By Andrea Cannas


September 17, 2023


Iodine and Thyroid Hormones for Brain Development

  • The Mighty Mineral for Healthy Moms and Bright Kids

My own study has been published in the British Journal of Nutrition where I discovered that Greek-Cypriot pregnant women are iodine deficient at their first-trimester. This was not a surprise as it is a public health matter affecting over 20 European countries. Iodine deficiency causes hypothyroidism and has shown to reduce fecundity (time taken to conceive) as well as impact on the ability to carry to term in the mothers. It can also impair the neurological health and growth of the newborn, including long-term issues for the child that may be irreversible if not addressed.

A pregnant woman needs double the amount of iodine compared to the average adult. This is because iodine supply during the first 12 weeks of pregnancy is critical for thyroid hormone production and foetal brain development. An iodine-containing supplement 100-150µg/d can be recommended during the first or second trimester by a health professional. However, in the case of unplanned pregnancies (which are more common), iodine supplementation at the point of pregnancy may be started too late and women may miss the critical window to optimise their thyroid stores. Scientists now advocate for optimal iodine nutrition in women of reproductive age and suggest women are iodine-sufficient 3 months before conception. 

I came up with a list of questions which may have crossed your mind and have provided some answers to these below.

  • Is dietary iodine the same with radioactive iodine? What’s the difference?

Iodine is an element that is used by the thyroid. Humans cannot produce iodine, so it must be consumed. Radioactive iodine is a treatment used for certain thyroid diseases and cancer.

  • Where do I get dietary iodine from?

You get iodine from dairy, white fish and seaweed. Fish provide you with more iodine per 100g of food compared to milk or dairy products. You can also get it from brown seaweed (kelp/kombu) but you need to be careful with this seaweed type as it can be dangerously high in iodine. Kelp and other commercially-available supplements may not always provide accurate information with regards to the true iodine content of the seaweed (i.e. it can be higher than what the label says it is).

  • What meals can I have to meet my iodine requirements?

Although everyone’s needs are different, here are some meals you can include in your diet:

  1. 1-2 fish dinners (140g fillet of trout, fresh tuna or cod) weekly to provide 100 µg iodine 
  2. 2-3 servings of goats cheeses and/or full-fat greek yoghurt
  3. Up to 8 free-range eggs per week

  • Am I at risk if I am a vegan?

If you are vegan, it is likely you are relying on dairy-free plant-based alternatives in place of cow’s milk. These dairy-free drinks are usually not fortified with iodine and are not an adequate substitute.  It is therefore important for vegetarians and vegans to mitigate any risk of iodine deficiency through a supplement or appropriate food combinations.

  • Do I need a supplement?

It is difficult to answer this question without providing you with a personalised assessment. International recommendations generally differ across the UK, Europe and US. While some countries i.e. America, New Zealand and Australia highlight the importance of supplemental iodine in advice provided to expectant mothers, it is not on the government agenda of others i.e. the UK. In Cyprus specifically, there is no official recommendation to take an iodine supplement and women are not made aware of its critical importance. In Cyprus, only 1/3 of women reported using supplements containing iodine and the most frequently recommended maternal supplement by healthcare professionals contained no iodine at all.

Also, there are so many multi-vitamin and/or pregnancy supplements out in the market and not all of them contain adequate amounts of iodine (some contain no iodine at all!). Finally, how well exposed you are to iodine is country-specific and varies between populations, due to the fact that some countries have adopted the WHO Iodised Salt programme while others have not.

  • Can iodine support hypothyroidism?

The benefits of iodine supplementation for thyroid function depend on the severity of iodine deficiency, duration (i.e. whether chronic or acute), food iodine content, formulation and dosage and the status of thyroid iodine stores. Caution is required with single nutrient formulations and seaweed formulations which are dangerously high in iodine. Excess iodine intakes can also negatively impact thyroid health in pregnancy and increase the risk of iodine deficiency disorders. I prefer taking iodine as part of a multivitamin as it tends to work with other key nutrients to support thyroid function such as selenium and iron. However, each case is different and single iodine sublingual or topical solutions may also be beneficial.

  • Can iodine support my child’s academic performance?

See another blog I wrote for Rise Up Children’s Therapy Center if you would like to know a bit more about how nutritional therapy can support your child’s learning and development here: 


  1. Fileleftheros Newspaper (2023). Ανεπάρκεια ιωδίου σε εγκυμονούσες γυναίκες στην Κύπρο. Available at:
  2. Simerini Cy Newspaper (2023). Sunday 28 May, Public Health 12, page 12. Available at:
  3. Iodine Global Network (2022). IDD Newsletter. Available at:


  1. Cannas A, Rayman MP, Kolokotroni O, Bath SC. Iodine status of pregnant women from the Republic of Cyprus. Br J Nutr. 2022 Mar 3;129(1):1-25. doi: 10.1017/S0007114522000617. Epub ahead of print. PMID: 35236523; PMCID: PMC9816652.
  2. BDA(2021). Iodine Food Fact Sheet. Available at:
  3. Bath SC, Verkaik-Kloosterman J, Sabatier M, Ter Borg S, Eilander A, Hora K, Aksoy B, Hristozova N, van Lieshout L, Tanju Besler H, Lazarus JH. A systematic review of iodine intake in children, adults, and pregnant women in Europe-comparison against dietary recommendations and evaluation of dietary iodine sources. Nutr Rev. 2022 Oct 10;80(11):2154-2177. doi: 10.1093/nutrit/nuac032. 


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