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11.6: Iodine

  • Page ID
    6833
  • Skills to Develop

    • Learn about the role of iodine

    Recall the discovery of iodine and its use as a means of preventing goiter, a gross enlargement of the thyroid gland in the neck. Iodine is essential for the synthesis of thyroid hormone, which regulates basal metabolism, growth, and development. Low iodine levels and consequently hypothyroidism has many signs and symptoms including fatigue, sensitivity to cold, constipation, weight gain, depression, and dry, itchy skin and paleness. The development of goiter may often be the most visible sign of chronic iodine deficiency, but the consequences of low levels of thyroid hormone can be severe during infancy, childhood, and adolescence as it affects all stages of growth and development. Thyroid hormone plays a major role in brain development and growth and fetuses and infants with severe iodine deficiency develop a condition known as cretinism, in which physical and neurological impairment can be severe. The World Health Organization (WHO) estimates iodine deficiency affects over two billion people worldwide and it is the number-one cause of preventable brain damage worldwide.[1]

    fig 11.6.1.jpg

    Figure \(\PageIndex{1}\): Deaths Due to Iodine Deficiency Worldwide in 2012. Image by Chris55 / CC BY 4.0.  

    fig 11.6.2.jpg

    Figure \(\PageIndex{2}\): Iodine Deficiency - Goiter. A large goiter by Dr. J.S.Bhandari, India / CC BY-SA 3.0.

    Dietary Reference Intakes for Iodine

    Table \(\PageIndex{1}\): Dietary Reference Intakes for Iodine.
    Age Group RDA Males and Females mcg/day UL
    Infants (0–6 months) 110* -
    Infants (7–12 months) 130* -
    Children (1–3 years) 90 200
    Children (4–8 years) 120 300
    Children (9–13 years) 150 600
    Adolescents (14–18 years) 150 900
    Adults (> 19 years) 150 1,100

    *denotes Adequate Intake. Health Professional Fact Sheet: Iodine. National Institute of Health, Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/. Updated June 24, 2011. Accessed November 10, 2017.

    Dietary Sources of Iodine

    The mineral content of foods is greatly affected by the soil from which it grew, and thus geographic location is the primary determinant of the mineral content of foods. For instance, iodine comes mostly from seawater so the greater the distance from the sea the lesser the iodine content in the soil.

    Table \(\PageIndex{2}\): Iodine Content of Various Foods.
    Food Serving Iodine (mcg) Percent Daily Value
    Seaweed 1 g. 16 to 2,984 11 to 1,989
    Cod fish 3 oz. 99 66
    Yogurt, low fat 8 oz. 75 50
    Iodized salt 1.5 g. 71 47
    Milk, reduced fat 8 oz. 56 37
    Ice cream, chocolate ½ c. 30 20
    Egg 1 large 24 16
    Tuna, canned 3 oz. 17 11
    Prunes, dried 5 prunes 13 9
    Banana 1 medium 3 2

    Health Professional Fact Sheet: Iodine. National Institute of Health, Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/. Updated June 24, 2011. Accessed November 10, 2017.

    Footnotes

    1. World Health Organization. “Iodine Status Worldwide.” Accessed October 2, 2011. http://whqlibdoc.who.int/publications/2004/9241592001.pdf

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