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Iodine is an essential trace element required for production of thyroid hormones, which regulate various biochemical reactions in the body, including protein synthesis and enzymatic activity.

Iodine sources

Seafood: Seafood, particularly fish, shellfish, and seaweed, are the richest natural sources of iodine.

Iodized salt: Many countries have programs that involve adding iodine to salt to ensure sufficient intake.

Dairy and Grain Products: These can be a good source of iodine, especially in regions where livestock and crops are raised on iodine-rich soil.

Supplements may be required especially for those with dietary restrictions.

Iodine role in the body

Iodine is crucial for the production of thyroid hormones, thyroxine (T4) and triiodothyronine (T3). Thyroid hormones are vital for body temperature regulation, growth and development, including the brain of the fetus during pregnancy and for general energy production in the body.

Iodine deficiency symptoms

Iodine deficiency can lead to hypothyroidism, goiter, and developmental issues. Deficiency can cause a whole range of symptoms from nearly all organs and tissue, including but not limited to symptoms such as

  • Fatigue and tiredness
  • Weight gain or difficulty losing weight
  • Cold intolerance
  • Constipation
  • Dry skin
  • Menstrual irregularities or heavy periods
  • Insulin resistance and diabetes
  • Increased blood lipids

Severe iodine deficiency during pregnancy can lead to cretinism in infants: intellectual disability, motor spasticity, and other health problems.

Iodine deficiency is very common in developing countries. Less so in the high-income countries and in countries where salt enriched with iodine. However, if you are suffering from hypothyroidism, it may be worthwhile to rule out iodine deficiency before embarking on a lifelong prescription medicine.

Other halogens

Fluoride, bromide, and chloride are all members of the same halogen group that iodine belongs to in the periodic table of elements. They can competitively reduce the update of iodine in the thyroid gland.

Excessive fluoride or bromide exposure can interfere with iodine uptake in the thyroid, leading to iodine deficiency disorders.

Chloride: Although it’s also a halogen, under normal circumstances, chloride does not interfere significantly with iodine uptake in the human body due to its lower reactivity. However, in some cases it may reduce the iodine uptake in the thyroid gland.

Recommended Daily Intake

  • The World Health Organization (WHO) recommends the following daily intake of iodine:
  • Adults and adolescents (14+ years): 150 micrograms/day
  • Pregnant and lactating women: 250 micrograms/day
  • Children (6–12 years): 120 micrograms/day
  • Infants (0–5 years): 90 micrograms/day

The Institute of Medicine at the National Academy of Sciences has set Tolerable Upper Intake Levels (ULs) for iodine:

  • Adults: 1,100 micrograms/day
  • Adolescents (14-18 years): 900 micrograms/day
  • Children (9–13 years): 600 micrograms/day
  • Children (4–8 years): 300 micrograms/day
  • Children (1–3 years): 200 micrograms/day
  • Infants (0–12 months): Not established; source of intake should be from food and formula only.

However, much higher doses are usually required for the development of toxicity. Under normal circumstances the risk of toxicity is very low even in cases of significantly higher doses than mentioned above.

DMH Functional Medicine and Iodine deficiency

If you are suffering from hypothyroidism, it may be due to iodine deficiency. At DMH Functional Medicine, we can help you investigate the causes of your hypothyroidism, including possible iodine deficiency.

Speak to us if you wish to hear more about our services.