The result was "Golden Rice", a variety of Oryza sativa rice produced through genetic engineering to biosynthesize beta-carotene, a precursor of retinol, in the edible parts of rice. In May 2018, regulatory agencies in the United States, Canada, Australia and New Zealand had concluded that Golden Rice met food safety standards. On 21 July 2021, the Philippines became the first country to officially issue the biosafety permit for commercially propagating Golden Rice. Researchers at the U.S. Agricultural Research Service have been able to identify genetic sequences in corn that are associated with higher levels of beta-carotene, the precursor to vitamin A. They found that breeders can cross certain variations of corn to produce a crop with an 18-fold increase in beta-carotene. Dietary diversification can also reduce risk of VAD. Non-animal sources of vitamin A like fruits and vegetables contain preformed vitamin A and account for greater than 80% of intake for most individuals in the developing world. The increase in consumption of vitamin A-rich foods of animal origin has beneficial effects on VAD. Global initiatives
Global efforts to support national governments in addressing VAD are led by the Global Alliance for Vitamin A (GAVA), which is an informal partnership between Nutrition International, Helen Keller International, UNICEF, WHO, and CDC. About 75% of the vitamin A required for supplementation of preschool-aged children in low- and middle-income countries is supplied through a partnership between Nutrition International and UNICEF, with support from Global Affairs Canada.
Night blindness
Night blindness is the difficulty for the eyes to adjust to dim light. Affected individuals have poor vision in the darkness but see normally when adequate light is present. A process called dark adaptation typically causes an increase in photopigment amounts in response to low levels of illumination. This occurs to an enormous magnitude, increasing light sensitivity by up to 100,000 times its sensitivity in normal daylight conditions. VAD affects vision by inhibiting the production of rhodopsin, the photopigment responsible for sensing low-light situations. Rhodopsin is found in the retina and is composed of retinal (an active form of vitamin A) and opsin (a protein). When VAD prevents the body from producing sufficient amounts of retinal, a decreased amount of rhodopsin is produced and night blindness results. Night blindness caused by VAD has been associated with the loss of goblet cells in the conjunctiva, a membrane covering the outer surface of the eye. Goblet cells are responsible for secretion of mucus, and their absence results in xerophthalmia, a condition where the eyes fail to produce tears. Dead epithelial and microbial cells accumulate on the conjunctiva and form debris that can lead to infection and possibly blindness.Decreasing night blindness requires the improvement of vitamin A status in at-risk populations. Supplements and fortification of food have been shown to be effective interventions. Supplement treatment for night blindness includes massive doses of vitamin A (200,000 IU) in the form of retinyl palmitate to be taken by mouth, which is administered two to four times a year.