Iodised salt

Studies in people

• Open question

  Child growth³

  Scientists do not yet know whether iodised salt helps children grow, as no review has pulled the evidence together.

• Benefit

  Iodine deficiency progress⁴

  In some countries, more dietary salt was adequately iodised, and many reached or neared eliminating iodine deficiency.

• Open question

  Iodine levels in pregnancy⁵

  In pregnant women in Turkey, iodised salt use was common but many still had low iodine levels.

• Concern

  Thyroid health in India⁶

  In Manipur, iodised salt did not stop goitre; thiocyanate from bamboo shoots was linked to thyroid disease.

• No harm found

  Thyroid and goiter risk⁷

  In Chinese people, iodised salt intake was not linked to goiter, two-degree goiter or cretinism.

• Benefit

  Iodine levels in children⁸

  In school-aged children on São Miguel Island, iodised salt use was linked to iodine levels that were not deficient.

• Benefit

  Thyroid health in pregnancy¹⁰

  Pregnant women who used iodised salt long-term had healthier thyroids than those who only started when pregnant.

• Open question

  Iodine levels in the body¹²

  Even where iodised salt is used, many adults in Gilgit-Baltistan still had low iodine levels.

• Benefit

  Iodine intake in children¹⁴

  Using iodised salt in meals fully met iodine needs for preschoolers but gave schoolchildren only part of what they need.

• No harm found

  Children's brain development¹⁵

  In children aged 4 to 6, iodised salt did not clearly improve thinking or language test scores.

• Concern

  Thyroid nodules and cancer¹⁶

  Eating more than 5g of iodised salt a day was linked to thyroid nodules and thyroid cancer in this study.

• Concern

  Iodine in pregnancy and children¹⁷

  In this Indian study, iodised salt gave pregnant women enough iodine, but their children got more than enough.

• Open question

  Iodine deficiency in children¹⁸

  Children in this area still lacked iodine even though most families used iodised salt.

• Open question

  Iodine deficiency and excess¹⁹

  Iodised salt raised iodine levels in Malaysian villagers, but some still had too little and others too much.

• Benefit

  Birth defects prevention²⁰

  Women who ate salt with added folic acid had more folate in their blood, which may help prevent spina bifida.

How it’s made and used

• Iodine intake in adults⁹

  In Italian adults, iodised salt supplied about 43% of iodine, but most still fell short of the recommended amount.

• Iodine intake in coastal areas¹¹

  In Zhejiang, people who used iodised salt had higher dietary iodine intake than those who did not.

• Iodine nutrition in pregnancy¹³

  Iodised salt gave most groups enough iodine, but pregnant women in Croatia were sometimes borderline low.

• Iodine in cooking²¹

  Iodised salt in bouillon cubes and powder keeps its iodine when boiled in broth or cooked into rice.

The signal at the top counts the findings in people and in animal and lab studies. A concern in studies of people outranks animal and lab studies, and “No concerns” needs at least one finding in people. When most findings in people point one way, the page leans that way (“Mostly”), and every finding is still shown. Findings whose study type is not stated are shown but not counted. This page is a reference, not medical advice. It describes what regulators and published research say. Talk to a doctor or dietitian about your own diet.