Like many people I have reduced the amount of salt in my diet to lower my risk of increased blood pressure.

But as a result I’ve also reduced my iodine intake.

A lack of iodine in our diet may well be a factor in the dramatically increasing incidence of breast cancer in western countries over the past 30 years.  

One in 10 Australian women and one in 9 New Zealand women will be diagnosed with breast cancer at some time in their lives.

There is significant evidence that abnormal thyroid function (especially an under-functioning thyroid) may increase our risk of breast cancer.  

Iodine is the trace element vital for a healthy thyroid.  Breast cancer patients are much more likely to also have an enlarged thyroid (goitre) than women without breast cancer, which is often due to iodine deficiency.  

Iodine levels in the breast tissue of breast cancer patients are very low compared with those in healthy breasts.

While a definitive causal link between breast cancer and thyroid disease (and iodine deficiency) is yet to be proven, there is evidence to suggest that such a link may exist.  

In clinical trials, lab rats are fed a carcinogenic chemical to induce breast cancer, a method that is almost 100% effective at inducing breast tumours.

Interestingly, when the rats are fed iodine rich Lugols solution before being exposed to the carcinogen, many don’t develop breast cancer and those that do take much longer to develop breast tumours.  

Japanese women have one of the lowest rates of breast cancer in the world but when they move to western countries they assume the much higher risk of their new country within a generation.  

One possible explanation is the change in their dietary iodine intake.  

Seaweed is a Japanese dietary staple, supplying the average woman with a high iodine count of around 12mg a day.  Contrast this with the pitiful 240mcg a day consumed by the average American woman, and 150mcg or less for Australian and New Zealand women. (1000mcg equates to one mg).

Iodine deficiency is a widespread and growing health concern in Australia and New Zealand, where much of the soil is lacking in the trace element iodine. As a result fruits, vegetables and grains grown there are also lacking in iodine.    

Until the 1980's iodine was used as a dough conditioner in the making of bread.  Since then bakers have replaced it with bromide, which actually competes for absorption with iodine in the thyroid gland.  

Milk used to contain significant amounts of iodine as a result of the disinfectants used in the vats.  Iodine disinfectants have been replaced with chlorine, and dairy content of this iodine has plummeted.

Iodised salt used to be found on every dinner table.  With the health message that salt increases blood pressure, many of us have stopped salting our food.  Even those of us who still add salt often buy uniodised salt and thus miss out this source of iodine.

Even with a balanced diet it is difficult to get enough iodine without supplementing or making a special effort to eat seaweed.

Richest dietary sources of iodine are eggs, fish, shellfish, seaweed (including kelp and nori)  and iodised salt.

The recommended daily allowance of iodine for adults is 150mcg a day, which many consider to be far too low when you consider that Japanese women with a very low breast cancer incidence routinely eat 12mg of iodine in their daily diet.

It is not advisable to supplement with iodine without the guidance of a health professional.

Lynda Wharton is a health and wellbeing writer, columnist and author. She also practises as an acupuncturist and naturopath.

lynda@lyndawharton.com

www.lyndawharton.com