Iodine in yogurt, fish and salt
In this investigation
My latest record includes a whole 32 oz nonfat yogurt tub, sardines and restaurant chicken. Their iodine quantities remain unknown. This is a measurement gap; the iodine guide explains the separate intake references and clinical limits.
What a measured comparison can establish
The 2024 USDA/FDA database reports regular plain nonfat yogurt at 59 µg iodine/100 g on average: eight samples, with observed values 33–146 µg/100 g. These 2023 convenience samples are comparisons, not a Trader Joe’s assay or bounds for my tub. The database contains several fish species and roast chicken breast/thigh, but no sardine entry or matching RT half-chicken. Those other foods cannot close this record’s gap. A future comparator must preserve product/species, preparation, edible or drained mass, analytical source and uncertainty. Original per100g dataset, sampling documentation.
Organic and seasonal labels do not specify a dose
A Northeastern U.S. study analyzed paired winter/summer raw milk from 83 farms, then 42 retail whole milks sampled in summer. Organic farm milk had lower iodine overall, with a season interaction; retail organic and conventional means did not differ significantly. Farm soluble iodide and retail total iodine were measured with different assays. Feed and farm management are plausible influences, but this observational comparison did not isolate their effects. It supplies no fixed “organic discount,” year-round retail result or iodine concentration for my yogurt. Original 2022 milk analysis.
Salty food does not reveal its iodine
U.S. rules distinguish iodized table salt, with added potassium or cuprous iodide, from table salt without added iodide. Retail statements normally identify the distinction, but individual packets below ½ oz and packages above 2½ lb have statement exemptions. These do not cover a multiunit retail pack’s outer wrapper. An absent statement on a restaurant salt container therefore needs supplier clarification. My sardine sodium declaration cannot identify either the fish’s iodine content or salt iodization. A verified salt ingredient would improve the model; taste and a sodium number do not provide that quantity. Current 21 CFR 100.155.
Availability differs from quantity
A 2019 randomized crossover study enrolled 12 iodine-replete adults; 11 completed it. Three drinks supplied the same 263 µg iodine: native-iodine milk, milk with added potassium iodide, and an aqueous iodide solution. These quantities describe iodine, not total iodide-compound mass. Urinary iodine excretion did not differ significantly between conditions; 80–93% of milk iodine was inorganic iodide. This supports good availability in that experiment, without proving equivalence of every dairy product. Government and foundation funding supported the work. Neither iodine in my yogurt nor a thyroid benefit was measured. Original balance trial, trial registry.
A urinary improvement is not a demonstrated thyroid benefit
A 12-week trial enrolled 78 women aged 18–45 who habitually drank little milk. A 3 L/week milk target versus usual intake increased spot urinary iodine concentration; changes in iodine:creatinine and thyroid hormones did not differ significantly between groups. The current registry lists urinary concentration as primary, but was posted after trial completion. The Dairy Council for Northern Ireland paid for milk provision. This supports a food source’s effect on a urinary marker in that population, rather than demonstrated thyroid, training or health improvement in a young man already eating a large yogurt tub. Original milk trial, registry and dates.
What changes today
Keep the foods I enjoy. Exact product composition and verified salt iodization could improve the estimate; the unknown quantity alone supplies no automatic reason to add food, salt or a supplement.