Biofortified Sweet Potato and Maize.

The enhancement of sweet potato and maize with provitamin A carotenoids was part of HarvestPlus’s research continuum since the formation of the biofortification project. The first efficacy study with high beta-carotene sweet potato was performed in South African schoolchildren. The study demonstrated improvement in liver stores of the children eating the orange-fleshed sweet potato compared with a white sweet potato control group. High beta-carotene varieties of sweet potato were introduced into Mozambique and an effectiveness study showed promise to improve vitamin A status, followed by dissemination efforts in Uganda. A randomized, controlled effectiveness trial tested extension models to promote sweet potato and assessed vitamin A intake among Ugandans. Concurrently, in vitro and animal studies were performed with sweet potato to guide breeding efforts. Orange maize breeding was initialing a challenge, but considering that the carotenoid biosynthetic pathway was in maize germplasm, breeders were quickly able to breed higher amounts of provitamin A carotenoids into the maize that was ultimately released in Zambia. Prior to human consumption and market release, a series of studies were done in in vitro and animal models to test bioaccessibility, bioavailability, and bioefficacy. These studies were followed by efficacy studies in Zambia. The first efficacy study with mid-provitamin A target levels did not maintain vitamin A status in preschool children who had received a high-dose supplement before the intervention. This was followed by two efficacy studies in older preschool children. One study showed improvement in total body stores of vitamin A and the other showed improvement in serum beta-carotene concentrations. Initial resistance occurred in communities because orange maize was associated with yellow maize, which had negative connotations due to food-aid and animal feed, and consumers preferred white. Currently, both orange crops are available on the market in a variety of African countries.