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Yodo

Also known as: Iodine, I, Yodo

Overview

Iodine is an essential mineral crucial for thyroid function and the production of thyroid hormones. It is naturally found in sources like seaweed, dairy products, and iodized salt. Iodine plays a vital role in preventing iodine deficiency disorders such as goiter and cretinism, and it supports overall thyroid health. As a highly reactive element, iodine is integral to human health, particularly for the synthesis of thyroid hormones, which regulate metabolism and growth. While research on iodine supplementation is extensive, more high-quality studies are needed, especially in areas of mild-to-moderate deficiency. Iodine is well-absorbed in the gastrointestinal tract, and its bioavailability can be influenced by dietary factors. Supplementation is common in areas where dietary intake is insufficient, but it should be approached with caution to avoid excessive intake, which can lead to thyroid dysfunction.

Benefits

Iodine supplementation primarily supports thyroid function by preventing or reducing the increase in maternal thyroid volume during pregnancy. However, research indicates that it generally does not significantly affect maternal or infant thyroid-stimulating hormone (TSH) and free thyroxine levels. Limited evidence suggests that iodine supplementation may have benefits for child neurodevelopment in areas of mild-to-moderate deficiency, but the effect sizes for cognitive and motor development are generally small and not statistically significant. Some studies also suggest that iodine supplementation may reduce adverse obstetric outcomes, such as miscarriages. Pregnant women benefit most from adequate iodine intake, as it is crucial for fetal brain development, although the benefits of supplementation in mildly deficient populations are not definitively established. Overall, the benefits are likely long-term and related to maintaining thyroid function.

How it works

Iodine is essential for the synthesis of thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3). These hormones regulate metabolism and growth. Iodine directly affects the thyroid gland, influencing overall metabolic rate and energy production. The primary molecular target is thyroid peroxidase, an enzyme involved in thyroid hormone synthesis. Iodine is absorbed from the gastrointestinal tract, and its bioavailability depends on dietary factors. Once absorbed, it is transported to the thyroid gland, where it is used to produce thyroid hormones. These hormones are then released into the bloodstream to regulate various bodily functions.

Side effects

Iodine supplementation is generally safe when used appropriately, but excessive intake can lead to thyroid dysfunction. Common side effects are not typically reported at recommended doses. Uncommon side effects, occurring in 1-5% of users, may include thyroid dysfunction if intake is too high or too low. Rare side effects, occurring in less than 1% of users, include iodism, characterized by a metallic taste, sore teeth and gums, and skin lesions, which can occur with excessive intake. Iodine may interact with thyroid medications, potentially altering their efficacy. There are no specific contraindications, but caution is advised in individuals with pre-existing thyroid conditions. Pregnant women should ensure adequate intake to support fetal development, but should also avoid excessive supplementation. It is important to adhere to recommended dosage guidelines to minimize the risk of adverse effects.

Dosage

The minimum effective dose of iodine is 150 μg/day for adults. For pregnant women, the optimal dosage range is 150-250 μg/day. The maximum safe dose for adults is 1,100 μg/day, although higher doses may be used under medical supervision. Consistent daily intake is recommended to maintain adequate levels. Iodized salt is a common source, but supplements can be used if dietary intake is insufficient. Absorption is generally good, but dietary factors like selenium and vitamin E may influence thyroid function. While there are no specifically required cofactors, a balanced diet supports overall thyroid health. It is important to adhere to recommended dosage guidelines to avoid potential adverse effects.

FAQs

Is iodine supplementation necessary for everyone?

Not everyone needs supplementation; it depends on dietary intake and geographical iodine availability. Individuals with sufficient dietary intake may not require additional iodine.

How does iodine affect thyroid function?

Iodine is essential for thyroid hormone production, but excessive intake can disrupt thyroid function. Maintaining a balanced intake is crucial for optimal thyroid health.

Can iodine supplementation improve cognitive function in children?

Current evidence does not strongly support significant cognitive benefits from supplementation in mildly deficient populations. More research is needed to confirm any potential benefits.

Research Sources

https://pubmed.ncbi.nlm.nih.gov/32320029/ – A systematic review and meta-analysis of 37 publications, including 10 RCTs, found that iodine supplementation did not significantly affect maternal or infant TSH and free thyroxine levels and had limited impact on child neurodevelopment. The study noted that most included studies had small sample sizes and methodological limitations, resulting in a moderate quality assessment.
https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/ – This fact sheet from the NIH provides comprehensive information on iodine, including its role in thyroid function, dietary sources, and recommended intake levels. It also covers the risks of iodine deficiency and excess, as well as special considerations for pregnant and breastfeeding women.
https://etj.bioscientifica.com/view/journals/etj/11/1/ETJ-21-0035.xml – An observational study with 1,980 participants (687 without iodine, 1,293 with iodine) found that iodine supplementation was associated with reduced adverse obstetric outcomes and miscarriages. The study's observational design limits causal inference, resulting in a fair quality assessment.
http://www.scielo.org.co/scielo.php?script=sci_arttext&pid=S0121-40042021000200006 – A systematic review of studies on iodine deficiency in women of childbearing age revealed that many studies had low methodological quality and high heterogeneity. This limits the strength of conclusions that can be drawn about the effects of iodine supplementation in this population.
https://www.webmd.com/vitamins/ai/ingredientmono-35/iodine – This WebMD page provides general information about iodine, including its uses, potential side effects, and interactions. It is a general resource and not a primary research article.