What Are Vitamin A and Carotenoids, and What Do They Do?
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Children at a cafeMedically reviewed by Allison Herries, RDN
What Is Vitamin A?
Vitamin A is an essential nutrient, meaning we can't make it in our bodies and must get it from an outside source to stay healthy. There are two sources of vitamin A: preformed vitamin A and carotenoids.
Vitamin A is a fat-soluble nutrient requiring fat for it to be effectively absorbed in the digestive tract. Vitamin A is stored in the liver.
Vitamin A is essential for the health of the following:
Epithelia (surface tissue, like skin)
The eyes
The immune system
Growth and development
Reproductive health
This article will discuss what you should know about vitamin A, including its potential uses, safety, and more.
Dietary supplements are not regulated the way drugs are in the United States, meaning the Food and Drug Administration (FDA) does not approve them for safety and effectiveness before products are marketed. Choose a supplement tested by a trusted third party, such as the U.S. Pharmacopeia (USP), ConsumerLab.com, or NSF.org whenever possible. However, even if supplements are third-party tested, they are not necessarily safe for all or effective in general. Therefore, talking to your healthcare provider about any supplements you plan to take and asking about potential interactions with other supplements or medications is essential.
Supplement Facts
Active Ingredient(s): Vitamin A
Alternate Names(s): Vitamin A, retinol, fat-soluble vitamins, fat-loving vitamins, essential vitamins, preformed vitamin A, carotenoids, provitamin A carotenoids
Legal Status: Substances added to food, nutrient found in food, dietary supplement
Suggested Dose: May vary based on age, sex, and medical condition
Safety Considerations: Possible side effects, interactions, and special considerations for children, pregnancy, and breastfeeding
What Are Some Effects of Vitamin A on Health?
Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian nutritionist (RD or RDN), pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.
While more extensive research is necessary in regard to effectiveness, people use vitamin A or carotenoids for various health conditions.
Research for the effects of vitamin A and carotenoids on health is most robust for the following conditions:
Vitamin A deficiency (low vitamin A)
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Children at a cafeAge-Related Macular Degeneration
AMD is a vision-threatening condition that tends to affect people over 50—including older adults over 65.
In AMD, blood leaks into the macula, which is the center of the retina in the back of the eye. The macula helps you see fine details.
In a clinical trial, study participants who took more vitamin A, beta-carotene, or lutein and zeaxanthin had a lower likelihood of worsening AMD when compared to participants who took less vitamin A and/or these carotenoids.
Since vitamin A toxicity is possible, however, speak with a healthcare provider before taking this vitamin.
Moreover, there is an AREDS2 supplement that decreases the risk of worsening AMD. But the most current AREDS2 supplement contains no vitamin A or provitamin A carotenoid—like beta-carotene.
Cancer
A few systematic reviews and meta-analyses suggested a lower risk of several different cancers with higher dietary amounts of the following:
Retinol
Carotenoids
Fruits and vegetables
Combination of the above
Results from some studies, however, didn't find a relationship between different forms of vitamin A and cancer risk.
There were also a few large and long-term studies that showed beta-carotene supplements with or without retinyl palmitate (a preformed vitamin A) had harmful effects—like lung cancer—on specific groups of people.
This includes people who currently or formerly smoked and people who had exposure to asbestos.
In other studies, these adverse effects were not seen, but these studies contained smaller groups of people who currently or formerly smoked.
Based on these articles, the evidence regarding the relationship between vitamin A and cancer is mixed.
Infections
There is a possible relationship between vitamin A deficiency (low vitamin A) and a higher risk of death from infections such as measles. Measles is a highly contagious and severe viral infection, which is preventable with a vaccine.
Results from a systematic review showed vitamin A supplementation reduced the number of new measles cases in children. Interestingly, however, vitamin A supplementation didn't affect the number of deaths from measles.
Vitamin A supplementation generally decreased the risk of morbidity and mortality in children. Morbidity is the state of having a medical condition, and mortality is death.
Data supported the continued use of vitamin A supplements in children younger than 5 at risk for low vitamin A. But additional clinical trials are still necessary to study vitamin A doses and various ways vitamin A is given.
Vitamin A Deficiency
While rare in the United States, it is possible to have a vitamin A deficiency.
However, low vitamin A levels in developing countries are more common—especially in pregnant and breastfeeding people. Infants—particularly preterm infants—and children are also at a higher risk.
Low vitamin A levels may occur in people who eat certain traditional diets that contain few foods with vitamin A. People in developing countries may also have difficulties accessing foods with vitamin A or provitamin A carotenoids.
Low vitamin A is also more likely with certain groups of people or in people with certain medical conditions.
What Causes a Vitamin A Deficiency?
Potential causes of vitamin A deficiency also include:
Cystic fibrosis (CF): CF is a medical condition that runs in families. CF affects the lungs, pancreas, and other organs. Because people with CF are more likely to have pancreatic problems, they also have problems absorbing vitamin A into the bloodstream. For this reason, there is a higher likelihood of vitamin A deficiency.
Digestive system conditions: People with certain digestive system conditions have a higher risk of vitamin A deficiency. Examples of these digestive system conditions include inflammatory bowel disease (IBD) and celiac disease.
Am I Getting Enough Vitamin A?
If you live in the United States, you're likely getting enough vitamin A.
However, if you're living in a developing country where access to vitamin A-containing foods is difficult, there's a chance you may not be not getting enough vitamin A.
If you have a vitamin A deficiency, short-term symptoms may include:
Trouble seeing in environments with low lighting
Long-term or worsening vitamin A deficiency symptoms may include:
Abnormal lung development
High risk of anemia
Irreversible (permanent) blindness
Lung conditions, such as pneumonia
Severe infections, especially from measles or infection-related diarrhea
Death
If you suspect that you're experiencing a vitamin A deficiency or if any of your symptoms feel life-threatening, call 911 and get medical help right away.
What Are the Side Effects of Vitamin A?
As with many medications and natural products, vitamin A supplements may have side effects.
Additionally, vitamin A is a fat-soluble vitamin. The body stores excess amounts, primarily in the liver. These levels can accumulate over time, potentially increasing the possibility of toxicity.
Common Side Effects
Common side effects of vitamin A may include:
Severe Side Effects
Severe side effects are possible, especially from vitamin A toxicity. Examples of serious side effects may include:
Severe allergic reaction: A severe allergic reaction is a serious side effect possible with any medication or natural product. If you're having a severe allergic reaction, symptoms may include breathing difficulties, itchiness, and rash.
Brain swelling: Too much vitamin A might cause some brain swelling. Symptoms of brain swelling may include vision changes, seizures, and memory problems.
Cancer: Vitamin A might have harmful effects—like lung cancer—on specific groups of people, such as people who currently or formerly smoked and people who had asbestos exposure.
Liver problems: There are reports of liver problems above the upper limit (UL)—the maximum amount not likely to pose harm—of daily vitamin A. If you have worsening liver function, symptoms may include upper right-sided stomach discomfort, dark urine, and yellowing of the eyes or skin.
Bone problems: Large amounts of vitamin A might cause bone pain and decrease bone mineral density (BMD). BMD measures the strength and thickness (density or mass) of your bones. And low BMD increases your osteoporosis (weak and brittle bones) and bone fracture (break) risk.
Negative effects on the unborn fetus: If a pregnant person takes too much vitamin A—or even uses skin products with retinol—adverse effects can happen to the unborn fetus.
If you're having a severe allergic reaction or if any of your symptoms feel life-threatening, call 911 and get medical help right away.
Precautions
A healthcare provider may advise against your taking vitamin A if any of the following applies to you:
Severe allergic reaction: Avoid vitamin A if you have a known allergy to it or its ingredients or parts. If you need clarification on whether it's safe, ask a registered dietitian, pharmacist, or healthcare provider for more information.
Pregnancy: There are recommended daily allowances (RDAs) for vitamin A from different sources—like foods and supplements—for pregnant people. However, harmful effects on your unborn fetus are more likely above the following daily UL—14 to 18 years: 2,800 micrograms (mcg), 19 years and over: 3,000 mcg. Contact a healthcare provider to discuss the benefits and risks.
Breastfeeding: There are RDAs of vitamin A for breastfeeding people. However, harmful effects for you or your child are more likely above the following daily ULs for vitamin A—2,800 mcg (14 to 18 years) to 3,000 mcg (19+ years). Reach out to a healthcare provider to discuss the benefits and risks. The healthcare provider may also help you know more about your vitamin A needs.
Adults over 65: Some older adults may have a higher likelihood of medication side effects. Discuss your vitamin A use with your healthcare provider.
Children: Children have different vitamin A needs compared to adults. Harmful effects for you or your child are more likely above the following daily ULs for vitamin A—600 mcg (birth to 3 years), 900 mcg (4 to 8 years), 1,700 mcg (9 to 13 years), and 2,800 mcg (14 to 18 years). Talk with your child's healthcare provider about giving your child vitamin A.
Age-related macular degeneration (AMD): A clinical trial showed that study participants who took more vitamin A, beta-carotene, or lutein and zeaxanthin had a lower likelihood of worsening AMD—when compared to participants who took less vitamin A and/or these carotenoids. The most current AREDS2 supplement for AMD doesn't contain vitamin A or beta-carotene. If you have AMD, contact a healthcare provider to discuss your options before taking vitamin A or beta-carotene.
Tobacco use or asbestos exposure: Studies suggest beta-carotene with or without retinyl palmitate (a preformed vitamin A) had harmful effects—like lung cancer—on people who currently or formerly used tobacco and people who had asbestos exposure. Therefore, talk with a healthcare provider before trying vitamin A or beta-carotene—especially if you smoke cigarettes or have in the past, or have had asbestos exposure.
Lung cancer: Beta-carotene with or without retinyl palmitate might increase the risk of harmful effects—like lung cancer—on specific groups of people, such as people who currently or formerly smoked and people who had asbestos exposure. If you have these risk factors or already have lung cancer, healthcare providers may recommend against vitamin A or beta-carotene.
Liver problems: Above the daily upper limit (UL) of vitamin A, there are reports of liver problems. If you already have liver problems, healthcare providers may want to closely monitor you and make any necessary medication adjustments.
Osteoporosis: Large amounts of vitamin A may decrease bone mineral density. And this may increase your risk of osteoporosis (weak and brittle bones) and bone fracture (break). If you have osteoporosis, healthcare providers may want to closely monitor you and make any necessary medication adjustments.
Dosage: How Much Vitamin A Do I Need?
Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs.
The Recommended Dietary Allowance (RDA) is the daily amount of vitamins or minerals needed.
RDAs may vary based on age, sex, pregnancy, and breastfeeding status.
Upper limits (ULs) are the maximum amounts of a vitamin or mineral people should ingest daily. Amounts ingested above the daily UL may produce side effects or toxicity.
The following includes information about different populations' RDAs and ULs.
Age | RDAs | UL for Animal-Based Foods and Vitamin A Supplements |
14–18 years | 750 micrograms (mcg) | 2,800 mcg |
19–50 years | 770 mcg | 3,000 mcg |
Age | RDAs | UL for Animal-Based Foods and Vitamin A Supplements |
14–18 years | 1,200 mcg | 2,800 mcg |
19–50 years | 1,300 mcg | 3,000 mcg |
Age | RDAs | UL for Animal-Based Foods and Vitamin A Supplements | |
Birth to 6 months | 400 mcg | 600 mcg | |
7–12 months | 500 mcg | 600 mcg | |
1–3 years | 300 mcg | 600 mcg | |
4–8 years | 400 mcg | 900 mcg | |
9–13 years | 600 mcg | 1,700 mcg | |
14–18 years | 900 mcg | 2,800 mcg |
In children with a high risk of vitamin A deficiency in developing countries, the recommended dosages for vitamin A are:
Infants between 6 and 11 months: 100,000 international units (IU) or 30,000 micrograms (mcg) of retinol activity equivalents (RAE) as a onetime dose
Children between 1 and 5 years old: 200,000 IU or 60,000 mcg RAE every 4 to 6 months
For these children, vitamin A supplementation might lower the risk of morbidity and mortality. Additional clinical trials are still necessary to study different vitamin A doses and various ways vitamin A is given.
RDAs | Upper Limit for Animal-Based Foods and Vitamin A Supplements | |
Females | 700 mcg | 3,000 mcg daily |
Males | 900 mcg | 3,000 mcg daily |
If you plan to use vitamin A, follow a healthcare provider's recommendations or product label instructions.
Vitamin A Toxicity
If you take too much vitamin A, toxicity is possible. Generally, the recommended daily amounts of vitamin A from different sources—like foods and supplements—are based on age, sex, pregnancy, and breastfeeding status.
Once you're older than 18, the upper limit (UL) for animal-based foods and vitamin A supplements is around 3,000 mcg daily.
If you accidentally took too much vitamin A, overdose symptoms are likely similar to vitamin A's potential and serious side effects. This may include the following:
Bone problems: Too much vitamin A may cause bone pain and decrease your bone mineral density (BMD). So, over time, large amounts of vitamin A may increase your risk of osteoporosis (weak and brittle bones) and bone fracture (break).
Brain swelling: High amounts of vitamin A might cause some brain swelling. Symptoms may include headaches, nausea or vomiting, vision changes, seizures, and memory problems.
Cancer: Vitamin A might have harmful effects—like lung cancer—on certain groups of people, such as people who currently or formerly smoked and people who had asbestos exposure.
Liver problems: There are reports of liver problems with vitamin A over the daily upper limit. Symptoms of worsening liver function may include upper right-sided stomach pain, dark urine, and yellowing of the eyes or skin.
Negative effects on the unborn fetus: Above the UL for daily vitamin A, there are reports of negative effects on the unborn fetus.
If you think you took too much vitamin A or suspect you are experiencing life-threatening side effects, seek immediate medical attention.
Does Vitamin A Interact With Medications or Other Dietary Supplements?
Limited information about possible vitamin A interactions with medications or other dietary supplements exists.
Possible interactions include the following:
Medications or supplements that affect fat absorption: Vitamin A is a fat-soluble vitamin, meaning it needs some fat to be absorbed into the bloodstream. Therefore, medications or supplements that affect fat absorption will likely affect vitamin A's absorption into your bloodstream. Examples of these medications may include Xenical (orlistat) for weight loss and Questran (cholestyramine) for cholesterol.
Retinoids: Retinoids are vitamin A-based medications. For this reason, combining vitamin A with retinoids may increase the likelihood of vitamin A toxicity and side effects. An example of a retinoid medication may include Soriatane (acitretin) for certain skin conditions, such as psoriasis.
It is essential to carefully read a supplement's ingredients list and nutrition facts panel to know which ingredients and how much of each ingredient is included.
Please review this supplement label with a healthcare provider to discuss potential interactions with foods, other supplements, and medications.
Similar Supplements
Vitamin A may affect health, such as supporting eye health and limiting the severity of infections. So, other potentially similar supplements may include the following:
AREDS2 supplements: AREDS2 supplements may slow down the worsening of a vision-threatening eye condition called age-related macular degeneration (AMD).
Vitamin C: Routinely taking vitamin C may help relieve your cold symptoms.
Only combine multiple natural products once you first talk with a healthcare provider, pharmacist, or registered dietitian nutritionist (RD or RDN). Checking in can help you avoid possible harmful interactions and side effects and ensure you're giving these supplements a fair trial at appropriate doses.
Sources of Vitamin A & What to Look For
There are several sources of vitamin A, but health nutrition guidelines typically place more importance on food sources to improve the diet.
Although food sources are preferable, there is still a place for supplements for people with nutrient absorption problems.
This may happen to people in certain age groups or with certain medical conditions.
What Foods Have Vitamin A?
Generally, there are two sources of vitamin A—preformed vitamin A and provitamin A carotenoids.
Preformed vitamin A—like retinol—is naturally available in various animal-based foods, such as the following:
Dairy (milk) products
Fish
Eggs
The provitamin A carotenoids are also naturally available in food—but plant-based products. And your body can change these carotenoids into vitamin A. These foods include the following:
Mangos
Papaya
Squash
Carrots
Sweet potatoes
Corn (not the white variety)
Red palm oil
Buriti palm oil
Summary
Vitamin A is a fat-soluble, essential vitamin for several normal bodily functions. Your body needs fat to absorb it.
Vitamin A deficiency in the United States is rare. However, vitamin A may have some potential effects on health, such as age-related macular degeneration, cancer, and measles.
Some of the evidence for vitamin A is mixed. And some studies showed that vitamin A or beta-carotene (a provitamin A carotenoid) supplements might have harmful effects in certain groups of people. Vitamin A and beta-carotene supplements tend to have a much higher concentration of these nutrients than foods. Try to get vitamin A and beta-carotene from food sources instead of supplements unless your healthcare provider advises differently.
It's essential to ensure the diagnosis and treatment of your medical conditions are completed on time. Avoid self-diagnosing and/or self-treating conditions that may be potentially serious. Involving an RD or RDN, pharmacist, or healthcare provider before taking vitamin A to help you safely achieve your health goals.
Frequently Asked Questions
What is vitamin A?
Vitamin A is a fat-soluble vitamin. It's also an essential vitamin because it's necessary for a number of normal bodily functions.
What does vitamin A do, and what is vitamin A good for?
Vitamin A plays several essential parts in your body, such as your eyesight and immune system (the body's defense system). It's also essential for normal growth, development, and reproductive health. Moreover, vitamin A affects your heart, lungs, and other organs.
What is the most common dosage form of vitamin A?
Vitamin A supplements are available in a few different dosage forms—with capsules being the most common.
