Cyanide is toxic and naturally found in some foods like bitter cassava. Using a new method to reduce the levels of cassava cyanide, Michigan State University researchers are linking improved food safety to an increase in cognitive development in children.

“In the United States, we rarely eat cassava and when we do, it’s usually highly processed and in small amounts, so this isn’t a problem for us,” said Felicia Wu, a John A. Hannah Distinguished Professor and an international expert on food safety in the Department of Food Science and Human Nutrition in the College of Agriculture and Natural Resources. “Plus, our diets are varied, and we have access to foods like eggs, dairy, meat and fish that can transform dietary cyanide into more harmless compounds.”

In places like the Democratic Republic of Congo or DRC in Central Africa that lack dietary variety, cassava is a primary food source consumed during most meals. A diet high in cassava can lead to cyanide poisoning, konzo (a paralytic disease) or even death.

Even low levels of cyanide exposure over time can cause cognitive impairment that may have lifelong effects. Wu and her colleagues have evaluated the cost-effectiveness of a wetting method, developed by her co-authors, to reduce cassava cyanide and improve children's cognitive impairment.

This research was published on July 21 in the journal Nature Food. 

Cassava cyanide is typically removed by soaking the cassava root in water for three to four days and letting the root dry in the sun for one to two days.  

“People are hungry and they can’t wait for days to eat,” Wu said. “They need an easy, effective and affordable way to remove cassava cyanide.”

The new wetting method developed in Africa by the other co-authors of this study involves grinding the cassava root into flour, mixing it with water in a basin and letting it stand in the shade for five hours or in the sunlight for two hours. It is effective in removing cyanide, but easy to implement in a family’s daily routine.

Co-author Michael Boivin, a professor in the Department of Psychiatry, director of the Psychiatry Research Program and professor in the Department of Neurology and Ophthalmology in the College of Osteopathic Medicine, served as one of the principal investigators on the Grand Challenges Canada project that funded this research. Desire Tshala-Katumbay at Oregon Health and Sciences University and the University of Kinshasa in the DRC and Esperance Kashala-Abotnes at the University of Bergen in Norway and the Institut National de Recherche Biomedicale in the DRC also helped lead this interventional study. Along with Boivin, they were the 2019 co-recipients of the MSU Community Engaged Scholars Award.

Previously, co-author Kashala-Abotnes and her colleagues tested the IQ levels as well as the fine and gross motor skills of children who were eating cassava flour contaminated with various levels of cyanide in the Congo. They found that higher cyanide levels in household cassava flour were associated with poor cognitive outcomes in children. Wu and colleagues estimated how the wetting method could reduce cassava cyanide and improve children’s cognitive outcomes aided by World Health Organization data.  

“This simple wetting method for cassava flour can dramatically reduce cyanide levels, resulting in improvements in children's cognitive development,” Wu said. “The goal is to reduce these children’s overall disability over the course of their lives. Importantly, because this method is simple, affordable, and feasible, it could be easily adopted in resource-poor parts of the world.”