Iodine Benefits And Functions
Iodine, known as iod in technical terms, is an essential micronutrient belonging to the trace elements. It must be obtained daily through diet, as the body cannot produce it on its own. A healthy adult contains about 10 to 20 mg of iodine, of which 70 to 80% is stored in the thyroid gland 1. The remaining portion is distributed throughout the body, especially in the ovaries, muscles, and blood 2. Iodine is water-soluble.
The iodine consumed through food is rapidly and almost completely absorbed in the stomach and duodenum 3. The absorption rate is over 90% in healthy individuals. Over 90% of the absorbed iodine is immediately excreted through urine, with small amounts being eliminated through feces 4.
Functions and Benefits
This nutrient is important for the functioning of the thyroid glands. Iodine, along with the non-essential amino acid tyrosine, is needed for the synthesis of the thyroid hormones thyroxine (T4) and triiodothyronine (T3) 5. A healthy organism relies on the thyroid-stimulating hormone to regulate the synthesis and release of these hormones.
The thyroid hormones are essential for numerous bodily processes. They are involved in regulating the metabolism of carbohydrates (glycolysis and gluconeogenesis), fats (thyroid hormones increase lipolysis), proteins, vitamins, and minerals 6. Furthermore, thyroid hormones are necessary for maintaining body temperature.
Thyroid hormones control protein synthesis, which enables cell division and is of immense relevance, for example, in vegan muscle building.
Iodine may also play a role in the immune response and could have a benefit on mammary dysplasia and breast mastopathy 7.
Iodine during pregnancy
Jod (Iodine) is also of great importance during pregnancy and for growing children. Thyroid hormones play a crucial role in body development and growth 8. The hormones directly influence the development of the nervous system, particularly the brain, and bone growth 9.
Adequate amounts of iodine are therefore essential for fetal nervous system development during pregnancy 10. Even mild iodine deficiency is associated with developmental disorders according to scientists. Pregnant and breastfeeding women therefore have higher iodine requirements.
Significance for Athletes
Thyroid hormones are important for protein synthesis, enzyme activity, and the regulation of lipid metabolism, including energy metabolism, which contributes to muscle building and weight loss 11.
In addition, thyroid hormones increase energy production for good performance and improve lipolysis (breakdown of fats and other lipids) 12.
Does iodine protect against breast cancer?
Increased iodine consumption may potentially reduce the risk of developing breast cancer. This assumption is based on the fact that Japanese women consume more iodine-rich algae and exhibit relatively low rates of breast cancer 13.
Determine plant components, known as goitrogens (thyroid-disrupting substances), can hinder the absorption of iodine into the thyroid gland, thereby inhibiting the production of thyroid hormones 14. Goitrogens are found in millet, cruciferous vegetables, flaxseeds, sweet potatoes, and soybeans (due to the isoflavones genistein and daidzein). They bind to iodine, making it less available to the body (low bioavailability). However, these substances only become significant when there is already an iodine deficiency. In that case, it can lead to an enlargement of the thyroid gland (goiter formation) as the body tries to compensate for the reduced production of thyroid hormones.
Considerations for Vegans
In many regions, iodine levels in the soil are depleted due to flooding, erosion, and glaciation 15. Therefore, plants grown on the surface contain very small amounts of iodine.
According to a Danish study, vegans have lower iodine intake levels compared to the general population 16. However, the study found that three vegans had extremely high iodine intake levels (971, 1,709, and 1,982 μg per day) due to consuming algae. Other studies also show that vegans have lower iodine levels and a higher incidence of iodine deficiency-related diseases 17 18 19 20 21.
Vegans should therefore pay attention to a diet rich in iodine and consume iodine-rich foods such as seaweed more frequently. However, they should consume them in small quantities due to their high iodine content. Most packaging of relevant seaweed products also indicates their high iodine content. Excessive iodine consumption, like iodine deficiency, can lead to severe thyroid diseases 22.