Vitamin A is a fat-soluble vitamin that includes a family of compounds known as retinals and retinols. Provitamin A, or carotenoids like beta-carotene, are also considered vitamin A as the compounds can be converted to retinol by the body. Vitamin A is necessary for normal vision, gene expression, reproduction, embryonic development, the immune system and proper red blood cell formation.
Recommendation Determinants
The recommended daily allowance for vitamin A is based on the amount needed for a healthy person to ensure adequate stores to support normal vision, immune function, and healthy reproductive function, according to the Linus Pau`ling Institute. The Institute of Medicine has set the recommended daily allowance for vitamin A in retinol activity equivalents (RAE) based on gender and age.
Recommended Dietary Allowance
Males 14 years and older require 900 mcg per day. Females 14 years and older need 700 mcg per day, unless pregnant or breastfeeding. Pregnant females need 750 mcg per day if she is 18 years old and under and 770 mcg per day if 19 years old and older. Breastfeeding mothers need 1,200 mcg per day if 18 years or younger and 1,300 mcg per day 19 years and older.
Food Sources
Vitamin A and its precursors are available in a variety of foods. Eggs, orange and yellow vegetables such as sweet potatoes and pumpkin, green leafy vegetables like spinach and kale, and cod liver oil all contain vitamin A or carotene. Vitamin A is also added to some breakfast cereal and milk, but be sure to check labels. A half cup serving of baked sweet potato or canned pumpkin provides over 900 mcg of retinol activity equivalents. An 8 oz. glass of low-fat or fat-free milk provides about 140 mcg.
Considerations
High storage levels of vitamin A, known as hypervitaminosis A, can lead to adverse effects. This is most often due to taking high doses of dietary supplements. Long term issues include reduced bone mineral density, birth defects, liver abnormalities and problems with the central nervous system. Short term symptoms of high levels include dizziness, headaches, nausea and vomiting, blurred vision and muscle problems. Upper tolerable limits are between 2,800 mcg to 3,000 mcg, depending on age.
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