Week 2: Element of the Week…Iodine

• Name: Iodine
• Symbol: I Atomic number: 53
• Atomic weight: 126.90447 (3)
• Standard state: solid at 298 K
• Group in periodic table: 17
• Group name: Halogen
• Period in periodic table: 5
• Block in periodic table: p-block
• Color: violet-dark grey, lustrous
• Classification: Non-metallic

The word Iodine comes from Greek: iodes meaning violet (or purple). Under normal conditions, Iodine is a shiny grey solid. However, when heated it becomes a gas that is violet-pink in color with a an irritating odor. This halogen forms compounds with many elements, but is less reactive than the other members of its Group VII (halogens).

Iodine naturally occurs in the environment chiefly as dissolved iodide in seawater, although it is also found in some minerals and soils. Although the element is actually quite rare, kelp and certain other plants have the ability to concentrate iodine, which introduces the element into the food chain. This helps us to understand how Iodine came to be required in trace amounts by all animals and some plants, while being the heaviest element commonly used by living organisms.
Iodine is used in pharmaceuticals, antiseptics, medicine, food supplements, dyes, catalysts, halogen lights, photography and water purification.

We humans need the proper amount of iodine in their diets for optimal thyroid and endocrine system function. I became aware of just how important Iodine is to our health, when I was diagnosed with hypothyroidism last year. That being said, I never realized it is because Iodine is actually used to create the steroid hormones.

According to the Linus Pauling Institute: “Iodine is an essential element that enables the thyroid gland to produce thyroid hormones. Three iodine molecules are added to make T3 (triiodothyronine), and four for T4 (thyroxine) -- the two key hormones produced by the thyroid gland -- so iodine is essential to the production of these two hormones of the master gland of metabolism. Iodine accounts for 65% of the molecular weight of T4 and 59% of the T3. 15–20 mg of iodine is concentrated in thyroid tissue and hormones, but 70% of the body's iodine is distributed in other tissues, including mammary glands, eyes, gastric mucosa, the cervix, and salivary glands. In addition to regulating many aspects of growth and development, thyroid hormone is important for mylenation of the central nervous system, which is most active before and shortly after birth.”

Thyroid enlargement, or goiter, is one of the earliest and most visible signs of iodine deficiency. The thyroid enlarges in response to persistent stimulation by TSH. But, without the proper amounts of Iodine in the system, the body is incapable of producing the T3 & T4 hormones regardless of the TSH istimulation.

In areas where there is little iodine in the diet—typically remote inland areas and semi-arid equatorial climates where no marine foods are eaten—iodine deficiency gives rise to hypothyroidism, symptoms of which are extreme fatigue, goiter, mental slowing, depression, weight gain, and low basal body temperatures. Iodine deficiency is also the leading cause of preventable mental retardation, called Cretinism, an effect which happens primarily when babies and small children suffer from hypothyroid symptoms due to lack of the element in their diets.

The addition of iodine to table salt has largely eliminated this problem in the wealthier nations, but iodine deficiency remains a serious public health problem in the developing world…what a pity, considering how easily it could be prevented by using iodized salt.