Natural sweet potatoes has been shown to provide needed vitamin A. However, some children will prefer to eat rice and some may not have access to the sweet potatoes.
More controversial than the naturally bred sweet potatoes is Golden Rice - genetically engineered to contain 30 micrograms of beta-carotene per gram. Ordinary rice has none.
Critics had claimed that the rice is impractical. According to calculations by Greenpeace, people would need to eat huge amounts - as much as 18 kilograms of cooked rice a day - to obtain enough vitamin A, but they are wrong by over 100 times.
A study involving 68 Chinese children demolishes the criticism. Guangwen Tang of Tufts University in Boston, Massachusetts, and colleagues have demonstrated that just 100 to 150 grams of the rice - about half the children's daily intake - provided 60 per cent of the recommended daily intake of vitamin A.
American Journal of Clinical Nutrition - β-Carotene in Golden Rice is as good as β-carotene in oil at providing vitamin A to children
An editorial in the New Scientist makes the case that Greenpeace needs to drop opposition to using genetically modified rice to prevent blindness and vitamin A deficiency.
Sweet Potato (non-GM) works as well
Introduction of β-Carotene–Rich Orange Sweet Potato in Rural Uganda Results in Increased Vitamin A Intakes among Children and Women and Improved Vitamin A Status among Children
A two-year project involving 10,000 households in Uganda found that vitamin A intake doubled in women and in children aged 6 to 35 months who ate the improved sweet potatoes compared with families that continued eating regular varieties. By the end of the project almost 90 per cent of the kids eating the new strain had escaped vitamin A deficiency, compared with just 50 per cent in a control group.