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Vitamin A is an essential nutrient that plays a role in many bodily functions. The fat-soluble vitamin is important for our vision, skin, immune system and more. Also known as retinol, vitamin A is a powerful antioxidant that's found naturally in many foods, added to food products, and available as a dietary supplement.
In the ABCs of vitamins, it's one of the most important — but too much vitamin A can also cause problems, which is why it's important to know if you actually need a supplement. Vitamin A is a fat-soluble vitamin, which means it dissolves in fats and gets stored in the body, primarily in the liver, , integrative medicine expert at Weill Cornell Medicine and NewYork-Presbyterian, tells TODAY.com.
Excess vitamin A builds up in the body, unlike water-soluble vitamins, which are excreted in urine. There are two main forms of vitamin A, which we obtain through our diet, according to the . Preformed vitamin A is the active, ready-to-use form, says Mulvihill.
This is found in animal-based foods, including fish, organ meats, and dairy products, per the NIH. Provitamin A carotenoids are plant pigments, which get converted to vitamin A in the body. These "precursors" to vitamin A, such as beta-carotene, are found in fruits, vegetables and other plants, says Mulvihill.
What does vitamin A do, and who should be taking a supplement? Experts break down the benefits and risks: Vitamin A plays many important roles in the body, Beth Czerwony, a registered dietitian at the Cleveland Clinic Center for Human Nutrition, tells TODAY.com. Vitamin A helps support: Vitamin A is crucial for healthy eyes.
It's needed for good vision, particularly at nighttime, because it allows the eye see the full spectrum of light, per . Retinol also supports skin health. The antioxidant helps maintain the integrity of epithelial tissue, or the layer of cells covering all external and internal surfaces of the body, says Mulvihill.
This includes the skin, gastrointestinal tract and respiratory tract. Vitamin A plays an important role in immune function, the experts note. "It seems to be related to the part of the immune system which acts as the first defense against invaders .
.. which you come into contact with through the epithelial linings," says Mulvihill.
It supports cell growth, the formation of bones, and aids in tissue repair and wound healing, Czerwony says. Vitamin A also plays a role in reproductive health by helping with the formation of sperm, Mulvihill adds. It also supports fetal development (in appropriate doses).
The amount of vitamin A you need per day varies by age, sex and health status. The recommended daily intake of both forms of vitamin A is measured in micrograms of (RAE), per the NIH: Preformed vitamin A is more potent, says Mulvihill, so you need less of it than provitamin A to meet the same daily intake. Most healthy children and adults get the recommended amount of vitamin A from their diet by eating a variety plant- and animal-based foods, as well as fortified dairy and grains, says Czerwony.
Inadequate vitamin A intake doesn’t always lead to a deficiency, Czerwony says, because the body stores vitamin A to use when we don’t get enough from food. Healthy adults may store vitamin A in their liver for a year or longer, Mulvihill adds. Over time, not getting enough vitamin A can lead to various health problems, including night blindness, dry eyes and rashes, says Mulvihill.
It can also cause heart and lung issues or increase a person’s susceptibility to infections, . Vitamin A supplements may be helpful for people who have or are at risk of a vitamin A deficiency. A deficiency may occur if a person does not get enough vitamin A from their diet or has an underlying condition which causes low vitamin A levels.
In the United States, vitamin A deficiencies are very rare, says Mulvihill, but they are a serious public health problem in countries where malnutrition is widespread. In the U.S.
, vitamin A deficiencies typically occur due to health conditions that impair the body's ability to absorb or store vitamin A, says Czerwony. These include celiac disease, cystic fibrosis, inflammatory bowel disease, as well as bariatric surgery. Always talk to your doctor before starting a vitamin A supplement, the experts emphasize.
If you're healthy and do not have a deficiency, taking extra vitamin A via supplements will not have additional benefits — in fact, excessive consumption can be harmful, says Czerwony. Vitamin A supplements have potential risks. "We have to be way more careful with fat soluble vitamins," says Mulvihill.
Excess vitamin A can build up to abnormally high levels in the body, aka hypervitaminosis. "The upper limit for adults is 10,000 international units (about 3,000 micrograms) per day," says Czerwony. Exceeding the upper limit over time can lead to toxicity — but even one big dose can be dangerous.
A vitamin A overdose typically occurs with doses of 200,000 mcg or higher, . This can quickly cause vitamin A poisoning, says Mulvihill. Symptoms of acute vitamin A poisoning include: Over time, taking more than 3,000 micrograms of vitamin A per day may lead to a toxicity.
Symptoms of chronic vitamin A toxicity include: In severe cases, vitamin A toxicity can lead to liver and kidney damage, low bone density or organ failure. "These may persist even after discontinuing vitamin A," says Czerwony. It's important to get routine blood tests to check your levels of vitamin A, and liver and kidney function, when taking supplements, says Mulvihill.
Some people should avoid vitamin A supplements due to the potential health risks. These include, but are not limited to: Excessive vitamin A during pregnancy can cause congenital birth defects, says Mulvihill, and research shows higher doses of vitamin A may have a carcinogenic effect in smokers. Vitamin A has made recent headlines as some tout the supplements as an unproven remedy for measles, which is spreading rapidly in Texas and nearby states.
U.S. Health and Human Services Secretary , and vitamin A-rich , to prevent and treat measles.
Covenant Children’s Hospital in Lubbock, Texas, has already treated multiple children for measles and vitamin A toxicity, some of whom reported taking vitamin A to treat and prevent measles, a spokesperson told TODAY.com in a statement. There is no evidence that vitamin A prevents measles, .
with two doses of the measles vaccine, which are 97% effective. In a recent health alert, the warned that vitamin A is “not a substitute for vaccination." Vitamin A won't "cure" measles either.
There is no specific treatment for measles, . A vitamin A deficiency can increase the chance of developing severe measles if you’re already infected, so supplements are sometimes given to measles patients in low-income countries where vitamin deficiencies are common (unlike in the U.S.
). Vitamin A may be given as supportive care to children who are hospitalized with severe measles, but only under the supervision of a healthcare provider, according to the . The appropriate dosage for vitamin A supplements varies by person.
Always talk to your doctor to determine the right dose for you. Vitamin A supplements may contain preformed vitamin A, the precursors (beta-carotene), or a combination, . Doses of vitamin A in supplements varies greatly, often ranging from 1,000–3,000 micrograms (333% of the daily value).
Most multivitamins contain vitamin A, but often lower amounts, per the NIH. "They contain about 50-100% of the recommended daily value, so more reasonable," Mulvihill adds. “I would not recommend taking more than 100% of the daily value,” Mulvihill adds.
The U.S. Food and Drug Administration does not approve the safety, effectiveness or labeling of supplements.
Always buy vitamins from reputable sources that are third-party tested, the experts note. You can take vitamin A supplements at any time of day, says Czerwony. However, it’s important to consider when you take other medications.
Vitamin A may interact with blood thinners and retinoids, for example, says Czerwrony. Always check with your doctor for possible drug interactions. It's best to take vitamin A with food, especially containing fats, the experts say.
"Like most fat-soluble vitamins, it helps the body to absorb it," says Mulvihill. Consider eating healthy plant-based fats like avocado, nuts or olive oil. If you're looking to up your intake, the experts recommend eating vitamin A-rich foods first.
Vitamin A is found naturally in foods and added to food products, including: “A varied diet is a natural multivitamin, and it’s not dangerous because food sources are safer than concentrated supplements,” says Mulvihill. Caroline Kee is a health reporter at TODAY based in New York City. She covers a range of medical news, consumer health, and wellness topics.
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