|Vitamin A occurs in nature in two forms: preformed vitamin A and provitamin A, or carotene. Sources of vitamin A can be divided into two groups: one is animal source, and the other is vegetable source. Vitamin A is better absorbed from an animal source,
but when it is not always possible to afford animal foods, vitamin A derived from vegetable sources are also important. While preformed vitamin A is fat-soluable and stored by the body, carotene is water-soluable and is not stored by the body. Any excess unabsorbed carotene is excreted in the feces. This makes carotene extremely safe and there should be little concern about taking supplements of it. Provitamin A carotenoids are abundant in darkly colored fruits and vegetables. Most fat free milk and dried nonfat milk solids are fortified with vitamin A to replace the vitamin A lost when the fat is removed.
Vitamin A comes from animal sources such as eggs and meat. Vitamin A, in the form of retinyl palmitate, is found in beef, calf, chicken liver; eggs, and fish liver oils as well as dairy products including whole milk, whole milk yogurt, whole milk cottage cheese, butter, and cheese. Vitamin A comes from animal sources, such as eggs, meat, milk, cheese, cream, liver, kidney, cod and halibut fish oil. However, all of these sources - except for skim milk that has been fortified with Vitamin A --are high in saturated fat and cholesterol. Preformed vitamin A is found only in animal products, one of the richest sources being fish-liver oil, and is readily destroyed with exposure to light, heat, and air.
The vegetable sources of beta-carotene are fat and cholesterol free. The body regulates the conversion of beta-carotene to vitamin A, based on the body's needs. Sources of beta-carotene are carrots, pumpkin, sweet potatoes, winter squashes, cantaloupe, pink grapefruit, apricots, broccoli, spinach, and most dark green, leafy vegetables. The more intense the color of a fruit or vegetable, the higher the beta-carotene content. Beta-carotene is a precursor for vitamin A. The body needs to convert it to retinol or vitamin A for use. Beta-carotene is found naturally in plant foods, mostly orange and dark green ones, such as carrots, sweet potatoes, mangos and kale. Carotene is found only in fruits and vegetables, and must be converted to vitamin A so the body can use it. Carotene is found abundantly in carrots, but is found in higher amounts in green leafy vegetables such as beet greens, spinach, and broccoli. These vegetable sources of beta-carotene are free of fat and cholesterol. Margarine is rich in beta-carotene, because this chemical is used as a coloring agent in margarine production.