It also helps maintain the health of the skin and mucous membranes – the body’s barriers against harmful agents in the external environment. It enhances the immune system by boosting cells that fight infection and tumors.
It is available in two principal forms in foods – retinol from animal sources – cod liver oil, liver, fish oils, egg, butter and whole milk – and carotenes from vegetable sources. Yellow and orange vegetables such as sweet potato, pumpkin and carrot contain significant quantities of carotenoids. Green vegetables such as spinach, broccoli and kale also contain carotenoids, though the yellow/orange pigment is masked by the green pigment of chlorophyll.
Deficiency can cause night blindness, dry skin, ear infections.