Decade-long research explores solutions to vitamin A deficiency in sub-Saharan Africa

Lincoln, Neb. — Key findings in a decade-long research project at the University of Nebraska–Lincoln may lead to solutions in sub-Saharan Africa’s challenge with vitamin A deficiency. A team led by Edgar Cahoon, George Holmes Professor of Biochemistry and director of the Center For Plant Science Innovation, focused on increasing amounts of provitamin A-beta carotene in cassava.

Cassava is a starch-rich root crop that is a primary calorie source for more than 250 million people in sub-Saharan Africa. Despite its dietary importance, cassava is relatively deficient in micronutrients such as provitamin A beta-carotene. As a result, childhood blindness and other health problems associated with vitamin A deficiency are problems in countries that heavily depend on cassava as a food source, such as Nigeria.

“Vitamin A deficiency continues to plague large portions of sub-Saharan Africa and has been estimated to affect the health of nearly 50 percent of preschool children in this region. Beta-carotene-enriched cassava offers one solution to this problem,” said Cahoon.  

As part of the project, the team partnered with the National Root Crops Research Institute to conduct the first government-approved confined field trial of a genetically modified crop in Nigeria. The study used cassava plantlets propagated and shipped from Cahoon’s lab at Nebraska.

The team was successful in its attempt of increasing beta-carotene in cassava roots. They found that the biofortification process actually reduced the starch content in the roots. Provitamin A-enhanced potatoes developed by the researchers using a similar strategy also reduced the starch content. The study also identified key genes that are likely targets for minimizing starch reductions in future biofortification efforts.   

The researchers made another surprising discovery during the course of this project, which could also bolster the cassava crop. A major challenge with current cassava production is its poor post-harvest storage properties that limit the ability of subsistence farmers to transport roots to urban markets. The researchers found that when the target beta-carotene amount is reached within the cassava roots, the shelf life of the harvested crop expands greatly.

“Cassava storage roots that have longer shelf life could provide additional income to farmers and allow them to purchase more nutritionally diverse foods. This would have a major impact on addressing malnutrition problems in sub-Saharan Africa,” Cahoon said.   

According to Cahoon, these findings highlighted genetic and biochemical links between beta-carotene enhancement and carbon storage that should be considered for breeding and biotechnology-based approaches for provitamin A biofortification of starch-rich crops. The biotechnological approach used in these studies also allows for “stacking” additional genes to improve other production and nutritional limitations of cassava such as plant virus sensitivity and low iron content for storage roots.

The results of the study were published in Plant Biotechnology Journal.

Nebraska researchers partnered with scientists from the Boyce Thompson Institute, Donald Danforth Plant Science Center, Kenya Agricultural Research Institute, New Mexico Consortium, Texas A&M University and the University of Puerto Rico.

Funding for the project was provided by the Bill and Melinda Gates Foundation, USDA-Agriculture and Food Research Initiative and the National Science Foundation.