Biochemical Reaction of Iodine in Human Body-Part 2

Excretion of Iodine

Almost all iodine(~80%-90%) is excreted in the urine because kidneys have no mechanism to conserve iodide. Therefore, iodine deficiency can be identified by urine test. There is about 20% of iodine secreted in feces.

To calculate daily iodine intake :

urinary iodide(mg/dl) x 0.0235 x body weight (kg)

Groff J., Gropper S., and Smith J. (2009). Advanced Nutrition and Human Metabolism.(5th Edition). Belmont, Ca: Wadsworth.

Food sources of Iodine......

Iodine is found in many foods and drinking water.

Seafoods, such as clams, lobsters, oysters, sardines and other salt water fish.

The iodine available in cow's milk and eggs is determined by the iodine available in the diet of the animal along with the iodine content of vegetables varying according to the iodine content of the soil in which they grow.

Food, Nutrition and Diet Therapy. Krause Page 139

Kristin G.

Biochemical and Metabolic Functions of Iodine.....

Iodine is a trace element essential for the metabolism of fat and minerals. It is important for physical and mental development. Iodine is concentrated in the thyroid gland and is an essential component of the thyroid hormone, thyroxine, which is the master regulator of metabolism.

Iodine increases metabolism, ie pulse rate, respiration, arterial pressure, quality of urine.

The primary role of iodine is for the synthesis of thyroid hormone thyroxine(T4) and triiodothyronine(T3) by the thyroid gland.






Mechanism

The thyroid cells actively collect iodide from blood. Then iodide is oxidized to iodine, which is then bound to the tyrosyl residues of the glycoprotein thyroglobulin. The process is catalyzed by thyroperoxidase and produces thyroglobulin-3-monoiodotyrosine(Thg-MIT). Next, MIT is iodinated and form thyroglobulin-3,5-diiodotyrosine(Thg-DIT). Two DITs couple to form Thg-T4 . This coupling reaction is catalyzed by thyroperoxides as well. Finally, DIT also couple with MIT to form T3 and reverse T3.

The DIT and MIT that are not used for thyroid hormone synthesis are deiodinated and the iodine is made available for recycling in the formation of new iodothyroglobulin.

All of the blood in the body passes through the thyroid every hour and a half. A diet lacking trace iodine weakens the thyroid function. This leads to formation of albuminous toxins, which can adversly affect the brain and nervous system.

Functions and Benefits

-Development and functioning of the thyroid gland

-Regulates the body's production of energy

-Helps to burn excess fat, metabolism stimulation

-Neutralizes albumin

-Aids in the assimilation of minerals, ie calcium, silica, phosphorus

Food, Nutrition and Diet Therapy. Krause Page 139-141

Kristin G.

Chemical Structure and Formula of Iodine......

Name: Iodine

Symbol: I

Atomic Number:53

Atomic Mass:126.90447 amu

Melting Point:113.5 C

Boiling Point:184.0 C

Protons/Electrons:53

Neutrons:74

Classification: Halogen

Color: Blackish

Chemicalelements.com

Kristin G.