Iodine (126,9 a.m.u.) — A vital element. A basis of thyroid hormones: thyroxine and triiodothyronine. Its physiological and pathological effects are depending on the dose.

Deficit of iodine is an important reason of thyroid gland diseases: hypothyroid infantilism, hypothyroidism with hypothyreosis, Hashimoto syndrome, impairment of fertility, stillbirth, congenital anomaly, bradygenesis of children and diminution of intellectual output of adults. High concentrations of iodine are containing in sea water and sea products. Concentration of iodine in ready-to-cook food is considered depending on its initial level and the type of processing such products has underwent. Some fast-food variations could contain concentration of iodine exceeding daily demands. Artificial iodine supplement in food is being widely used for prevention and treatment of iodine deficit diseases of thyroid gland, including mass events in endemic regions (iodized salt, iodized oil, etc.).

Disinfecting options of iodine are being used in medicine, but iodine-containing agents are being used to decrease the deposition of radioactive iodine. However, overdoses of iodine due to uncontrolled intaken of specific food supplements, as well as a deficit of iodine could be the reason of severe pathology: thyroid gland (thyrotoxicosis), skin and respiratory passages damages, weakness, depression, teratogenic effect on the foetus, allegropathy, Plummer’s disease and Pendred’s syndrome.

Concentration of iodine in hair correlates to the level of iodine intake by the body, but the proportion is not obvious. Decrease of iodine level in hair was reported for 59% of inhabitants of regions with iodine deficit. In cases of thyroid gland diseases, level of iodine in hair and nails could be decreased (more often), or even increased.