According International Council for the Control of Iodine Deficiency Disorder, Iodine is one of the chemical elements existing in nature in various forms such as iodide (I-), iodate (IO3-) and elemental iodine (I2). Iodine is found in form of salts in sea water in fairly constant amounts, but is not distributed evenly in land water or fresh water. Iodine is present as an important constituent in the chemical structure of thyroid hormones. The butterfly shaped thyroid glands present in frontal part of the neck produce two hormones namely Thyroxine (T4) and Triiodothyronine (T3).
These thyroid hormones are carried to their target organs namely liver, kidneys, muscles, heart and developing brain through the medium of blood. The thyroid hormones play a key role in the manufacture of proteins influencing various chemical reactions (2005). According to the World Health Organization, iodine is a micronutrient and its deficiency was termed as Iodine Deficiency Disorders (IDD) in the year 1983 to broadly focus on the ill-effects of iodine deficiency such as goitre and cretinism.
Cretinism is a “condition of severe brain damage” leading to mental impairment in normal children in iodine deficient areas. The consequences are poor school performance, reduced intellectual ability and impaired work capacity. According to a report issued by National Academy Press (NAP), whereas the Recommended Dietary Allowance (RDA) of iodine for adult men and women is 150µg per day; the daily median intake is about 240µg to 300µg and 190µg to 210µg for men and women respectively.
The Thyroid hormones namely thyroxine (T4) and triiodothyronine (T3) containing about 65% and 59% of iodine by weight respectively move through the blood circulation get attached to various binding proteins synthesized by the liver including thyroxine-binding globulin, transthyretin, and albumin. These bound hormones then migrate to the target tissues wherein the thyroxine is deiodinated to metabolically active triiodothyronine.
This iodine of T4 then returns to the serum iodine pool and recycles following the iodine cycle or is excreted through urine. Iodine deficiency has severe consequences on the development of brain and it may also be noted that the “thyroid hormone is particularly important for myelination of the central nervous system, which is most active in the perinatal period and during fetal and early postnatal development. Numerous population studies have correlated an iodine-deficient diet with increased incidence of mental retardation.
” Cretinism is characterized by gross mental retardation, short stature, deaf mutism and spasticity with about one in ten suffering ill-effects of severe deficiency from iodine. Thyroid gland enlargement (goitre) is one of the earliest clinical symptoms depicting iodine deficiency followed by attainment of nodular form later leading to autonomous nodules or thyroid follicular cancer. In addition iodine deficiency also leads to impaired reproductive outcome, childhood mortality, decreased educability and economic stagnation.
According International Council for the Control of Iodine Deficiency Disorder, seafood is the best source of iodine and iodine is added to table salt to make it iodized salt to improve the intake of iodine in nutrition. The iodine content in the salt differs in different countries, for example in US and Canada 100 ppm of iodized salt contains 77 ppm of potassium iodide, thus 2 grams of iodized salt in US and Canada contains 150 mcg of iodine. Depending on the daily intake of salt 10-40 mcg of iodine per one gram of salt is added in most other countries.
In addition there are other sources of iodine such as certain food colorings (i. e. , erythrosine), skin disinfectants like povidone iodine which is absorbed ultimately reaching the blood stream, health foods like kelp, dyes used in X-ray procedures for contrast and medicines such as Amiodarone, from farm animals while cleaning udders with iodine containing medicines and iodate used as bread stabilizer in baking. The daily requirements as recommended by World Health Organization and Food and Agriculture Organization (FAO) are depicted in table form as follows:
Age Daily intake of Iodine 0-6 months 40µg 7-12 months 50µg 1-10 years 60-100µg Adolescents & Adults 150µg From the above discussion it is clear that iodine deficiency or sufficiency is dependent on the area to which a population belongs and their food habits. It can be safely stated that iodine requirement starts right from the womb and it plays a key role as a micronutrient which is essential for the production of necessary proteins.
Though, the ill-effects of iodine deficiency are avoidable majority population i. e., over one billion people do not get iodine in their diets (allthyroid. org, 2004). Serious steps should be initiated to educate people of the Iodine Deficiency Disorders (IDD) and explain the serious consequences to eradicate the root cause. Necessary iodine content be regulated in common salt to enable balanced intake of iodine and avoid excess iodine intake since this may lead to hyperthyroidism.
International Council for the Control of Iodine Deficiency Disorder (ICCIDD). Iodine Deficiency Disorder (2005). Page retrieved on November 13, 2006 from: http://indorgs.virginia.edu/iccidd/aboutidd.htm