The Importance of Being Iodine

There has been a surge in thyroid disease over the last several decades, and anyone living with a thyroid disorder is highly likely to have heard the words iodine and thyroid in the same sentence more than once. But what is all the fuss about and why is this trace element so important for the thyroid? It’s actually very simple. Iodine is one of the ingredients needed by the thyroid so that it can synthesise the hormones, T4 & T3. Think of it like making a cake, and iodine is the flour. The thyroid gland has special receptors located on it so that the iodine (flour) can be transported from the bloodstream directly into the thyroid gland (the mixing bowl) via the receptors (sieve) known as the sodium iodide symporter. Once combined with a few other vital ingredients T4 and T3 are then created. T4 is made up of 4 iodine molecules and T3 consists of 3. These hormones then exit the thyroid, head back out into the bloodstream and make their way to their target cells.

Iodine Deficiency:

It can be easy to assume that if you have been diagnosed with hypothyroidism you may be deficient in iodine, due to its natural affinity for the thyroid gland and central role in the production of thyroid hormones. A deficiency is often listed as one of the reasons someone may have developed hypothyroidism, but unlike other countries, the UK has never introduced an iodine-fortification programme and even now iodine deficiency isn’t considered a major concern. Historically, during the 1930’s, dairy farmers began adding iodine to cattle feeds as they believed it improved the health, fertility and lactation of the herds. Around the same time, large-scale milking parlours began replacing more traditional hand milking methods and iodine was applied to the teats of cows to reduce bacterial contamination from mastitis. Milking equipment was also cleaned and sanitised using products called iodophor disinfectants which contained iodine. These various techniques influenced iodine in the food chain and inadvertently increased the iodine status of the general population. The discovery was described as an ‘accidental public health triumph’, as it had allegedly prevented iodine deficiency in the UK.

The goldilocks approach:

When considering how much iodine to include in your diet, it’s prudent to adopt a goldilocks approach, so that you are neither under or over consuming, as too much can equally have a detrimental effect on the body and potentially cause free radical damage in the thyroid. This sends an alert to the immune system, which creates local inflammation, destroys thyroid cells and reduces the conversion of inactive T4 to active T3.  

Using radioactive iodine (which destroys thyroid tissue) to treat thyroid conditions like hyperthyroidism and Graves’ Disease has actually been a method employed by the medical industry since the 1940’s to reduce thyroid hormone production and output. Unfortunately, over 2/3 of people who elect for this treatment then go on to develop hypothyroidism and need to synthetically replace hormones the thyroid is no longer able to produce naturally with medication instead. If you have a thyroid condition and are unsure about how much iodine you need it’s best or consult with either your doctor or a qualified practitioner who can advise you accordingly.

Recommended daily amount:

The recommended iodine intake for adults is 140 micrograms per day, and there are plenty of natural food sources available to meet this amount. They include, white fish (cod and haddock), shellfish and sea vegetables like dulse and kelp which can be added to smoothies, soups or stews. Just one gram of dulse flakes contains 150-300 micrograms of iodine. Other foods rich in iodine include strawberries, mushrooms, sunflower seeds and iodised salt. Using fortified products like iodised salt is very common but it’s important to be mindful of your intake. Just 3g of iodised salt per day (3g = half a teaspoon which is half the recommended daily amount of salt), equates to roughly 250mcg iodine. That’s 110mcg more than the recommended daily intake which could put someone over a safe upper limit if combined with other food sources or supplements.


Iodine is integral to your thyroid, but other factors including your nutrient status, physical, emotional and mental stressors, exposure to toxins and chemicals, as well as viral load and reactivation of the Epstein Barr virus may be affecting your thyroid health too.

It can be difficult knowing where to start and what actions to take to restore thyroid function and improve your symptoms, but making simple changes to your diet and lifestyle is a great starting point. If you are interested in addressing your health concerns the natural way or would like to find out more about working with me and how nutritional therapy could benefit you, I offer free 20-minute exploratory calls. Please do get in touch by sending an email to as I’d love to be part of your wellness journey!

References: Iodine: Food Factsheet. Available at:

British Thyroid Foundation. Available at:

He, S. Wang, B. Lu, X et al. (2018). ‘Iodine stimulates estrogen receptor singling and its systemic level is increased in surgical patients due to topical absorption’, Oncotarget, 9 (1). pp.375-384.

The UK Iodine Group. Available at:

Woodside, J.V. & Mullan, K.R. (2020), ‘Iodine status in UK–An accidental public health triumph gone sour’, Clinical Endocrinology, 94 (4). pp.692-699.