What is Iodine?
Iodine is an essential trace mineral, known for its role in medicine for treating infections, colds, and lung diseases. Iodine is also required for the healthy functioning of many areas of the human body.
The oceans contain the largest repositories of iodine, hence why fish, shellfish, and sea vegetables (seaweeds) contain the highest amounts. Populations who consume the largest levels of sea food and vegetables have been found to have the lowest incidence of iodine deficiency and associated disorders.
In contrast, those who do not live near to the earths iodine rich oceans have been found to have the highest instances of iodine deficiency. Soils are no longer viable sources of iodine due to nutrient depletion, and plant foods contain minimal amounts.
The WHO estimates that around 1/3 of the global population are living in iodine poor regions and are at the highest risk of deficiency.
Thyroid Health
The role of iodine in Thyroid health has long been established. iodine is an essential component of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). Our Thyroid hormones regulate many important biochemical reactions, and are required for metabolism, growth and DNA replication. Iodine deficiency may lead to a deficiency in thyroid hormones and underactivity, a condition called Hypothyroidism, on the other hand too much Iodine can cause over activity of the Thyroid gland, known as Hyperthyroidism. It is suggested that Iodine deficiency is the leading cause of preventable Thyroid disorders.
Iodine in Women’s Health
Whilst ¾ of iodine is found in the thyroid, the majority of the rest is found in breast tissue and some within reproductive tissues, making iodine an essential component of female health. iodine plays a key role in regulating oestrogen receptors and promoting healthy oestrogen metabolism and thus stabilises oestrogen sensitive tissues of the breasts, uterus, ovaries, and the brain.
Breast Health
Studies have demonstrated many beneficial effects of iodine on breast tissue including breast cancer risk, fibrocystic breast disease, premenstrual breast tenderness and mammary dysplasia.
One of the key benefits for breast health is the role of iodine as an antioxidant, which helps to protect from cellular damage. It is this mode of action that is attributed to the development of healthy breast tissue and is associated with the reduced risk of breast cancer in women with sufficient dietary intake of Iodine. Certain populations with diets rich in iodine foods report the lowest instances of breast cancer.
Iodine deficiency is also found to increase the risk of fibrocystic breast disease, a condition characterised by non-cancerous lumps in the breast tissue. Fibrocystic breast disease can affect up to 50% of women of reproductive age. Studies have shown iodine supplementation to be beneficial in treating the condition, aiding in reduction of pain and tenderness.
Female Reproductive Health
In reproductive health iodine is required for ovulation, progesterone production and oestrogen metabolism. Recent studies have found iodine to be involved in the expression of the genes responsible for oestrogen clearance, with the ability to up-regulate oestrogen clearance whilst adapting the regulation of oestrogen–responsive genes.
This suggests that iodine can be particularly helpful in relieving pre-menstrual breast tenderness, low progesterone and pre-menstrual syndrome which occur in the second half of the menstrual cycle.
Pre-conception, Pregnancy, and Breast Feeding
With iodine’s influence on the correct function of both the thyroid and reproductive system it is easy to see it’s critical role in fertility. Impaired thyroid function can interrupt the menstrual cycle, lower libido, and cause conception issues. A 2018 study found women with lower iodine status took longer to conceive than those with optimal levels.
Iodine is critical for healthy development of a baby, both in the uterus and infancy, during breast feeding. Iodine is required for foetal growth, the development of the thyroid, central nervous system, and brain.
Severe iodine deficiency has been associated with miscarriage, still birth, congenital abnormalities, and low birth weight.
Research demonstrates that even mild iodine deficiency is associated with neurological and cognitive impairments in children. Children born to iodine deficient mothers were found to have lower verbal IQ, reading accuracy, and reading comprehension by age 8, than those whose mothers had sufficient levels during pregnancy.
What are the Best Sources of Iodine?
- Seafood incl. Shellfish (10 – 190 mcg per 100 grams).
- Seaweed such as kelp, nori, kombu, and wakame (2 – 800 mcg per 100 grams).
- Egg yolks (24 mcg per yolk).
- Meat & Poultry (10mcg per 100grams).
- Milk, (50-100mcg per 200ml), yoghurt (50-100mcg per 150g) and cheese (15mcg per 40g)
- Plant foods such as mushrooms and leafy greens, but only if they’re grown on iodine-rich soil.
- Fortified foods including plant-based milks.
N.b Actual iodine content will vary
How Much Iodine Do I Need?
Recommendations vary. The European Food Safety Authority recommends Adults to consume 150mcg iodine per day. Pregnant and breast-feeding women should increase this to 200mcg.
In the UK the reference nutrient intake is 140mcg for adults, pregnant and breast-feeding women.
The WHO recommends 150mcg per day for adults and 250mcg for pregnant and breast-feeding women. The US and Australia also suggest higher recommended intakes than the UK for pregnant and breast-feeding women.
Those who consume iodine rich foods in their diet typically do not need to add an additional supplement. However, those on vegan and vegetarian diets, or those with a seafood or dairy allergy, should consider a suitable iodine-containing supplement. Therapeutic supplementation can be advised by a registered practitioner.
Important Caution. More Isn’t Better with Iodine.
It is important not to eat too many of the rich iodine foods such as seaweeds and sea vegetables, as you can experience iodine overdose. Having some seaweeds 1-2 times per week is adequate.
Important Caution. Thyroid Disorders.
If you have already been diagnosed with a Thyroid disorder or Thyroid autoimmune disease, iodine supplementation is cautioned as it may make your condition worse. It is recommended you seek advice of a trained nutritionist or naturopath to aid you in supporting your condition naturally.
Disclaimer
The information in this article is designed for educational purposes only and is not intended to be a substitute for informed medical advice or care. This information should not be used to diagnose or treat any health problems or illnesses without consulting a doctor.
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https://www.vegansociety.com/resources/nutrition-and-health/nutrients/iodine
https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/#en1
