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Scientists Suggest Adding Selenium to Diets in Malawi

  • Kim Lewis

Scientists say adding a naturally-occurring mineral to fertilizers could help reduce disease and death among Malawians. It’s all part of an international study conducted by researchers at the University of Nottingham in the U.K. on the nutritional value of soil in Malawi. The report has found that dietary deficiency of the mineral selenium, which plays a vital role in keeping the immune system healthy, is endemic in Malawi.

The study, which was published in the journal Scientific Reports, found that most Malawi soils do not have an adequate amount of selenium required for human nutrition. In the report, researchers are calling for further investigation into the benefits and costs of enriching crops with selenium through fertilizers.

Dr. Martin Broadley, one of the lead researcher of the study at the University of Nottingham’s school of biosciences said, “one of the issues is the natural acidity of the soil in Malawi and in many areas. So it may be that there is rather a lot of selenium around in terms of the total concentration in the soil, but in terms of the amount of selenium that is available to be taken up by plants, that could be very, very low.”

The study examined the diet and nutritional status of a total of 120 relatively healthy women between 18 and 50 years of age living in villages in Zombwe in northern Malawi and Mikalango in the south.

“It was a joint study with several collaborating groups in Malawi itself, and we were working with the Ministry of Health, and with Lilongwe University. Our colleagues from those organizations spent a period of time in the homes of volunteers from two different regions: one region where the soils were very, very acidic, and where we had previously observed very low transfer of the element selenium into the local crop, and one area where the soils were much more alkaline,” explained Broadley.

“Our colleagues,” he continued, “spent time and a period of 24 hours with each of the volunteers of the study and were able to collect samples of food and drink that were consumed in the home over that period. And we were also able to collect blood and urine samples from the volunteers.”

Generally speaking, scientists have found that a lack of proper levels of selenium in the body adversely affects the immune system. As a result, people tend to be more susceptible to infectious diseases and cardiovascular problems. One example of where enriched crops are showing success is in Finland.

“For the past 30 years, they have been using micronutrients, enriched fertilizers, to make sure that adequate levels of selenium were going into the diet. So the technology is in place. What isn’t known is the benefit cost of analysis of adopting something like this approach, said Broadley.

In Malawi, the staple maize, dominates the diet. But, Broadley said the key to a healthier diet and to getting more selenium is to eat a larger variety of foods.

“People have to try and diversify their diets as much as possible, and that may mean trying to eat more fish, or more animal produce of some description, or more vegetables, or more nuts—that type of thing, which general have high levels of selenium in them. And we’re going to be a long way short of adequate intakes without some radical changes in the intakes of the Malawi population. And, again, you are dealing with a situation in Malawi where many people are living on extremely low income levels, and don’t have access to sufficient purchasing power to be able to afford to buy such a diverse range of foods,” Broadley explained.

He also pointed out that a lot more research needs to be conducted to identify whether the cost of adding or changing the existing fertilizer practices in Malawi would be the most beneficial approach to improving the nutritional value of crops.