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Vitamin A Facts: Everything You Need to Know

Medically Reviewed by Dr Samantha Miller, MBChB

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Vitamin A should be an integral part of every person's diet. It plays vital roles in your body by helping to maintain your vision, skin health and even your immune system's ability to work properly. But it's important to consume the right amount; vitamin A can be harmful when your body gets too much of it. Learn more about vitamin A, including what it does, where to find it and what happens when you get too much of it.

What Does Vitamin A Do?

Vitamin A is actually a group of fat-soluble vitamins like retinol, retinal and retinyl esters, all of which have various health benefits. Vitamin A is particularly important in the maintenance of vision — especially your ability to see in low light. Your body converts this vitamin to retinal, which combines with other molecules to form rhodopsin. This is the protein principally responsible for your eyes' absorption of light. If you're worried about your vision getting worse over time, make sure you get enough vitamin A. It's a good way to strengthen your sight naturally.

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Consuming sufficient amounts of vitamin A can also work wonders for your immune system. Vitamin A promotes the production of white blood cells, particularly T cells, which eliminate viruses and bacteria from your body. Vitamin A also stimulates the production of special T cells called regulatory T cells. These help to reduce the risk of your body attacking its own healthy cells, which is what happens with some autoimmune diseases. Furthermore, vitamin A fortifies the linings of your respiratory, intestinal and urinary tracts, along with your skin and mucous membranes. It also sends additional immune cells there to prevent bacteria from entering your body and causing an infection.

Vitamin A is also involved in the maintenance of healthy skin by helping immature skin cells age properly into mature skin cells. It reduces sebum production, which can be problematic in oily skin. In fact, Isotretinoin is a common prescription-only vitamin A derivative used as a treatment for acne.

Vitamin A can also contribute to improved bone growth, cell division and cell differentiation. It even promotes reproduction and is a healthy supplement for people who are breastfeeding.

Food Sources of Vitamin A

Vitamin A is quite easy to come by naturally. Many of the most basic staples in our diets — meat, eggs, milk and cheese, for example — are excellent sources of vitamin A. Other specific animal sources have high vitamin A levels as well, such as kidney and liver. However, it's important to note that some of these foods have high cholesterol and saturated fat levels, so be sure to keep a healthy balance of these in your diet if you choose to eat them.

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Vitamin A exists as either preformed vitamin A or as provitamin A carotenoids. Preformed vitamin A is found in animal and dairy sources. Provitamin A carotenoids include beta-carotene and alpha-carotene, which your body converts into vitamin A and other derivatives. Beta-carotene is found in foods like carrots, pumpkins, sweet potatoes, cantaloupes, grapefruits, spinach, broccoli and apricots. As a general rule, the more vibrant the color of a fruit or vegetable is, the more beta-carotene it contains. As a bonus, you won't have to worry about the fat or cholesterol content in these foods.

Side Effects of Too Much Vitamin A

Getting the right amount of vitamin A in your diet shouldn't have any negative side effects. However, a vitamin A deficiency can lead to health issues over time. If you don't get enough vitamin A, you could develop vision problems. Plus, your immune system could weaken, leaving you susceptible to infectious diseases.

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Perhaps even more serious are the side effects of consuming too much vitamin A, also known as hypervitaminosis A. Initially, too much vitamin A can cause headaches, dizziness, nausea and even vomiting. Because vitamin A is fat-soluble, it tends to get stored in your liver if you consume too much of it, which can lead to liver problems and even liver failure. There's also evidence that getting excess vitamin A can cause osteoporosis and bone fractures.

In particular, pregnant people must be careful about their intake of vitamin A, as getting too much vitamin A can cause birth defects. Pregnant people shouldn't eat foods that are high in vitamin A, such as pate and fish liver oil. In general, babies and small children are more sensitive to vitamin A overdoses and deficiencies, so it's important to closely monitor their daily vitamin A consumption, too.

Taking Vitamin A: Daily Dosage Recommendations

According to the Institute of Medicine Food and Nutrition Board, most adult men should consume around 900 micrograms (mcg) of vitamin A per day, and women should have around 700mcg per day. The recommended daily intake is lower (750–770mcg per day) in pregnant people and higher (1200–1300mcg per day) for people who are breastfeeding.

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The daily dosage for children varies with age. From 0 to 6 months, infants should have 400mcg per day, after which they should consume 500mcg per day until they reach the age of 1. Children 1 to 3 years of age should get 300mcg per day, while those from 4 to 8 years of age need 400mcg per day. Those from 9 to 13 years old need 600mcg each day. Daily recommendations for children don't change based on gender.

These dosage requirements are general guidelines. Individuals may have differing daily recommendations for vitamin A, depending on their health status and lifestyle. Most people can get a sufficient amount of vitamin A simply by eating a balanced diet. Consult a doctor before taking any vitamin A supplements or changing from the recommended dosage for your age and sex.

In summary, it's important to be aware of the foods that'll give you an adequate supply of vitamin A. Provided you have a balanced diet, you might not need to take vitamin A supplements. Be aware of foods containing high levels of vitamin A, and avoid eating too much of these, particularly during pregnancy.

Resource Links:

https://medlineplus.gov/vitamina.html

https://bnf.nice.org.uk/treatment-summary/vitamins.html

https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-a/

https://ods.od.nih.gov/factsheets/VitaminA-Consumer/

https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6470929/pdf/nutrients-11-00681.pdf

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