What Role the Trace Element Iodine Plays in Our Body

As an essential component of thyroid hormones, iodine is indispensable for growth, development and numerous metabolic processes. However, the trace element iodine does not occur naturally in the human body and must therefore be supplied through the diet. About 70 percent of the iodine ingested is consumed in the thyroid gland, where growth and cell division are controlled. Outside the human body, iodine is used as a disinfectant or X-ray contrast agent.

Iodine in food

Iodine is found in large amounts in sea fish and seafood. In addition, the trace element is found in milk and eggs, as well as in all foods that have been seasoned with iodized salt during preparation (e.g., bread). An adult person has a daily iodine requirement of about 200 micrograms, children about 50 micrograms less. The daily iodine dose for adults is contained, for example, in

  • 48 g haddock
  • 76 g pollock
  • 104 g plaice
  • 154 g mussel
  • 166 g cod
  • 340 g oyster
  • 380 g halibut
  • 400 g tuna
  • 1000 g spinach
  • 2100 g rye bread

Detect iodine deficiency

The lack of iodine intake is widespread. It is estimated that more than one billion people worldwide are affected by iodine deficiency. Depending on the occurrence of iodine in the soil, iodine deficiency is regional. An externally visible sign of iodine deficiency is often a goiter (goiter = enlarged thyroid gland).

Iodine deficiency has a particularly serious effect on newborns and young children. There is a risk of serious, irreversible developmental disorders, including cretinism. In adults, iodine deficiency can manifest itself in the form of reduced temperature tolerance and severe weight fluctuations.

Preventing a deficiency of iodine

To prevent iodine deficiency, Germany enacted the Iodized Salt Ordinance in 1989, which allows the trace element iodine to be added in small amounts to conventional table salt. According to the Iodine Deficiency Working Group, iodized salt is now used in 85 percent of German households.

Since then, iodine deficiency is relatively rare in Germany – only pregnant women, nursing mothers, competitive athletes or people with hypothyroidism have an increased need for iodine. This should be covered with a regular consumption of dairy products, sea fish, iodized salt and, if necessary, iodine tablets.

Iodine: overdose rare

An iodine overdose or iodine poisoning can hardly arise from a normal diet. According to the law, no more than 25 milligrams of iodine may be added to a kilo of salt. An iodine overdose is therefore more likely to result from the improper consumption of iodine tablets.

People with iodine allergy can also show the symptoms of iodine overdose when eating iodine-containing foods excessively or when taking iodine supplements. These manifest as headaches, conjunctivitis, gastrointestinal distress, burning in the mouth and throat, and iodine acne.

Iodine and radioactivity

Iodine is basically a natural element and completely harmless. However, nuclear fission produces the radioactive iodine-131 and iodine-123. If these isotopes get into the human body, they are deposited in the thyroid gland, where they can cause considerable damage, and in the worst case even thyroid cancer.

Therefore, in the event of a reactor accident, for example, iodine tablets are distributed to the population, which contain iodine in a high dose and thus protect the thyroid gland. However, the iodine tablets must be taken as a precaution and as soon as possible, because once the dangerous iodine-131 or iodine-123 has entered the thyroid gland, even the tablet can do nothing.