There are two types of vitamin A that are found in the diet.
Preformed vitamin A is found in animal products such as meat, fish, poultry, and dairy foods.
Precursors to vitamin A, also known as provitamin A, are found in plant-based foods such as fruits and vegetables. The most common type of pro-vitamin A is beta-carotene.
Vitamin A is also available in dietary supplements. It most often comes in the form of retinyl acetate or retinyl palmitate (preformed vitamin A), beta-carotene (provitamin A) or a combination of preformed and provitamin A.
Function
Vitamin A helps form and maintain healthy teeth, skeletal and soft tissue, mucus membranes, and skin. It is also known as retinol because it produces the pigments in the retina of the eye.
Vitamin A promotes good eyesight, especially in low light. It also has a role in healthy pregnancy and breastfeeding.:
Vitamin A is found in two forms in food:
Retinol: Preformed retinol is an active form of vitamin A. It is found in animal liver, whole milk, and some fortified foods.
Provitamin A carotenoids: Carotenoids are plant pigments (dyes). Once ingested, the body converts these compounds into vitamin A. There are more than 500 known carotenoids. One such carotenoid is beta-carotene.
Beta-carotene is an antioxidant. Antioxidants protect cells from damage caused by substances called free radicals.
Free radicals are believed to:
Contribute to certain long-term diseases
Play a role in aging
Eating food sources of beta-carotene may reduce the risk for cancer.
Beta-carotene supplements do not seem to reduce cancer risk.
Food Sources
Vitamin A is found in both plant and animal foods.
Foods with the highest levels of vitamin A include:
Beef liver and other organ meats (these are high in saturated fat and cholesterol, so limit the amount you eat)
Some types of fish such as herring and salmon and cod fish oil
Eggs
Dairy products such as cheese and fortified milk (choose non-fat and low-fat dairy options)
Fortified breakfast cereals
Orange and yellow vegetables and fruits, such as carrots, sweet potatoes, mangos, and cantaloupe
Broccoli, spinach, and most dark green, leafy vegetables
The deeper or brighter the color of a fruit or vegetable, the higher the amount of carotenoids. Vegetable sources of beta-carotene are fat- and cholesterol-free. Their absorption is improved if these sources are eaten with a small amount of fat.