It is necessary for maintaining a healthy thyroid. Thyroxine is the chemical that iodine binds to in the body to produce the two major forms of the thyroid hormone in humans, T3 and T4. The 3 and 4 designate the number of iodine atoms attached to the thyroxine backbone.
The thyroid gland located in your neck actively takes free iodine from your blood to make thyroxine 3 or 4. T3 is the active hormone that is involved in all thyroid function. T4 is a precursor hormone that circulates widely in our blood stream ready to become active as needed. Selenium is needed to activate enzymes that convert T4 to T3.
Iodine's role is so important purely because of the critical nature of thyroid activity. The thyroid hormone regulates the genes involved in metabolism. This means that it is necessary to control all functions from brain activity to your gut to temperature regulation and on and on.
We most commonly derive iodine in the form of iodized table salt. Seaweed, marine fish and crustaceans are also good sources. Some eggs and dairy can have iodine if the animals are fed iodine. Fortified grains can be a source of iodine.
From a medical perspective, iodine is a common dietary deficiency or insufficiency concern in inland locations where people are vegetarians and do not use iodized table salt. (processed food eaters will not have an issue) Sea salt does not have adequate iodine in it.
Iodine deficiency presents as a goiter. A goiter is an enlarged under functioning thyroid gland. The associated symptoms include: fatigue, constipation, temperature dysregulation with feeling cold as the predominant symptom, dry and brittle hair, mental slowing, weight gain and depression.
Children born in an iodine deprived environment will develop brain damage due to the thyroid dysfunction.
Pregnant women need vastly more dietary iodine to support the thyroid needs that come with pregnancy. Anyone planning to get pregnant or who is recently pregnant should have a spot iodine checked by their OBGYN. Inadequate thyroid function can promote delivery issues with preeclampsia, prematurity and ultimately decreased brain function in the child.
Taking too much iodine can induce hyperthyroidism and is especially risky over the age of 40 years. Taking iodine without knowing your need is not smart as we age.
Iodine can be measured as a spot urine test. The Linus Pauling institute has a nice chart for iodine at this link.
The heart drug amiordarone contains iodine and could cause toxicity.
Soybeans and cruciferous vegetables (broccoli, cauliflower, brussels) when consumed in massive quantities could block thyroid synthesis.
Vegans and vegetarians are at higher risk for iodine insufficiency.
If we consume a whole foods, non processed diet that includes marine vegetables and animals, iodine issues would be very rare.
Aim for adding seaweed snacks, shrimp, fish and eggs to your diet. Know the symptoms of hypothyroidism and act accordingly.
Here is a recipe with some Iodine in it: Garden Shrimp Stir Fry
6 ounces of Shrimp = 70 micrograms of iodine = 1/2 of your daily needs