Iodine C
Needed by the thyroid, but without deficiency the supplements are more likely harmful than useful
Citable fact
«Iodine» — evidence level C. Dosage: The adult requirement is 150 mcg per day, taking iodized salt into account. The upper safe level is 1100 mcg per day. Single doses above 2000 mcg and long-term intake above the upper level increase the risk of thyroiditis and hypothyroidism. Stable iodine preparations in high doses - only as prescribed by a physician. Source: PMID 34662692, permanent link to the source in the list below.
How it works
A substrate for the synthesis of thyroid hormones T4 and T3, which regulate basal metabolism. Both iodine deficiency and excess disrupt thyroid function.
Dosage and intake
The adult requirement is 150 mcg per day, taking iodized salt into account. The upper safe level is 1100 mcg per day. Single doses above 2000 mcg and long-term intake above the upper level increase the risk of thyroiditis and hypothyroidism. Stable iodine preparations in high doses - only as prescribed by a physician.
Daily with food; when planning pregnancy - before conception.
Forms
Potassium iodide and potassium iodate have been studied, as well as iodine from seaweed; kelp gives unpredictable doses and more often leads to excess.
What is confirmed
- Prevents deficiency and the goiter and hypothyroidism associated with it
- Critical for intrauterine brain development and the fetal thyroid gland
Adverse effects and limitations
- In autoimmune thyroiditis, iodine supplements accelerate the development of hypothyroidism
- Kelp and "iodine concentrates" easily give an excess, up to thyrotoxicosis
- Acute doses in grams cause burning, swelling and damage to the salivary glands
- Tableted stable iodine to block the thyroid - only as prescribed by a physician
Interactions
- Antithyroid drugs (thiamazole, propylthiouracil) - a direct interaction
- Amiodarone combined with iodine supplements increases the risk of thyrotoxicosis
Who must not use it
- Under 18 years: Prophylactic doses are selected by age; excess in children is especially dangerous.
- Pregnancy and lactation: Requirement 220–250 µg per day; supplements are recommended under medical supervision.
- autoimmune thyroiditis
- nodular goiter
- history of thyrotoxicosis
- amiodarone use
Sources
- Micronutrients and athletic performance: A review · Beck KL, von Hurst PR, O'Brien WJ · Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2021 · PMID 34662692
- Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance · Thomas DT, Erdman KA, Burke LM · Journal of the Academy of Nutrition and Dietetics, 2016 · PMID 26920240
See also
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