Iodine

 Main Characteristics

• It is an important trace element for health and its importance lies in the fact that it is a component of thyroid hormones. Iodine metabolism is related to the thyroid, as it is the only organ that can accumulate iodine in large quantities and incorporate it into thyroid hormones.

• It is not considered toxic, but chronic excess intake can cause an increase in the thyroid gland.

• Excess iodine is excreted mainly through urine and milk, and to a lesser extent through saliva, tears and sweat.

• It participates in the regulation of enzymes and metabolic processes and is involved in the growth, maturation and development of the organism, but especially of the Central Nervous System.

• Iodine deficiency is the main cause of brain damage and mental retardation, and is the most easily predictable. Due to its serious consequences for human development and growth, it still represents one of the biggest public health problems.

 

Main Functions and Mechanisms of Action

• Production of Thyroid Hormones: The iodine consumed is transformed into iodine, then absorbed by the thyroid and stored in the form of thyroglobulin. TSH stimulates increased iodine uptake and the synthesis of more hormones.

• Prevention of Goiter: Iodine deficiency increases the volume of the thyroid gland, causing Goiter.

• Prevention of Hypothyroidism and Hyperthyroidism: Excess iodine in the thyroid gland interferes with the release of thyroid hormones, which can cause Hypothyroidism. In the case of Hyperthyroidism, it is related to Iodine deficiency.

• Prevention of Brain Damage: Iodine participates in the maturation of the Nervous System, and its deficiency can cause irreversible damage to this System, such as cretinism or mental retardation.

• Pregnancy: Iodine homeostasis is important to keep the mother's thyroid hormones functioning normally, and these are necessary for the proper cognitive, motor and auditory development of the fetus.

 

Bioavailability

• Iodine in its inorganic form is almost entirely absorbed in the small intestine as iodide, while in its organic form, only 50% is absorbed in the gastrointestinal tract.

• The presence of other nutrients does not appear to influence iodine absorption. However, there are substances present in some foods that are considered goitrogenic, such as glucosinolates, which reduce the use of iodine by the thyroid. Other goitrogenic substances can be found in cassava, bamboo shoots, some legumes, etc.

• It is worth noting that selenium deficiency prevents the conversion of T4 to T3.

 

Possible interactions

• There is no record of iodine interacting with medications.

Interaction between Nutrients

• There are some reports of interactions between iodine and chlorine molecules, in which case the latter would hinder the absorption of the former.

 

Scientific evidence regarding the effectiveness of supplementation

• The impact of iodine deficiency and maternal hypothyroidism on the fetus has been evaluated in several studies, and some authors have even recommended iodine supplementation for mothers in the first months of pregnancy. Other authors have shown that supplementation improves maternal thyroid function, but inhibits fetal thyroid function, and therefore do not recommend this treatment.

• The occurrence of goiter in people living in deficient areas can be prevented through iodine supplementation. A one-year study was conducted in which it was found that iodine was slightly more effective than levothyroxine in reducing the size of the thyroid gland of individuals with goiter.

Risks of overdose

• Chronic high levels of iodine intake can lead to abdominal pain, fever, nausea and vomiting.

• There are reports that excessive iodine consumption in old age can lead to hyperthyroidism and, as a consequence, to dysregulation of atrial fibrillation.

• Excess iodine can cause health problems, especially damage to the thyroid gland itself.