The most reliable way to ensure you are getting enough vitamin A is through food. According to the Office of Dietary Supplements (ODS), the most common sources of vitamin A-rich foods are liver, fish, fortified cereals, and dairy products. Fruits and vegetables such as carrots, broccoli, and squash contain provitamin A. The body stores most of its vitamin A in the liver in the form of retinyl esters.
The maximum daily limits for preformed vitamin A include intake from all sources (foods, beverages, and supplements). Vitamin A is essential for eye health, vision, immune function, cell growth, reproduction, and fetal development. It is also used as a treatment for measles and dry eye in people with low levels of vitamin A. Preformed vitamin A is found in animal foods such as liver, salmon, and egg yolks.
Provitamin A carotenoids are found in plant foods such as sweet potatoes, kale, and carrots. The American Heart Association suggests that people should obtain antioxidants like beta-carotene by following a balanced diet high in fruits, vegetables, and whole grains instead of taking supplements until more is known about the risks and benefits of supplementation. The total vitamin A content of a food is usually expressed in micrograms (µg) of retinol equivalents (RE). Vitamin A also helps maintain surface tissues such as the skin, intestines, lungs, bladder, and inner ear.
Preformed vitamin A is more easily absorbed and used by the body than plant-based sources of provitamin A. Consuming too much preformed vitamin A (usually through supplements or certain medications) can cause severe headaches, blurred vision, nausea, dizziness, muscle aches, and coordination problems. Therefore, pregnant women should avoid eating liver or liver-derived products like pâté since they are high in vitamin A. You can also get vitamin A if you include good sources of beta-carotene in your diet since the body can convert it to retinol.
In some cases, fortified foods and dietary supplements are useful when it is not possible to meet the needs of one or more nutrients (for example during pregnancy). Vitamin A has a positive effect on health by controlling oxidative stress, boosting the immune system and protecting against certain diseases. Plant sources of vitamin A (from beta-carotene) include sweet potatoes, carrots, spinach, and apricots. Vitamin A toxicity can have negative effects including liver damage, vision disorders, nausea and even death.
Vitamin A affects immune health by stimulating responses that protect the body from diseases and infections.
