An international team of scientists, led by researchers from Nottingham University, have reported that the addition of a naturally occurring soil mineral to fertilisers in Malawi could reduce disease and premature death in the country.

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The researchers suggested that adding selenium to fertilisers could help augment the health properties of foods, particularly maize, the country's staple crop. Selenium plays a vital role in keeping the immune system healthy and fighting illness, but researchers discovered that soils in Malawi are often low in the mineral. They suggested that, as a result, levels in crops would be too low to keep people consuming them healthy.

In light of their findings, the researchers called for further investigation into the benefits and costs of using selenium-enriched fertilisers and other strategies to boost selenium levels within the country's food.

The Nottingham team found that the natural acidity levels of soil in two regions — in other words how acid or alkaline the soil was — had a huge impact on the selenium levels of those eating food produced from it. Selenium intake was found to be eight times higher in areas with more alkaline rich soils, than where soils were acidic.

Leading the study was Nottingham's Dr Martin Broadley, who said, "Selenium is a naturally occurring mineral of fundamental importance to human health, with critical roles in immunity. People with low dietary selenium intakes are at increased risk of suffering from a variety of diseases. Most soils in Malawi have extremely low levels of the selenium available to plant roots and so selenium is not transferred into crops in sufficient amounts for optimal human health.

"We urgently need to assess strategies to address this problem in Malawi and the wider Southern African region in the context of wider mineral malnutrition (for example, iron, zinc and iodine deficiencies), often referred to as the 'hidden hunger'."

The study also looked at the nutritional status of otherwise healthy women aged between 18 and 50. It was conducted in association with the Ministry of Health in Malawi.

The team said that, due to a current lack of information, they are not yet able to estimate the impact of selenium deficiency on the whole using frameworks devised by the World Health Organization. However, the study's authors pointed out that similar frameworks are already in place for deficiencies of other minerals such as zinc which, it is estimated, carries an annual economic burden of £70 million in Malawi alone.

Dr Broadley added, "It is of course feasible for people to diversify their diets to increase the consumption of other selenium-rich foods such as meat, poultry, fish and eggs but this is particularly challenging for people who are living in developing countries on an extremely low income."

The researchers recommend that further research is needed into the benefits and costs of introducing a programme to enrich nitrogen-based soil fertilisers — used relatively widely in maize cultivation in Malawi — with selenium as a way of increasing the levels of the mineral in maize. A precedent for this has already been set in other countries such as Finland, where supplemented fertilisers have successfully increased the selenium concentrations in Finnish foods and diets since the mid 1980s.