Not an ordinary sweet potato

The MRC's Nutritional Intervention Research Unit is at the forefront of efforts to find affordable, nutritious food for South African children. Dr Mieke Faber tells MRC News about two recent projects.

Children need enough vitamin A in their diet in order to stay healthy. It is well known that severe vitamin A deficiency can eventually lead to blindness, but less extreme levels of deficiency can still have harmful effects: many children with such deficiencies have less resistance against diarrhoea and respiratory problems.

A trial participant hungrily tucks into a bowl of mashed orange-fleshed sweet potato.

Dietary sources of vitamin A are preformed vitamin A, commonly found in foods of animal origin; and beta-carotene, from dark, green, leafy vegetables and yellow-and orange-fleshed fruits and vegetables.

Small wonder, then, that under the International Potato Center's Vitamin A for Africa Initiative, nutritionists and agriculturists have been promoting the production and consumption of orange-fleshed sweet potatoes to alleviate vitamin A deficiency among children in sub-Saharan Africa.

Local community members help with the mixing
and dishing up of the orange-fleshed sweet potatoes

The NIRU scientists have been the first to investigate quantitatively the benefits of the orange-fleshed sweet potato. The project, led by Dr Paul van Jaarsveld, studied two groups of 5-10-year-old children in rural KwaZulu-Natal over a period of 53 school days.

The scientists first did a baseline survey to determining the children's vitamin A status. On school days, the test group received a 125 g portion of boiled, mashed orange-fleshed sweet potato ( Resisto variety). The control group received a similar portion of boiled, mashed white-fleshed sweet potato ( Bosbok variety). In subsequent blood tests, the scientists found that the vitamin A status of the test group improved significantly, compared to the control group. The orange-fleshed sweet potato provided two-and-a-half times the recommended dietary allowance of vitamin A for 4-8-year-olds.

One problem that the scientists have encountered is that the plant material is not commercially obtainable. To solve this, they have started a community-based nursery in Ndunakazi. When the planting season starts this year in September, the nursery will be able to provide approximately six thousand runners per month to the Ndunakazi community and other food-based projects, so they can plant the sweet potato in their respective communities.

NGOs have expressed interest in the project. Faber says that this illustrates the difference between "old-style" scientific research and public health research. "Scientists don't descend on a community, do their research and vanish anymore. We stay involved in the community - working on problems as they arise. I find that immensely satisfying."