The carotenoids are a family of yellow-orange pigments that have an antioxidant role.
Lutein and zeaxanthin are carotenoids pigments in the crystalline lens and the retina that absorb UV rays and act as a filter for the retina cells. In humans, the risk of cataracts is inversely proportional to the quantity of lutein ingested. Supplementation is also recommended in people suffering from retina degeneration (macula degeneration). Lutein specifically protects the rod cells, while zeaxanthin protects the retinal cones.
Cats are carnivores, so their health depends on the regular intake of animal nutrients. Contrary to dogs, cats do not convert beta-carotene from vegetable sources into vitamin A.
Carotenoids are natural antioxidants that stimulate the immune system. In bitches, beta-carotene promotes the synthesis of progesterone and oestrogen hormones involved in behavioural changes during oestrous and in preparing the uterus for possible gestation. Through these hormones, beta-carotene in food provides a favourable environment for the development and growth of the embryo. There is a synergy between the various carotenoid pigments: lutein permits the regeneration of zeaxanthin, which regenerates the beta-carotene, which in turn regenerates the lycopene.
Carotenoids are generally found in fruit and vegetables, like carrots (beta-carotene), tomatoes (lycopene), oranges, marigold, pumpkins and maize gluten (lutein and zeaxanthin).