11 Benefits Of Iodine, Dosage, Sources, And Side Effects

Reviewed by Merlin Annie Raj, RD
Written by Ravi Teja Tadimalla, Professional Certificate In Food, Nutrition & Health

Iodine, though present in trace quantities in our body, is crucial for neurological and reproductive functions and thyroid health. The benefits of iodine are far-reaching. It helps produce thyroid hormones that, in turn, play a vital role in optimal brain function, pregnancy, fetal development, and metabolism. So, it is highly essential to obtain this mineral in recommended quantity through a healthy diet or supplements.

Most iodine present in our body is headed to thyroglobulin and is found in the thyroid gland (1). It determines the thyroid function, and a deficiency could result in serious disorders. For instance, iodine deficiency during pregnancy and growth can lead to impaired cognitive function. A severe deficiency can even result in the onset of goiter and hypothyroidism (2). Iodine also has antiseptic and disinfectant properties that help treat infections and minor burns. This article looks at these benefits deeply and understands the symptoms of iodine deficiency and its daily recommended intake. Keep reading.

What Are The Benefits And Uses Of Iodine?

1. Promotes Thyroid Health

Thyroid function is absolutely crucial for metabolism. The hormones T3 and T4 (triiodothyronine and thyroxine) contain iodine as an essential component and are responsible for regulating thyroid function (3). Iodine is a requisite substrate for the synthesis of the thyroid hormones and is critical in the autoregulation of the thyroid gland and its function. This helps in combating minor fluctuations in the endocrine system (4).

Apart from that, iodide – a form of iodine – is known to control thyroid function. The thyroid stimulating hormone (TSH) is modulated by the thyroid, with iodide playing a crucial role (5),(6).

Excess or deficiency of iodine can lead to different thyroid disorders which are discussed in detail in the following sections.

2. May Reduce The Risk For Some Goiters

The availability of iodine plays an important role in the production of thyroid hormones by the thyroid gland (7). In adults, mild to moderate iodine deficiency increases the incidence of hyperthyroidism due to toxic goiter (7), (8).

Studies have shown that the excess iodine, in combination with the dysfunctional thyroid gland, may manifest as a multinodular goiter, which sometimes leads to thyrotoxicosis (4). Thus, it is important to curate the dosage programs of mass iodization carefully.

3. May Help In Managing Overactive Thyroid Gland And IIH

Radioactive iodine (RAI) therapy for hyperthyroidism was first used in 1941 by physicians at Massachusetts General Hospital in Boston (9). Studies have shown that radioactive iodine can be used in the management of hyperthyroidism in children (10). This therapy has shown high cure rates at appropriate doses. However, there is a potential risk of genetic damage or thyroid cancer, which is why these radioactive iodine-based therapies are used conservatively until further research is available (10).

Recent studies have shown that using radioactive iodine for managing hyperthyroidism may be contraindicated (11). Iodine-induced hyperthyroidism (IIH) occurs as a consequence of correction iodine deficiency, usually in the elderly population with multinodular goiter with underlying cardiovascular risk factors. Monitoring the process of iodization can help in managing IIH (12).

IIH may also occur due to an increase in iodine intake in individuals whose hyperthyroidism (Graves’ disease) is not expressed because of iodine deficiency (12).

4. May Help In Treating Thyroid Cancer

Thyroidectomy is one of the standard practices for treating well-differentiated thyroid cancer (13). However, radioactive iodine is administered to identify any leftover tissue. Studies conducted on the role of radioactive iodine are controversial due to many factors such as the lack of understanding of the mechanisms involved and a lack of consensus regarding the dosage and administrative practices by hospitals (13), (14), (15).

5. May Help In Neurodevelopment During Pregnancy

Iodine is also critical for the development of the central nervous system in the fetus and children (3). The thyroid hormones from the mother are essential for the development of the fetus as they regulate neurodevelopment, especially in the later stage of the first trimester (16). Thus, it is recommended for pregnant women to increase iodine consumption by 50% either through diet or supplements. We have discussed the recommended dosage levels in detail in the section below.

As the pregnancy progresses, the fetus starts to produce these hormones (16). Hypothyroxinemia, fetal hypothyroidism, and cretinism are some of the serious consequences of thyroid deficiency and neural impairment during pregnancy (16). Autoimmune thyroid disease (AITD), Transient Gestational Hyperthyroidism Syndrome, and different types of goiter are also common during pregnancy, although their prevalence is lower. Iodine deficiency remains the leading cause of preventable mental retardation worldwide (6), (17).

Studies have shown that children born to women with hypothyroidism exhibit lower scores in a neuropsychological test measuring parameters such as language, intelligence (intelligent quotient), attention, and visual-motor performance (18). Although further research is required to rule out other factors that might play a role in neonatal complications, it is recommended that all pregnant women be screened for thyroid diseases so that preventive measures can be taken (18), (19).

Iodized salt is not the preferred method for delivering iodine during pregnancy as excess salt intake may lead to further complications and water retention. Multivitamins are a better option to meet the recommended dietary requirements for iodine during pregnancy (20).

6. May Improve Cognitive Function

As discussed above, iodine is critical for the development of the central nervous system in the fetus and children (3). Iodine supplementation is recommended to counteract hypothyroidism due to iodine deficiency during pregnancy. This can help in improving the cognitive function of children and prevent learning disabilities to some extent (1), (3).

Iodine is also essential for brain development, formation, and differentiation of neurons, myelination, and even the formation of synapses (1).

Iodine supplementation has been shown to successfully improve physical and mental development in children. However, further research is needed to understand the role of iodine in improving cognitive function (21).

7. May Help In Improving Birth Weight

Research has found an association between thyroid function, iodine status, and prenatal growth (22). High maternal thyroid hormone levels during the first half of pregnancy were related to lower birth weight (23).

Iodine supplementation has the potential to positively impact the birth weight of newborns (24).

Studies have shown that oral iodine administration improves the survival rates of infants in populations at risk for iodine deficiency (25).

8. May Help Treat Fibrocystic Breast Disease

The safety and efficiency of iodine therapy in treating and managing fibrocystic breast disease in animals has been well documented (26), (27), (28).

However, patients with fibrocystic breast disease responded differently to iodine replacement therapy (29). Studies are limited to validate this claim, but there is preliminary data suggesting that iodine may help in managing fibrocystic breast disease and breast cancer (26).

9. May Help In Disinfecting Water

Iodine is known to be a cheap and effective water disinfectant due to its germicidal properties (30). However, it might lead to the ingestion of iodine in excess of the daily recommended amount. This may pose a risk as excess iodine can lead to several health complications (30). Iodine is used in swimming pools regularly to clean and disinfect water.

10. May Provide Protection From Nuclear Fallout

WHO recommends potassium iodide (KI) administration as a prophylactic measure following nuclear accidents (31). It is one of the safest and most effective methods to counteract accidental radioactive exposure during a nuclear reaction (32). Potassium iodide saturates the thyroid transport and negatively regulates the deposition of radioactive iodine into the thyroid gland. This helps in preventing thyroid dysfunction and thyroid cancer (32).

11. May Help In Treating Infections

Povidone iodine (PVP-I) is an antiseptic and antimicrobial agent. It can be used to treat cuts, abrasions, and minor burns (33). In fact, it is recommended in the list of essential medicines by WHO (34). It is commonly used to treat wounds (pre- and post-surgery) and skin infections as it has broad spectrum antimicrobial activity.

Now that you know all about the health benefits of iodine, let’s check out all the ways you can ingest it safely.

Sources Of Iodine

Natural sources of iodine are listed below (21):

  • Iodine is found naturally in abundance in seaweed (kelp, nori, kombu, and wakame), shrimp, and fish such as cod and tuna.
  • Dairy products are another rich source of iodine. Include milk, cheese, and yogurt in your diet to reap the health benefits of iodine.
  • Bread and grain-based cereals also contain iodine.
  • Vegetables and fruits are major sources of iodine. The iodine found in the soil where they are cultivated may play an important role in their nutritional value.

You can also take iodine in the form of dietary supplements and iodized table salt (21).

You can learn more about the sources of iodine and how to include them in your diet.

Now, let’s talk about how much iodine you need to consume in the next section.

How Much Iodine Do You Need?

The amount of iodine you need to eat each day depends on your age. The average daily recommended amounts are listed below in micrograms (mcg) (21).

  • Life Stage And The Recommended Intake
  • Birth to 6 months: 110 mcg
  • Infants 7-12 months: 130 mcg
  • Children 1-8 years: 90 mcg
  • Children 9-13 years:120 mcg
  • Teens 14-18 years: 150 mcg
  • Adults: 150 mcg
  • Pregnant teens and women: 220 mcg
  • Breastfeeding teens and women: 290 mcg

Women who are pregnant or breastfeeding need extra iodine as the babies get the iodine from their mothers, especially during the early stages of pregnancy. The American Thyroid Association and American Academy of Pediatrics recommend that women who are pregnant, planning to become pregnant, or breastfeeding take a daily supplement containing 150 mcg iodine as potassium iodide (21).

Generally, iodine is safe at recommended levels. However, care should be taken when it is taken alongside certain medications that are listed in the next section.

Is There A Risk Of Drug Interactions With Iodine?

  1. Iodine supplements are known to interact with several medications such as M1ethimazole/Tapazole (treats hyperthyroidism). Most anti-thyroid medications and the intake of high doses of iodine will be counterproductive. They could lead to a reduction in the production of thyroid hormones (21).
  2. Potassium iodide, when taken with ACE inhibitors (Benazepril/Lotensin, Lisinopril, Prinivil, or Zestril) that are often prescribed for high blood pressure, may lead to increased levels of potassium in the bloodstream (21).
  3. Drugs like Spironolactone/Aldactone and Amiloride/Midamor – which are potassium-sparing diuretics – can also increase the potassium levels in the body when they interact with potassium iodide (21).

Always consult your doctor or a medical professional before taking iodine supplements.

Iodine is a great supplement for thyroid function, but it also poses the risk of certain side effects. Check them out in the next section.

What Are The Side Effects Of Iodine?

Too little or too much of iodine can upset the delicate balance of thyroid function. Apart from thyroid disorders, high iodine intake can cause vomiting, burning sensation in the mouth, throat, stomach, and fever. You may also experience symptoms such as weak pulse, diarrhea, and nausea (21). Thyroid inflammation, cancer, and goiter are also manifestations of iodine status and thyroid regulation.

What Are Signs And Symptoms Of Iodine Deficiency?

On the other side of the scale is iodine deficiency. Environmental iodine deficiency is one of the leading causes of thyroid disorders such as goiter, cretinism, fetal and infant mortality, and rise in cognitive and neuromotor disabilities (4), (35). This has been tackled by implementing mass iodization programs with successful results (1), (4).

Since iodine status and thyroid hormone production are correlated, the symptoms for iodine deficiency also overlap with those of hypothyroidism:

  • Swelling In The Neck: This is a common symptom of goiter, which is caused by iodine deficiency. Low iodine levels trigger the thyroid cells to multiply at exponential rates, which causes the swelling in the neck.
  • Unexpected Weight Gain: Iodine levels and thyroid glands are involved in the regulation of metabolism. This may lead to weight gain. However, further studies are needed to understand the exact mechanism behind this (36), (37).
  • Fatigue And Weakness: As thyroid function is correlated with energy expenditure, iodine deficiency or hypothyroidism can cause feelings of tiredness, lethargy, and fatigue (38).
  • Hair loss (38)
  • Dry, flaky skin (38)
  • Feeling colder than usual (38)
  • Changes in heart rate (38)
  • Trouble learning and remembering (38)
  • Problems during pregnancy (38)
  • Heavy or irregular periods (38)

So, let’s answer the most important question.

Who Should Take Iodine?

Iodine is essential for the normal functioning of the body. Iodine supplements should be taken by:

  • Women who are pregnant and breastfeeding (21).
  • People with iodine deficiency or hypothyroidism (21).
  • People living in iodine-deficient areas (21).
  • Iodine-deficient people who consume excessive amounts of goitrogens, such as soy and cruciferous vegetables (21).

Iodine deficiency early in life impairs cognition and growth, but iodine status is also a key determinant of thyroid disorders in adults. Severe iodine deficiency causes goiter and hypothyroidism. Both iodine deficiency and iodine excess are associated with an increased risk of thyroid disorders. Further research is warranted to verify the optimal ranges of iodine intake and to clarify the effects of iodine intake on thyroid disorders.

From preventing hypo or hyperthyroidism and thyroid cancer to reducing the risk of goiter and cognitive decline, the benefits of iodine are wide-ranging. It is highly essential for pregnant women to ensure the cognitive and neurological development of the fetus, so they must increase their consumption of iodine-rich foods. It also aids in treating infections, thanks to its antiseptic and antimicrobial properties. Foods like seaweed, tuna, cod, dairy products, bread, cereals, veggies, and fruits are rich in this trace element. Include these in your diet to keep iodine deficiency in check. However, excessive iodine levels may also impact thyroid health, so practice caution.

Frequently Asked Questions

Are iodine supplements safe?

Iodine supplements should be taken under medical supervision. Studies have shown that excess iodine can be harmful (39).

How long does it take to correct iodine deficiency?

Although there is limited data, people have shown improvement in 3 months after taking iodine.


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Merlin Annie Raj

(Registered Dietitian Nutritionist)
Merlin Annie Raj is a Registered Dietitian based out of Hyderabad, India. She has vast experience in Clinical Nutrition as... more