Iodine is required for the production of thyroid hormones, which are necessary for normal brain development and cognition. Either low or high intake of iodine may lead to thyroid disease.

In normal adults, the daily production rate of the two biologically active thyroid hormones, tetraiodothyronine (which is better known as thyroxine and has four iodine atoms) and triiodothyronine (which has three), is approximately 100 µg and 30 µg, respectively. All of the thyroxine, but only about 20 percent of the triiodothyronine, is produced by the thyroid gland; the remainder of the triiodothyronine is produced through the extrathyroidal deiodination of thyroxine. A minimum of approximately 70 µg of iodine is therefore needed to produce these two hormones in the thyroid gland each day. A seaweed called bladder wrack has a high content of iodine.

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Iodine deficiency
Humans obtain iodine from their diets. The amount of iodine in food or water depends upon the amount of iodine in the local soil. Iodine deficiency is not common in the United States, but can occur. Inadequate intake of dietary iodine can lead to an enlarged thyroid gland (goiter) or other iodine deficiency disorders. Iodine deficiency is the world's leading cause of mental retardation in children. There are several countries where iodine deficiency is still a significant problem. For instance, China still has a way to go to eradicate iodine deficiency because of difficulties in fortifying salt in some remote regions. In these villages, iodine deficiency can cause neck goiters and mental retardation; more than 700 million Chinese live in iodine-deficient regions.
   Endemic goiter and cretinism associated with iodine deficiency have been depicted in paintings and statues since ancient times. Only during the past three decades, however, have iodine deficiency disorders been recognized as the leading cause worldwide of intellectual impairment. Development of the central nervous system for normal intellectual functioning depends on an adequate supply of thyroid hormones which require iodine for biosynthesis.

Radioactive Iodine Treatment
The main advantage of radioactive Iodine treatment for hyperthyroidism is that it tends to have a much higher success rate than medications. Depending on the dose of radioactive iodine chosen, and the disease under treatment (Grave's versus toxic goitre, versus hot nodule etc), success rate in achieving definitive resolution of the hyperthyroidism may vary from 75-100%.

Radioactive Iodine Side Effect
A major expected side effect of radioactive iodine in patients with Graves disease is the development of life long hypothyroidism requiring daily treatment with thyroid hormone. Occasionally, some patients may require more than one radioactive treatment, depending on the type of disease present, the size of the thyroid, and the initial dose administered. Many patients are initially unhappy at the thought of having to take a thyroid hormone pill for the rest of their lives. Nevertheless, as thyroid hormone is safe, inexpensive, and easy to take, and is identical to the thyroid hormone normally made by our own thyroid, this therapy is generally extremely safe and very well tolerated by the vast majority of patients.
   The long-term risk of developing a tumor in the thyroid gland or autoimmune thyroiditis, a progressive inflammatory disease of the thyroid, is increased after exposure to radioactive iodine therapy in childhood.

Tincture of iodine
Tincture of iodine (3% elemental iodine in water/ethanol base) is an essential component of any emergency survival kit, used both to disinfect wounds and to sanitize surface water for drinking (3 drops per liter, let stand for 30 minutes).

Food containing iodine - Low Iodine Diet - Source of Iodine
Iodine is found in seafood, iodised salt and some vegetables. Iodine is important for essential hormone development in the human body.  Iodine is found in foods as iodide. Our bodies need it to make thyroid hormones. The two main thyroid hormones, thyroxine and tri-iodothyronine, are synthesized from the amino acid, tyrosine, and from iodide.

Use of iodine
Iodine compounds are important in organic chemistry and very useful in medicine. The artificial radioisotope 131I, with a half-life of 8 days, has been used in treating the thyroid gland. The most common compounds are the iodides of sodium and potassium (KI) and the iodates (KIO3). Iodides, and thyroxin which contains iodine, are used internally in medicine, and as a solution of KI and iodine in alcohol is used for external wounds. Potassium iodide finds use in photography.

iodine supplement - Iodine Pill
Since the introduction of iodized salt, iodine supplements are unnecessary and not recommended for most people. For strict vegetarians who avoid salt and sea vegetables, 50 to 150 mcg per day is commonly supplemented. This amount is adequate to prevent iodine deficiency and higher amounts are not necessary.

Iodine requirement in pregnancy and neonatal period
The requirement for iodine by the mother during pregnancy is 250-300 microg per day. During lactation the iodine requirement is 225-350 micrograms. During the neonatal period the requirement of the infant is 90 microg a day. Pregnant women and young infants, but especially the second group, are more sensitive to the effects of an iodine deficiency than the general population because their serum thyroid-stimulating hormone (TSH) and thyroxine are increased and decreased, respectively, for degrees of iodine deficiency that do not seem to affect thyroid function in the general population.

Infant Survival Is Improved by Oral Iodine Supplementation
The Journal of Nutrition Vol. 127 No. 4 April 1997, pp. 574-578
Although reports suggest that infant mortality is increased during iodine deficiency, the effect of iodine supplementation on infant mortality is unknown. A double-masked, randomized, placebo-controlled, clinical trial of oral iodized oil was conducted in Subang, West Java, Indonesia to evaluate the effect of iodine supplementation on infant mortality. Infants were allocated to receive placebo or oral iodized oil (100 mg) at about 6 wk of age and were followed to 6 mo of age. Six hundred seventeen infants were enrolled in the study. Infant survival was apparently improved, as indicated by a 72% reduction in the risk of death during the first 2 mo of follow-up. Other infant characteristics associated with reduced risk of death included weight-for-age at base line, consumption of solid foods, female gender and recent history of maternal iodine supplementation. This study suggests that oral iodized oil supplementation of infants may reduce infant mortality in populations at risk for iodine deficiency.

Iodine allergy - Allergic Reaction to Iodine
The term iodine allergy is misleading since iodine is an essential trace element present throughout the body. No one is allergic to iodine. Patients who report iodine allergy usually have had either a prior contrast reaction or a shellfish allergy.

iodine test
organic iodine
potassium iodine
iodine soil
iodine therapy

Iodine crystals
The best form of iodine for water purification seems to be USP-grade resublimed iodine crystals. The crystals go from a solid to a gaseous state without passing through a liquid phase in between. A small pinch of iodine crystals (4-8 grams) can be re-used almost indefinitely for water purification.

Iodine and Hashimoto's thyroiditis
Like most autoimmune diseases of humans, Hashimoto's thyroiditis results from the combination of a genetic predisposition and an environmental trigger. A body of clinical and epidemiologic evidence points to excessive ingestion of iodine as an environmental agent. In genetically determined thyroiditis in animals, iodine enrichment has been shown to increase the incidence and severity of disease.

Iodine in China
There has been an increase in the prevalence of overt hypothyroidism, subclinical hypothyroidism, and autoimmune thyroiditis with increasing iodine intake in China.

Iodine questions
Q. What type of iodine treatment is best for hypothyroidism? Iodine tablet, iodine solution?
   A. Iodine deficiency disorder is rare in industrialized countries due to enrichment of table salt and cattle feed with iodine. Iodine deficiency is common in developing countries. Hypothyroidism in Western countries is most likely not due to low iodine intake or iodine deficiency. Iodized salt provides several hundred micrograms per teaspoon. The minimal recommended daily allowance (RDA) for iodine is 80 to 100 micrograms, with the average American diet containing between 200 and 700 micrograms.

Q.  I have noticed that the baby food sold at the health food stores (Whole Foods) contains no salt, and therefore, I assume, no Iodine. How do you suggest my 15month old grandson obtain sufficient Iodine in his diet if I make his baby food?
   A. I am not an expert in the topic of iodine requirement of babies or infants. Iodine is found in small amounts in various foods, including milk, grains, meat, and seafood. Iodine deficiency is rare in the United States. However, if you wish, you could add a small amount of iodized salt to the baby's food a couple of times a week.