Iodation of Salt


What is iodine?

Iodine is a mineral found in the food we eat. It is absorbed from the soil into the plants that form part of our daily diets. It is an essential mineral playing a role in important processes within the human body. Iodine forms part of the thyroid hormones, which are essential for normal physical and mental development.

Why is iodine important?

A lack of iodine from the diet can result in a number of Iodine Deficient Disorders (IDDs). IDDs include loss of energy, reduced mental ability, retarded physical development, and can results in still births or the development of goitre (enlargement of the thyroid gland).

It is estimated that 1.6 billion people throughout the world are living in iodine-deficient environments. About 200 million have goitre, while 20 million suffer from brain damage that could have been prevented.

IDD was one of the earliest micronutrient-related problems identified in South Africa. Incidence of iodine deficiency was first reported in the Langkloof area of the former Cape Province in 1927. Goitre was observed in several areas in the country before the 1950s. A “goitre belt” was identified as an area along the southern and eastern parts of the country, extending through central South Africa. Since then, iodisation of salt (adding iodine to salt) has been done and the incidence of goitre has notably decreased.

Why do we need to iodate salt?

Most of the world’s iodine is found in our oceans, although it is also present in soil. Over the centuries, large amounts of iodine have been leached from surface soil by rain and carried back to the sea. Iodine then returns to the soil via rainfall after being absorbed into the atmosphere from the sea’s surface, but this process is very slow.

Repeated flooding of areas also increases the depletion of iodine from the earth. Crops grown in these areas therefore often lack iodine, and as a result, people who are dependent on food grown in iodine-poor soil become iodine deficient.

When goitres and brain damage are caused by lack of iodine, they can be cured in the early stages by large doses of iodine, but in later stages, there is no help for the sufferers.

Preventing Iodine Deficiency Disorders (IDDs)

Iodine can be provided to the human diet in several ways, but the fortification of salt with potassium iodate is the most common way. The costs of fortification are low, the process is simple and iodine intolerance is very rare. Adding iodine to salt also does not affect the colour or taste of the end product.

Iodation of Salt in South Africa

Through encouragement from UNICEF (United Nations Children’s Fund) and agreement by heads of state of many countries; there was a worldwide objective to eliminate IDDs as a public health problem by the end of the twentieth century through the compulsory addition of iodine to salt.

In South Africa already as early as 1948 a Goitre Research Committee at the University of Pretoria was established and in 1954 the voluntary iodisation of salt (10 ppm to 20 ppm) became legal. In 1995 the National Department of Health passed a regulation that after 1 December 1995, all salt sold in stores must be iodated at a concentration of 40-60mg/kilogram (40-60 parts per million) at the time of packing. In 2006, this mandatory band was widened to 35 ppm to 65 ppm.

Normal daily consumption of commercial salt will supply all the iodine an adult needs, although a much higher consumption than this is safe to consume. Non-iodated salt still remains available in pharmacies for the few people who are iodine intolerant. Salt sold to food manufacturers is also iodine-free.

Since iodisation of salt became mandatory, studies have reported that South Africa has nearly achieved the elimination of IDDs. Although the complete elimination of IDD is not possible because non-iodised salt often still enters the market. Rural and poor consumers often trade in non-iodised salt. Salt used for agriculture and animal feed is often sold in informal settlements as this form of salt is very cheap. Salt sifted directly from salt pans is also traded informally in the Northern Cape and contains no added iodine.

“Iodine deficiency is so easy to prevent that it is a crime to let a single child be born mentally handicapped for that reason.” Henri Labouisse, Executive Director, UNICEF, 1978.

(Note: There is no difference between iodised and iodated salt – iodated simply refers to the fact that potassium iodate is used.)