DEFINITION

Iodine is an essential trace element that the body needs to produce special substances called thyroid hormones, which control growth and development.

DESCRIPTION

The adult human body contains about 17 mg of Iodine and most of this is stored and used by the thyroid gland, which traps and concentrates the Iodine that circulates in the blood. The thyroid gland is located at the base of the neck and it produces hormones that control a wide range of bodily processes. Thyroid hormones are important in controlling the body's metabolic rate (the rate at which the body produces and uses energy), as well as physical and mental growth and development.

DEFICIENCY

Iodine deficiency is a common problem in certain areas of the world. This is because Iodine is extracted from the soil by vegetable crops and is absorbed into the bodies of animals that feed on those crops. This means that people that live in areas where the soil is Iodine deficient are at risk of developing Iodine deficiency diseases. Areas such as India, Bangladesh, Burma and certain areas in Asia have soil with a very low Iodine content. In recent years there has also been signs of widespread deficiency of iodine in the population of Australia and other developed countries. Iodine cannot be stored in the body for long periods of time, so small amounts must be consumed regularly.

Iodine deficiency can cause hypothyroidism and goitre (a swollen thyroid gland). Lack of iodine also has a seriously adverse effect on the developing brain of the foetus and the newborn child. A pregnant or breastfeeding woman has a greater need for iodine (an additional 100 - 200 ug per day) than the general population for her developing baby. A child with a severe Iodine deficiency may present with a condition called iodine-deficiency disorder (IDD). This can cause poor control of body movements, hearing problems, an IQ 10 to 15 points below normal, and a greater incidence of attention deficit hyperactivity disorder (ADHD). The extreme form of this condition, usually only seen in developing countries like China and India, is called cretinism. IDD is the single most common cause of preventable mental retardation and brain damage in the world today.

IODINE EXCESS Excessive intake of Iodine causes Iodine toxicity. This occurs when the daily dose of the mineral is 20 times the recommended dietary intake. Iodine toxicity causes signs of hyperthyroidism and goitre, as well as a brassy, metallic taste in the mouth, increased production of saliva, irritation of the stomach lining and acne-like skin lesions.

SOURCES

Iodine-rich foods include marine fish, shellfish, eggs, milk, iodised salt, meat and seaweed (e.g kelp and nori). Iodine is also available as part of many multi vitamin supplements.

DOSAGE

In Australia, the recommended dietary intake (RDI) for Iodine is 120 micrograms (mcg). Women who are pregnant require an additional 30mcg and those who are breastfeeding require an additional 50mcg.. Iodine supplements are generally not necessary in parts of the world where the soil is Iodine-rich. Always consult your health care professional before taking additional Iodine, as an excess intake of Iodine can have toxic effects.