By Yassir Islam
Yassir Islam is the Head of Communications at HarvestPlus, a Washington, D.C.-based organization that is working to address global micronutrient deficiency, by adding nutrients to staple crops and making those crops more accessible.
Cassava is possibly the most adaptable of all tropical food crops. It tolerates drought, does not need much land preparation or weeding, and thrives in poor soils without chemical inputs. The leaves are nourishing, and the thick fleshy roots are used to make many different types of foods from cassava flour to tapioca pearls.
A girl enjoying yellow cassava. (Photo credit: International Center for Tropical Agriculture)
So what’s not to like?
Well, no matter how cassava is prepared, one fact remains: it is a good source of calories but provides few other nutrients. Could this food that is so popular in the tropics, and a lifesaver in times of drought, be made more nutritious? Scientists began investigating this question in 2003, focusing on a critical nutrient: vitamin A.
Vitamin A deficiency (VAD) is common in sub-Saharan Africa. In Nigeria, VAD afflicts almost 20 percent of pregnant women and about 30 percent of children under five. VAD lowers immunity which can increase the chances of getting ill or infected with disease. It can also lead to impaired vision, blindness, and even death. While Nigeria has mandated that foods such as wheat and maize flours be fortified with vitamin A since 2000, and provides vitamin A supplements to young children during national immunization day, coverage is low and vitamin A deficiency has decreased only marginally.
Other than maize, cassava is the most important staple food in sub-Saharan Africa. Nigeria happens to be the largest producer and consumer of cassava—more than eight million Nigerian farmers grow it. So developing a more nutritious cassava for Nigeria made sense.
Under the leadership of HarvestPlus, an international research program that makes staple foods eaten by the poor more nutritious, plant breeders from several institutes started working with cassava in 2003. Using conventional breeding methods, they combined improved South American cassava varieties, which had higher amounts of vitamin A, with African ones that were suited to the local environment and diseases such as cassava mosaic virus, which causes loss of chlorophyll and severely decreases yields. The candidate varieties that resulted were evaluated through performance trials on both research station and farms in Nigeria to discern which ones performed the best.
Technically, there is no preformed vitamin A in cassava. Breeders increase the amount of beta-carotene, a substance that the body then converts into vitamin A when the cassava is eaten. We simply refer to vitamin A as shorthand for this process.
The effort paid off. In November, after being presented with evidence from field trials, the Nigerian government approved three vitamin A cassava varieties for release. These cassava roots are yellow due to their higher vitamin A content. In parts of Nigeria, palm oil is often mixed into freshly grated cassava roots when processing gari, a popular food. The palm oil gives the gari a yellow color which is associated with quality, and many farmers responded well to the yellow vitamin A varieties during field tests.
HarvestPlus partners will now multiply these new varieties through stem cutting, a laborious process, to distribute plants to 25,000 farmers in 2013. After planting these stems, it’s expected that by mid-2014 farmers will be harvest and feed vitamin A cassava to their families, reaching about 150,000 people.
Although Nigeria is increasingly urban, more than half the population lives in rural areas. Children under five, a target population for vitamin A cassava, account for about 17 percent of the population in rural areas. Children and women will be the main beneficiaries of these new yellow varieties, which, given the large amount of cassava eaten daily, could provide up to 25 percent of their daily vitamin A needs, according to HarvestPlus nutritionists.
“The next wave of cassava varieties with enough vitamin A to provide up to half of their daily needs are already in the breeding pipeline and should be ready for release in a few years,” says Paul Ilona, the HarvestPlus Country Manager for Nigeria. These cassava varieties will also be adapted to other countries in Africa, beginning with the Democratic Republic of Congo, where similar vitamin A-rich varieties are also being multiplied to give to farmers.
“Scientists have turned a food crop that is nutritionally poor, except for calories, into a product that will now deliver a vital nutrient, in addition to calories, to low income families, especially children and women,” notes Barbara Underwood, a former president of the International Union of Nutritional Science, who has also advised HarvestPlus.
The future is indeed looking brighter for cassava and for the millions of people who eat it every day.
To read more about cassava, see: FAO: Cassava Disease Outbreak Close to Close to an Epidemic, More Research and Funding Needed, Ensuring Food Security in Africa, Through Agricultural Research, Innovation of the Week: Getting the most from crops, in the field and at the market, and New Cassava Varieties Save Zanzibar’s Food Security.