For hundreds of years, iodine has been known as the element that is necessary for thyroid hormone production. Altough iodine has other positive effects in the body, they are often overlooked or not mentioned. Iodine is not only necessary for the production of the thyroid hormone, but is also responsible for the production of all the other hormones in the body. Adequate levels are required for proper immune system function. Iodine also contains potent antibacterial, antiparasitic, antiviral and anti-cancer properties. It is essential for the normal physical growth & intellectual development of children, with severe deficiency resulting in mental impairment and deafness.
The World Health Organisation has recognised that iodine deficiency is the world’s greatest single cause of preventable mental retardation. Approximately one-third of the world’s population lives in iodine deficient areas and up to 72% of the world’s inhabitants is affected by an iodine deficiency disorder.
Iodine is a relatively rare element, ranking 62nd in abundance amongst the elements of earth and it is not very plentiful in the earth’s crust; as a result, unlike other vitamins and minerals, iodine is not present in adequate amounts in most foods. Specific plants absorb iodine when it is present in the soil. Iodine is primarily found in seawater (but in very small quantities) and solid rock near the ocean. As a result the best available sources come from seafood; marine fish generally contain more iodine than fresh water fish. A significant part of the iodine is found in the thyroid, located in the head of the fish which is NOT commonly eaten. Typical amounts for some common fish are suggested below (in mcg/100g):
Cod (110), Haddock (250), Herring (29), Mackerel (140), Sardines (29), Tuna (30), Atlantic Salmon (76), Rainbow Trout (13).
Seaweeds have an ability to uptake large amounts of iodine from the ocean water, resulting in their high levels of iodine. The iodine level in seaweed is dependent on the type of seaweed. Kelp has the highest amount of iodine, with some kelp species having 8165 mcg/gm. Most Kelp has about 2500 mcg/gm. Other common seaweeds are much lower; for example, values for other common seaweeds are expressed here: Nori (16 mcg/gm), Wakame (32 mcg/gm), Dulse (72 mcg/gm), Hijiki (629 mcg/gm). That is why seaweed are said to be the best source of iodine in nature. Iodine content is reduced by storage (e.g., in paper bags or open to the air) and cooking. Most of the iodine in seaweed comes in the form of iodide, but it varies depending on the type of seaweed.
In many industrialised countries, iodine has also been added to salt products with a goal to prevent goiter. Although the addition of iodine to the salt supply has lessened the prevalence of goiter, it is inadequate to supply the body’s need for iodine. Every cell in the body contains and utilises iodine but it is in the glandular system that it is most concentrated. Large amounts are also found in the salivary glands, the brain and cerebrospinal fluid, gastric mucosa, breasts, ovaries and some parts of the eye. Read more about the salt controversy.
“Iodine: Why You Need It”; Dr David Brownstein; 2007
Health Salon: Iodine for Greatest Mental and Physical — Dr Abraham and Dr Flechas