Micronutrient malnutrition is caused by a lack of vitamins and minerals in the diet. Poor people are particularly vulnerable to micronutrient malnutrition, as their diets consist mainly of grains and don’t include many vital fruits, vegetables or animal products.
HarvestPlus as part of the CGIAR research programme on agriculture for nutrition and health, has promoted the selective breeding of staple food crops to provide more essential micronutrients as a new potentially important strategy in the fight against micronutrient malnutrition. This ‘selective breeding’ is known as biofortification. Though several investments in large-scale biofortification projects are underway, until recently little rigorous evidence has supported the impact of these investments.
To fill this knowledge gap, with support from the Gates Foundation, HarvestPlus conducted the reaching end users project in Mozambique and Uganda from 2006-2009. The project aimed to reduce vitamin A deficiency among children under 5 and among women of child-bearing age by introducing provitamin-A-rich orange sweet potato (OSP) to 24,000 farming households. The varieties of OSP disseminated were all bred locally using conventional methods, had attractive agronomic properties, and reached or exceeded a target level of vitamin A. Research done at the beginning of the REU showed that a majority of consumers participating in tastings were either indifferent to or preferred the new varieties of OSP to native white - or yellow-fleshed sweet potato varieties.
The impact evaluation of the REU randomly assigned farmer groups in both countries into two treatment groups, with treatments differing in intensity, and a control group. The more intense treatment included agricultural and nutrition extension over a period of two or three years (three years in Mozambique). The less intense treatment model conducted intense extension only in the first year, scaling back interactions in the second year, to test whether this approach was more cost-effective. In Uganda, OSP vines were given to farmers at the beginning of the project, whereas in Mozambique they were given on an annual basis.
The impact evaluation team conducted socio-economic and dietary intake surveys both before the project began and after two or three years of project implementation; these surveys measured the project’s impact on participants’ vitamin A intake, as well as its impact on farmers’ adoption of OSP and mothers’ knowledge of the importance of vitamin A to their children’s health. In Uganda, blood tests measured the interventions’ impacts on serum retinol levels, a biomarker for vitamin A status in the bloodstream.
The results showed promise for biofortification. Among treated households, the amount of inadequate vitamin A intakes fell by 25-33% among children aged 12-35 months in Mozambique and by 31-34% among the same group in Uganda. Among mothers of child-bearing age, the amount of inadequate vitamin A intakes fell by 20-35% in Mozambique and 26-36% in Uganda.
Among Ugandan children aged 3-5 years with low levels of serum retinol (serum retinol<1.05 μmol/L) at the start of the project, the prevalence of low serum retinol decreased by 9.5%. And even more good news: the less intense treatment appears just as effective as the more intense one, suggesting that more households can be reached for the same money in future biofortification projects with similar impacts.
In a recent paper, we also measure the project’s impacts on OSP adoption and nutritional knowledge. We use a technique called causal mediation analysis to help us ascertain what proportion of improvements in dietary intake of vitamin A can be attributed to the project’s intervention components. Unsurprisingly, we saw large impacts on farmers’ adoption of OSP; across both countries, adoption rates attributable to the project were between 61-68% of targeted households.
Participants also learned about vitamin A sources. We estimate that specific messages about nutrition contributed no more than 5% of the project’s overall increase in vitamin A intake, which suggests that the nutritional gains were due more to increased access to OSP than they were to increased information. However, our measures of informational gains were narrow, and interviews with participants suggest the general health message influenced adoption.
Our findings suggest that future biofortification interventions can have similar impacts with even simpler nutrition messages about biofortified crops. The project’s results also highlight avenues for further research. One important unanswered question is how to deliver biofortified varieties effectively and sustainably. In related research, we found that farmers’ social and information networks play an important role in the diffusion of OSP within communities because farmers often share planting materials with their neighbors.
More research is needed to better understand of how diffusion of biofortified varieties can be promoted to further increase the cost-effectiveness of future biofortification programmes.
Alan de Brauw is senior research fellow at the markets, trade, and institutions division, and Dan Gilligan is senior research fellow at the poverty, health and nutrition division, both at the International Food Policy Research Institute.
HarvestPlus is coordinated by IFPRI and the International Center for Tropical Agriculture.