carotenoids than golden rice (up to 37 µg/g) because psy gene of maize is the most effective gene for carotenoid synthesis, and preferentially accumulates beta-carotene (up to 31 µg/g of the 37 µg/g of carotenoids). Vitamin A deficiency The research that led to Golden Rice was conducted with the goal of helping children who suffer from vitamin A deficiency (VAD). Estimates show that around 1.02 billion people are severely affected by micronutrient deficiencies globally, with vitamin A to be the most deficient nutrient in the body. In 2012, the World Health Organization reported that about 250 million preschool children are affected by VAD, and that providing those children with vitamin A could prevent about a third of all under-five deaths, which amounts to up to 2.7 million children that could be saved from dying unnecessarily. The World Health Organization has classified vitamin A deficiency as a public health problem affecting about one third of children aged 6 to 59 months in 2013, with the highest rates in sub-Saharan Africa (48 per cent) and South Asia (44 per cent). VAS programs began in the 1990s in response to evidence demonstrating the association between VAD and increased childhood mortality. Between 1990 and 2013, more than 40 efficacy studies of VAS in children 6–59 months of age were conducted, and two systematic reviews and meta-analyses have concluded that VA supplements can considerably reduce mortality and morbidity during childhood. As of 2017, more than 80 countries worldwide are implementing universal VA supplementation (VAS) programs targeted to children 6–59 months of age through semi-annual national campaigns. Periodic, high-dose vitamin A supplementation is a proven, low-cost intervention which has been shown to reduce all-cause mortality by 12 to 24 per cent, and is therefore an important program in support of efforts to reduce child mortality. However, UNICEF and a number of NGOs involved in supplementation note more frequent low-dose supplementation is preferable. As many children in VAD-affected countries rely on rice as a staple food, genetic modification to make rice produce the vitamin A precursor beta-carotene was seen as a simple and less expensive alternative to ongoing vitamin supplements or an increase in the consumption of green vegetables or animal products. Initial analyses of the potential nutritional benefits of golden rice suggested consumption of golden rice would not eliminate the problems of vitamin A deficiency, but could complement other supplementation. Golden Rice 2 contains sufficient provitamin