I 6 pp - Iodine Form Iodine 2011 Iodine is typically found...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Iodine 2011 Iodine: Form • Iodine is typically found in its ionic form iodide (I - ) • Dietary iodine (I) is either bound to an amino acid or free as iodate (IO 3- ) or I - • In enterocyte, all iodine = iodide (I - ) Iodine: Food Sources • Water – Concentration varies regionally – Fresh water: 0.5-2 ppb – Seawater: 17-50 ppb • Seafood – Fish, shellfish, seaweed • Meat and vegetable content varies depending on soil content of region where produced Iodine: Food Sources • Food processing – Iodides in bread production – Dairy industry in cleaners used for milking equipment Iodine: Regional Differences = areas of low soil/water iodine content Iodized Salt • Salt is the recommended vehicle for distributing iodine • Effective for >50 years in US, Canada, Switzerland • Iodine deficiency and goiter were once common
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Iodine: Absorption • Iodide rapidly and ~100% absorbed in stomach and small intestine • Iodate (IO 3- ) used in fortification – High bioavailability Test Question Iodine is a voluntary addition to “enriched” cereal grain products by the food industry in the US. (a) True (b) False Test Question Iodine is a voluntary addition to “enriched” cereal grain products by the food industry in the US. (a) True (b) False Transported as free iodide Fig. 12-18, p. 517 Iodine: Transport • Rapidly taken up by thyroid gland or kidney •Thyroid uptake varies with iodine intake – Adequate intake, ~10% of absorbed iodine – Iodine deficiency, >80% may be taken up Test Question Iodine is transported in circulation bound to thyroglobulin. (a) True (b) False
Background image of page 2
Test Question Iodine is transported in circulation bound to thyroglobulin. (a) True (b) False Iodine: Excretion • Primary route of excretion is urinary – ~80-90% • Kidneys – no mechanism to conserve iodide • Low fecal excretion Iodine: Distribution and Storage • Total body – 15-20 mg iodide (adequate intake) – May be reduced to <20 g (deficiency) • Thyroid gland – Contains 3/4 of total body iodide Iodine: Metabolism • Blood iodide concentration cleared rapidly from plasma by thyroid gland • The thyroid gland - not the intestinal tract or kidney controls the concentration of blood iodide Test Question The primary regulation of blood iodine concentration is uptake by the thyroid gland. (a) True (b) False Test Question The primary regulation of blood iodine concentration is uptake by the thyroid gland. (a) True (b) False
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Iodine: Function Iodide’s single function Synthesis of thyroid hormones by the thyroid gland Triiodothyronine (T3) Thyroxine (T4) Iodine: Thyroid Hormones Thyroid Hormone Synthesis: Step 1 •Thyroid cells trap iodide via Na + /K + ATPase pump Colloid Thyroid Cells K + Na + I - •Iodide is oxidized to iodine I - Thyroid Hormone Synthesis: Step 2 •Iodine binds to tyrosyl residues of thyroglobulin (Thg) Colloid Thyroperoxidase Thg-MIT •Thg-MIT is formed •Hydrogen peroxide accepts electron H 2 O + OH· Thyroid cell H 2 O 2 I - • Thg-MIT is iodinated •T hg-DIT is formed
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/09/2011 for the course HUN 4445 taught by Professor Sitren during the Spring '08 term at University of Florida.

Page1 / 12

I 6 pp - Iodine Form Iodine 2011 Iodine is typically found...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online