mineral · for dry skin
Iodine
Thyroid hormones set how fast skin renews itself, and iodine is what they are made from.
Say that in clinical terms
Thyroid hormones regulate keratinocyte turnover and sebaceous gland activity, maintaining skin hydration and barrier function.
How strong is the research?
1 paper read.
Who was studied: The cited paper is about thyroid blood test ranges in elderly patients. No iodine-deficient group was studied.
No human clinical trial has measured dry skin or any skin outcome as an endpoint in an iodine supplementation study. PubMed returns zero results for this combination. We cannot stand behind this claim on the evidence we have, so it carries no rating.
How much to take
daily
150–250 mcg
Most effective when dry skin is due to subclinical hypothyroidism. Monitor thyroid markers.
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
The biology holds, but the evidence chain does not.
The detail
Thyroid hormones do control skin turnover and oil production, and an underactive thyroid often shows up as dry, coarse skin. What is missing is any evidence that iodine supplements help skin in people who get enough iodine.