Iodine Deficiency in Breast Cancer, Fibrocystic Breast Disease and the Thyroid

Iodine deficiency is linked to hypo-thyroidism, breast cancer, fibrocystic breast disease, oestrogen excess, hypertension, miscarriage, low birth weight in babies, infertility, diabetes, gut and skin conditions and lowered immunity.

Iodine is a nutrient deficiency which is a leading cause of hypothyroidism and thyroid issues in the world.  The World Health Organization (WHO) estimates that 72% of the worlds population is deficient in Iodine and is effected by this.  The earths soil has very little Iodine, thus there is very little to make it into our food.  What little there is in the soil is so strongly bound that it is unable to be transferred into our vegetables.  The ocean and coastal soils have the highest levels of Iodine, so eating seafood’s, seaweeds and fish are good ways to obtains iodine.  Small amounts can be found in eggs, dairy and meat.  Iodised salt is not the best form of Iodine as it contains Iodide which is only about 10% bio-available in the body.  The table iodised salt has also been bleached with chlorine.

In the 1920’s Iodine was added to our salt to help reduce the high number of goitres.  While this helped some, it is not now stopping the deficiency that we are facing today.  In New Zealand the dairy industry used to use Iodine tank sanitisers and today it is predominantly Bromides used for cleaning.  A lot of the commercially prepared foods and some medications contain Bromides.

The group of Halides compete with Iodine for absorption in the body.  These Halides are Bromides from pools, spa’s, some vegetable oils, carbonated drinks and some asthma inhalers, Chlorine in water and bleached products and Fluoride in water and toothpastes.  They compete by displacing Iodine in the body and interrupt the ability of the body to transport the Iodine into the cells from the blood.

New Zealander’s only have on average around 57% of the recommended daily intake (RDI = 150mcg) of Iodine.  The optimal amount of Iodine per day is 12.5mg for the thyroid, breast tissue, ovaries, prostate gland, skin, intestines, salivary glands and the red and white blood cells.  In an adult with ideal levels of Iodine, approximately 15-20 mg of iodine is concentrated in the tissues of the thyroid gland, in which only 30% of this is concentrated in the thyroid tissue and thyroid hormones.  The balance is found in breast tissue, eyes, gastric mucosa, cervix and salivary glands.  Iodine in the breast tissue is not only for the benefit of feeding an infant adequate amounts of Iodine, but it also acts as an antioxidant.  For those that are breastfeeding, it is interesting to note that breast milk has
4 times the amount of Iodine than the thyroid.

Studies on Iodine and breast cancer in both humans and animals, show a close association with Iodine and malignant cell growth.  An Iodine deficiency appears to alter the structure and function of the mammary glands, which can lead to dysplasia or even neoplasia.  This occurs by pathological changes in RNA/DNA ratios, oestrogen receptor proteins and cytosol iodine levels that then lead to the dysplasia.

Because the breast concentrates iodine to a greater degree than the thyroid gland, it stands to reason that if there is a deficiency of iodine they will be adversely effected.  The breast tissue also produces 2 separate enzymes which can convert T4 to T3 (the non-active thyroid hormone to the active form for the body).  Low levels of iodine in the breast leads to the tissue being more vulnerable to over stimulation by oestrogen.  It is iodine which effects oestrogen metabolism and converts oestrone and oestradiol to the oestriol form.  Iodine effects the ovarian production of oestrogen and oestrogen receptors in the breast.

The RDI is 150 mcg for adults, 220 mcg for pregnancy and 270 mcg during lactation.  The safe upper limit is set an 1000 mcg (1mg).  Many studies and general opinion suggest that this is too low and would be better set higher.  Intake of over 1000 mcg (1mg) is not recommended especially if not being monitored by your GP or Natural Health Practitioner.  A Selenium deficiency will also impair Iodine’s role in the thyroid.

Assessing iodine levels is an easy test to complete.  A urine sample is used to determine levels as 90% of dietary iodine is excreted in the urine.  A single random urine sample is the most common and is the standard accepted method.  There are also 24 hour urine evaluations.  Some side effects may occur when taking iodine if the levels are very low.  These may include a headache, nausea, rash, fatigue, sneezing, gastritis and possibly a metallic taste in the mouth.

Written by Carolyn Fletcher (McSweeney)

Text based on Alternative Medicine Review, Vol 13, Number 2, June 2008