The detour through water, soil and feed trough
Whether a food contains much or little of a trace element is usually settled long
before the kitchen. For iodine and for selenium these decisive points even lie in entirely
different places — once in the atmosphere, once in the subsoil.
Evaporation, rain and the distance from the coast
By far the largest reserve of iodine lies in seawater. A small share leaves the water surface, is
carried over land by the wind and deposited with rain and snow. Because this transport diminishes
with distance, inland farm soils carry less iodine than areas near the coast. Ice-age erosion has
additionally reduced the reserve of some Central European soils.
A large part of the intake here therefore comes not from the soil but from two deliberate
decisions: iodized table salt in the kitchen and bakery, and supplemented feed in dairy farming.
Both are subject to labeling and can be read on the packaging.
pH value, redox state and the solubility of selenium
Selenium occurs in several oxidation states, and this determines how mobile it is in the soil. In
well-aerated, rather alkaline soils, selenate predominates, which plants take up readily. In acidic
or waterlogged soils there is more selenite, which binds to iron and aluminum oxides and thereby
becomes harder to reach.
For this reason the levels of the same crop vary considerably from region to region. Grain from
areas with selenium-rich parent rock delivers many times what grows on a neighboring, acidic field.
Figures from nutrient tables are therefore ranges, not properties of a variety.
Two entries, quoted twice
The register entry for iodine reads: „Iodine contributes to normal thyroid function“
— In accordance with Regulation (EU) No 432/2012. The entry for selenium reads:
„Selenium contributes to normal thyroid function“ —
In accordance with Regulation (EU) No 432/2012. Both entries stand here one after the other and not
in a single joint sentence.
They are addressed to the general population with a sufficient supply. A statement about individual
findings, about symptoms or about the course of an illness is not contained in the entries.
Everything else on this page is a description of origin, level and labeling — and therefore
editorial text without a health claim.