Iodine is an essential element for human body to create thyroid hormones. Iodine can not be generated in the body and can only be taken from food source. When Iodine is deprived in a body, thyroid can not generate hormones and long term deprivation can cause hypothyroidism.
Thyroid hormone helps increase metabolism and burn energy. When not enough thyroid hormone is produced, increase in sensitivity to cold, increase in white hair, swelling, constipation, fatigue may occur. Thyroid hormone also plays a major roll in development of infants and fetus. For these very reasons, iodine is essential nutrient for human body.
When excessive amount of iodine is taken in your body, usually extra iodine will be discharged. Though, long-term continuous excessive intake of iodine or people with pre-existing problem with thyroid may cause harm to your body. Food Nutrition Board has determined tolerable upper intake level for ages.
|Birth to 6 months||Not possible to establish*||Not possible to establish*|
|7–12 months||Not possible to establish*||Not possible to establish*|
|1–3 years||200 mcg||200 mcg|
|4–8 years||300 mcg||300 mcg|
|9–13 years||600 mcg||600 mcg|
|14–18 years||900 mcg||900 mcg||900 mcg||900 mcg|
|19+ years||1,100 mcg||1,100 mcg||1,100 mcg||1,100 mcg|
|Birth to 6 months||
* Formula and food should be the only sources of iodine for infants.
Source: Office of Dietary Supplements
For people with iodine hypersensitivity, a people naturally sensitive to iodine, needs to be cautious regardless of tolerable upper intake level on above graph.