Last Updated: September 28 2022

Iodine is a mineral for thyroid function found mostly in iodized table salt, fish, and highest in seaweed. Despite most first world diets being sufficient in iodine, it may benefit those who do not consume seafood and are also in a high risk population (pregnancy and intentional salt restriction).

Iodine is most often used for


Iodine is an essential mineral in the diet due to its importance towards cognition and fetal development secondary to being required for thyroid hormones; iodine is central to the active thyroid hormones T3 and T4, and a true iodine deficiency results in less of these hormones and may result in reduced cognition (if a subclinical deficiency) or cretinism (severe deficiency in utero).

Despite the importance of iodine, it is not a common dietary supplement. This is due to table salt being iodized (added iodine) and even relative deficiencies being quite rare in first world countries (it is a common issue in developing countries due to iodine only naturally occurring from fish and seaweed which may not be consumed); actually benefitting from supplementation of iodine requires a 'perfect storm' of situations to occur which are outlined in the dosing section but not many people will meet these requirements.

Supplementation of high doses of iodine in otherwise healthy people does not appear to result in much, since it is readily excreted and normalized. There may be a very small and (clinically) irrelevant antiinflammatory effect and a small reduction in thyroid hormones (rather than an increase), but that seems to be it. Obscenely high doses for a prolonged period of time, which occurs with consumption of unprocessed seaweed (mostly kombu) will result in benign goiter in all persons and thyrotoxicity in some persons with underlying thyroid issues.

What else is Iodine known as?
Iodine should not be confused with:
  • Table salt (chemically sodium chloride
  • but it also contains iodine)
Dosage information

Supplementation of iodine is designed to circumvent a deficiency, and deficiencies of iodine are quite rare in first world countries. For those in a first world country, iodine should only be considered if you meet all of the following requirements:

  • You are a vegetarian or vegan who actively avoids processed foods, or a meat eater who never eats fish and avoids processed foods
  • You avoid adding additional iodized salt to your diet
  • You avoid consumption of seaweed or seaweed based products (such as sushi, which are wrapped with Nori)

Assuming all the criteria are met, recommendations for iodine intake tend to be in the range of 75-150 μg (micrograms) or 0.075-0.15 mg daily while higher doses are not inherently dangerous although there may be a slight suppression of thyroid hormones (T3 and T4) at 500 μg or above.

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