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Your Thyroid and the Importance of Iodine

I clearly remember my father chastising me for saying “seaweed”.  It’s a “sea vegetable” he would insist, as I rolled my eyes and crunched my favourite snack; a toasted nori sheet covered with Umeboshi (a sour fermented plum paste from Japan).

It wasn’t until I was an adult that I came to appreciate the significance a name has. Dad is also an integrative physician, and what he was doing by being pedantic, was to help me appreciate that these “sea vegetables” were as important as “land vegetables” for our health.

Sea veggies like nori, kelp and dulse, as well as shellfish and seafood are rich in trace minerals and iodine; a nutrient of special concern in NZ.  Our soils are notoriously deficient in this important mineral and with the growing concern for ocean welfare, many are opting out of eating kiamoana (seafood).

My protocols for addressing stress often also include supportive nutrients, botanical medicine, injectable therapies, mindfulness practices, adequate sleep and physical activity, reducing light at night and background noise, a diet that balances your blood sugar and time in nature.

History Lesson

In the 1920’s most school age children in NZ were found to have some degree of goitre (a thyroid condition due to insufficient iodine intake). By the 1960’s thanks to the mandate to iodize salt and the dairy industry using iodophors as sterilizers which led to the contamination of milk with iodine, iodine intakes increased. For most of us in developing countries, our primary source of iodine is in the form of sodium or potassium iodide, added to table salt and mandated to be used in products like bread since 2009. Among school aged children, 51% of dietary iodine comes from bread (1). 

This begs the question, if we don’t eat commercially produced bread or table salt due to the presence of flow agents, and avoid fish because of ethical or environmental concerns where do we get this important mineral?

Iodine is essential for normal brain development and iodine deficiency is one of the leading causes of mental retardation around the world. Iodine deficiency in children is associated with a drop in 12.45 IQ points, and children who do not get enough iodine may have impaired intellectual and motor performance and an increased risk of ADHD (3). When babies do not get sufficient iodine during pregnancy the damage to the brain can last a lifetime.

Reduced mental ability and cognitive challenges due to iodine deficiency occurs in almost 300 million people around the world (4). To make matters worse, not only does iodine deficiency rob our intelligence, it can also increase our risk of depression. With 1.3 million prescriptions for antidepressants doled out to kiwis in 2018 (5), we have to ask the question, could nutrient deficiencies be partly to blame?

Why Iodine?

The thyroid is a small butterfly shaped gland at the base of your neck.  If you’ve ever noticed pronounced lines or swelling on someone’s neck, you may have been looking at a person with a thyroid condition. 

The thyroid gland produces thyroid hormones which affect the function of every single cell in the body. Thyroid hormones control metabolism, heart rate and temperature. When thyroid function decreases due to lack of iodine or other cofactors such as L-tyrosine, selenium and zinc, our body slows way down. We get sick more often, we pile on weight no matter what we eat, we lose our hair, our hormones are thrown into a tailspin, we get constipated, confused, depressed and feel cold all of the time. 

Super Nutrient for Women’s Health?

While we largely regard iodine as a nutrient for thyroid and brain health, this nutrient places a significant role in estrogen metabolism and clearance, breast development ovulation.  Iodine is largely concentrated in breast tissue, as well as the female reproductive system.

Iodine has shown to be highly beneficial for women with fibrocystic breasts, premenstrual tenderness and may reduce risk of breast cancer (5). It helps to protect breasts from cell damage, which is likely why we see that countries with higher dietary iodine intake having lower risk of breast cancer. Iodine deficiency is associated with increased risk of fibrocystic breasts which may affect up to 50% of women, and supplementation often shows improvement in lumpiness.

Iodine deficiency and resulting thyroid problems is also associated with development of breast cancer and the increased risk of metastasis in people already diagnosed. Iodine is taken up by breast cells and is thought to prevent cell changes leading to the development of cancer (6).

Iodine is required for progesterone production and ovulation as well as clearance of excess estrogen in the body. Many women I work with have imbalances of estrogen with relatively low progesterone levels. Clinically speaking iodine may benefit women who experience symptoms during the second half of their cycles, including PMS, breast tenderness, low energy and fatigue.

Bad Bread, Broccoli and “Goitrogens”

Goitrogens are substances that disrupt the production of thyroid hormones and interfere with iodine uptake and mess with thyroid function. Goitrogens generally increase TSH (thyroid stimulating hormone) and cause the thyroid to grow in size, eventually leading to goitre (swelling of the gland and the appearance of a thick neck). 

Environmental goitrogens such as parabens, phthalates and BPA found in plastics and personal care products (anything that includes ‘fragrance’ on the label), perchlorates from dry cleaning and certain pesticides (another reason its important to choose organic) all disrupt thyroid function (7).

Other important goitrogens include halogen family elements such as chlorine, fluoride and bromide that compete with iodine and block its uptake in the thyroid gland. Swimming in pools treated with chlorine or breathing steam from showering in chlorinated water also disrupts thyroid function by blocking iodine (8). Consuming commercially baked bread containing bromide in dough conditioners, chlorinated and fluoridated drinking water and exposure to household and personal care products containing goitrogens is one reason we are seeing thyroid issues in epidemic proportions around the world.

Brassica family vegetables, including broccoli, cauliflower and kale, if consumed raw and in large proportion may also block iodine uptake in animals (9). Up to two cups per day is generally not problematic for those with a healthy thyroid. Soy is also known to bind iodine and can be considered a “goitrogen”. This may be one reason that in countries like Japan, soy is generally consumed with seaweed.  In my practice I generally don’t recommend people avoid brassica’s as these foods have so many other benefits. Rather, I suggest as dad would, we all consume sea veggies as part of a healthy whole foods diet.

Sea Veggies to the Rescue!

As an Integrative Physician, I cannot in good conscience recommend people consume processed foods like bread to meet their dietary needs for iodine.

Consuming kelp, nori, dulse not only provide large amounts of iodine but come packaged with other important trace minerals and nutrients not found in land veggies.

New Zealand brown kelp is a highly sustainable and nutritious local superfood many of us should consider adding to our diets. Not only does it contain iodine, but is a natural source of trace elements, minerals like zinc, selenium, magnesium, iron, copper and calcium.

Iodine such as found in kelp can help us to detoxify other halogens from our body and promote healthy thyroid function, immunity, weight, metabolism and brain function.

Kelp can be added to food as sprinkles in place of salt, and sea veggies like nori and dulse make delicious additions to salads and stir fries. However if the thought of crunching on a sour plum covered nori sheet, or a seaweed salad isn’t your thing, consider a kelp supplement like Powerdine. Powerdine is high dose as compared to the low dose available in most supplements.

Your body, brain and babies will thank you.

Who Would Benefit Most?

Iodine is essential for proper thyroid function and metabolism, enhancing immunity and brain function. When we take iodine or eat foods containing iodine we are looking not only to avoid deficiency, but to optimize levels. The general recommendation for dietary iodine intake set at 2mg/kg/per day is generally far too low for most.

 Generally, the following people would benefit from supplementing with sea vegetables like kelp:

  • Those avoiding processed foods
  • Those who are pregnant or breastfeeding
  • Those who do not eat seafood
  • Those who avoid adding additional iodized salt to their diet
  • Athletes or those who are physically active/sweat a lot.
  • Women with fibrocystic breasts
  • Diagnosed low thyroid hormone production

For those of us with a healthy thyroid taking a kelp supplement or additional iodine daily or every other day can help support our metabolism, hormones, brain function, mood and help us feel our best. Iodine is a crucial and often underappreciated nutrient that many of us are deficient in, and deficiency symptoms often overlooked.

If you have a thyroid condition please speak to your GP or naturopath, as it is important to monitor TSH levels, when taking high dose iodine supplements like Powerdine.

The information in this blog is for educational purposes only.  Please speak to your doctor or naturopath before engaging in a new supplement routine. High dose iodine supplements may be contraindicated in autoimmune thyroiditis or hyperthyroid.


  1. (NZ stats)



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