Iodine is a trace mineral as well as an essential element of the thyroid hormones called triiodothyronine (T3) and thyroxine (T4) that regulate the metabolic functions of most cells and have an important role in the process of early growth and development of most organs, particularly the brain. Iodine has many neurological effects on the brain, including improving cognition and the fetal development. It has great effect on the intellectual development of infants and children. As the body cannot produce it, iodine must be obtained from the diet. And the dietary supplementation of iodine helps you in energy metabolism, increases the immune system and stimulates the activity of antioxidants.
Iodine is an important element for the normal growth and development of the body. Iodine deficiency is a common world health problem and the most recognized form of deficiency is goiter. Since about 60% of iodine in the human body is usually stored in the thyroid gland, it is called the element of the thyroid hormones. Actually, iodine affects every cell in the human body as an element of thyroid hormones. Iodine comes with numerous health benefits including maintaining optimal thyroid function, supporting energy metabolism, increasing the immune system, stimulating the activity of antioxidants, and holding an important effect on reproduction, growth and neurological development.
The common health benefits of Iodine include:
- Improves cognitive performance 
- Regulates metabolic rate 
- Helps fight cancer 
- Some users report that it maintains optimal energy levels
- Increases immunity 
- Acts as an antioxidant 
- Is an anti-inflammatory 
- Is used for skin health 
- Helps with thyroid disease 
- Helps with growth and development in children 
Iodine reduces thyroid hormone and can kill fungus, bacteria, and other microorganisms such as amoebas. A specific kind of iodine called potassium iodide is also used to relieve the effects of a radioactive accident.
Iodine is used to remove iodine deficiency and its consequences, including goiter. It is also used for relieving a skin disease caused by a fungus (cutaneous sporotrichosis), helping with eye disease, diabetes, and heart disease and stroke; and as an expectorant. People also use it for radiation emergencies, to protect the thyroid gland against radioactive iodides. Iodine is applied to the skin to kill germs, prevent soreness inside the mouth (mucositis) caused by chemotherapy, and relieve diabetic ulcers. Iodine is also used for water purification.
How it works
Iodine is an essential micronutrient needed in human diets. As iodine is an integral component of thyroid hormone, it mediates the effects of thyroid hormone on brain development. Iodine deficiency is the most prevalent and preventable cause of mental impairment in the world. Though the exact mechanism through which iodine influences the brain is unclear, it is generally thought to begin with genetic expression. Many brain structures and systems appear to be affected with iodine deficiency, including areas such as the hippocampus, microstructures such as myelin, and neurotransmitters.
Thyroid hormones – thyroxine (T4) and triiodothyronine (T3) are essential for the development of the central nervous system as they regulate genes involved in myelination and neuronal/glial cell differentiation, and play an important role in axonal and dendrite growth in synaptogenesis and myelination. Deficiencies in thyroid hormones in pregnant women directly affect brain development of the fetus, resulting in neurological and neurocognitive disorders in infants with defects ranging from decrease in intelligence and lethargy to mental retardation. Women taking iodine supplements as soon as pregnancy starts, or earlier can help remove iodine deficiency in children. 
Iodine is generally safe when taken at recommended amounts. But it can cause significant side effects in some people which include nausea and stomach pain, runny nose, headache, metallic taste, and diarrhea. Sensitive people can show different symptoms including swelling of the lips and face, severe bleeding and bruising, fever, etc. Again, higher dosage can also show some risks of side effects including metallic taste, soreness of teeth and gums, burning in mouth and throat, increased saliva, throat inflammation, stomach upset, diarrhea, wasting, depression, skin problems, etc. Directly use of iodine may cause skin irritation, stains, allergic reactions, and other side effects. Prolonged use or high doses of iodine may make some conditions worse. Consult your doctor or healthcare provider before using any supplement.
A standard dosage for Iodine supplement depends on several factors including thyroid function, overall health status, age, gender, diet, toxin exposure and geographic location. According to the World Health Organization, 40% of the human population is iodine deficient. Iodide should be taken just prior to, or as soon as possible after, exposure.
Adequate Intake (AI) of iodine for infants has been set by the National Institute of Medicine: 0 to 6 months, 110 mcg per day; 7 to 12 months, 130 mcg per day.
For children and adults, Recommended Dietary Amounts (RDA) has been set: children 1 to 8 years, 90 mcg per day; 9 to 13 years, 120 mcg per day; people age 14 and older, 150 mcg per day. For pregnant women, the RDA should be 209 mcg per day, and breastfeeding women, 290 mcg per day.