Of all the nations in the world, it is estimated that mostly people living in Japan where seaweed is a large part of the diet get enough iodine from dietary sources. Almost everyone else probably has some degree of iodine deficiency.
Iodine deficiency is implicated in thyroid cancer and many other diseases. Giving T4 (synthroid) to iodine deficient women increases their risk for breast cancer. Anyone needing to take thyroid hormones should also take supplemental iodine. Normalization of iodine is also important before selenium supplementation in order to prevent hypothyrodism. Normal but borderline thyroid panel lab values make a thyroid problem highly suspect.
Hormone imbalances in estriol, estrone, and estradiol, which can lead to weight gain can benefit from iodine. Iodine has been shown to help maintain the balance in favor of estriol. Iodine can induce apoptosis (death) in cancer cells, especially those of thyroid and breast. However, this effect is negated if a goitrogen is given. Iodine is incorporated into lipids and helps stabilize cells. All women should be evaluated for iodine deficiency before they reach the stage of breast cancer.
Iodine is needed by various cells and tissues in the whole body, not just the thyroid. Female reproductive tissues have a large need for iodine. Radioactive iodine used to destroy thyroid cells also goes to other iodine concentrating tissues in the body. It does increase the risk of cancer. Autoimmune thyroid problems need to have the underlying cause visited, be it food sensitivity or iodine deficiency, or vitamin or mineral deficiency.
Vitamin B2 100 mg and B3 500 mg twice a day can help cells use iodine better. These are co-factors in the NADPH oxydase pathway. "ATP co-factors" by Optimox can be used as a supplement.
Bromine, used as a dough conditioner, is found in many breads. It competes with iodine at tissues, can inhibit thyroid hormone production, and can worsen and cause iodine deficiency. Canada and some other countries have wisely banned its use. Avoid any food with ingredients such as potassium bromate, brominated vegetable oil, azodicarbonamide, etc. Enriched flour may contain bromide as an unlisted ingredient. Many fast-food establishments add azodicarbonamide to their breads, while Pepperidge Farm bread is supposedly bromide-free. Bromine should be considered a toxic element and needs to be avoided. It can cause delirium, psychomotor retardation, schizophrenia, depression, headache, and irritability. Iodine as well as chloride from salt will help with excretion of bromide.
Fructose intake can create copper deficiency, which in turn can decrease thyroid hormone production. Fluoride at concentrations found in drinking water has also shown to damage thyroid tissue. Other environmental toxins that depress thyroid gland and hormone function include PCBs, dioxins, DDT and its metabolites, aminotriazole, HCB, and phthalates.
Everyone does not need iodine supplementation, so have your levels checked by your physician before starting any supplementation.