Iodine is an essential trace element that the body requires in very small, but vital, amounts. It plays a central role in the production of thyroid hormones , which control energy metabolism, growth, brain function, and the regulation of many bodily processes . Without iodine, the thyroid gland cannot produce a sufficient amount of hormones – a deficiency can therefore have far-reaching effects on health, energy levels, and mental performance.
The human body contains only about 10–20 milligrams of iodine in total, of which around 70–80% is stored in the thyroid gland. Since the body cannot produce iodine itself, it must be regularly obtained through food. The best sources include oily fish, seaweed, seafood, iodized table salt , and, to a lesser extent, dairy products and eggs.
Iodine is essential for the production of the thyroid hormones thyroxine (T4) and triiodothyronine (T3) . These hormones affect almost every cell in the body and are crucial for regulating metabolism , growth , and nerve function .
Thyroid function and metabolism:
The thyroid gland uses iodine to synthesize T3 and T4, which stimulate energy metabolism. They regulate how efficiently the body obtains energy from food, maintains body temperature, and processes fats, proteins, and carbohydrates. A balanced iodine level thus ensures stable energy production and a healthy body weight.
Growth and development:
Iodine is particularly important during pregnancy and childhood, as thyroid hormones regulate the development of the brain, bones, and nervous system . A deficiency during this time can impair mental and physical growth.
Nervous system and mental performance:
Iodine influences concentration, memory, and mood through its effect on the nervous system. Adequate iodine intake contributes to clear thinking and emotional balance.
Hormonal balance:
Iodine interacts closely with other hormonal systems, particularly with sex hormones and adrenal gland function. It can help regulate hormonal imbalances – for example, during menstruation or menopause.
Immune system and cell protection:
Iodine also possesses antimicrobial and antioxidant properties . In the right amount, it supports the immune system and contributes to maintaining healthy mucous membranes, especially in the mouth and throat.
Supports the production of thyroid hormones (T3 and T4)
Regulates metabolism and promotes energy production
Supports growth, brain and nervous system development
Promotes mental performance, concentration and mood
Contributes to a balanced hormonal system
Supports the immune system and has an antioxidant effect
Contributes to the health of skin, hair and nails.
Both iodine deficiency and iodine oversupply can cause health problems.
Iodine deficiency:
A long-term deficiency leads to an underactive thyroid (hypothyroidism) , which can manifest as fatigue, weight gain, sensitivity to cold, dry skin, hair loss, and difficulty concentrating. In severe cases, the thyroid gland can enlarge – a goiter (struma) develops.
Iodine excess:
Excessive iodine intake can trigger hyperthyroidism or inflammatory reactions in sensitive individuals. Therefore, people with existing thyroid conditions should only take iodine supplements after consulting a doctor.
Iodine-containing medications or contrast agents can also affect thyroid function.
Iodine is a key nutrient for the thyroid gland and therefore essential for energy, concentration, and metabolism. It supports mental clarity, hormonal balance, and the development of the brain and nervous system—especially during pregnancy and growth phases. A balanced iodine intake is crucial: both deficiency and excess can impair well-being. An iodine-rich diet with fish, seaweed, and iodized salt optimally meets the needs of most people and keeps body and mind in balance.
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