Thyroid Substance
Also known as: Iodine, I, Selenium, Se, Selenomethionine, Vitamin D, Vitamin B12, iodized salt, selenium supplements, Iodine, Selenium, Vitamins D and B12
Overview
Iodine, selenium, and certain vitamins are essential micronutrients for optimal thyroid function. Iodine is crucial for the synthesis of thyroid hormones (T3 and T4) and is primarily sourced from iodized salt, seafood, and dairy products. Selenium, an important antioxidant, supports the function of selenoproteins involved in thyroid hormone metabolism, and can be found in Brazil nuts, fish, and turkey. Vitamins D and B12 play complementary roles in overall metabolic health, with potential indirect influences on thyroid function from sources such as fatty fish (for Vitamin D) and meat and dairy (for Vitamin B12). These supplements are particularly relevant for individuals with thyroid disorders—like hypothyroidism and autoimmune thyroiditis—and pregnant women in iodine-deficient areas, highlighting their significance in various health contexts.
Benefits
Iodine supplementation has been found effective in reducing maternal thyroglobulin levels during pregnancy, although it has no significant impact on children's cognitive outcomes in iodine-deficient areas. Selenium supplementation is beneficial for patients with autoimmune thyroiditis, significantly lowering thyroid peroxidase antibody levels as evidenced by systematic reviews demonstrating clinical efficacy. Additionally, while Vitamin D supplementation does not target thyroid function directly, it may confer general health benefits that indirectly support thyroid status, especially in individuals with deficiencies.
How it works
Iodine is key in the synthesis of thyroid hormones through the iodination of tyrosine residues, leading to the production of T3 and T4. Selenium serves as a cofactor for antioxidative selenoproteins, crucial for protecting the thyroid from oxidative damage and promoting hormone metabolism. Vitamins D and B12 influence metabolic pathways and gene expression, indirectly impacting thyroid function and health.
Side effects
While iodine is generally safe at recommended doses, high intakes can cause iodine-induced hyperthyroidism or thyroiditis, though this occurs rarely. Selenium, also safe in moderate doses, can lead to selenosis with symptoms such as garlic breath, nausea, and fatigue at high doses. Uncommon side effects may include allergic reactions or gastrointestinal upset. Rarely, excessive iodine can lead to thyroid nodules or goiter, while very high selenium can cause kidney damage. Iodine may interact with thyroid medications, and selenium may affect blood thinners. Caution is advised for pregnant women and individuals with prior sensitivities or autoimmunity.
Dosage
The recommended daily intake is approximately 150 μg of iodine for adults, increasing to 250-300 μg during pregnancy. For selenium, the typical intake is around 55 μg per day for adults, with therapeutic doses reaching 100-200 μg for those with autoimmune thyroiditis. The maximum safe dose for iodine is set at 1,100 μg/day, and for selenium, it is 400 μg/day. Iodine should be maintained continuously during pregnancy, while selenium can be supplemented daily with meals for enhanced absorption.
FAQs
Is it safe to take iodine supplements?
Yes, iodine supplements are generally safe when taken within recommended doses, but excessive intake should be avoided to prevent adverse effects.
How should I take these supplements?
It’s best to take iodine and selenium supplements with meals to improve absorption, with consistent dosing, especially for pregnant women.
What results should I expect from these supplements?
Iodine supports maternal thyroid health, while selenium helps lower autoantibody levels in autoimmune thyroiditis. Significant cognitive improvement for children hasn't been substantiated.
Research Sources
- https://pubmed.ncbi.nlm.nih.gov/32320029/ – This systematic review and meta-analysis involving 37 publications highlighted the importance of iodine supplementation during pregnancy. It reported no significant effects on child cognitive scores but noted reductions in maternal thyroglobulin levels.
- https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0197244 – A comprehensive meta-analysis of PFAS exposure found a negative correlation with total T4 levels, demonstrating the endocrine-disrupting effects of these substances on thyroid hormones.
- https://pubmed.ncbi.nlm.nih.gov/35440339/ – This systematic review discussed the roles of dietary supplements like iodine and selenium in managing thyroid diseases, emphasizing their benefits against associated risks.
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