and other sea vegetables.  There are small amounts in other foods, such as dark green vegetables, eggs (20mcg), butter and iodised foods such as salt.  As you can imagine, the major sources of dietary iodine are rarely consumed by the general population, if at all.  Seafood is a common offender in food allergies and intolerances, and many vegetarians and vegans are also not able to rely on these high potency dietary sources of iodine.

Iodine deficiency has been a major problem in Australia’s health history, which is actually what led to salt becoming an iodised product.  Milk was also a good source of iodine as milk vats were cleaned with an iodine rich solution (unfortunately, chlorine is now the preferred option).  I’m sure you would be familiar with iodised table salt as well.  Once again, many make decisions not to consume salt at all, and salt used in processed foods is not iodised.  So, you are getting more salt than you need from processed foods, but unfortunately still missing out on iodine. 

Iodine deficiency is one of the major factors in the development of hypothyroidism or an under-active thyroid.  Thyroid hormone affects every single cell in the body, controlling metabolic rate (the rate at which cells function to perform bodily processes and keep us alive!).  Iodine is also an essential natal nutrient, required for proper human development and growth.  The RDI for pregnant and breastfeeding women is 200mcg.  Deficiency can lead to retarded mental and physical growth, congenital defects and a higher risk of spontaneous abortion and stillbirth.  Other problems involved in iodine deficiency include fibrocystic breast disease (iodine modulates the effects of oestrogen on the breast tissue), impaired mental function, and development of goitre; an enlarged thyroid gland.

Iodine deficiency is induced by consuming less than 50mcg daily, which many people would struggle to achieve.  So, without the obvious lack of iodine in the diets of the general population, what else can lead to iodine deficiency?

Some foods will block the uptake of iodine, and are termed goitrogenicRaw soy milk is amongst the highest classed goitrogenic foods, along with foods from the Brassica family such as horseradish, mustard, cabbage, broccoli, cauliflower and kale.  Much of the goitrogenic component of these foods is broken down through the heating and cooking process, which is a relief for those of us that depend on cauliflower as a rice substitute!  (Soy, however, is recommended to be avoided for those with thyroid problems, unless fermented.)

Urine tests can be done to detect low iodine levels.  Supplementation is often the best way to increase iodine levels, along with careful dietary education and increasing iodine-rich foods for those where this is an option.  Potassium iodide and ammonium iodide are, in my opinion, the best forms for supplementation, preferably with complimentary selenium, which are available from your registered healthcare practitioner.  Betacarotene, the precursor to vitamin A, is also needed for iodine absorption, and another factor to consider in supplementation. 

As you can see, something as straightforward as iodine deficiency uncovers a number of aspects about diet – and this is only one of the many components that can be responsible for an under-active thyroid or poor thyroid health. 

I treat many women with under-active thyroids, and the first thing we start with is pathology to show TSH (thyroid stimulating hormone – AKA the thyroid messenger telling it to work), T4 (made from iodine, and is converted to T3), T3 (the thyroid hormone which cells respond to), anti-thyroid antibodies (to detect if autoimmunity is a driving factor), and urinary iodine (to detect iodine deficiency).  This is a very thorough thyroid profiling test.  You will manage to get your TSH tested by a GP, but for further testing of antibodies, thyroid hormones and iodine, to understand how the thyroid is actually functioning, this will likely be an out-of-pocket expense unless your TSH appears outside of the normal range.  This is where your Naturopath can refer you for comprehensive thyroid profiling pathology.

Iodine deficiency is the most easily explainable reason for hypothyroidism.  The other reasons, such as autoimmunity and functional or cellular hypothyroidism, are a little harder.  Autoimmunity is briefly discussed in my previous blog, and in another fortnight I will be covering the ins-and-outs of how they thyroid works and what happens when there’s a hitch in these processes – a must read for anyone with diagnosed or suspected thyroid conditions!  The more you understand what and how things might not be working in the body, the more power you have over making positive and healthy changes!