Iodine mineral is an essential micronutrient. The adult human being contains about 50 gram of iodine and the blood level is about 8-12 micrograms. Iodine occurs in two forms:
- Inorganic or filterable ionic form: This represents about 0.5% of the total plasma iodine. On usual diet, plasma iodide level is 0.3-0.5 µg
- Organic or hormonal iodine: This iodine is the part of the thyroid molecule which mostly occurs as bound with specific plasma protein.
- Animal Sources: The best sources of iodine are the seafood that is sea fish, sea salts etc and the cod liver oil. It also occurs in a smaller amount such as in milk, meat, and poultry.
- Plant Sources: It is found in turnips, cabbage, carrots, peas, peaches, leafy vegetables, cereals etc.
About 90% of iodine which enters in our body is from the food we eat and the remainder from the water. The iodine content of the soil determines its presence in both the water and locally grown foods. The deficiency is genomic in nature, therefore.
Goitrogens: These are the chemical substances leading to the development of goiter. They interfere with iodine utilization by the thyroid gland and they may occur in food and water. The basic group of vegetables e.g. cabbage, cauliflower, turnips, peas, carrots etc contains a high amount of iodine within themselves. Most important of them are probably cyanoglycosides and the thiocyanates
- It is required for the synthesis of the thyroid hormones, thyroxine, and tri-iodothyronine, the normal levels of these thyroid glands are very necessary for our body.
- It is also necessary for the normal human growth and development and well being of all humans.
- It plays an essential role in the formation of the nervous system of the fetus.
- It has been shown to be beneficial in overcoming the fibrocystic breast disease due to its effects on estrogen receptors present in the breast.
- It protects our body from the dangerous effects of radioactive substances.
- It also seemed to plays an important role in the development of fingernails, hair teeth, and skin.
The most obvious consequence of iodine deficiency is goiter but recent research has indicated that there is a much more spectrum of diseases some of them are so severe as to be disabling. These include
- Retarded physical development and impaired mental function
- Increased rate of spontaneous abortion and stillbirth
- Neurological cretinism including deaf-mutism
- Myxedematous cretinism which includes dwarfism and severe mental retardation.
To express this, endemic goiter is now replaced by the term iodine deficiency disorders to refer to all the effects of iodine deficiency on human growth and development which can be prevented by correction of iodine deficiency
The daily requirement of iodine for adults is 150 micrograms per day. This amount is normally supplied by well-balanced diets and drinking water except in certain regions where food and water are deficient in iodine.
An excess intake of iodine can lead to thyrotoxicosis and goiter.