Iodine is an essential mineral which is most commonly known for its involvement in thyroid hormone production. It is also critical for oestrogen metabolism, breast health, ovulation, progesterone production, pregnancy and lactation. Iodine is crucial for human health, and though we only need small amounts of it, deficiency is common.

How much iodine do we need?

The recommended daily intake (RDI) for iodine is 90mcg/day for infants 0-6 months, 110mcg/day for infants 7-12 months, 90mcg/day for children 1-8 years, 120mcg/day for children 8-9-13 years, 150mcg/day for children 14-18 years, 150mcg/day for adults, and 220mcg/day during pregnancy, as set by the National Health and Medical Research Council (NHMRC).


Iodine is one of the most essential nutrients required during pregnancy. Deficiency is associated with infertility, miscarriage, stillbirth, preterm delivery and problems for the baby including developmental delays, deafness, impaired growth and development, and reduced IQ. Even mild deficiency may be associated with lowered IQ in offspring.

What are the consequences of low iodine intake?

Any or all of the symptoms below can be influenced by low iodine levels*:

  • Weight gain or inability to lose weight
  • Memory loss/brain fog
  • Swollen neck/throat (goitre)
  • Fatigue
  • Hair loss
  • Dry, flakey skin
  • Changes in heart rate
  • Cold hands and feet
  • Constipation
  • High cholesterol
  • Reduced heart rate
  • Heavy periods
  • Irregular periods
  • Infertility
  • Miscarriage
  • Ovarian cysts
  • Breast pain
  • Premenstrual dysphoric disorder (PMDD)

*Please note: the above signs and symptoms can also be indicative of other nutrient deficiencies and/or health conditions. A nutrient deficiency should not be assumed and supplementation should not be commenced without seeking professional advice from your healthcare practitioner.

Which foods contain iodine?

Iodine is found naturally in soil and seawater, however many countries unfortunately have iodine deficient soil, hence iodine deficiency and thyroid problems are on the rise. Common sources of iodine include:

  • Iodised salt
  • Eggs
  • Saltwater fish
  • Seaweed
  • Shellfish

Does anything reduce the absorption of iodine?

Iodine absorption into the thyroid gland is inhibited by a group of compounds called goitrogens. These are found in a surprising number of foods, including:

  • Tofu
  • Tempeh
  • Soy milk
  • Edamame

Another source of goitrogens are uncooked brassica/cruciferous vegetables, such as:

  • Broccoli
  • Kale
  • Cauliflower
  • Bok choy
  • Pak choy
  • Brussels sprouts

These are clearly healthy foods, and should not be avoided completely. To reduce the goitrogenic activity of these foods and to enhance iodine absorption, simply ensure they are cooked prior to eating – a quick blanch or steam will deactivate the goitrogens.

Are there problems with taking too much iodine?

Yes. Taking too much iodine can also cause problems, and can worsen thyroid conditions. Always seek professional advice from your healthcare practitioner prior to supplementing with any iodine.

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