Requirements

The Recommended Dietary Allowance for iodine is: 150 µg

Signs of Deficiency
In adults an iodine deficiency can result in hypothyroidism, a reduced rate of thyroid hormone secretion characterised by lethargy, weight gain and sometimes goiter. A deficiency can result in impaired growth and neurological development and has been linked with thyroid cancer in a number of studies.4 In adult women, iodine deficiency has been linked with breast cancer.3,5 In children, a iodine deficiency can result in mental retardation, growth stunting, impaired movement, speech or hearing and cretinism.

Interactions
Certain foods, consumed raw and/or in large quantities can inhibit the uptake of iodine by the thyroid gland. These foods include: Brussels sprouts, cabbage, cauliflower, kale, peaches, pears, spinach and turnips.3

Signs of Toxicity
Large doses of iodine can produce a metallic taste in the mouth and sores in the mouth, swollen salivary glands, diarrhoea and vomiting.3,5

Current Research

Brain function
Researchers have linked low iodine consumption with impaired cognition. Countries such as China, Ecuador, Indonesia, Switzerland and Zaire, for example, traditionally have a low rate of iodine excretion in the urine.1 In Indonesia, supplementing infants with iodised oil reduced infant mortality less than 4 months of age.1

Immune Function
According to Alexander Schauss, "Iodine also plays an important role in the immune system where it supports the microbicidal activity of polymorphonuclear leukocytes."6