Where can you find Iodine in the diet and what is it? Iodine is a trace mineral found in food whose main purpose in the body is to support the thyroid, namely to produce hormones. Iodine is converted in to iodide in the body by the intestinal tract. It is the iodide that is used to produce the hormones in the thyroid. The trace mineral selenium also forms a part of the process, so it's important that the correct amounts of selenium are also in the diet when discussing iodine.

So what does a healthy thyroid do for your body?

  • regulates body temperature
  • regulates the production of energy
  • influences growth and differentiation (where ordinary cells in the body are converted in to something more complex to perform a specific task)
  • influences growth, blood cell production, nerve & muscle function
  • stimulates your metabolism
  • helps your body burn excess fat
  • mental clarity & cognition (including speech)
  • the condition of your hair, nails, skin & teeth
  • converting carotene to vitamin A
  • protein synthesis
  • carbohydrate absorption from the intestines
  • the creation of cholesterol in your body (your body actually produces most of it's own cholesterol, very little comes from what you eat - read this Harvard article for more information)

What happens to the body when you're deficient in iodine?

When it comes to iodine in the diet and not having enough of it, the most common symptom is goitre, which is enlargement of the thyroid gland (big puffy neck in laymans terms). It's not common in Australia but there are around 200 million people in the world with goitre, mainly from South America, Asia & Africa. 96% of the cases are caused by an iodine deficiency.

You can certainly have an under or over functioning thyroid without a goiter appearing. Hypothyroidism, which is the under production of hormones is also common. Those with a poorly functioning thyroid can also suffer from:-

  • weight gain associated with a sluggish metabolism
  • sensitivity to the cold
  • rapid pulse
  • heart palptations
  • hardening of the arteries
  • dry hair & skin
  • nervousness, restlessness, irritability
  • slowed mental responses

Where can I get iodine in the diet?

Seafood, kelp & sea vegetables are the best dietary sources of iodine. Seafood such as haddock, perch, salmon, tuna, prawns & oysters contain iodine. For vegetarians & vegans, you can also get dietary iodine from Dulse Flakes & Kelp. Stepping out of the sea, you can get small amounts of iodine from spinach, broccoli, mushrooms, potatoes and asparagus if they were grown in iodine rich soil, although this is not the ideal situation to get iodine from. Most people get the bulk of iodine in their diet from iodizes salt, but it's becoming less common for its use and as a result, many people are becoming deficient.

The richest source of iodine in the diet is kelp.

The body doesn't store iodine like many other minerals, so a regular intake in the diet is essential. The recommended daily intake is 150mcg for adults. This increases to 220mcg for pregnant women and 270mcg for lactating women.

Iodine can also also be absorbed through the skin in a Lugol's Iodine solution for those who have issues absorbing it through the intestinal tract, but please, DO NOT do this without seeking professional advice first.

While iodine toxicity hasn't been reported through dietary measures, please only use therapeutic doses under supervision. Excess iodine supplements can encourage acne, cause mouth sores, a metallic taste in the mouth, diarrhea & vomiting.

For those with a deficiency, therapeutic doses of supplements are available from qualified practitioners after a suitable diagnosis. Please do not self-diagnose or treat low iodine or thyroid issues.

Iodine in pregnancy

The daily requirements for iodine increase during pregnancy (from an average of 150mcg a day to 220mcg a day). Severe iodine deficiencies during pregnancy can cause an extreme & irreversible mental & physical retardation called cretinism. On the flip side, excessive amounts of iodine can cause an unborn child to develop a goitre so severe that their airway can be blocked. The recommended upper daily limit is 1100mcg per day, which is closet to 5x the recommended does. Please, DO NOT self medicate with iodine during pregnancy.

Can any foods block the absorption of iodine in the body?

Yes. They even have a special name, goitrogens. They are usually inactivated by cooking, so it's recommended to cook these foods if you have an iodine deficiency in your diet or if you have been diagnosed with a thyroid condition. If you have normal thyroid function, eating these foods raw should not impair normal thyroid function unless you're eating excessive amounts of them raw and have a low intake of iodine at the same time. This accounts for approx 4% of the goitre cases in the world. The goitrogen foods include:-

  • cabbage
  • mustard
  • turnips
  • soy beans
  • millet
  • cassava root
  • peanuts
  • pine nuts

Hashimoto's Disease

Hashimoto's is an auto-immune disease that effects the thyroid. It's caused by inflammation of the thyroid because the immune system attacks it. This produces an under active thyroid, called hypothyroidism. When the thyroid is inflamed, it is unable to effectively produce the hormones it needs, which shows similar symptoms to low iodine in the diet. I am no expert in Hashimoto's. If you show any of the signs of a sluggish thyroid, please seek a medical diagnosis and treatment from some one who understands the disease.

One of the most prominent sufferers of Hashimoto's in Australia is Sarah Wilson. The I Quit Sugar diet is designed to reduce inflammation in the body, but again, please, under no circumstances should you self diagnose or self treat a thyroid issue. You can read the Auto-Immune section of her personal blog to read about her journey.

Bibliography
  1. Nutrition Almanac, Sixth Edition
  2. Laugh With Health
  3. Understanding Nutrition
  4. Wardlaw's Perspectives in Nutrition