Food sources and facts of Iodine


Human life is not possible without iodine. Iodine is an essential part of thyroid hormones, which regulate metabolism. Thyroid hormones affect essentially the entire body and must be in the correct range for good health. The same is true for iodine—it must be in the correct range for good health.

Found in many foods and in iodized salt, iodine is a mineral that the body requires to make thyroid hormones. Thyroid hormones control the metabolism of the body as well as other functions such as bone and brain development during pregnancy and infancy. Since the body is unable to make iodine, people must obtain it from their diet and, sometimes, supplementation.

Historically, iodine deficiency was fairly common in northern parts of the United States. However, the introduction of iodized salt almost a century ago virtually eliminated severe iodine deficiency. Still, in many other parts of the world, large numbers of people are unable to obtain sufficient amounts of dietary iodine and may be iodine deficient. In fact, the American Thyroid Association has noted that about 40 percent of the world’s population is at risk for iodine deficiency.

Although iodine is found naturally in soil and seawater, the actual amount of iodine varies from location to location. Since the amount of iodine in a particular product may not be listed on nutrition labels, it may be difficult to determine the actual iodine in a specific food. Likewise, when cooking iodine-rich foods in water, a large amount of the iodine may seep into the water. This is fine if the water will be consumed, as in a soup, but this is an unfortunate waste of a valuable mineral when the water is discarded.

Food Sources that offer Iodine

Sea vegetables, such as the various forms of edible seaweed, are the best sources of iodine. Brown sea vegetables have more iodine than red sea vegetables. But there are other excellent sources such as scallops and cod. Very good sources of iodine include yogurt, shrimp, cow’s milk, eggs, and strawberries. Sardines, salmon, and tuna are good sources. Iodine is readily available as a dietary supplement, generally as potassium iodide or sodium iodide. Multivitamins often contain iodine, and kelp and some other types of seaweed may be purchased as a supplement.

Food name Weight Iodine (µg) DV%
Lima beans 125 mL 8 5%
Corn 125 mL 7 4%
Green peas 125 mL 4 2%
Crisped rice 30 g 20 13%
Oat 30 g 14 9%
Wheat 30 g 8 5%
Raisin bran 30 g 6 4%
Cottage cheese  250 mL 65 43%
Cheddar cheese 50 g 22 14%
Turkey 75 g 30 20%
Beef 75 g 14 9%
Chicken 75 g 13 8%
Cod 75 g 87 58%
Haddock 75 g   87 58%
Tuna 75 g  15 10%
Soynuts 60 mL 60 40%
Navy beans 175 mL 53 35%
Eggs 2 large 52 34%
Kidney beans 175 mL 28 18%
White rice 125 mL  4 2%


Recommended Daily Intake

The Food and Nutrition Board has established the following Recommended Dietary Allowances for iodine. Lactating women should consume 290 mcg per day, while pregnant women should consume 220 mcg per day. Males and females aged 14 years and older should take in 150 mcg, while children between the ages of 9 and 13 years should take in 120 mcg. Children between the ages of 1 and 8 years should take in 90 mcg; children between the ages of 7 and 12 months should take in 130 mcg; and children between birth and 6 months should take in 110 mcg. There are also tolerable upper intake levels for iodine. Adults 19 years and older should consume no more than 1,000 mcg per day, while teens between the ages of 14 and 18 years should consume no more than 900 mcg. For children between the ages of 9 and 13 years, the upper limit is 600 mcg; for children between the ages of 4 and 8 years, the limit is 300 mcg; and children between the ages of 1 and 3 years should take in no more than 200 mcg per day. No upper limits have been established for infants. People who are taking supplemental iodine under the supervision of a medical provider should ignore these limits.

Health Benefits of Iodine

Here are some health benefits discussed on Iodine:

  1. Thyroid hormone synthesis

The only known function of iodine in the body is as an essential component of the thyroid hormones. The thyroid gland removes iodine from the blood and attaches it to tyrosine-containing proteins to form the thyroid hormones, thyroxine (T4) and triiodothyronine (T3). The thyroid hormones are then secreted into the bloodstream and are important regulators of cell activity and growth, both in utero and throughout life. Although they affect all tissues, they are particularly important in the development of the nervous and skeletal systems.

  1. Helpful for Thyroid Disorders and Lower Cholesterol Levels

In a randomized, controlled study published in 2015 in the Journal of Nutrition, researchers from Zurich, Switzerland, and Marrakesh, Morocco, wanted to learn more about the effect iodine supplementation has on thyrotropin (also known as the thyroid stimulating hormone) and levels of serum cholesterol. Iodine is required for the production of thyroid hormones. A deficiency of iodine may lead to elevated levels of thyrotropin, which, in turn, is a predictor of higher levels of cholesterol. The cohort consisted of 163 overweight or obese Moroccan women, between the ages of 20 and 50 years, who were iodine deficient. For six months, the women took a daily 200 mcg iodine supplement or a placebo. The researchers found that the subjects with elevated baseline cholesterol levels who took iodine experienced an 11 percent reduction in total cholesterol. At a six-month follow up, the levels of thyrotropin were 33 percent lower in the treatment group than the placebo group. But the most dramatic results were in levels of cholesterol. Only 21.5 percent of the subjects in the iodine supplementation group continued to have elevated levels of cholesterol. That was in contrast to 34.8 percent of the placebo group. The researchers commented that iodine supplementation in people who are deficient may decrease thyroid disorders and help to reduce cardiovascular disease.

  1. Regulation of Metabolic rate

Iodine promotes thyroid glands function by supporting hormones production which is responsible for controlling base metabolic rate of the body. Metabolic rate affects organs efficiency and regular processes such as sleep cycle and food absorption and also transformation into usable energy. Triiodothyronine and thyroxine are certain hormones which influence heart rate, body weight, blood pressure and temperature. Body maintains Basic Metabolic Rate with the support of these hormones that assist in protein synthesis. It ensures normal creation or distribution in body for maintaining good health.

  1. Stillbirths prevention

Pregnant women with adequate iodine help to prevent stillbirths and neurocognitive conditions such as cretinism in newborn babies. It results various complications and gestational hypertension during infancy. It promotes proper growth and movement of baby with hearing and speech abilities. Moreover, besides its effect on baby’s health once conceived, iodine deficiency could make women infertile. Pregnant women should realize iodine intake for child as well as themselves because it passes into breast milk and is lost every day. Study have shown that nursing and pregnant women could lose more than entire needed dose of iodine daily that could result in serious deficiency even after pregnancy or breastfeeding.

  1. Boost immunity

People focus on thyroid gland implications of iodine but it has other functions as well which includes major booster for immune system. It scavenges free hydroxyl radicals and alike Vitamin C, it promotes antioxidant activity throughout body for providing strong defensive measure against diseases such as cancer and heart diseases. Study have shown that it protects brain cells of rats from free radical’s effects by linking to fatty acids in cell membranes and allows lower chances for free radicals to affect organism.

  1. Treat Hypothyroidism

Hypothyroidism is a condition outlining by under-active thyroid gland and results slowing down of bodily process as chemical balance in body goes off track. Hyperthyroidism is commonly resulted due to large increase in weight as the body does not burn off calories to convert them into energy. Though hypothyroidism occurs for various reasons not only deficiency of iodine but it is a great idea to promote iodine intake and stimulate hormonal activity that eventually helps to lose weight. Hypothyroidism shows some other effects such as dry skin, fatigue, constipation, troubled concentration, leg swelling and cramps. If left untreated, it could lead to serious conditions such as coma and heart failure.

  1. Fibrocystic Disease treatment

Iodine lowers conditions such as turgidity, fibrosis and breast tenderness. It provides relief from fibrocystic diseases and is used widely in both modern and traditional therapies. Studies concluded significant correspondence between molecular iodine and lowering signs or symptoms of fibrocystic breast disease.

  1. Cancer prevention

Iodine also possesses anti-carcinogenic property. Study has shown that cancer cells diminish after being injected with iodine and even they undergo apoptosis and replaced with healthier cells. But the exact mechanism for this process is unknown. Studies have shown positive connection in terms of effects on promoting apoptosis in breast cancer carcinoma cells.

It is required to prevent these harmful forms of cancer. Study shows that thyroid cancer patients have lower symptoms of cancer after increasing intake of iodine. Thus, thyroid cancer is common in people with iodine deficiency.

  1. Prevent Apoptosis

Iodine assures apoptosis and programmed cell death which is required for formation of new organs as well as in elimination of malignant cells such as diseased or cancer cells that might become harmful to any individual. This function is derived from thyroid gland effects and regulation or hormonal secretion.

  1. Flushes out toxins

Iodine flushes out harmful chemicals such as lead, fluoride, mercury or biological toxins. Role of extra thyroidal iodine is crucial as it does other work throughout body.  It possess antibacterial qualities such as Helicobacter pylori that is a harmful bacterial infection in stomach commonly known to be H. Pylori which is associated with gastric cancer.

What happens due to deficiency or excess Iodine?

Ingestion of multiple grams of iodine at one time can cause acute poisoning. A very large amount of iodine causes fever, abdominal pain, burning of the mouth, throat & stomach, nausea, vomiting, diarrhea, heart problems, and coma.

Over the long term, both excessive and inadequate intake of iodine can cause thyroid problems, depending on previous intake of iodine and any underlying problems with the thyroid. People with thyroid autoantibodies, meaning they are making antibodies against their thyroid gland, are more susceptible to problems with both excessive and inadequate intake of iodine.

Excessive iodine ingestion can cause hyperthyroidism, the opposite of low thyroid. It can also cause goiter, thyroid inflammation (thyroiditis), and thyroid cancer. Long-term consumption of excessive amounts of iodine may also cause hypothyroidism. This can happen at any age. The reaction of a person’s thyroid to excess iodine may depend on his or her previous levels of iodine and any existing thyroid disease, as noted above. Case reports have shown that high iodine intake can also potentially slow down thyroid function.

There is a serious illness highlighted by a rash specific to high iodine intake called iodermia. The rash can look like acne, hives, or be red and itchy. Iodermia can actually lead to death.

The first measurable change with excess iodine consumption is an elevated TSH. TSH values were used to help set safety limits by the IOM. The No Observed Adverse Effect Level (NOAEL) for adults is 1,000 to 1,200 μg per day. The Lowest Observed Adverse Effect Level (LOAEL) for adults is l,700 μg a day. The Upper Limit (UL) for adults is 1,100 μg a day. This is the upper limit considered to be completely safe.

Infants should only get iodine from breast milk, food, or formula. The UL for other ages has simply been extrapolated based on size. The UL for children 1 to 3 years of age is 200 μg a day. The UL for children 4 to 8 years of age is 300 μg a day, and for children 9 to 13, the UL is 600 μg a day of iodine.

People who have autoimmune thyroid disease may be more susceptible to problems from increased iodine intake. These are common conditions, especially among older women. One, called Graves’ disease, is associated with hyperthyroidism. Another, called Hashimoto’s thyroiditis, is associated with hypothyroidism.

In addition to iodine in supplements, iodine is contained in some medications, for example, amiodarone (for irregular heart rhythm). It is also contained in disinfectants like povidine-iodine and in some contrast media used for x-ray studies. Molecular iodine (I 2) does not cause the same problems as iodine (I), and larger amounts may be tolerated.


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