Iodine is an element hardly found in its pure form in nature. Usually it is present in the form of its salts or compounds. Anorganic iodine salts are mainly sodium iodate or sodium periodate, organic compounds can be found in seaweed, algae or sponges.
Iodine can be extracted from these raw materials, at room temperature it is solid, lustrous, flaked and of anthracite colour. Iodine vapour is violet, thus giving the element its name from the Greek word for coloured like a violet („ioeides“ ιώο-ειδης).
Iodine is a component of the thyroid hormones triidothyronine T3 and tetraiodthyronine T4, that play a major role in the embryonic development, in metabolism, the control of tissue growth and cell proliferation and in cell division.
Triidothyronine T3
Tetraiodthyronine T4
Half of the iodine in the body is found in the thyroid gland, a quarter in muscles and the rest in blood and other parts of the body.
Many areas are iodine deficient areas, also the Alps. In Austria table salt has been iodine enriched since 1923, since that time the most severe forms of iodine deficiency have diminished. Iodine deficiency during pregnancy leads to limited intellectual capacity of the children, cretinism, dwarfism, and impairment of hearing. Iodine deficiency in school children can lead to decreased intellectual performance. In developing countries these symptoms can still be found.
Iodine containing materials as seaweed ash or roasted sea sponge have been recommended to prevent goitre even before the element iodine had been discovered. The iodine source water of Bad Hall had been sold and used to prepare “goitre bread”.
1811 the essential micronutrient was accidentally discovered when manufacturing saltpetre from sea weed and was used for goitre treatment in 1816 already.
Recommended daily intake of iodine in DACH (Germany, Austria, Switzerland)
| Age | Recommended daily intake µg iodine per day |
| 0 – 4 months | 40 |
| 4 – 12 months | 80 |
| 1 – 4 years | 100 |
| 4 – 7 years | 120 |
| 7 – 10 years | 140 |
| 10 -13 years | 180 |
| 13 – 51 years | 200 |
| 51 years or older | 180 |
| Pregnant women | 230 |
| Breastfeeding women | 260 |
With 5 g of iodine enriched salt (20 g iodine per kg of salt in Austria) used for cooking the organism gets 80 µg of iodine.
Other sources of iodine are sea fish, shellfish, algae, milk and dairy products, kiwi fruit, rocket, sour cherry and iodine rich mineral waters (iodine source water in Bad Hall: approx. 40 mg/L).
Effect of iodine outside of the thyroid gland
The anion iodide is a very large molecule with low charge density, in aqueous medium it is able to break structures and destroy hydration shells contrary to the other halogenids fluoride, chloride and bromide which have high charge density and strong hydrate shells.
Iodide generates a greater mobility of water molecules which can interact with other molecules. This influences the properties of proteins in aqueous media.
Structure proteins like elastin in connective tissue show swelling by incorporation of water molecules, this effect is promoted by iodide.
Another mechanism of action is iodide’s reaction as an antioxidant. It is easily oxidised and neutralises oxidants in the body. It also reacts easily with free radicals and similar compounds.
The iodine radical reacts slowly thus inhibiting the prolongation of the radical reaction, acting as a radical scavenger.
Effects
Iodine is antiseptic (germicidal against bacteria, virus, fungi) and is applied as lotion, ointment or suppository.
Iodine is secretolytic and is used for the treatment of the respiratory system.
Iodine has effects on the connective tissue, it enhances swelling. Collagen synthesis is encouraged leading to better healing of wounds, blood vessels (arteriosclerosis), cartilage (arthrosis) and eye media (corpus vitreum, cornea, and lens) can be influenced by iodine.
In the eye iodine has an effect on the corpus vitreum when it develops floaters, on the dry eye, the first stages of macula degeneration and cataract.
Generally it is a radical scavenger and inhibits effects of free radicals in the body which play a role in degenerative diseases of the advanced age (arteriosclerosis, diabetes, diseases of the eyes and joints).
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