Varied diet repels poisoned fungus

Maize fungus.jpg
Copyright: Andrew McConnell / Panos

Speed read

  • Maize is popular in parts of Africa but is prone to fungal contamination
  • Switching to sorghum, millet and cassava would lower toxin exposure
  • Checking harvested crops and improving storage would also help

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Food contamination with fungal toxins is best prevented by improving post-harvest processing and diversifying crops, according to a World Health Organization agency report.

Aflatoxins, produced by Aspergillus fungi that grow on grains, cause deadly liver cancer and stunting in children. They have been known since the 1960s, but still regularly contaminate food in Africa, Asia and Latin America, says the report, launched by the International Agency for Research on Cancer last month (17 February).

The report recommends various methods to reduce the threat of aflatoxins, including better ways of storing and processing grains. Research reviewed in the report has studied toxin levels in the urine and blood of people in affected areas, rather than just monitoring the toxin’s presence in contaminated food.

“We want the measure of success to be a measure of health and not just a measure of agricultural success,” says David Miller, a chemist at Carleton University in Canada, who helped edit the report.

Using available evidence, the authors determine that four out of 15 interventions to prevent the toxins’ health effects are ripe for implementation in low-income countries.

“The intervention for which the strongest evidence of improvement of health exists, but which is also the most difficult to achieve, is to increase dietary diversity,” they write.

In the 1950s, sorghum, millet and cassava were a large source of starch calories in Sub-Saharan Africa, Miller says, but their consumption has dropped in favour of maize, which is more prone to fungus. The study calls for more investment in appropriate crops for the target region, both in terms of climatic and cultural suitability.

“There are a whole bunch of interesting crops that have suffered a reduction in use globally,” says Miller. Diversification is not easy, but is “not an impossible dream” either, he adds. “It’s one of the things we know will work.”

Another possible intervention is better food processing, says the report. This includes sorting crops early to exclude contaminated food and improving storage conditions to lower humidity, which the fungus needs to grow.

“The solutions mentioned in the report are good to implement in developing countries,” says Anitha Seetha, a food safety researcher at the International Crops Research Institute for the Semi-Arid Tropics in Malawi. “For example, post-harvest management methods like drying and storing grains appropriately are very simple with no involvement of chemicals.”

In Latin America, another method called nixtamalization reduces mycotoxins in maize by cooking the grain in an alkaline solution. But this requires lots of water and has not been adopted in Africa and Asia, the report says.

On 23-24 March a meeting in Ethiopia of the Partnership for Aflatoxin Control in Africa discussed the report’s findings and interventions to reduce the health risks from aflatoxin exposure.

The health impact of mycotoxin contamination “has been neglected for too long”, Christopher Wild, director of the International Agency for Research on Cancer, said in a statement. “We have the tools to make a difference. Now we must find the political will.”


Mycotoxin control in low- and middle-income countries (International Agency for Research on Cancer, 2015)