Orange sweet potato is now an important crop for two-thirds of those in the trial

Flickr/Anna Fischer

[CAPE TOWN] Orange sweet potato that has been bred to contain more of a precursor of vitamin A has successfully passed a crucial test of its practical use.

Scientists have been working on the sweet potato for years, in the hope of battling deficiencies in vitamin A that afflict around 200 million of the world's poor.

A programme aiming to persuade Mozamibican villagers to switch from eating white and yellow sweet potato to the biofortified orange version has proved successful, with two-thirds of the targeted households adopting the new variety. 

Researchers distributed the sweet potato to more than 10,000 households in Zambezia Province in Mozambique, where people eat roots and tubers as well as maize.

Mozambique, like many poor countries, has a high prevalence of vitamin A deficiency, which can erode the immune system and cause blindness. Pregnant woman and young children in low-income countries are often hit the hardest, according to the WHO, and 600,000 children are estimated to die from a lack of vitamin A each year.

The biofortified sweet potato was created using conventional techniques. One fear, when new food varieties are created by outsiders, is whether local people will want to adopt them. For three years, researchers used agricultural extension methods and market development activities, combined with 'demand creation' and nutrition education, to introduce six varieties to the province.

The study, published in the British Journal of Nutrition last month (10 October) showed that the varieties were welcomed, and the researchers deduced that average vitamin A intake doubled in children and women in the trial.

The study did not assess whether eating orange sweet potato caused levels of vitamin A to rise in the blood, though a previous, much smaller study in the same area had demonstrated this connection.

"There has been a growing body of evidence to show that betacarotene [a precursor of vitamin A] in orange sweet potato is bioavailable and converted to vitamin A in the body," Christine Hotz, former coordinator of HarvestPlus Nutrition, which led the research, told SciDev.Net.

As a result of the project many farmers have replaced the sweet potato that they produce on their farms, say the researchers.

Maria Andrade, sweet potato breeder and seed specialist with International Potato Center in Peru, said the sweet potato was good for food security.

“The orange fleshed sweet potato is safe," Andrade told SciDev.Net.  “It is a natural product.”

HarvestPlus said that new, more drought-tolerant, orange-fleshed sweet potato varieties will be distributed to 120,000 households over the next two years.

This article was updated 29 November 2011 to clarify a finding of the study; and on 2 December 2011 to correct an error in the scientific paper.

Link to full paper in British Journal of Nutrition