Jod er nødvendig også til andet end hormoner

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Jeg er faldet over tidsskriftet Current Chemical Biology, der har ofret det meste af pladsen i Volume 5, Number 3, September 211 på betydningen af jod i andre væv end til syntese af thyreoideahormoner i skjoldbruskkirtlen (The Extrathyroidal Functions of Iodine), introduceret med følgende ord:

Most investigations of iodine metabolism in humans and animals have focused on its role in thyroid function. Public health policies have been established to supply deficient populations with the necessary amount of this element in order to eradicate the iodine deficiency diseases, primarily cretinism. However, considerable evidence indicates that iodine could also be implicated in the physiology of other organs.

In humans, the total amount of iodine in the body is 30-50 mg, and less than 30% of it is present in the thyroid gland and its hormones. About 60% of total iodine is non-hormonal and is concentrated in extrathyroidal tissues, where its biological role is still unknown.

Moreover, it has been demonstrated that iodine distribution in the organism depends on the chemical form of iodine ingested, and that molecular iodine (I2) is not totally reduced to iodide (I-) in the blood before it is absorbed systemically from the gastrointestinal tract. Indeed, in iodine deficiency conditions, I- appears to be more efficient than I2 in restoring the thyroid gland from a goitrous to a normal state, whereas I2 supplementation diminishes the symptoms of mammary fibrosis in women, causes a 50-70% reduction in the occurrence of mammary cancer induced chemically in rats and exhibit antiproliferative and apoptotic effects in several human tumoral cell lines. Nevertheless, these findings have been viewed with caution, because exposure to moderate or high iodine is thought to be a potential risk to thyroid physiology.

Careful examination shows that pathological responses occurred at low or moderate iodine intake in patients with underlying or evident thyroid pathology (e.g. Hashimoto's thyroiditis, history of treated Graves' diseases, etc.); in normal subjects, however, these pathologies occurred only with excessively high doses of iodine or iodide (>20 mg/day). No damaging effects were reported in either the human or animal studies that used therapeutic I2 concentrations (3 to 15 mg/day). This issue will provide an overview of so-called extrathyroidal iodine, its role, and its potential clinical applications. (Source)

Desværre koster hver artikel på Current Chemical Biology online hele 71 dollars, men jeg fandt en af artiklerne i full text på nettet: Evolutionary Significance of Iodine

En god oversigt over jod-artikler inkl. abstracts, i netop dette nummer af Current Chemical Biology findes på ChemWeb.com på dette link.