Research overview: vitamin A and the inability to convert plant carotenoids

Cats cannot make vitamin A from the plant pigment beta-carotene the way many animals do, and this overview reviews this dependence on preformed vitamin A. Lacking sufficient enzyme activity to convert carotenoids, cats must obtain active vitamin A directly from animal tissues such as liver, another nutrient they get only from a carnivorous diet. Both deficiency and excess of vitamin A cause health problems. Researchers established the requirement through nutritional biochemistry. Why it matters: the vitamin A case adds to the pattern of feline nutrients that must come preformed from prey, reinforcing why cats are obligate carnivores at the biochemical level. It shows how losing a metabolic pathway, harmless on a meat diet that always supplies the end product, leaves cats unable to thrive on plant sources that suffice for omnivores.