Health Benefits of Vitamin A

Vitamin A is an umbrella term for a group of fat-soluble substances concentrated in plant and animal foods. In animal foods, vitamin A is found in the form of retinol and retinyl esters. Plant-based foods contain pro-vitamin A carotenoids, which are converted into active forms of vitamin A.

This important vitamin can offer benefits such as improved vision, immune function, cognitive abilities, and reproductive health. You can find it naturally in several types of plant and animal foods. You can also take it as a supplement.

Taking vitamin A supplements can support your health in several ways and may be necessary for some people, especially those who may not be able to receive vitamin A properly through their diet.

Supports Eye Health

Vitamin A is a component of a pigment concentrated in the retina called rhodopsin. The retina is a layer of tissue located at the back of the eye that senses light and sends signals to your brain that allow you to see. Rhodopsin is essential for vision and especially important for low-light vision. In fact, a vitamin A deficiency can lead to a condition called night blindness, which makes it difficult to see in low-light conditions.

In addition to being necessary for overall vision health, vitamin A protects against common eye diseases, such as age-related macular degeneration (AMD), a leading cause of vision loss in older adults. Maintaining higher blood levels of certain pro-vitamin A carotenoids, such as beta-carotene and alpha-carotene, may significantly reduce your risk of developing AMD and slow the progress of AMD in people who already live with the condition.

Vitamin A supplements may also benefit people living with dry eye disease (DED), a condition that causes symptoms like dry eyes, blurred vision, and sun sensitivity. One study of 60 men found that taking 1,500 milligrams (mg) of vitamin A supplements for three consecutive days significantly improved the quality of the tears in males with dry eye, including their tear film.

The tear film is a layer of tears that covers the surface of your eyes, keeping them moist and preventing dryness. Reduced tear film quality is common with DED.

Could Boost Immune System

Vitamin A is essential for a healthy immune response, including the function of your immune cells, like natural killer cells (NK cells) and macrophages, which protect the body from infections and regulate inflammation.

Research suggests that taking vitamin A through dietary supplements may benefit people with certain infections, such as COVID-19. One seven-day study that included 60 people who were seriously ill from COVID found that those who received 25,000 international units (IU) of vitamins A, B, C, D, and E noticed a decrease in symptoms severity and an improved inflammatory response, compared to those who were given placebo treatment.

This study used multiple vitamins as their treatment, not just vitamin A, so it’s unclear if vitamin A would have the same effect if used but itself. If you decide to take vitamins for an infection you're experiencing, it's always important to talk to your healthcare provider first to ensure that the supplements are safe for you and your condition.

Necessary for a Healthy Pregnancy  

People who are pregnant or breastfeeding need more vitamin A than non-pregnant people. This is because vitamin A plays a critical role in fetal growth and development and overall maternal health. Pregnant and breastfeeding people need an extra 70 micrograms (mcg) and 600 mcg retinol activity equivalents (RAE)—the standard of measurement for vitamin A—per day compared to people who aren't pregnant or breastfeeding.

If vitamin A needs aren’t met during pregnancy, it can result in anemia (low red blood cell count), a weakened immune system, vision issues, and abnormalities in the fetus. Though vitamin A deficiency is relatively uncommon in the U.S., most prenatal supplements contain vitamin A to support optimal vitamin A levels.

May Improve Certain Health Conditions 

Some underlying health conditions can negatively affect your body's ability to absorb vitamin A from the food you eat. Examples include inflammatory bowel disease (IBD) and cystic fibrosis (CF), which can both interfere with vitamin A absorption in the digestive tract. This interference can often lead to a vitamin A deficiency.

If you live with a condition that may make it difficult for you to absorb vitamin A properly, your healthcare provider may recommend vitamin A supplements alongside other treatments you may be using.

Can Enhance Cognitive Function

Beta-carotene is a pro-vitamin A carotenoid that has powerful antioxidant properties. Due to its strong cellular-protective effects, taking beta-carotene supplements may improve cognitive function. 

One review of 16 studies found that supplementation with beta-carotene at doses ranging from 6 mg to 50 mg per day in combination with other nutrients (like vitamin E, vitamin C, zinc, or selenium) for at least 16 weeks could improve cognitive function such as memory and attention.

However, there’s no evidence that beta-carotene improves cognitive function when used independently, so more research is still needed to understand the relationship between vitamin A and brain health. 

Good Sources of Vitamin A

Vitamin A is found in both plant and animal foods. Plant foods contain vitamin A in the form of carotenoids, like beta-carotene, while animal foods contain preformed vitamin A. 

Here are some of the best dietary sources of vitamin A:

• Beef liver: 6,582 mcg RAE per 3 ounces (oz), or 731% of the Daily Value (DV)
• Carrots, raw: 1070 RAE per chopped cup, or 119% of the DV
• Spinach: 573 mcg RAE per half cup, or 64% of the DV
• Cantaloupe: 270 RAE per cup, or 30% of the DV
• Atlantic or pickled herring: 219 RAE per 3 oz, or 24% of the DV
• Ricotta cheese, part skim: 133 RAE per cup, or 15% of the DV
• Sweet, red peppers: 117 RAE per chopped cup, or 13% of the DV
• Mangoes: 112 RAE per whole mango, or 12% of the DV
• Hard-boiled egg: 75 RAE per large egg, or 8% of the DV

Many other plant and animal foods are also high in vitamin A, which is why a vitamin A deficiency is rare in people who follow a well-rounded diet. If you have dietary restrictions, talk to your healthcare provider for a referral to a registered dietitian who can help you make a list of foods high in vitamin A that suit your dietary needs.

How To Consume Vitamin A

While you can absorb vitamin A directly from certain foods, it's also available in the form of vitamin A-only supplements. You can also find this vitamin in multinutrient supplements, like multivitamins. Vitamin A supplements come in several forms, such as capsules, tablets, liquids, gummies, and powders. 

Vitamin A is a fat-soluble nutrient, which means it’s better absorbed with fat. Micelles, which are a cluster of molecules your body forms when it digests fats, can boost the absorption of vitamin A in the small intestine. That said, you can take vitamin A supplements at any time of day, but it’s best to take vitamin A supplements with meals or snacks containing fat.

Dosage 

Your body absorbs preformed vitamin A much more efficiently than provitamin A carotenoids. For example, between 70-90% of preformed vitamin A from supplements are absorbed in the digestive tract compared to 8.7-65% of beta-carotene.

Because of this significant difference, recommended intake levels for vitamin A are given as retinol activity equivalents (RAE), which represents the amount of vitamin A absorbed in the digestive tract. One microgram (mcg) RAE is equivalent to:

• 1 mcg of retinol
• 2 mcg of supplemental beta-carotene
• 12 mcg of dietary beta-carotene
• 24 mcg of dietary alpha-carotene or beta-cryptoxanthin

The current recommended daily allowance (RDA) for vitamin A in adults is 700 mcg RAE for people assigned female at birth and 900 mcg RAE for people assigned male at birth. The RDA for pregnant and breastfeeding people is 770 mcg RAE and 1,300 mcg RAE, respectively.

Doses of vitamin A used in supplements vary, but most vitamin A-only supplements contain around 3,000 mcg RAE or 333% of the DV. Multinutrient supplements, like multivitamins, often contain lower doses of vitamin A, usually between 750 to 1,050 mcg RAE or 83% to 117% of the DV.

Is Vitamin A Safe?

When used appropriately, vitamin A supplements are safe. However, preformed vitamin A can accumulate in the body, primarily in the liver. Consuming too much preformed vitamin A can lead to vitamin A toxicity, which can lead to serious side effects, some of which can be life-threatening.

Vitamin A toxicity is usually related to ingesting very large doses of preformed vitamin A supplements or vitamin A-based medications. Acute vitamin A toxicity occurs within a few days to weeks after ingesting a very high dose of vitamin A, usually exceeding 100 times the RDA. Chronic vitamin A toxicity can occur when someone regularly takes high doses of vitamin A over longer time periods.

High doses of preformed vitamin A can also cause congenital anomalies (previously known as birth defects), including deformities of the eyes, lungs, skull, and heart. Because higher doses of preformed vitamin A can be dangerous during pregnancy, pregnant people should avoid taking vitamin A in doses exceeding 3,000 mcg RAE or 10,000 IU per day.

Though provitamin A carotenoids are much safer than preformed vitamin A in terms of toxicity, taking high doses of beta-carotene has also been associated with an increased risk of lung cancer in people who smoke cigarettes.

Potential Drug Interactions

Vitamin A supplements can interact with certain medications, and some drugs can interfere with the absorption of vitamin A in the digestive tract. These medications include:

• Alli (orlistat): This weight loss medication can decrease the absorption of vitamin A, which can lead to vitamin A deficiency. To prevent deficiency, it's recommended that people taking Alli use a vitamin A-containing supplement, among other fat-soluble vitamins your healthcare provider may recommend. 
• Synthetic retinoid medications: Medications derived from vitamin A, such as Soriatane (acitretin) for psoriasis and Targretin (bexarotene) for cancer, can cause vitamin A toxicity when taken with vitamin A supplements. 

Vitamin A supplements may also interact with other medications, so it’s important to talk to your healthcare provider before using these supplements to ensure that they don't interact or negatively harm other medications you may be taking.

Can You Take Too Much Vitamin A?

Yes, it’s possible to take too much vitamin A. Taking too much preformed vitamin A can be dangerous and even life-threatening in extreme cases. Because preformed vitamin A can harm health when overconsumed, it has a set tolerable upper limit (UL). A UL is the maximum daily intake of a nutrient unlikely to cause harm. The UL for vitamin A is set at 3,000 mcg or 10,000 IU daily.

It’s important to avoid exceeding the UL, as taking high doses of preformed vitamin A can lead to serious side effects, such as vitamin A toxicity.

Side Effects of Vitamin A

Vitamin A toxicity, also known as hypervitaminosis A, can cause the following symptoms:

• Severe headache
• Poor appetite
• Eye problems
• Muscle pain
• Nausea and vomiting
• Dry skin
• Fatigue 
• Depression
• Liver injury

In extremely serious and rare cases, vitamin A toxicity can also lead to coma and potentially be fatal.

A Quick Review

Vitamin A is the collective name for a group of fat-soluble compounds that play vital roles in health. Taking vitamin A supplements may be necessary for certain people, such as those with malabsorption issues and pregnant or breastfeeding people. Vitamin A supplements may also benefit vision, immune system functioning, and brain health.

While vitamin A supplements have benefits, be sure to talk to your healthcare provider to ensure these supplements are safe for your body's needs.