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Vitamin A

Retinol; Retinal; Retinoic acid; Carotenoids

Vitamin A is a fat-soluble vitamin that is stored in the liver.

There are two types of vitamin A that are found in the diet.

Vitamin A is also available in dietary supplements. It most often comes in the form of retinyl acetate or retinyl palmitate (preformed vitamin A), beta-carotene (provitamin A) or a combination of preformed and provitamin A.

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Vitamin A benefit
Vitamin A source

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Function

Vitamin A helps form and maintain healthy teeth, skeletal and soft tissue, mucus membranes, and skin. It is also known as retinol because it produces the pigments in the retina of the eye.

Vitamin A promotes good eyesight, especially in low light. It also has a role in healthy pregnancy and breastfeeding.

Vitamin A is found in two forms in food:

Beta-carotene is an antioxidant. Antioxidants protect cells from damage caused by substances called free radicals.

Free radicals are believed to:

Eating food sources of beta-carotene may reduce the risk for cancer.

Beta-carotene supplements do not seem to reduce cancer risk.

Food Sources

Vitamin A is found in both plant and animal foods.

Foods with the highest levels of vitamin A include:

The deeper or brighter the color of a fruit or vegetable, the higher the amount of carotenoids. Vegetable sources of beta-carotene are fat- and cholesterol-free. Their absorption is improved if these sources are eaten with a small amount of fat.

Side Effects

DEFICIENCY:

If you do not get enough vitamin A, you have more risk of eye problems such as:

Lack of vitamin A can also lead to hyperkeratosis or dry, scaly skin.

HIGH INTAKE:

If you get too much vitamin A, you can become sick.

Babies and children are more sensitive to vitamin A. They can become sick after taking smaller doses of vitamin A or vitamin A-containing products such as retinol (found in skin creams).

Large amounts of beta-carotene will not make you sick. However, high amounts of beta-carotene can turn the skin yellow or orange. The skin color will return to normal once you reduce your intake of beta-carotene.

Recommendations

Recommendations for vitamin A, as well as other nutrients, are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine. DRI is a term for a set of reference intakes that are used to plan and assess the nutrient intakes of healthy people. These values, which vary by age and sex, include:

Recommended Dietary Allowance (RDA): The average daily level of intake that is enough to meet the nutrient needs of nearly all (97% to 98%) healthy people. An RDA is an intake level based on scientific research evidence.

Adequate Intake (AI): This level is established when there is not enough scientific research evidence to develop an RDA. It is set at a level that is thought to ensure enough nutrition.

Dietary reference intakes for vitamin A:

Infants (AI)

The Recommended Dietary Allowance (RDA) for vitamins is how much of each vitamin most people should get each day. The RDA for vitamins may be used as goals for each person.

Children (RDA)

Adolescents and adults (RDA)

The best way to get the daily requirement of important vitamins is to eat a wide variety of fruits, vegetables, fortified dairy foods, legumes (dried beans), lentils, and whole grains.

Related Information

Retina
Beta-carotene blood test

References

Markell M, Siddiqi HA. Vitamins and trace elements. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 27.

Mason JB, Booth SL. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 205.

National Institutes of Health website. Vitamin A: fact sheet for health professionals. ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/. Updated March 26, 2021. Accessed April 30, 2021.

Ross CA. Vitamin A deficiencies and excess. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 61.

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Review Date: 3/11/2021  

Reviewed By: Meagan Bridges, RD, University of Virginia Health System, Charlottesville, VA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 09/29/2021.

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