Role of Iodine in Thyroid Health

Iodine Quiz

Let's see how well you know about IODINE!
* scroll down for answers

1) What is the RDA for iodine?
a. 150 mcg/day
b. 1500 mcg/day

2) What is the main function of iodine in human body?
a. Prevent heart diseases
b. Regulate thyroid hormone

3) Which of the following is the disease caused by iodine deficiency?
a. Hypertension
b. Goiter

4) Take excess of iodine cannot cause toxicity.
a. True
b. False

5) Iodine is a ......
a. metallic element
b. non-metallic element

6) What is cretinism?
a. A reversible growth retardation in infant cause by iodine deficiency.
b. An irreversible mental retardation in infant caused by iodine deficiency.

7)Which of the following is rich in iodine?
a. sea vegetables
b. tofu

8)Most of the iodine (~80%-90%)is excreted in...
a. urine
b. feces

9)Iodine increases metabolism, ie pulse rate, respiration, arterial pressure, quality of urine.
a. True
b. False

10) Iodized salt is available in all the countries.
a. True
b. False













Answers:
1. a 2.b 3.b 4.b 5.b 6.b 7.a 8.a 9.a 10.b

Recommended Dietary Allowances

An Iodine intake of 150 mcg/day has been suggested as sufficient for all adults and adolescents.
The RDA for pregnant and lactating women is increased to 25 mcg and 50 mcg respectively.
The RDA is 40 mcg for infants up to 6 months of age, and 50 mcg for older infants.
The RDA for children is between 70 and 120 mcg, increasing with age (or body size).

Food, Nutrition and Diet Therapy, Krause :Page 140

Kristin G.

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.

Iodine Deficiency-Part 3

Besides goiter, iodine deficiency can also cause cretinism - a preventable mental retardation. Cretinism is a condition of severely stunted physical and mental growth due to untreated congenital deficiency of thyroid hormones or congenital hypothyroidism, due to iodine deficiency affected pregnancy.

The infants with cretinism usually have poor length growth at the first year of life. In addition, they also have delayed bone maturation and puberty. Infertility in both sexes is common as well. They may also have mild neurological impairment along with reduced muscle tone and coordination.

In severe cases, they cannot walk or stand by themselves. Cognitive impairment may occur in different severity that they may not able to take care of themselves. They thoughts and reflexes are tend to be slower. Other signs may include thickened skin, enlarged tongue, or a protruding abdomen.

In conclusion, sufficient iodine intake is especially important in women who are pregnant or nursing their infants. Severe iodine deficiency in the mother can cause miscarriages, stillbirth, preterm delivery, and congenital abnormalities in their babies. There are studies suggested that even mild iodine deficiency in the mother can result lower intelligence children.

Thanks for stopping by.

Resource:

Zimmermann, M.B.(2009) .Iodine deficiency in pregnancy and the effects of maternal iodine supplementation on the offspring: a review.Am J Clin Ntr, 89(2), 668s-72s

Biochemical Reaction of Iodine in Human Body-Part 1

Digestion, Absorption, Transport and Storage of Iodine

Dietary iodine (I) is either bound to amino acids or found free, primarily in the form of iodate or iodide. For example, iodate from breads is normally reduced to iodide by glutathione. Iodide ion is the best form of iodine to be absorbed.

Iodide is absorbed rapidly and completely in the stomach and gastrointestinal tract.Then it will be carried into circulation by serum protein. Thus, very little iodide found in feces.

Most iodide is trapped in the thyroid gland where it then forms an essential component of thyroid hormones. The thyroid gland contains up to 70% to 80% of the total body iodide. It takes up about 120mg of iodide per day.

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

Iodine Deficiency-Part 2

Goiter refers to the abnormal enlargement of the thyroid gland. A goiter when the thyroid gland is producing too much hormone (hyperthyroidism), too little hormone (hypothyroidism), or the correct amount of hormone (euthyroidism). A goiter indicates there is a condition present which is causing the thyroid to grow abnormally. One of the most common causes of goiter formation is iodine deficiency. Goiter was prevalent in the United States many years ago, however it is no longer commonly observed after the presence of -Iodized Salt.

The primary activity of the thyroid gland is to concentrate iodine from the blood to make thyroid hormone. If thyroid gland does not have enough iodine, it cannot make enough thyroid hormone. Therefore, people with iodine deficiency will become hypothyroid. As a result, the pituitary gland in the brain senses low level of thyroid hormone and then sends a signal to the thyroid to stimulate the production of thyroid hormone. This signal is called thyroid stimulating hormone (TSH). The condition will make the thyroid gland to grow in size and this abnormal growth is termed a “goiter”. The cells become enlarged when iodine is not available to complete the thyroxine synthetic process.

Source:
Advanced Nutrition: Macronutrients, Micronutrients and Metabolism(2009). CRC Press, Boca Raton, FL.

Iodine Deficiency - Part 1

According to American Thyroid Association(ATA), iodine is an element that is needed for the production of thyroid hormone. Our body does not make iodine, so it is an essential mineral and only come from our diet.

Iodine not only found in iodized salt, it also can be found in breads, cheese, saltwater fish, cow’s milk, seaweed (including kelp, dulce, nori), eggs, shellfish, frozen yogurt, soy milk and soy sauce. We need enough iodine in our body to make enough thyroid hormone.

Iodine deficiency can lead to enlargement of the thyroid—goiter, hypothyroidism and mental retardation in infants and children whose mothers were iodine deficient during pregnancy.

Despite all the effects of iodine deficiency, too much of iodine can cause toxicity. A tolerable upper intake level is 1100mg/day. The adverse effects occurs at intake of ~ 1700mg/day. The toxicity signs and symptoms are burning sensation of mouth, throat and stomach, nausea, vomiting, diarrhea, and fever. When urinary iodine concentration has reached up to 500mg/dL, it is considered iodine toxicity and indicates thyroid dysfunction(called Wolff-Chaikoff effect).

* I am going to explain how iodine is related to goiter in next post. Thanks for stopping by.

Introduction - Sook-Yhin

Hi everyone,

My name is Sook-Yhin and I am a dietetics student from Life University.
Currently, I am taking the Study of Vitamins & Minerals class. Me and my partner, Kristin will post informations about iodine in this blog.

I will cover:
Biochemical reactions of Iodine in body
Iodine deficiency
Iodine quiz

Finally, welcome to our blog!

Introduction: Kristin G.

Hello All :)
I am a student at Life University currently enrolled in a Vit/Minerals class.
Through the duration of this quarter I will be posting periodically information about Iodine.
I will be including information on the following:
-chemical structure/formula
-biochemical and metabolic functions
-dietary requirements
-dietary sources

Look Forward to Bloggin' with Ya!
Kg