Vitamin A: uses, benefits, how much to take
LAST UPDATED: Nov 04, 2021
4 MIN READ
HERE'S WHAT WE'LL COVER
You may have heard the old saying that eating carrots helps you see in the dark because of all the vitamin A they contain. While vitamin A can’t give you night vision, it does help protect your eyesight and prevent problems seeing in the dark, along with a whole host of other benefits. Keep reading to learn more about vitamin A and its role in the body.
What is vitamin A?
The nutrient vitamin A is one of the four fat-soluble vitamins, meaning it’s absorbed and stored with fat. The active form of vitamin A is found in animal products, while many plant foods contain related substances, called carotenoids, which turn into vitamin A in the body.
You might see vitamin A (or related compounds that turn into vitamin A in the body) called by different names, including (Chea, 2021):
What does vitamin A do?
Vitamin A has numerous functions in the body. It helps support cell growth, cell division, reproductive health, cell membrane health, immune health, and vision.
Another role of vitamin A comes from its antioxidant properties. Antioxidants are compounds that help protect cells from damage caused by oxidation from free radicals. Free radicals may come from pollution, tobacco smoke, and other harmful substances.
Research shows antioxidants help prevent cell damage, potentially lowering the risk of chronic diseases and cancer (Lobo, 2010).
Benefits of vitamin A
Research suggests vitamin A intake helps (Huang, 2018):
Protect eye health
Prevent night blindness and eye disease caused by retina and cornea damage
Support a healthy immune system
Promote healthy skin
Support healthy cell growth
Benefit reproductive health
Food sources of vitamin A
Vitamin A is found in many types of animal and plant foods, including:
Beef liver and organ meats
Green, leafy vegetables
Vitamin A supplements
For most people, the risk of vitamin A deficiency is low, and they won’t need to supplement with vitamin A since it’s found in a wide range of foods. If you’re looking for a supplement, most multivitamins contain the recommended daily requirement for vitamin A.
If you are concerned about a possible vitamin A deficiency, talk to your healthcare provider to better understand your vitamin A needs.
How much vitamin A per day?
If you’re feeling confused about how much vitamin A you need each day, the National Academy of Medicine (formerly the Institute of Medicine) has made clear recommendations to follow. The recommended dietary allowance (RDA) represents the amount of vitamin A needed each day for adequate nutrition, and it includes both what you get from your diet and supplementation.
The RDA for vitamin A is 700 micrograms (or about 2100 IU) per day for women and 900 micrograms (about 2700 IU) per day for men (Hodge, 2021).
You might think more is better, but as we’ll talk about a little further down in this article, there is a limit to how much vitamin A is good for you—with very high doses potentially causing significant side effects.
A quick note on these measurements: A microgram represents one-millionth of a gram, abbreviated as mcg or ug. The unit IU is an international unit used to measure fat-soluble vitamins.
Vitamin A deficiency
Recommendations and information about vitamin A used to be put on food labels. But over recent years, vitamin A and vitamin C have been removed from food labels because deficiencies for these vitamins are rare in developed countries.
Vitamin A is easy to get from food sources either in its active or inactive forms. In developed countries, where food tends to be readily available for most people, vitamin A deficiencies are very rare.
People can develop vitamin A deficiencies if they have certain medical conditions that affect the absorption of vitamin A, like bariatric surgery, inflammatory bowel disease, and other conditions affecting the intestines.
Also, conditions affecting the liver, like alcoholism, cirrhosis, and fatty liver disease, may impact the liver’s ability to convert precursors to the active form of vitamin A.
Symptoms of a vitamin A deficiency include (Hodge, 2021):
Nyctalopia, also known as night blindness (trouble seeing in dim light or during the night)
Xerophthalmia (severely dry eyes)
Vitamin A toxicity
Since vitamin A is a fat-soluble vitamin, it can be stored in fat—unlike water-soluble vitamins, like B-vitamins and vitamin C, where extra amounts are moved out of the body through urine. That means vitamin A can potentially build up in the body to toxic levels and cause side effects.
Vitamin A toxicity, also called hypervitaminosis A, is rare and usually only occurs with very large doses of the vitamin or long-term supplement use. It’s very rare for vitamin A toxicity to develop through diet alone.
Acute vitamin A toxicity may develop after a single dose greater than 25,000 IU per kilogram of body weight. Chronic vitamin A toxicity may develop after taking more than 4,000 IU per kilogram of body weight for 6–15 months (Chea, 2021).
Symptoms of vitamin A toxicity include (Olson, 2021):
Dry, cracked, peeling lips
Dry, rough skin
Thick, coarse hair
Sores or ulcers in the corner of the mouth
Peeling skin on the palms or soles
High calcium levels in the blood
Vitamin A and pregnancy
Vitamin A is an important vitamin during pregnancy because of its role in cell division and growth. It helps support your health and your baby’s developing organs, bones, and eyes.
With that said, too much vitamin A during pregnancy can cause harm to the fetus. Research suggests doses greater than 10,000 IU per day from supplements may cause congenital disabilities in up to 1 of 57 babies (Olson, 2021).
Taking prenatal vitamins as directed by your healthcare provider and eating a healthy diet should provide enough vitamin A to support the needs of breastfeeding and pregnant women. If you’re taking other vitamins, be careful that, together with your prenatal vitamins, they don’t contain more than your daily allotment. If you are pregnant or plan to become pregnant, it’s best to speak with your healthcare provider about supplements you plan to or currently take.
If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.
Chea, E. P., Lopez, M. J., & Milstein, H. (2021). Vitamin A. [Updated 2021, July 25]. In: StatPearls [Internet]. Retrieved on Oct. 17, 2021 from https://www.ncbi.nlm.nih.gov/books/NBK482362/
Hodge, C. & Taylor, C. (2021). Vitamin A deficiency. [Updated 2021, July 27]. In: StatPearls [Internet]. Retrieved on Oct. 17, 2021 from https://www.ncbi.nlm.nih.gov/books/NBK567744/
Huang, Z., Liu, Y., Qi, G., Brand, D., & Zheng, S. G. (2018). Role of vitamin A in the immune system. Journal of Clinical Medicine , 7 (9), 258. dio: 10.3390/jcm7090258. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6162863/
Lobo, V., Patil, A., Phatak, A., & Chandra, N. (2010). Free radicals, antioxidants and functional foods: impact on human health. Pharmacognosy Reviews , 4 (8), 118–126. doi: 10.4103/0973-7847.70902. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249911/
Olson, J. M., Ameer, M. A., & Goyal, A. (2021). Vitamin A toxicity. [Updated 2021, Aug 14]. In: StatPearls [Internet]. Retrieved on Oct. 17, 2021 from https://www.ncbi.nlm.nih.gov/books/NBK532916/