Vitamin A is actually a group of natural compounds that your body needs for clear vision, healthy bones and skin, normal cell division and differentiation, and reproduction. Vitamin A also helps your body’s immune system fight off infections.
The form of vitamin A found in foods of animal origin is called retinol, or pre-formed vitamin A. It’s the most active form of vitamin A, and your body can convert it into retinal or retinoic acid, two additional active forms of vitamin A, if needed. Sources of retinol include dairy products, eggs, liver and fortified foods.
The forms of vitamin A found in plants are called provitamin A carotenoids. The best known carotenoids are beta-carotene, alpha-carotene and beta-cryptoxanthin. Your body converts these carotenoids to retinol, and they are also thought to be antioxidants that may protect your body from free-radical damage. The best sources of carotenoids are brightly colored and dark green vegetables including carrots, spinach, and kale, and fruits like apricots, papaya and mango.
Because vitamin A is an important component for normal vision, vitamin A deficiency will cause night-blindness, or a decreased ability to see in dim light. Another symptom of vitamin A deficiency is diminished immune system function, which means your body will have difficulty fighting infections.
Vitamin A deficiency due to poor diet is rare in developed countries and is more likely to result from inflammatory diseases that damage the digestive tract and prevent absorption of vitamin A, such as Crohn’s disease and celiac disease. Alcoholism, zinc deficiency and pancreatic diseases can also affect the amount of vitamin A in the body.#