Iodine deficiency a number of Market's are Boycotting Iodized Salt

Iodine deficiencyClassification and external resourcesSpecialtyEndocrinologyICD-10E00–E02DiseasesDB6933eMedicinemed/1187

Iodine deficiency is a lack of the trace element iodine. It may result in goiter(so-called endemic goiter), as well ascretinism, which results in developmental delays and other health problems. Iodine deficiency is an important public health issue as it is a preventable cause of intellectual disability.

Iodine is an essential trace element; thethyroid hormones thyroxine andtriiodothyronine contain iodine. In areas where there is little iodine in the diet—typically remote inland areas where no marine foods are eaten, iodine deficiency is common. It is also common in mountainous regions of the world where food is grown in iodine-poor soil.

Prevention includes adding small amounts of iodine to table salt — a product known as iodized salt. Iodine compounds have also been added to other foodstuffs, such as flour, water and milk in areas of deficiency.^[1]Seafood is also a well known source of iodine.^[2]

Iodine deficiency resulting in goiter occurs in 187 million people globally as of 2010 (2.7% of the population).^[3] It resulted in 2700 deaths in 2013 up from 2100 deaths in 1990.^[4]

GoiterEdit

Main article: Goiter

A low amount of thyroxine (one of the two thyroid hormones) in the blood, due to lack of dietary iodine to make it, gives rise to high levels of thyroid stimulating hormone (TSH), which stimulates the thyroid gland to increase many biochemical processes; the cellular growth and proliferation can result in the characteristic swelling or hyperplasia of the thyroid gland, or goiter. In mild iodine deficiency, levels of triiodiothyronine (T₃) may be elevated in the presence of low levels of levothyroxine, as the body converts more of the levothyroxine to triiodothyronine as a compensation. Some such patients may have a goiter, without an elevated TSH. The introduction of iodized salt since the early 1900s has eliminated this condition in many affluent countries; however, in Australia, New Zealand, and several European countries, iodine deficiency is a significant public health problem.^[5] It is more common in third-world nations. Public health initiatives to lower the risk of cardiovascular disease have resulted in lower discretionary salt use at the table. Additionally, there is a trend towards consuming more processed foods in western countries.^{[citation needed]} The noniodized salt used in these foods means that people are less likely to obtain iodine from adding salt during cooking.

Goiter is said to be endemic when the prevalence in a population is > 5%, and in most cases goiter can be treated with iodine supplementation. If goiter is untreated for around five years, however, iodine supplementation or thyroxine treatment may not reduce the size of the thyroid gland because the thyroid is permanently damaged.

CretinismEdit

Main article: Cretinism

Iodine deficiency is one of the leading causes of preventable mental handicaps worldwide, producing typical reductions in IQ of 10 to 15 IQ points. It has been speculated that deficiency of iodine and other micronutrients may be a possible factor in observed differences in IQ between ethnic groups: see race and intelligence for a further discussion of this controversial issue.

Cretinism is a condition associated with iodine deficiency and goiter, commonly characterised by mental deficiency, deafness, squint, disorders of stance and gait, stunted growth andhypothyroidism. Paracelsus was the first to point out the relation between goitrous parents and mentally retarded children.^[6]

As a result of restricted diet, isolation, intermarriage, etc., as well as low iodine content in their food, children often had peculiar stunted bodies and retarded mental faculties, a condition later known to be associated with thyroid deficiency. Diderot, in his 1754Encyclopédie, described these patients as "crétins". In French, the term "crétin des Alpes" also became current, since the condition was observed in remotevalleys of the Alps in particular. The word cretin appeared in English in 1779.

While reporting recent progress towards overcoming iodine-deficiency disorders worldwide, The Lancet noted: "According to World Health Organization, in 2007, nearly 2 billion individuals had insufficient iodine intake, a third being of school age. ... Thus iodine deficiency, as the single greatest preventable cause of mental retardation [sic], is an important public-health problem."^[7] (In this context it is noted that the term "mental retardation" has been widely replaced by "intellectual disability".)

Fibrocystic breast changesEdit

Main article: Fibrocystic breast changes

There is preliminary evidence that iodine deficiency enhances the sensitivity of breast tissue toestrogen.^[8][9] In rats treated with estrodiol, iodine deficiency has been shown to lead to changes similar to benign breast changes that are reversible by increased iodine in the diet.^[8][9] In a few studies, iodine supplementation had beneficial effects (such as reducing the presence ofbreast cyst, fibrous tissue plaques and breast pain) in women with fibrocystic breast changes.^[8][10]

Protective effects of iodine on breast cancer have been postulated from epidemiologic evidence and described in animal models.^[11][12][13] In view of the antiproliferative properties of iodine in breast tissue, molecular iodine supplementation has been suggested as an adjuvant in breast cancer therapy.^[13]

Deficient populationsEdit

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.^[14]

Iodine deficiency is the leading cause of preventable mental retardation, a result which occurs primarily when babies or small children are renderedhypothyroidic by a lack of the element. The addition of iodine to table salt has largely eliminated this problem in the wealthier nations, but as of March 2006, iodine deficiency remained a serious public health problem in the developing world.^[15]

Iodine deficiency is also a problem in certain areas of Europe. In Germany it has been estimated to cause a billion dollars in health care costs per year.^[10]A modelling analysis suggests universal iodine supplementation for pregnant women in England may save £199 (2013 UK pounds) to the health service per pregnant woman and save £4476 per pregnant woman in societal costs.^[16]

Iodine may also help prevent diseases of the oral and salivary glands.^[17]

The human encephalization quotient, an expression of the size and complexity of the brain, and other iodine-concentrating organs, is high in the animal kingdom.