'Sight saving' sweet potatoes

South African researchers are developing nutrient-rich varieties of vegetables to stave off health problems related to vitamin A deficiency


Fortifying vegetables could help people in some of the world’s poorest regions to stave off blindness related to vitamin A deficiency (VAD), according to researchers in South Africa.

Researchers at the Agricultural Research Council in Pretoria are developing bio-fortified versions of sweet potato to combat VAD. A popular staple in the region, sweet potato contains high levels of beta-carotene, which gives the vegetable its characteristic orange colour, and which is converted by the body to vitamin A. The team tested 12 varieties of the vegetable to boost their nutrient value.

“We realised it would be great if we could develop a local variety [of sweet potato] which has good yield, high dry mass and desirable taste attributes, and promote it to combat vitamin A deficiency,” explained senior researcher, Dr Sunette Laurie.

Two of the varieties tested, Implio and Purple Sunset, were found to have good taste, good yield and acceptable dry mass. A 125g serving of the varieties provided 113% and 261% of a child’s vitamin A requirement, respectively. While a third variety, Bophelo, had a higher beta-carotene content and fared better in taste tests.

Food processing facilities are reported to have started using sweet potatoes to make flour and baked products. Dr Laurie said: “There are so many options and we are trying to get international development funds to set up more agro-processing units.”

She added: “We would like to have varieties with more tolerance to diseases, such as stem and leaf blight, and pests such as weevils. Ideally we would be able to develop a variety that resembles Bophelo with more resistance.”

According to the World Health Organization (WHO), VAD is an issue in more than half of countries worldwide, particularly in South-East Asia and Africa. Deficiency can result in a number of health problems, including reversible night blindness, or nyctalopia. Young children and pregnant women are most at risk and the WHO estimates that as many as 250 million school age children may be vitamin A deficient.

Bio-fortification is a process by which the nutrient value of crops is boosted through selective breeding or molecular techniques in the laboratory. The concept has been applied in the UK for decades to boost the nutritional value of breakfast cereals and spreads by adding vitamins and micronutrients.

The research is published in the journal Crop Science.