The Thyroid

The thyroid gland is the “master controller” of metabolism.
Iodine Deficiency

Iodine Deficiency

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Iodine and thyroid health

Thyroid disorders are some of the most frequent diseases in the world, with about 1.6 billion people worldwide at risk.1 Iodine is an integral part of thyroid hormones and is therefore an important factor in the development of hypothyroidism (under active thyroid) and hyperthyroidism (overactive thyroid). Without sufficient iodine, hypothyroidism, cretinism and other iodine deficiency disorders can develop. Conversely, excessive iodine intake can lead to hyperthyroidism in susceptible individuals.1

Why is iodine important?

Iodine is essential for thyroid hormone production, for foetal and infant development, and it is a crucial nutrient for proper health at all stages of life.2 As our bodies cannot produce iodine, it should be supplied regularly through a healthy diet.2 Iodine deficiency exists in about 54 countries around the world, according to a report by the World Health Organization (WHO).3

Iodine is the key component in the production of the thyroid hormones thyroxine (T4) and triiodothyronine (T3).4 Thyroid hormones help the body to optimally use energy, stay warm, and keep the brain, heart, muscles and other organs working as they should.5 Thyroid hormones and therefore iodine are essential for foetal growth, bone maturation and brain development.2 According to the WHO, insufficient iodine intake is the most common preventable cause of mental retardation.3

A global campaign to iodise the salt supply in almost all countries has led to an estimated 68% of households now using iodised salt.6 Prior to this campaign, an estimated 2 billion people showed iodine deficiency by way of having a goitre in 2005 where as the actual number was 700 million, sparing 1.3 billion people from this disorder.6 Despite this, approximately 40% of the global population remains at risk for iodine deficiency.7

How much iodine do you need?

A teaspoon of iodine is all you need in your lifetime; however, as the body cannot store iodine for long periods, tiny amounts are needed regularly.2 Most people can tolerate large amounts of iodine without adverse effects. An intake of more than 1,000 micrograms per day may be harmful.2

The daily iodine requirement changes over a person’s life:4

  • Infants: 110–130 micrograms
  • Children (1–8 years): 90 micrograms
  • Children (9–13 years): 120micrograms
  • Adolescents and adults: 150micrograms
  • Pregnant women: 220 micrograms
  • Breastfeeding women: 290 micrograms

Note: Infants are at high risk for iodine deficiency because their need for iodine and thyroid hormones in relation to their weight is much higher than at any other time of life. It is important to note that while iodine is essential, giving babies extra salt is not recommended. The best way to ensure that infants receive an adequate amount of iodine is by providing a well-balanced diet that includes iodine-rich foods to the breastfeeding mothers.8

How to meet your needs for iodine

Pregnant women, breastfeeding mothers, and infants are the most vulnerable groups to iodine deficiency.10

Seafood is a good source because the oceans are rich in iodine. Although, eggs, meat and dairy products contain less iodine than most seafood, they are richer in iodine than most foods of plant origin. Any salt used at home should be iodized.2 To ensure sufficient intake for babies in the weaning period, the iodine content of homemade or commercial complementary formula/foods should be considered.8

Common sources of dietary iodine:12

  • Iodised salt
  • Seafood (fish, prawns, squid)
  • Seaweed
  • Meat
  • Eggs
  • Milk and cheese
  • Ice cream
  • Frozen yoghurt

The best method to prevent iodine deficiency is long-term dietary supplementation with iodised salt, the strategy recommended by the World Health Organization (WHO).13 The WHO recommends a salt intake of less than 5 grams per day (equivalent to about 1 teaspoon of salt per day) to prevent cardiovascular disease.13 One teaspoon of iodised salt contains about 400 micrograms of iodine.7 To meet the total demand of iodine you should not eat more salt but consume other iodine-rich foods.2

Summary

  • Too little or too much iodine in the diet is associated with thyroid disorders
  • The daily iodine requirement changes over a person’s life, with higher requirements in pregnant and breastfeeding mothers 
  • A well-balanced diet with iodine containing food is generally sufficient to provide daily iodine requirement.

Useful websites

<p style="color:#fe369c; font-weight:bold">International Council for the Control of Iodine Deficiency Disorders </p>

https://www.givewell.org/international/top-charities/IGN/2014-interim-review

The International Council for the Control of Iodine Deficiency Disorders (ICCIDD)is a non-profit, non-government organization for the sustainable elimination of iodine deficiency and the promotion of optimal iodine nutrition worldwide.

 

<p style="color:#fe369c;font-weight:bold">United Nations Children’s Fund</p>

http://www.unicef.org/progressforchildren/2007n6/index_41509.html

United Nations Children’s Fund (UNICEF) publishes “Progress for Children”, astatistical review that documents progress towards the “Millennium Development Goals”.

<p style="color:#fe369c;; font-weight:bold">American Thyroid Association</p>

http://www.thyroid.org/patients/patient_brochures/iodine_deficiency.html

Patient information on thyroid health published by the American Thyroid Association (ATA).

References

  1. Khan A, Khan MMA, Akhtar S. Thyroid disorders, etiology and prevalence. J Med Sci 2002; 2: 89-94.
  2. Nutrition Australia. Nutrition fact sheet: iodine. Available at: https://nutritionaustralia.org/app/uploads/2020/05/Iodine_Printable-Detailed-Summary.pdf. Last accessed February 2022.
  3. World Health Organization. Micronutrient deficiencies. Available at: http://www.who.int/nutrition/topics/idd/en/. Last accessed February 2022.
  4. Institute of Medicine of the National Academies. Dietary reference intakes for vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc. Washington DC: National Academy Press; 2001.
  5. American Thyroid Association. Hypothyroidism. Available at: http://www.thyroid.org/wp-content/uploads/patients/brochures/ata-hypothyroidism-brochure.pdf. Last accessed February 2022.
  6. United Nations. Sixth report on the world nutrition situation. Available at: http://www.unscn.org/files/Publications/RWNS6/report/SCN_report.pdf. Last accessed February 2022.
  7. American Thyroid Association. Iodine deficiency. Available at: http://www.thyroid.org/wp-content/uploads/patients/brochures/IodineDeficiency_brochure.pdf. Last accessed February 2022.
  8. Zimmermann M. Low iodine intakes in weaning infants. IDD Newsletter 2010; 38: 1-3. Available at: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.187.3644&rep=rep1&type=pdf. Last accessed February 2022.
  9. American Thyroid Association. American Thyroid Association (ATA) issues statement on the potential risks of excess iodine ingestion and exposure. Available at: http://www.thyroid.org/american-thyroid-association-ata-issues-statement-on-the-potential-risks-of-excess-iodine-ingestion-and-exposure/.  Last accessed February 2022.
  10. Padilla CD, Fagela-Domingo F. Eliminating iodine deficiency: obstacles and their removal. Ann Acad Med Singapore. 2008; 37(Suppl 3): 45-8.
  11. Mynt NS. Sources and analysis of iodine in Singapore diet. 22 February 2005. Available at: https://scholarbank.nus.edu.sg/handle/10635/161070. Last accessed 26 May 2023.
  12. World Health Organization. Unhealthy diet. Available at: http://www.who.int/gho/ncd/risk_factors/unhealthy_diet_text/en/index.html. Last accessed February 2022.
SG-NONT-00025 | December 2023