The World Health Organization recommends a daily intake of 45 milligrams (mg)/day of vitamin C for healthy adults, and 25–30 mg/day in infants.[5] Vitamin C is necessary for production of collagen and other biomolecules, and for the prevention of scurvy.[6] Vitamin C is an antioxidant, which has led to its endorsement by some researchers as a complementary therapy for improving quality of life.[7] Since the 1930s, when it first became available in pure form, some physicians have experimented with higher than recommended vitamin C consumption or injection.[8] Certain animal species, including haplorhine primates (which includes humans),[9][10] members of the Caviidae family of rodents (including guinea pigs and capybaras),[11] most species of bats,[12] many passerine birds,[13] and about 96% of fish (the teleosts),[13] do not synthesize vitamin C internally.