The importance of iodine for women's health

There are many nutrients that have been researched for their role in women’s health, but one often overlooked nutrient is iodine. Largely recognised for the role it plays in thyroid health, iodine is an oft-forgotten nutrient when it comes to women’s health, and yet this nutrient plays a significant role in processes such as oestrogen metabolism, breast tissue development, ovulation, foetal development and more. In addition to the thyroid, iodine is heavily concentrated in the breasts, ovaries and cervix, highlighting the many areas of women’s health in which it plays a role. Although the full extent of iodine’s role in women’s health is yet to be uncovered, there is a growing body of research exploring just how essential this nutrient is, despite only being required in minute doses!

Iodine and Breast Health

Perhaps one of the most exciting and interesting areas of research on iodine is the role it plays in breast health, in particular, the beneficial effects it has demonstrated with regards to breast cancer risk, fibrocystic breast disease, premenstrual breast tenderness and mammary dysplasia. In the breasts, iodine has been shown to have antioxidant properties, meaning it helps protect from cellular damage (1), which might in part explain why diets containing sufficient iodine are associated with reduced risk of breast cancer. Iodine is also known to promote the development of normal breast tissue and to protect against the formation of abnormal cells (2).

In addition to breast cancer risk, iodine deficiency is also associated with increased risk of fibrocystic breast disease; a condition characterised by lumpiness in one or both breasts. Fibrocystic breast disease affects up to 50% of women of reproductive age, but fortunately, iodine supplementation has been shown to be beneficial in treating the condition (3). If you have lumpiness or discomfort in one or both breasts, it is worthwhile having it investigated, and if fibrocystic breast disease is identified as the cause, it may be worthwhile to work with a naturopath or healthcare provider who can investigate potential iodine deficiency as a contributing factor.

Iodine and the Reproductive System

In addition to its role in breast health, iodine plays many important roles in women’s reproductive health, being required for ovulation, progesterone production and oestrogen metabolism. Iodine appears to affect the genes involved in oestrogen metabolism, up-regulating genes required for oestrogen clearance, whilst down-regulating oestrogen-responsive genes - although the research on this is in its infancy, this may be another way in which iodine intake affects breast cancer risk. Clinically-speaking, iodine is particularly helpful for some women who experience unpleasant symptoms in the second half of their menstrual cycle, such as pre-menstrual breast tenderness, low progesterone and PMS.

Iodine in Fertility, Pregnancy and Lactation

Iodine deficiency is rampant in Australia, particularly in pregnant and breast-feeding populations. According to the Australian National Health Survey of 2011-12, nearly two thirds of Australian women had an iodine level below that recommended by the World Health Organisation for pregnant and breast-feeding women (4). Iodine is absolutely essential for baby’s development in utero, as well as for their development in the early years of life. Interestingly, research from 2018 suggests women with lower iodine status have a longer time to conception (on average) than those with adequate iodine levels (5). Severe iodine deficiency in utero is also associated with increased risk of miscarriage, stillbirth, congenital abnormalities and low birth weight (6). Researchers are well aware that iodine is essential for the baby’s growth, thyroid development and brain development, and sadly, even mild iodine deficiency during pregnancy is associated with neurological and cognitive impairments in children. For example, research suggests children of iodine-deficient mothers are more likely to have a lower verbal IQ, reading accuracy and reading comprehension by age 8, than those whose mothers had sufficient iodine levels during pregnancy (7). Compared to the average population, for whom the RDI for iodine is 150 mcg/day, it is recommended pregnant and breast-feeding women consume 220 mcg and 270 mcg of iodine per day respectively, which is why guided iodine supplementation is often warranted during pregnancy and lactation.

Iodine and Thyroid Function

Of course, an article on the role of iodine in women’s health wouldn’t be complete without a mention of thyroid function. The thyroid contains the highest concentration of iodine of any tissue in the body (in both men and women), accounting for 70-80% of the body’s iodine stores. In fact, more than half of our daily recommended intake of iodine is used solely for the production of thyroid hormone (8). Our two main thyroid hormones, Triiodothyronine and Thyroxine, contain three and four atoms of iodine per molecule, hence their abbreviated names ‘T3’ (denoting three iodine atoms) and ‘T4’ (for four atoms). Without sufficient iodine, the thyroid can swell in an effort to trap more iodine from the blood, potentially causing discomfort, hoarseness or difficulties swallowing. When inadequate iodine intake persists, eventually the production of thyroid hormone will start to decline, potentially leading to symptoms of hypothyroidism such as fatigue, weight gain, constipation, menstrual irregularities and hair loss. Hypothyroidism is five times more common in females than males, and according to Australian government data, affects between six to ten percent of Australia women, with the incidence increasing with age - For this reason, if you have any of the symptoms commonly associated with an under-active thyroid, I sincerely encourage you to request further investigation of your thyroid function from your doctor or naturopath, especially if you are >30, have a family history of thyroid disease, are pregnant or have another autoimmune condition (such as type 1 diabetes or coeliac disease).

Correcting an Iodine Deficiency

When it comes to correcting iodine deficiency, the thyroid is like a big sponge, absorbing iodine from the blood to make thyroid hormone. Unfortunately, too much iodine can be just as problematic as not enough, so it is essential to supplement with the right type of iodine, at the correct dose and pace for your personal situation. There are many forms of iodine on the market (for example, molecular iodine, potassium iodide and seaweed-based forms) and not every form is created equal (especially when it comes to the research examining their use for breast health). For example, whether I prescribe molecular or potassium iodide depends on various factors, including the target tissue (e.g. breast or thyroid), the dose required and the patient’s previous response to iodine supplementation. Some over-the-counter supplements provide the recommended daily intake of iodine at 150 MICROGRAMS, whilst others contain more than 85 times this dose!! This is why it is essential to discuss iodine supplementation with a qualified healthcare practitioner, to determine not only if it is right for you and your personal circumstances, but also what dose and type of iodine is best indicated. Individuals with thyroid disease need to be particularly careful when it comes to iodine, as both too much or too little can exacerbate the situation, so any form of iodine supplementation in such instances must be closely monitored.

Ultimately, iodine plays many wonderful roles in women’s health as an essential nutrient for the thyroid, breasts, ovaries, uterus and more. Unfortunately, iodine levels in Australian soils are generally quite low, meaning our locally-grown produce are not necessarily a reliable dietary source. Whilst various dietary fortification programs have reduced the incidence of iodine deficiency in Australia, certain groups continue to be at increased risk of deficiency, including women, pregnant or breast-feeding mothers, foetuses, newborn babies, vegans, vegetarians and/or those who avoid iodised salt or bread. In Australia, those living in NSW, Victoria, Tasmania and rural areas are also at increased risk of deficiency, due to lower iodine content in the local soils. As more and more research is coming to light on the benefits of iodine for both breast and thyroid health however, ensuring iodine adequacy across all stages of the lifespan is essential!

Niki x