Iodine is a constituent of thyroxine hormone secreted by thyroid gland. Thyroid glands weighing 25 g in an adult contains 10 mg of iodine.

    • Iodine plays an important role as it is incorporated into thyroxine hormone. It is responsible for the rate of oxidation within the cells.
    • Thyroxine is related with the tissues of nerves and muscles.
    • It maintains heart rate.
    • Iodine helps in converting glycogen to glucose. In this way it increases blood sugar level. Liver is affected because there is a possibility of emptying of glucose stores.

    • Deficiency of iodine results in a disease known as goitre. Goitre is an enlargement of the thyroid gland.
    • This occurs due to the deficiency of iodine, the secretion of thyroxine hormone is also reduced, so the gland cells try to produce iodine, in large quantity which leads to multplication of cells, resulting in the enlargement of the gland, that forms goitre.
    • Goitre is more in the hilly regions where soil lacks iodine.
    • So the vegetables, cereals and pulses grown here do not contribute iodine in an appreciable amount.
    • The entire population in such areas suffer from goitre hence the name endemic goitre.

    Cretinism: Cretinism is caused in children when there is deficiency of thyroxine hormone. Infants suffer from this disease when the infant’s mother is suffering from goitre and who is unable to meet the foetal demand for iodine. The symptoms of cretinism are:

    Low basal metabolic rate.
    Muscular flabbiness and weakness
    Dry skin
    Rough hair
    Enlarge tongue
    Thick lips
    Retardation of skeletal development
    Mental retardation

    Iodine deficiency in adults results in Myxedema. Face becomes thick and looks puffy. Facial expression are poor and person becomes inactive.

    This condition may be due to a tumor of thyroid gland which produces an excess of thyroid hormone or it may be due to Grave’s disease (toxic Goiter) an increased production of the hormone due to over active thyroid gland

    Hyperthyroidics shows hyper activity, tremors, a rapid heart rate, high blood pressure, bulging eyes, accelerated growth with loss of weight and emotional instability. If the symptoms do not subside with medicines surgery is required.

    Goitrogenic Substances in Foods
    Certain foods of brassica genus like cabbage, cauliflower, turnip, soya flour contain substances which react with iodine present in the food and make it unavailable. The substances are known as goitrogenic substances. Consumption of these foods in large quantities makes the iodine non available to the body.

    Good source: Sea foods like fish, shellfish, fish liver oils, fortified salt.

    Recommended daily requirements of iodine according to age group and physiological status
    Age/Physiological group
    RDA of iodine(g/d)

    Infants 90
    Young children (1+ to 5+ y) 90
    School age children (6+ to 11+ y) 120
    Adolescents and adults ( 12 y) 150
    Pregnant & Lactating women 200
Last modified: Monday, 4 June 2012, 6:32 AM