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iodine, the essential trace mineral required by our bodies

iodine, an essential trace mineral.

  • Iodine is an essential trace mineral needed by our bodies.

  • Iodine is naturally present in some foods and is added to some types of salt.

  • Iodine is required for the synthesis of thyroid hormones. Iodine serves as a component of thyroid hormones.

  • In addition to protein synthesis and enzyme activities, thyroid hormones regulate the rate at which the human body uses energy, in other words, the human body's metabolic rate.

  • The thyroid hormones act by affecting gene expression in target cells. Through gene expression, thyroid hormones promote protein synthesis and regulate basal metabolic rate, growth, and development.

  • In addition. Thyroid hormones are required for proper skeletal and central nervous system development in fetuses and infants.

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  • Thyroid hormones are two hormones: thyroxine and triiodothyronine.

  • Our bodies carefully control levels of thyroid hormones. If blood levels of the thyroid hormones drop, the thyroid-stimulating hormone is released from the pituitary gland( A part of the brain). The hormone signals the thyroid gland in the neck to take up iodine and synthesize thyroid hormones. When the supply of iodine is adequate, thyroid hormones can be made, and their sufficient presence turns off the synthesis of thyroid-stimulating hormone.

_Adequate Intake (AI).For infants from birth to 12 months, AI for copper is established as
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iodine

Iodine deficiency reduces the production of thyroid hormones.

  • Metabolic rate slows with insufficient thyroid hormones, causing fatigue and weight gain.

  • The most obvious outward sign of deficiency is an enlarged thyroid gland called a goitre. Goiter is formed when reduced thyroid hormone levels cause thyroid-stimulating hormone to be released, stimulating the thyroid gland to make more thyroid hormones. However, due to the low availability of iodine, thyroid hormones cannot be made, and the stimulation continues, causing the thyroid gland to enlarge. With the use of iodized salt, goitre rarely is caused.

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Recommended Amounts

Recommended dietary allowance (RDAs) for iodine.

  • For people 14 years and older, the RDA is 150 micrograms. For pregnant females 14 years and older, the RDA is 220 micrograms, and for females 14 years and older in lactation, the RDA is 290 micrograms daily.

  • If you consume an excess of iodine, the high intake may cause the same symptoms as an iodine deficiency in some people. Excess iodine inhibits thyroid hormone production, and as a result, goiter can develop. Excessive iodine can also result in confusion and irregular heartbeat. Tolerable upper intake levels, ULs of iodine from food, beverages, and supplement intakes are given in units of micrograms. Long-term intakes above the UL increase the risk of adverse health effects.

  • The iodine ULs for 14-18 years is 900 micrograms. The ULs for 19 years and older are 1100 micrograms.

  • The ULs do not apply to individuals receiving iodine for medical treatment, but such individuals should be under the care of a physician.

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The current RDAs for iodine are listed in the table. For infants from birth to 12 months, the AI is equivalent to the mean intake of iodine in healthy, breastfed infants in the United States.

Table: Recommended Dietary Allowances (RDAs) for Iodine.

_Adequate Intake (AI).For infants from birth to 12 months, AI for copper is established as
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The daily Upper Limits (ULs)for Iodine.

The daily upper limits for iodine include intakes from all sources—food, beverages, and supplements—and are listed below. These levels do not apply to people who are taking iodine for medical reasons under the care of a doctor.

_Adequate Intake (AI).For infants from birth to 12 months, AI for copper is established as
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The food sources of iodine.

 

  • Iodine is naturally present in some foods and is also added to salt labeled as “iodized”.

  • Iodine is found naturally in saltwater fish.

  • Sea vegetables, such as seaweed, kelp, wakame, kombu, and nori, are among the best sources, with the iodine content varying widely depending on the seaweed species and sources.

  • Fish, seafood, and eggs are good sources of iodine.

  • Dairy products also contain iodine.

  • Most of the iodine in the Canadian diet comes from salt fortified with iodine, referred to as Iodized salt.

 

The top selected foods with iodine content:

  • Cod, baked

  • Seaweed

  • Oyster

  • Yogurt

  • Milk

  • Iodized table salt

  • Fish sticks

  • Eggs

  • Cheese

  • Beef liver

  • Shrimp

  • Tuna

  • Beef

  • Soy beverage

  • Chicken breast

  • Brown rice

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References:

Institute of Medicine, Food and Nutrition Board. 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.

 

Iodine, Fact Sheet for Health Professionals, Department of Health and Human Services. Iodine Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/

Updated: August 10, 2023

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