Iodine - what is it?
Iodine, New RDA* 150 µg
Iodine was one of the first minerals to be recognised as vital for good health. It is still considered one of the most important.
Iodine is greyish-black in colour. When heated, it yields corrosive fumes of a rich violet colour. In the human body, it forms an essential component of thyroxin, the main hormone produced by the thyroid gland.
The excessive consumption of certain foods like cabbage, cauliflower, and radish can cause iodine deficiency. These foods contain a substance which reacts with the iodine present in the food and makes it unsuitable for absorption.
Iodine, as iodide, is present in multivitamin and mineral supplements (providing up to 0.49 mg iodine/day) and is a component of kelp products
*Sourced from EFSA WEBSITE
Iodine - what does it do?
Needed to make thyroid hormones, which control many metabolic processes, and keep our bodies healthy.
Iodine forms part of the thyroid hormones, thyroxine (T4) and triiodothyronine (T3).Receptors binding T3 and T4 have been found in the cell nucleus and in mitochondria.These hormones are involved in the maintenance of metabolic rate, cellular metabolism and integrity of connective tissue. Thyroid hormones are necessary for the development of the nervous system in the foetus and infant.
Deficiency
A variety of mechanisms exist to compensate for low levels of iodine intake. These include enlargement of the thyroid gland (goitre). Only when these mechanisms fail do the clinical signs of hypothyroidism (also known as myxoedema) develop. Symptoms and signs of hypothyroidism include lethargy, weakness, weight gain, poor concentration, oedema, myalgia, dry skin, delayed tendon reflexes and slow heart rate. In pregnancy, iodine deficiency is associated with an increased risk of miscarriage, stillbirth and congenital abnormality. Cretinism is the result of iodine deficiency in the developing foetus, and is characterised by mental retardation, deaf mutism, and spastic diplegia. A less common form of cretinism is the myxoedematous type, which is characterised by hypothyroidism and dwarfism.
Iodine - Sources
Milk, sea fish, shellfish, seaweed and iodine-fortified foods, such as some salt.
High levels of iodine are present in marine fish (up to 2.5 mg/kg), shellfish (up to 1.6 mg/kg) and sea salt (up to 1.4 mg/kg). Levels in cereals and grains vary depending on the iodine content of the soil.
The food colour erythrosine is also rich in iodine. In the UK, iodine is also present in cows’ milk (average level 0.15 mg/kg), probably as a result of the use of supplemented cattle feeds and iodophors as teat sterilants.
The content of iodine in raw food is reduced by cooking. It is also present in licensed medicines, topical antiseptics and radiographic contrast agents. Iodine intakes in children are higher than those in adults, because of a greater consumption of milk, and are likely to be higher in the winter than the summer because winter milk contains more iodine.
