Diets can easily become deficient in iodine, particularly if they are low in seafood or milk and dairy products. The WHO has indicated that median urinary iodine of 100–199 μg/l in a population is regarded as indicative of an adequate iodine intake.
Iodine: A global concern
The International Council for the Control of Iodine Deficiency Disorders , who were formed to better understand the spectrum of iodine deficiency disorders, has supported the use of household iodized salt and the use of such salt in food processing and manufacture to combat major iodine deficiency in areas of low iodine intake. During the past 25 years, the number of countries with iodine deficiency has reduced to 32; these still include many European developed countries. To ensure that adequate iodine status is maintained there must be continuous monitoring and where this has not been performed iodine deficiency has often recurred.
Iodine deficiency and pregnancy
Mild iodine deficiency can lead to impaired development and neurocognition and overt deficiency is known to cause cretinism in extreme cases. Iodine deficiency is particularly important in pregnancy as the foetus relies on maternal thyroxine (T4) exclusively during the first 14 weeks and also throughout gestation. As this hormone is critical to brain and nervous system maturation, low maternal T4 results can result in low child intelligence quotient. The recommendation for iodine intake in pregnancy is 250 μg/day to prevent foetal and child brain function impairment. More randomized controlled trials of iodine supplementation in pregnancy are required in mild iodine-deficient areas to inform public health strategy and subsequent government action on suitable provision of iodine to the population at risk.
To ensure you are achieving enough iodine you should not go below the RDA of 150 μg/day and 250 μg/day if you are pregnant. This amount can be achieved by a combination of diet and supplementation for those who do not consume adequate iodine in their diets. Testing can be carried out using urinary analysis of iodine.
Lazarus JH. The importance of iodine in public health. Environ Geochem Health. 2015 Feb 7. [Epub ahead of print]