|Description||Iodine is an essential trace element – only small amounts are needed to maintain good health.|
|Function/ Used for||Iodine is used to form thyroid hormones (thyroxine and tri- iodothyronine), which regulate metabolic rate.|
EU NRV: 150µg
UK average daily intake
Requirements vary depending on age and gender. The UK National Diet and Nutrition Survey lists up-to-date intake requirements and average intakes1
|As a supplement||Available as a single supplement. Also commonly available as part of a multivitamin and mineral formula.
Different multivitamin and minerals products will vary in the percentage NRVs they include. People should always check the label for information about a specific product.
|Found in (dietary sources)||Good sources include saltwater fish and shellfish, kelp, seaweed, sea salt, iodised salt, and dairy products.|
|Deficiency||Deficiency may lead to hypothyroidism. Symptoms include tiredness, muscle weakness, breast pain and tenderness, sudden or unexplained weight gain. A classic deficiency sign is goitre (enlargement of the thyroid gland in the neck in order to compensate for low levels of iodine intake).
Infants born to severely deficient mothers are likely to suffer from cretinism (stunted physical and mental growth).
|Precautions and contraindications||Supplements usually only necessary on medical advice.
Safe Upper Level: 500µg /day2
|Use in pregnancy and breastfeeding||Doses exceeding the NRV should not be used during pregnancy or breastfeeding (they may result in abnormal thyroid function in the infant)3.|
|Interactions e.g. with other medications||Iodine may interact with thyroid medication3.|
|Adverse effects||High iodine intake may induce hyperthyroidism (particularly in those over the age of 40 years) or hypothyroidism in autoimmune thyroid disease.
Toxicity is rare with intakes below 5000µg daily and extremely rare at intakes below 1000µg daily.
Hypersensitivity reactions including headache, rashes, symptoms of head cold, swelling of lips, throat and tongue, and joint pain have been reported.3
3. Mason, P. Dietary Supplements. Pharmaceutical Press, London, 2001.