Vitamin A is a fat-soluble vitamin important to bone growth, vision, reproduction, cell differentiation and division, and immune system regulation. The vitamin also helps prevent infection by producing white blood cells and is important for healthy skin and mucous membranes, according to the Office of Dietary Supplements. The Daily Value (DV) for vitamin A is 5,000 IU, and deficiency in the United States is rare. Excessive intake can cause acute or chronic toxicity and lead to headaches, dizziness, fatigue, nausea, bone pain, blurry vision, or intrahepatic cholestasis, according to the National Institutes of Health (NIH).
Darkly colored fruits and vegetables are good sources of vitamin A. Just 1/2 cup of boiled carrots contains 270 percent of the DV of vitamin A, while eating one raw carrot provides about 175 percent. One cup of cubed cantaloupe provides approximately 110 percent, and 1/2 cup of boiled spinach provides an impressive 230 percent of the DV of the vitamin. Plant sources supply vitamin A in the form of provitamin A carotenoid, which includes alpha-carotene, beta-carotene and beta-cryptoxanthin. Beta-carotene is the form of vitamin A best made into retinol, according to the Office of Dietary Supplements, but vitamin A from plant sources is not as well absorbed as that from animal sources. The NIH states that eating five servings of fruits and vegetables per day contributes about 50 to 65 percent of the DV of the vitamin.
Many meats and animal products are abundant in vitamin A. From animal sources, vitamin A is supplied as preformed vitamin A and absorbed as retinol, according to the Office of Dietary Supplements. Cooked beef liver is very rich in vitamin A, with a 3-oz. serving providing about 545 percent of the DV. One cup of whole milk and 1/4 cup of egg substitute both provide 5 percent of the DV of vitamin A. Fat-free dairy products are not good natural sources of vitamin A but are recommended over whole milk for heart health. For this reason, fat-free milk products are now fortified to replace the vitamin A lost during the fat removal process. One cup of fortified skim milk supplies 10 percent of the DV of vitamin A and is considered an ideal source of the vitamin, as it is lower in saturated fat and cholesterol than other sources of the vitamin, according to the NIH.
In addition to fortified dairy products, many cereals and other foods are enriched with vitamin A to ensure the public meets the recommended daily intake of the vitamin. One cup of instant plain oatmeal provides 25 percent of the DV of vitamin A, and fortified, ready-to-eat cereals typically contain at least 25 percent of the recommended allowance of vitamin A, according to Ohio State University. Margarine is now fortified so that its vitamin A content is equal to that of butter.