Iodised salt is one of the most common ‘fortified foods’ that we consume, and one of the main ways people get their daily iodine. But why was it added in the first place? What does iodine do? What about using sea salt and rock salt? And why is New Zealand facing another emergence of iodine deficiency in the population? All good questions! Let’s take a look at this vitally important mineral that is about so much more than salt.
Iodised Salt: A History
Iodine was discovered during the manufacture of gunpowder in the early 1800’s, and then went on to become the first known effective treatment for goitre (thyroid enlargement). Goitre was extremely common in many areas of USA in the early 1900s, and after repeated studies, finally the widespread use of iodised salt all but eliminated goitre from the general population. This was adopted worldwide. In New Zealand, iodine was added to salt from 1924, but the amount was increased in 1938. Iodised salt, if consumed in the right quantities, does get rid of most goitre- but is it enough?
Iodised salt, while succeeding in getting rid of most goitre issues, is still problematic for a number of reasons:
- The iodine in iodised salt is not easily absorbed by the body
- Not many people use iodised salt (many use rock salt or sea salt)
- People eat more processed food that uses non-iodised salt
- Many people reduce their salt consumption due to blood pressure concerns (and just to be clear, sodium added to foods to make them salty doesn’t contain iodine)
- Even if everyone got their allocated amount of iodised table salt, there is a difference between avoiding a goitre and having an OPTIMAL level of iodine in the body.
Iodine Deficiency is associated with:
- Intellectual disability
- Growth retardation
- Increased miscarriage rates
- Increased infant mortality
- Neonatal thyroid disorders
- Attention Deficit disorders
- Increased risk of breast, prostate, endometrial and ovarian cancers
- Thyroid disorders
- Potentially Chronic Fatigue and Fibromyalgia
The primary and most well-known use of iodine is in the formation of thyroid hormone. The thyroid is a wee gland in the neck that regulates your metabolic rate- how fast or slow all your cells and physical processes happen. Low thyroid function (hypothyroidism) means things slow down- this leads to fatigue, hair loss, constipation, dry skin, weight gain, depression, lack of mental clarity, mood imbalances and hormonal problems. If your thyroid is over-active (hyperthyroid) things speed up- this leads to anxiety, sweating, rapid pulse, and weight loss.
The thyroid takes the iodine you consume and turns it into thyroxine (T4) or thyroid hormone, which it sends out to all the cells in the body, where it is turned into Triiodothyronine (T3). T4 has four iodine molecules while T3 has…you guessed it…3! So you can see that iodine is totally essential for thyroid function.
Hypothyroidsim or low thyroid function is often caused by an autoimmune reaction, and is known as Hashimoto’s. Grave’s disease is less common and is an autoimmune reaction that causes Hyperthyroidism. Naturopathically we see a lot of sub-clinical low thyroid function. That is, people who have less than optimal thyroid function but are still not in a state of extreme pathology that would raise a red flag on a blood test.
Effects on Oestrogen and Breast Tissue
Iodine has a key role to play in many areas of women’s health. Oestrogen balance requires adequate iodine, as it helps the body metabolise oestrogens and keep them functioning in positive ways within the body. Breast tissue is uniquely responsive to iodine, where a lack of iodine can cause an excessive stimulation from oestrogens, leading to not only conditions such as Fibrocystic Breast Disease, but also breast cancers. Iodine also alters gene expression in breast tissue.
Iodine is especially important:
- During pregnancy for foetal development
- For infants and children
- For correct thyroid function in all people
- For consideration in women with Fibrocystic Breast Disease or reproductive cancers
New Zealand Deficiency Identified
The Ministry Of Health since 2009 is not only advocating the use of iodised salt, but has made it compulsory for iodised salt to be used in commercial bread preparation. This is to help counter the iodine deficiency that has been identified in our New Zealand population in various studies. In 2002 a study of children found that 28% showed iodine deficiency. Pregnant women in New Zealand are now given 150mcg of iodine by their GP or midwife to be taken throughout their pregnancy to support their developing baby.
Why you may be low in Iodine:
- Vegetarian or Vegan diet
- Diets low in seafood and seaweeds
- Dairy food used to be a food source of iodine as iodine was used to wash out and sterilise vats for milk and other processing equipment, but this is no longer the case.
- High consumption of bakery foods which may contain bromides that block iodine absorption
- Living in a area far away from the sea where there are iodine deficient soils
- Increased need during pregnancy
- Excessive consumption of ‘goitrogenic’ foods that block iodine uptake: eg. bromide/bromine, turnips, cabbage, cassava root, soy, peanuts, millet.
Halides: Bromides, Flouride, Chloride and Iodide
If you remember your periodic table, you’ll perhaps remember the halogens. These are a group of chemically similar elements which are known as halides in their ionic form or when they join with other elements. So Iodine is the halogen, iodide is the halide; flourine/flouride, bromine/bromide and chlorine/chloride. Because they are chemically so similar, they all compete in our bodies for absorption. This means that in the presence of higher levels of flouride or bromide for example, its harder for the body to absorb iodine as receptors are already bust absorbing flouride or bromide. All of these elements have been shown to be toxic to the body, whereas iodine is non-toxic except when taken in massive doses. This toxicity is exacerbated when iodine is deficient. Treatment with iodine helps to detoxify these halides from the body.
The Take-Home Message on Iodine:
- Increase consumption of foods with naturally occuring iodine: seaweeds and seafood especially
- Reduce exposure to toxic halides
- Test for it! Especially if you have any of the conditions mentioned above
- Iodine is a key mineral for our health. Don’t be lulled into a false sense of security because it is added to table salt and bread and no-one’s great aunty has a goitre. The effects of iodine deficiency may be less visible these days but they are far-reaching, and, crucially, avoidable.