• Integral component of the thyroid hormones thyroxine (T4) and triiodothyronine (T3).
• T3 and T4 regulate cell division, growth and differentiation, energy metabolism and brain development.

• By regulating these thyroid hormones, iodine plays a crucial role in energy metabolism and in the expression of genes that affect a variety of physiological functions, including not only embryogenesis and growth, but also the development of neurological and cognitive functions [2, 9].
• An adequate iodine supply is therefore considered necessary for most pregnant and breastfeeding women (in the absence of thyroid disease) [7, 12, 15].
• Although breastfeeding women have the same requirements as pregnant women, the mean urinary iodine content is lower because iodine is excreted via breast milk [10].

• contributes to normal energy metabolism
• contributes to normal cognitive function
• contributes to the normal functioning of the nervous system
• contributes to normal production of thyroid hormones and normal thyroid function
• contributes to the maintenance of normal skin

• Iodine plays a central role in the synthesis of the thyroid hormones triiodothyronine (T3) and thyroxine (T4) and is therefore essential for maintaining optimal thyroid function. To meet the body's needs for these hormones, the thyroid extracts iodine from the blood and incorporates it into thyroglobulin, an important protein.
• Through a degradation process, this protein is converted into T4 (thyroxine), which is then stored and released into the bloodstream when needed. In tissues such as the liver, muscles, and brain, T4 can be converted into the active form T3 by selenium-dependent enzymes known as deiodinases. T3 then interacts with thyroid hormone receptors in cell nuclei to control gene expression. Due to this mechanism, thyroid hormones play an important role in regulating various physiological processes, including growth, development, metabolism, and reproduction.
• When there is not enough iodine, the production of T4 is impaired, leading to a drop in T4 levels in the blood. In response, the pituitary gland increases the secretion of thyroid-stimulating hormone (TSH).
• Persistently high TSH levels can lead to an enlargement of the thyroid gland, also called a goiter, which reflects the body's attempt to absorb more iodine from the bloodstream to produce thyroid hormones.

Iodine is also considered a critical nutrient in a primarily plant-based diet.

However, the iodine intake of the majority in Germany is below the recommended daily intake. However, studies also show that vegans are even worse off than vegetarians, as fish and dairy products are also not possible sources of iodine [1].