Early evidence in the UK, published in 2001, pointed to low levels of selenium in the soil as the primary cause of falling levels of the micronutrient in food. In 2008, work on the long-term wheat archive at Rothamsted Research implicated plant breeding and physiology (notably, the introduction of shorter, high-yielding varieties of wheat) in falling levels of other minerals in grains; levels in the soil have been stable or increasing since the institute’s founding in 1843.
Subsequent research has shown that enhanced fertilisers could “biofortify” crops with selenium, whose natural levels in wheat are well below those needed to help maintain daily intake recommendations through foodstuffs, such as bread. Demand for artificial additives could surface and grow if climate change further reduces levels of selenium in the soil, as research published in 2017 predicts.
But there is little “economic pull” for such initiatives with low-value commodities like bread, potatoes and milk; and there is little political push these days if the public are not demanding change or, indeed, if they are wary of change. When Finland discovered, in the 1980s, that levels of selenium in the population were too low, the government passed legislation to increase the mineral’s concentration in fertiliser. The initiative worked but Finnish authorities admit that public scepticism about additives would likely prevent them from doing the same today.