Iodine

Iodine is a natural essential mineral belonging to the supplement  class.

Iodine is also known as iodate and iodide.

Iodine is an essential mineral required for the formation of thyroid hormones. It regulates various critical biological processes, particularly protein synthesis and enzymatic activity.

Iodine is a vital mineral primarily found in iodized salt, seaweed, fish (including cod and tuna), prawns, dairy products (like milk, yoghurt and cheese), eggs and other marine items.

The small intestine primarily absorbs iodine, which then travels to the thyroid gland for synthesizing hormones T4 and T3; the body eliminates any excess through urine.

The common side effects of iodine include gastrointestinal effects like abdominal cramps, diarrhea and nausea.

Biochemical action of iodine

Iodine belonging to the supplement class helps produce and regulate thyroid hormones. Iodine acts via the thyroid hormone synthesis pathway.

Thyroxine (T4) and triiodothyronine (T3) are thyroid hormones essential for regulating growth, maturation, thermogenesis, oxidation, CNS myelination, and general tissue metabolism, and these are synthesised from iodine. T3 works explicitly by attaching to nuclear receptors on cell surfaces. The zinc protein receptor interacts with specific DNA sequences because of this binding, triggering a series of events that either activate or inhibit gene transcription. As a result, several cellular functions, including metabolism, protein synthesis, and energy generation, are controlled. An ideal amount of iodine intake, hormone production, and receptor binding is essential for maintaining healthy physiological function and general health.

Iodine is available in gel, ointment and oral liquid solutions.

• Gel/ointments iodine is to be applied as directed by the doctor. It should be applied in a small amount to the affected area after cleaning it properly, as applicable.
• Oral solutions are to be taken by mouth, as applicable.

Iodine can be used as a supplement for synthesising thyroid hormones necessary for brain development, growth, metabolism, and many other body functions.

Iodine supplement orally is used for preventing and treating iodine deficiency.

Iodine might help to treat foot ulcers related to diabetes.

Adequate oral intake of Iodine supplements can protect the thyroid after exposure in a radiation emergency.

Vitamins and natural supplements should not replace a balanced diet.

This product is not intended to diagnose, treat or prevent any disease(s).

Iodine may be useful as a supplement for the following health benefits:

• Treatment and prevention of deficiency: Global brain damage is mostly caused by iodine deficiency, which affects 740 million people. Even a little shortage during pregnancy can affect brain development, affecting intelligence and leading to psychomotor impairments. It is crucial to confirm any potential associations with ADHD.
• Pregnancy: Iodine shortages during pregnancy might affect the fetus's ability to develop neurologically, resulting in hypothyroidism in both the mother and the foetus. The effects depend on the intensity and timing of the hypothyroidism; cretinism is the most severe condition.
• Fetal development: Iodine intake during pregnancy and breastfeeding is essential for the healthy growth and development of the baby during pregnancy. Iodine is obtained from breast milk by nursing newborns. However, the intake of iodine in a woman will affect the content of iodine in her breast milk.
• Cognitive function: The development of the brain and nervous system is adversely affected by severe iodine shortage in childhood. Although it is more challenging to determine, insignificant iodine deficit throughout childhood may have unnoticeable consequences on cerebral development. When adolescents with a minor iodine shortage are given supplements, their thinking skills and general cognitive function improve.
• Antiseptic: The iodine solution has been widely used for over a century as a topical antiseptic for wounds because it effectively cleans intact skin and mild injuries with little toxicity.
• Fibrocystic breast disease: It primarily affects females who can reproduce; however, it may occur during menopause. Very high iodine supplement doses might reduce pain and other fibrocystic breast disease symptoms, but further research is needed to confirm.

Iodine supplementation may be administered orally and topically.

• Orally: Iodine supplements are available as solutions, which can be taken orally. Some formulations may need to be taken with food or milk, while others can be taken without regard to meals.
• Topically: Iodine is applied to heal wounds or prevent skin infection in minor cuts, scrapes, or burns.

The dosage and duration of treatment should be as per the clinical judgment of the treating healthcare professional).

Vitamins and natural supplements should not replace a balanced diet

This product is not intended to diagnose, treat or prevent any disease(s).

• Gel: 0.9% iodine
• Ointment: 4.7%
• Oral liquid solution: 1%, 2%, 5% or 10%.

Iodine is available in gel, ointment and oral liquid solutions.

Iodine should be used as supplement support for maintaining strong bones along with appropriate dietary restrictions.

• Limit the consumption of drinks that include caffeine, such as coffee, tea, chocolate, and alcoholic beverages, as this substance could hinder Iodine absorption.
• Before iodine therapy, avoid foods like fish, seafood, seaweed, kelp and raw green vegetables such as spinach and broccoli, as these foods have high levels of iodine. Avoid consuming food containing thiocyanates like cabbage family (e.g. cabbage, kale, cauliflower, broccoli, turnips and Brussels sprouts) and in linseed, cassava, millet and soybean as they may interfere with Iodine absorption.
• Stay within your daily calorie needs.

The dietary restriction should be individualized as per patient requirements.

Recommended Daily Allowance (RDA)

The adult RDA set for adult men and women is 150 μg/day day

Upper Tolerable Intake (UTL):

The UTL is set for iodine is 1,100 μg/day

Iodine supplementation may be contraindicated in the following conditions:

• Hypersensitivity to Iodine supplements.
• History of Iodine-containing nephrolithiasis should avoid excessive Iodine intake.
• For individuals with thyroid disorders, excessive iodine intake may exacerbate thyroid problems.
• In patients with chronic renal disease, high levels of iodine can stress the kidneys.
• Graves ophthalmopathy (moderate to severe)
• Severe thyrotoxicosis.

• The treating healthcare must closely keep a watch and monitor for signs and symptoms such as nausea, diarrhoea and allergies. It is recommended to discontinue iodine in case of allergies.
• Iodine supplements should be used cautiously in patients with renal impairment.
• Iodine should be kept away from the eyes because it may irritate.
• Smoking has been demonstrated to elevate thiocyanate levels and decrease iodine content in smoking mothers' breastmilk.

Caution is advised when consuming alcohol with iodine.

It is excreted in breastmilk; Use cautiously during breastfeeding.

Use cautiously during pregnancy.

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Limit the consumption of foods and beverages that include caffeine, such as coffee, tea, chocolate, and alcoholic beverages, as this substance could hinder the absorption of iodine.

Iodine is generally well-tolerated.

The adverse reactions related to iodine can be categorized as-

• Common: Skin rash or itching, upset stomach, diarrhoea and nausea.
• Less Common: Headache, metallic taste in the mouth, fever and swelling of the salivary glands.
• Rare: Allergic reactions, severe stomach pain and irregular heart rhythms or palpitations.

The clinically relevant drug interactions of iodine are briefly summarized here:

• Goitrogen: Thiocyanates, present in some foods and chemicals like perchlorate and disulfides, constitute substances that hinder the absorption of iodine and the synthesis of thyroid hormones. Cosmetics, insecticides, and plasticizers may trigger thyroid endocrine disruption.
• Soy: The goitrogenic activity of soy involves isoflavones like genistein and daidzein suppressing T3 and T4 synthesis and soy decreasing iodine absorption, primarily when given as thyroxine in the gut. When using thyroid hormone pills, avoid soy.
• Selenium: Selenium is crucial for the metabolism of thyroid hormones, assisting in converting T4 to T3 and permitting iodine recycling through deiodinases, promoting a beneficial interaction in the body.

The common side of iodine includes the following:

• Nausea
• Upset stomach
• Diarrhoea
• Skin rash or itching
• Metallic taste
• Soreness of teeth and gums
• Burning in mouth and throat

The use of iodine should be prudent in the following group of special populations

• Pregnancy:

The RDA for Iodine in pregnant women is 220 mcg/day.

Due to possible associations with a higher incidence of postpartum thyroiditis and other thyroid function abnormalities, caution should be exercised when consuming large doses during pregnancy.

• Paediatrics:

Iodine is vital for producing the hormones that control the pediatric population's metabolism, growth and development.

Iodine supplements are the best way to help children get enough iodine daily.

The RDA for Iodine in paediatrics ranges from 90-150 mg/day.

Dosage Adjustment for Paediatric Patients

There are no specific dosage adjustments provided.

• Geriatrics: There is no sufficient scientific evidence traceable regarding the use and safety of iodine for use in special populations.
• Lactating mothers: Using iodine during breastfeeding is generally acceptable but as iodine is excreted in breastmilk; Use cautiously during breastfeeding.

The RDA for Iodine in lactating mothers is 290 mcg/day.

Dosage Adjustment in Kidney Impairment

There are no specific dosage adjustments provided.

Dosage Adjustment in Hepatic Impairment

There are no specific dosage adjustments provided.

Dosage Adjustment for Adult Patients

Cleaning Wet Ulcers and wounds

Spread in 1/8-1/4 inch to dry sterile gauze; apply not more than 50 g per application on the gauze and apply it on the wound; no more than 150 g/week

Change 3 times/week or when the colour turns yellow/grey.

Antiseptic for Minor Cuts, Scrapes, Burns

Apply a small amount to the affected area qDay to q8hr

The physician should be vigilant about the knowledge pertaining to identifying and treating overdosage of iodine. Overdosing on Iodine supplements may cause gastrointestinal disturbances and cardiovascular symptoms and induce hypo- and hyperthyroidism.

There is no specific antidote or treatment for excessive intake of supplemental iodine. When an overdose is suspected, iodine should be terminated immediately and follow management by supporting the airway, breathing, and circulation. In the case of a stable patient, activated charcoal should be given to decontaminate the gastrointestinal tract. Physical therapy might be added if necessary.

Biochemistry profile of iodine

Iodine is an essential mineral for many physiological functions in the human body. The body absorbs iodine in various forms, including its reduced form of iodide (I-), its oxidised form of iodate (IO3-), and organic molecules such as thyroxine (T4) and triiodothyronine (T3). Its primary function is the production of the thyroid hormones T4 and T3, which are necessary for various physiological processes.

Thyroperoxidase (TPO) and hydrogen peroxide oxidise iodide inside the thyrocyte. The precursors of thyroid hormones, monoiodotyrosine (MIT) and diiodotyrosine (DIT) are generated by this mechanism, which links iodine to tyrosyl residues on thyroglobulin. To produce thyroid hormones, TPO catalyses the development of a diether bridge between iodotyrosine phenyl groups. T4 is produced by joining two DITs, whereas T3 is generated by combining an MIT and a DIT.

Foetal cell development, postnatal growth, and basal metabolic rate are all regulated by thyroid hormones. Sufficient iodine consumption is essential for thyroid health since deficiencies can cause goitre or hypothyroidism.

Kinetic profile:

• Absorption: The small intestine's stomach and proximal part mainly absorb iodine and enter the bloodstream through dietary intake.
• Distribution: Iodine distributes throughout the body after reaching the bloodstream, with the thyroid gland as the primary centre of concentration.
• Metabolism: Iodide (I-) is converted to iodine (I2) during the generation of hormones (T4 and T3) as part of the thyroid glands iodine metabolism. These hormones control several physiological processes, including growth, development, and metabolism.
• Elimination: To help keep the body's iodine levels balanced, any excess iodine that is not used in hormone production is primarily excreted through urine.

1. Braun L, Cohen M. October 1, 2014.Herbs and Natural Supplements; 4th Edition Vol-2. Australia. Elsevier.
2. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/
3. https://www.ncbi.nlm.nih.gov/books/NBK554545/
4. https://www.ncbi.nlm.nih.gov/books/NBK549792/
5. https://reference.medscape.com/drug/caltrate-os-cal-Iodine-carbonate-vitamin-d-999885#0
6. https://ods.od.nih.gov/factsheets/Iodine-Consumer/