Sources of Iodine
Iodine is a micronutrient that is required in adequate amount for the metabolism and proper functioning of the human body. Iodine is required for the active functioning of thyroid hormone, hence, thyroid gland, that plays a vital role in the growth and development of the human body. In this article, I will discuss sources of Iodine, Iodine benefits, Signs of Iodine deficiency and Iodine rich fruits and vegetables.
It is important for pregnant women and infants to meet the body demands.
HISTORY OF IODINE
Iodine was derived from a Greek word, Iodides: purple vapors. In the 19th century, a French chemist named Bernard Courtois discovered iodine while extracting sodium salts necessary for the manufacture of gunpowder. He discovered this element while he observed purple colored vapors arising from seaweed.
HISTORY OF IODINE FORTIFICATION
Until 1924, iodine was not added to the salt. With the outbreak of goiter and other iodine related deficiencies, especially, in Great Lakes and Pacific Northwest, salt was fortified with iodine to overcome the deficiency. People were facing this problem because their diet and soil levels were drastically lacking iodine.
Salt is something that is consumed by everyone, either rich or poor. Iodization of salt is one of the most common and cheapest methods adopted to overcome iodine deficiencies. It is mandated in many countries to meet the deficient levels of iodine in a community. Moreover, this method is of low cost and it can be done manually. Salt iodization is done during packaging and processing. Most of us are asking, “How much Iodine is in salt”, so here you go, the usual ‘dose’ of iodine is between 10-50 mcg per kg salts such as sodium chloride, potassium iodide, and potassium iodate.
IODIZED OIL (Lipiodol): Oil is also iodized as it is the essential component of cooking and it is consumed on daily basis.
Water is the necessity of life and it is consumed on daily basis. Water can be iodized by adding a few drops of iodine in drinking water. It is also the cheapest method to eradicate deficiency of iodine commercially.
BIOFORTIFICATION OF VEGETABLES:
Bio fortification is something to fortify vegetables such as spinach, potatoes and tomatoes with iodine to meet up iodine deficiency in any community.
Bread is fortified with iodized salt to avoid low thyroid activity and to improve the nutritional status of a population. It is an easy way to overcome iodine deficiency especially in the people suffering from hypertension, who should not consume too much salt.
Iodine drops and tablets in the form of supplements can also be taken to avoid iodine deficiency and to carry out normal functions of the body.
Following are the iodine uses in the human body:
- Iodine is important for producing energy in the human body as it plays a vital role in producing components of cell-like mitochondria.
- Iodine plays an important role in the metabolism of the human body.
- Iodine is required for synthesis of thyroid hormone i.e.Triiodothyronine (T3) and Thyroxin (T4) from thyroid glands.
- TSH (Thyroid stimulating hormone), produced from the hypothalamus, regulates the levels of T3 and T4.
- Low levels of T3 and T4 lead to low heart rate, constipation, and weight gain.
- High levels of T3 and T4 lead to increased heart rate, diarrhea, and weight loss.
- Thyroid hormone carries out basic functions of the human body like:
- Muscles strengthening
- Maintaining body weight
- Maintaining body temperature
- Regulating heart rate
- Maintaining cholesterol levels
- Developing Central and Peripheral nervous systems
- Regulating the menstrual cycle
- Regulating Intestinal functions
- Thyroid hormone regulates protein production in the body.
- Iodine is also required for proper growth and development of the body.
- Iodine is also essential for the brain development otherwise its deficiency can cause mental retardation as in cretinism.
- It regulates the blood glucose level in the body.
- It mobilizes fat for producing extra energy in the body.
- Iodine act as an antioxidant and it helps to remove the free radicals. Hence, it reduces the chances of cancer.
- An adequate amount of iodine is required for the pregnant women, for the growth and development of fetal organs.
- Insufficient iodine during pregnancy might lead towards miscarriage, stillbirth or premature birth and other congenital anomalies.
- A diet that is high in iodine decrease chances of breast cancer.
- iodine is also used for water purification.
- Iodine is also used in radiation emergencies against radioactive iodides. Potassium iodide tablets are approved by FDA for this purpose.
- Iodine is also used for sterilization of surgical tools and cleaning of wounds.
- Tincture of iodine and other supplements are also available that are used widely.
SOURCES OF IODINE:
Iodine is not produced by the body, therefore, there is a need to take an adequate amount of iodine from the diet. Iodine contents in any food depend upon the soil in which it is grown and mostly it contains 3-75mcg /serving. Food from marine origin contains more iodine because iodine contents in seawater are more than that in the soil. Processed foods also contain a high concentration of iodine owing to the addition of iodized salt, calcium iodide, potassium iodide, cuprous iodide.
Following are the Iodine rich fruits and vegetables that contain different contents of iodine (in microgram, mcg) in them and are listed below:
- 1 tablespoon of Kelp=2000mcg
- 1 tablespoon of Arame =730mcg
- 1 tablespoon of Hizki =780mcg
- 1 tablespoon of Wakame =80mcg
- 1 inch of Kombu =1450mcg
SALMON AND SARDINES: Per 4 ounce serving =25-140 mcg
COD: Per 3 ounce =99 mcg
FISH STICKS: 2 fish sticks = 35 mcg
DRIED SEAWEED: ¼ ounce = 4500 mcg
SHRIMPS: 3 ounce = 35 mcg
CANNED TUNA: 3 ounce = 17 mcg
LOBSTERS: 100 grams = 100mcg
BANANAS: 1 medium size =3 mcg
STRAWBERRIES: 1 cup = 13 mcg
CRANBERRIES: 4 ounce = 400 mcg
CANTALOUPE: Per serving size = 6 mcg
CANNED CORNS: ½ cup = 14 mcg
FORTIFIED IODIZED SALT: 1 gram = 77 mcg
BAKED TURKEY BREAST: 3 ounce = 34 mcg
BEEF: Per 75 g = 11-14 mcg
CHICKEN: Per 75 g = 11-13 mcg
LIVER: Per 75 g = 32 mcg
MILK: 1 cup = 56 mcg
BOILED EGG: 2 large eggs = 48 -52 mcg
YOGURT: 1 cup = 154 mcg
CHEDDAR CHEESE: 1 cup = 22 mcg
COTTAGE CHEESE: 1 cup = 65 mcg
DRIED PRUNES: 5 pieces = 13 mcg
WHITE BREAD: 2 slice = 45 mcg
GREEN BEANS: ½ cup = 3 mcg
NAVY BEANS, Cooked: ½ cup = 32 mcg
BAKED POTATOES: 1 medium potato = 60 mcg
OATS: Per 30g = 14 mcg
PASTA / EGG NOODLES: ½ cup = 9 mcg
RICE(white, cooked ): ½ cup = 4 mcg
SOYNUTS: ¼ cup = 60 mcg
Goitrogens are the substances that limit iodine uptake by thyroid gland thus disrupting production of thyroid hormone. Foods that contain goitrogens include:
- Brussels sprouts
- Collard greens
- Cabbage cauliflower
- Mustard green
FRUITS AND STARCHY PLANTS
- Sweet potatoes
- Pine nuts
- Bamboo shoots
- Soy milk
RECOMMENDED DIETARY ALLOWANCE FOR IODINE:
Iodine is one of the crucial micronutrients in the body should be consumed in sufficient amount to meet the demands of growing body and to maintain a healthy lifestyle. Daily recommended intake for iodine in different ages is given below:
- 0-6 months= 110mcg/day
- 7-12 months = 130mcg/day
- 1-3 years = 90mcg/day
- 4-8 years = 90 mcg/day
For both Male and Female:
- 9-13 years = 120 mcg/day
- 14-18 years = 150 mcg/day
- 19-70 years = 150 mcg/day
- >70 years = 150 mcg/day
- Pregnant women: 220 mcg/day
- Lactating women: 290 mcg/day
SIGNS AND SYMPTOMS OF IODINE DEFICIENCY:
- SWOLLEN NECK :
It is the most obvious sign of iodine deficiency, a condition is commonly known as goiter. In this case, the thyroid gland couldnot secrete thyroid hormone due to less intake of iodine. As a result thethyroid gland had to work harder and therefore cells grow abnormally, manifesting swollen neck.
- WEIGHT GAIN:
If abody is deficient in iodine, thyroid gland would not work properly. This can affect metabolism drastically, causing an unusual and unexpected weight gain due to fewer calorie burn and fat storage.
- WEAKNESS AND FATIGUE:
Thyroid hormone is responsible for producing energy in the body. Low levels of iodine lead to poor functioning of thyroid glands and low energy production, consequently causing weakness and fatigue.
- HAIR LOSS AND WEAK HAIR:
Thyroid hormone controls the growth and regeneration of hair follicles. Iodine deficient people, therefore,face the problem of weak or thin hair and hair loss because their hair follicles are affected due to poor functioning of thyroid hormone.
- DRY SKIN:
Thyroid hormones help to regenerate skin cells. People suffering from iodine deficiency have dry and flaky skin. Moreover, thyroid hormone regulatesperspiration, therefore, iodine deficient people sweat less than those having normal levels of thyroid hormone.
- FEELING COLD:
People having low levels of iodine and thyroid hormones are more sensitive to cold than the normal ones. Brown fat is something that generates heat in body and thyroid hormone boost the activity of this brown fat. Therefore, people with low thyroid activity have less heat generation in the body resultantly feeling cold.
- VARIATION IN HEART RATE:
Low levels of T3 and T4 decrease heartbeat. A severe iodine deficiency cause abnormally slow heart rate to a level that a person might feel dizziness, weakness and might be at the risk of unconsciousness.
- LEARNING PROBLEMS:
A study found that people with low levels of thyroid hormone have small hippocampus (part of the brain responsible for long-term memory). Another study suggested that children with good levels of iodine and thyroid hormones performed better in learning and tests.
- COMPLICATIONS DURING PREGNANCY:
Pregnant women suffering from iodine deficiency may experience underactive thyroid, goiter, cold and fatigue. They may have premature babies or children with stunted growth and an underdeveloped brain. Iodine is equally essential for lactating mothers because it is passed from mothers to the infant through breast milk to meet body demands.
- IRREGULAR PERIODS:
Thyroid hormone regulates the menstrual cycle. Low levels of iodine disturb the menstrual cycle and it can also cause excessive bleeding. A study suggested that 68% of women with low thyroid levels experience irregular menstruation as compared to 12 % of the women with normal thyroid levels.
- Bone fractures:
People with iodine deficiency have high chances of spine and hip bone fractures due to poor thyroid function.
Iodine deficiency concentration is given below:
|Mild iodine deficiency||50-99mcg/L|
|Moderate iodine deficiency||20-49mcg/L|
|Severe iodine deficiency||< 20 mcg/L|
TESTS FOR IODINE DEFICIENCY
It is the simplest and fastest test that gives result in minutes. But, this test is less accurate than other iodine tests.
This test tells the amount of iodine in blood. It is a simple and accurate test but it consumes more time than the urine test.
IODINE PATCH TEST:
In this test, the doctor paints a patch of iodine on the patient’s skin and checks it after 24 hours. Iodine absorbed more quickly in the patients suffering from iodine deficiency. This test is relatively inexpensive but it is not the most accurate one.
IODINE LOADING TEST:
This test measures the amount of iodine excreted in urine within a period of 24 hours. This test is neither fast nor convenient but it’s quite accurate.
PEOPLE WHO ARE AT THE RISK INCLUDE:
- Pregnant women.
- Chances of iodine deficiency are more in females.
- People who don’t consume iodized salt.
- People who don’t use iodine fortified food.
- People suffering from SELENIUM deficiency.
- People who consume alcohol too much.
- People who smoke.
- People who expose to radiations mostly.
- People who consume a vegetarian and vegan diet.
- People living in the countries where iodine contents in the soil are very low. This includes Southeast Asia, South Asia, New Zealand and other European countries.
IODINE DEFICIENCY DISORDERS:
Goiter is one of the most common iodine deficiency disorders. Goiter is abnormally enlarged thyroid gland (thyroid gland is a butterfly-shaped gland located at the base of the neck just below Adam’s apple). Itis caused due to insufficient levels of T3 and T4 in blood that is due to less intake of iodine in the diet. In this case, TSH (thyroid stimulating hormone) levels rise to compensate for the insufficiency of thyroid hormone.
This leads to the abnormal growth and proliferation of the cell causing abnormally enlarged thyroid gland. Goiter in early stages is diffused but later it becomes nodular because abnormal cells in follicles proliferate more than other cells, enlarges and thus causes hemorrhage, cystic degeneration, and calcification.
Goiter can be assessed by palpation and also by ultrasonography. Ultrasonography is most preferred, quantifiable and easily performed method for the last two decades.
Goiter can be treated with iodine supplementation but if it lasts for more than 5 years of age iodine supplementation and thyroxine treatment may not reduce the size of the thyroid gland because it had permanently damaged.
A condition with very low levels of thyroid hormone due to less intake of iodine. It is related to goiter.
DEFICIENCY DURING PREGNANCY:
Sufficient intake of iodine is very important for pregnant women. Mothers suffering from iodine deficiency or untreated hypothyroidism have chances of congenitally defected babies because thyroid hormone is responsible for maturation of central nervous system (especially in its myelination). For the first 12 weeks of gestation, fetus is totally dependent on maternal T3 and T4. During 10th and 12th week, fetal TSH appears and it is now capable of concentrating iodine and its components. During 18th and 20th-week little thyroid hormone synthesis occurs. Therefore, adequate intake of iodine during the early trimesters is strictly recommended.
It is characterized by physical and mental retardation or disability, gait disturbance, deafness, and short stature due to hypothyroidism. It may be caused by restricted diet, intermarriages, low iodine in diet and isolation. According to WHO (WORLD HEALTH ORGANISATION), in 2007, almost 2 billion people have insufficient iodine intake. Hence, concluded that iodine deficiency is one of the most prevalent causes of INTELLECTUAL DISABILITIES.
Infants born with hypothyroidism and mental disabilities are more prone towards infectious diseases, nutritional deficiencies and hence mortality. It is most common in rural areas where intake of iodine is very limited.
Iodine is one of the most essential micronutrients and it should be consumed in adequate amount in the human body to carry out normal functions of the body, to prevent various fatal diseases, to improve nutritional status and to maintain a healthy and active lifestyle.BECAUSE
‘HEALTH IS TRUE WEALTH, AND NOT PIECES OF SILVER AND GOLD’.
I am HIRA NAQVI and I am doing my bachelors in Human Nutrition and Dietetics. I have written this article on iodine to make people aware of the countless benefits of this trace element because deficiency of this micronutrient can be life-threatening.
As it is important to realize the worth of your life and live accordingly.
Team- Nutrition Lab