Iodine is an element which is essential in the human body for the production of thyroid hormones. Our bodies cannot make it, so we need to make sure we get it in our diet.

Firstly, let me tell you about the thyroid gland. It’s a small gland which sits at the front of the neck, just above the notch in your breast bone. You won’t really be aware of it unless you have a goitre, which is enlargement of the gland. Your thyroid produces a hormone, thyroid hormone, which sets your basal metabolic rate; the rate at which your cells break down energy. Thyroid hormone also has a function in normal growth and mental development in babies and children.

As iodine is required for the normal production of thyroid hormone, a deficiency can result in a goitre and hypothyroidism, or an under-active thyroid. The generalised symptoms of this include tiredness, weight gain, dry skin and hair, mental slowness and intolerance to the cold. Under-activity of the thyroid can affect most systems in our body, but other symptoms you might notice include impotence, heavy periods, constipation and a hoarse voice.

When a developing foetus is deprived of iodine, it can result in Congenital Hypothyroidism, which simply means hypothyroidism that you are born with. Unfortunately, the result of this is quite serious, in that it can cause mental retardation and growth problems.

Iodine levels are not usually tested by your GP, but because excess iodine is excreted by the kidney, this means that levels can be checked by measuring the amount in your urine. However, iodine status would normally be monitored by checking your thyroid hormone level, which is done with a blood test.

Unfortunately, iodine is usually found in seafood, meat and dairy products. It is also found in some vegetables, but because the iodine content will depend on the soil content, it varies regionally and is difficult to predict. The best vegan source of iodine is sea vegetables, although again the actual content can be unpredictable, varying between 16mcg and 165mcg per gram of kelp. Some parts of the world fortify their salt with iodine, but this is not recommended because of current guidelines to minimise salt intake. Current recommendations for daily iodine doses are 150mcg for adults, and 250mcg for pregnant and breastfeeding women.

If you are unsure that you are getting enough iodine from seaweed and fortified foods, the safest and most reliable way to maintain your levels is with a supplement, particularly if you are pregnant or breastfeeding.

If any of the above symptoms of hypothyroidism sound familiar to you, make sure you see your GP who can consider testing your thyroid function.

Thanks for reading,

The Vegan Doctor



4 thoughts on “Iodine”

  1. Hi,

    I’m only recently Vegan, I’m definitely concerned about getting enough Iodine, can I ask how you make sure you get enough?

    I’m tempted by a supplement, can this be dangerous? Can you have too much iodine?




    1. Hi Charlotte, as I mentioned in the article, food sources are often unreliable as you can’t always predict the iodine content. I take a daily kelp supplement for my iodine. Good luck with your vegan journey! Rebecca


  2. Hi I have hypothyroidism and take daily prescribed Thyroxine. My levels are checked regularly by my gp and are within normal levels.
    I have been a Vegan for nearly 4 years , I am a bit confused about whether I should be doing about iodine supplements or not?


    1. Hi, I can’t offer personalised medical advice, but I would recommend you speak to your doctor about this, as iodine supplementation, although necessary, can interfere with thyroid medication


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