iodine
4 interactions related to iodine
cabbage + levothyroxine
Cabbage and other brassica vegetables release thiocyanates and goitrin that can compete with iodide uptake at the thyroid and interfere with hormone synthesis. In normal, mostly-cooked portions this has no meaningful effect on levothyroxine in iodine-sufficient adults. Concern is limited to very large, sustained raw-cruciferous intakes or iodine-poor diets.
selenium + iodine
Iodine is the raw material the thyroid uses to build the hormones T4 and T3, but selenium is required to make the deiodinase enzymes that convert inactive T4 into active T3 in peripheral tissues. Selenium also powers glutathione peroxidase, which protects thyroid cells from the oxidative stress generated during iodine handling. The two minerals work as a pair: each is far less useful without the other.
methimazole + iodine
Methimazole blocks new thyroid hormone synthesis but does not prevent the gland from using iodide already inside it. Adding a large iodine load (kelp, iodine drops, iodine-containing contrast, amiodarone) can fuel hormone production, blunt methimazole's effect, and in some people worsen hyperthyroidism or, rarely, precipitate thyroid storm.
cauliflower + levothyroxine
Cauliflower is a cruciferous vegetable whose breakdown products (thiocyanates) can theoretically compete with iodine uptake by the thyroid. In practice, a 2024 systematic review found brassica vegetables at normal dietary intakes do not impair thyroid function when iodine is adequate, and because levothyroxine is hormone you swallow as a tablet, ordinary cauliflower portions do not meaningfully affect it.