Research overview: the cat's need for preformed vitamin A

Unlike many mammals that can convert plant-derived beta-carotene into vitamin A, cats lack sufficient enzymatic capacity for this conversion and therefore require preformed vitamin A from animal sources in their diet. This requirement reflects their carnivorous evolution and influences cat-food formulation, while also creating a risk of toxicity from over-supplementation, as seen historically in cats fed excessive liver. This overview compiles the nutritional literature rather than one source, describing why cats cannot rely on carotenoids for vitamin A, the consequences of both deficiency and excess, and how diets balance this essential nutrient. It matters because the preformed vitamin A requirement is a classic example of feline nutritional specialization, illustrating both the dependence on animal-source nutrients and the need for careful balance to avoid the harms of deficiency or oversupply.