Up to 250,000 children around the world die each year from the lack of a simple vitamin, according to the World Health Organization. Vitamin A is essential for the body to fight life-threatening infections. It's also important for vision - and the lack of it leaves more children blind than any other preventable cause. Vitamin A deficiency is especially common among the poor - who cannot afford to eat many fruits, vegetables and other vitamin-rich foods. So, as VOA’s Steve Baragona reports, researchers are working to make the staple foods they can afford more nutritious.