The body uses selenium, a mineral vital for good health, to make 'selenoproteins' which protect cells from damage. The mineral's consumption cuts down chances of developing pancreatic cancer, says a UK study.
Experts say that depleting soil selenium levels, thanks to intensive farming methods and fertilisers, are affecting the food chain, diets and the risk of disease.
Last week, researchers at the University of East Anglia found people who eat large amounts of the mineral, along with vitamins C and E, are 67 percent less likely to develop pancreatic cancer.
Previous research has shown that in old age a good selenium intake helps enhance brain function, so that cognition remains sharp and active, the Daily Mail reports.
The richest food sources of selenium are Brazil nuts, kidney, liver and fish, but the foods that make the largest contribution to our selenium intake - because we eat proportionately more of them - are cereals, bread, meat and poultry.
In the long-term, the effects of low intakes can be devastating, says Margaret Rayman, professor of nutritional medicine at the University of Surrey and a leading researcher in selenium's effects.
Earlier this year, in a paper in The Lancet, Rayman detailed selenium's links to everything from enhanced fertility and thyroid function to preventing plaque build-up in the arteries and regulating blood pressure.
One study of men with fertility problems showed that 100 microgrammes of selenium supplements taken daily significantly increased sperm cells' ability to swim, indicating they had been selenium-deficient. Eleven percent of men who took the supplement went on to father a child.
"Selenium is an essential component of two selenoproteins required for healthy sperm," says Rayman. "One of these is needed for transportation of selenium into the testes and the other gives sperm a stable structure that allows it to swim."