Keywords: thyroid health, breast health, controls oestrogen
- Thyroid hormone production
- Iodine is also actively concentrated from the blood by the gastric mucosa, salivary glands, the choroid plexus of the brain, and the lactating mammary glands, suggesting further functions as yet unknown.
Good food sources
- Fish and seafood
- Seaweed products (e.g. sushi)
Exceptionally large quantities of iodine are found in the artificial food additive erythrosine (E127), which is used as a red colouring for cocktail and glace cherries. A high consumption of these foods is not advised if they contain this additive.
- Enlargement of the thyroid gland in the neck (goitre)
- Deficiency may stimulate the sex glands in women to produce excess oestrogen, which is a risk factor for breast, uterine and ovarian cancers
- Deficiency may cause fibrocystic breast disease
- Deficiency may cause nerve damage leading to hearing loss
- Deficiency reduces the activity of some white blood cells
Populations with a higher intake of iodine-containing foods (such as Japan) may have a lower incidence of breast cancer.
Many parts of the world lack iodine in their soil, and in these areas goitre and cretinism (a congenital condition involving dwarfism and mental retardation) are a widespread health problem. According to a 1987 study, the evidence suggests that multiple sclerosis, motor neurone disease, cancers of the thyroid and nervous system, Parkinson’s disease and Alzheimer’s disease are also associated with iodine deficiency. Rats on experimental iodine-deficient diets show many of the metabolic changes associated with these diseases. (Foster HD: Disease family trees: the possible roles of iodine in goitre, cretinism, multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer’s and Parkinson’s diseases and cancers of the thyroid, nervous system and skin. Med Hypotheses 24(3):249-63, 1987.)
Until recently most of the iodine in the diets of people in the developed world was provided by dairy products, due to the use of iodine-containing antiseptics used to clean cows’ teats. There is a growing tendency to use other forms of antiseptics, and there are concerns that as a result iodine deficiency is becoming much more prevalent in the developed world (Zimmermann MB. Symposium on Geographical and geological influences on nutrition: Iodine deficiency in industrialised countries. Proc Nutr Soc. 2010. Feb;69(1):133-43).
Goitrogens (certain chemicals found in turnips, raw cabbage, soy beans and peanuts) interfere with iodine uptake by the thyroid, but this is only likely to be a problem for individuals with a borderline iodine intake.
Information compiled by Linda Lazarides
Naturopathic Nutritionist, Author, Educator