mineral · for chronic fatigue
Iodine
Your thyroid needs iodine to make the hormones that set your metabolic rate.
Say that in clinical terms
Essential substrate for thyroid hormones T3 and T4, which regulate basal metabolic rate and cellular energy production.
How strong is the research?
2 papers read.
Who was studied: People with an underactive thyroid in iodine-deficient regions. If you get enough iodine, this does not apply.
Neither of the two cited papers qualifies and neither points toward a wider trial record. DOI 10.1007/s12020-019-01897-4 concerns radioactive iodine-131 (a radiopharmaceutical given to thyroid-cancer patients), not a nutritional supplement. DOI 10.1093/ajcn/nqaa071 is confirmed (PMID 32320029) as a systematic review and meta-analysis of iodine supplementation in mildly-to-moderately deficient pregnant women; it measures thyroid hormone levels, thyroglobulin, and child cognition — not fatigue or tiredness at any point. Broader searches found iodine trials measuring cholesterol (Morocco RCT, 150 µg/day), cognitive scores in schoolchildren (Albania), and thyroid-stimulating hormone in pregnancy
How much to take
daily
150–300 mcg
Do not exceed 1100 mcg/day. Test thyroid function before high-dose supplementation.
Before you take it
- Benefit from supplementation in iodine-sufficient individuals is not established; iodine status testing before supplementation is advisable given the documented risk of harm in sufficient individuals.
- Drug interaction: combined use with antithyroid medications (methimazole, propylthiouracil) produces an additive hypothyroid effect at high iodine doses (NIH ODS).
- Drug interaction: potassium iodide salt forms increase hyperkalemia risk when combined with ACE inhibitors (benazepril, lisinopril, fosinopril) — NIH ODS.
- Drug interaction: potassium iodide salt forms increase hyperkalemia risk when combined with potassium-sparing diuretics (spironolactone, amiloride) — NIH ODS.
- NIH ODS Tolerable Upper Intake Level (UL) for adults 19+ is 1,100 mcg/day from all sources (food, beverages, and supplements combined).
- Pregnancy RDA increases to 220 mcg/day (WHO recommends 250 mcg/day); UL remains 1,100 mcg/day; supplementation during pregnancy and lactation should be medically supervised.
- Risk of triggering or accelerating autoimmune thyroiditis (Hashimoto's disease) in individuals with pre-existing thyroid autoimmunity, a common and often undiagnosed condition.
- Wolff-Chaikoff effect: excess iodine intake in iodine-sufficient individuals can paradoxically suppress thyroid hormone synthesis, potentially inducing the very hypothyroidism it purports to treat.
What we make of it
Real biology, but only if you are deficient — and most people are not.
The detail
Iodine genuinely is the raw material for thyroid hormones, and deficiency causes the tiredness of an underactive thyroid. That only helps if the deficiency is there, which in iodine-sufficient countries it usually is not.