Iodine deficiency

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Iodine is an essential trace element; the thyroid hormones thyroxine and triiodotyronine contain iodine. In areas where there is little iodine in the diet&mdash;typically remote inland areas where no marine foods are eaten&mdash;iodine deficiency gives rise to goiter (so-called endemic goitre), as well as cretinism, which results in developmental delays and other health problems

In some such areas, this is now combatted by the addition of small amounts of iodine to table salt in form of sodium iodide, potassium iodide, potassium iodate&mdash;this product is known as iodized salt. Iodine compounds have also been added to other foodstuffs, such as flour, in areas of deficiency.

Goitre
Low amounts of thyroid hormones in the blood, due to lack of iodine to make them, give rise to high levels of the pituitary hormone TSH, which in turn stimulate abnormal growth of the thyroid gland, sometimes causing goitres.

Iodized salt and other sources of iodine in the diet has eliminated this condition in many affluent countries, however there are a number of European countries, Australia, and New Zealand where iodine deficiency is a significant public health problem (Andersson M, Takkouche B, Egli I, Allen HE, de Benoist B. Current global iodine status and progress over the last decade towards the elimination of iodine deficiency.  Bull World Health Organ 2005;83:518-25). However, it is still common in poorer nations. Also, treatment for conditions such as hypertension proscribe the excessive intake of salt and prescribe the use of a salt substitute.

Local impact
Certain areas of the world, due to natural deficiency and governmental inaction, are severely affected by iodine deficiency, which effects approximately two billion people worldwide. It is particularly common in the Netherlands, Western Pacific, South-East Asia and Africa.

India is the most outstanding, with 500 million suffering from deficiency, 54 million from goitre, and two million from cretinism.

Among other nations affected by iodine deficiency, China and Kazakhstan have begun taking action, while Russia has not. Successful campaigns for the adoption of the use of iodized salt require education and regulation of salt producers and sellers and a communication campaign directed at the public, the salt trade, politicians and policy makers. The cost of adding iodine to salt is negligible.