Vitamin A Benefits, Deficiency, Dosage and Side Effects - Dr. Axe

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Vitamin A Benefits Eye, Skin & Bone Health


Vitamin A benefits

Doubling as both an important fat-soluble vitamin and potent antioxidant, getting enough vitamin A is absolutely crucial to maintaining overall health. Not only does it play a role in keeping your skin healthy and clear, but it’s also a key factor in disease prevention, immunity and even bone health.

A deficiency in this vital vitamin can cause some pretty scary consequences, ranging from night blindness to scaly skin and stunted growth. However, striking the right balance is equally important, as overdoing it with supplements can also result in serious issues like birth defects and liver problems.

So what does vitamin A do, and how can you be sure you’re getting the right amount in your diet? Here’s what you need to know about this essential micronutrient and how it can impact your health, along with the top vitamin A foods you should consume.

What Is Vitamin A?

Vitamin A is a fat-soluble vitamin that also acts as a powerful antioxidant in the body. It plays a critical role in maintaining vision, neurological function, healthy skin and more. Like all antioxidants, it’s also involved in reducing inflammation through fighting free radical damage.

Vitamin A is found in two primary forms: active vitamin A (also called retinol, which results in retinyl esters) and beta-carotene. Retinol comes from animal-derived foods and is a type of “pre-formed” vitamin A that can be used directly by the body. The other type, which is obtained from colorful fruits and vegetables, is in the form of provitamin carotenoids. Beta-carotene and other types of carotenoids found in plant-based products need to first be converted to retinol, the active form of vitamin A, in order to be utilized by the body. Another form of vitamin A is palmitate, which usually comes in capsule form.


So what is vitamin A good for? Studies have repeatedly shown that antioxidants like vitamin A are vital to good health and longevity. They benefit eye health, boost immunity and foster cell growth. Nutrition experts and physicians recommend obtaining antioxidants primarily by eating a well-balanced diet high in fruits, vegetables and whole foods whenever possible rather than from vitamin supplementation to maximize the potential health benefits.


1. Protects Eye Health

One of the most well-known benefits of vitamin A is its ability to boost vision and keep your eyes healthy. This is because it is a critical component of the rhodopsin molecule, which is activated when light shines on the retina, sending a signal to the brain that results in vision. Beta-carotene plays a role in preventing macular degeneration, one of the leading causes of age-related blindness.

In fact, a study published in the Archives of Ophthalmology found that people at high risk for the disease who took a daily multivitamin that included vitamin A, vitamin C, vitamin E, zinc and copper had a 25 percent reduced risk of advanced macular degeneration during a six-year period.

2. Supports Immunity

Vitamin A plays an integral role in immune health and may be especially beneficial for warding off illness and infections. According to a review out of Baltimore, a deficiency in this key vitamin can weaken immunity and even alter the function of immune cells.

It’s been shown that vitamin A deficiency blocks the regeneration of the mucosal barriers, resulting in increased susceptibility of infections. Interestingly, a 2014 study out of Colombia actually estimated that giving 100,000 children vitamin A supplements could save over $340 million in medical costs by reducing the incidence of serious conditions like diarrhea and malaria.

3. Relieves Inflammation

Beta-carotene acts as a powerful antioxidant in the body, helping reduce the buildup of harmful free radicals and prevent oxidative damage to cells while also blocking inflammation.

The anti-inflammatory effects of vitamin A and beta-carotene can have far-reaching effects on many aspects of health, as inflammation is at the root of many chronic conditions, ranging from cancer to heart disease and diabetes. Reduced levels of inflammation are also correlated with a lower risk for neurodegenerative diseases like Alzheimer’s and Parkinson’s as well as improvements of inflammatory conditions like rheumatoid arthritis and Crohn’s disease.

4. Keeps Skin Glowing

Often prescribed by dermatologists to fight acne and wrinkles alike, vitamin A is revered for its potent skin-enhancing properties. One study out of the University of Michigan Medical School’s Department of Dermatology even found that applying retinol topically to the skin significantly improved fine lines and wrinkles, plus increased the skin’s ability to withstand injury.

Due to its anti-inflammatory properties, such as retinaldehyde, vitamin A may also be useful in the treatment of a wide range of skin concerns. In fact, studies show that retinoids may be therapeutic for common skin conditions like psoriasis, eczema and acne.

5. Contains Cancer-Fighting Properties

With the growing body of research demonstrating a strong link between what you eat and your risk of cancer, it should come as no surprise that upping your intakes of vitamin A foods could help protect against cancer development. According to a review published in BioMed Research International, retinoids have been shown to block the growth of skin, bladder, breast, prostate and lung cancer cells in in vitro studies.

High doses of retinoic acid can be toxic to cells, so it’s best to include it through food sources in your diet to prevent or suppress cancer progression over time. Additionally, keep in mind that more is not always better, so moderate your intake to maximize the potential health benefits.

Vitamin A - Dr. Axe

6. Boosts Bone Health

Most of us are well aware of the connection between bone health and nutrients like calcium and vitamin D, but did you know that vitamin A is also a crucial component of bone growth as well?

Hitting just the right balance of vitamin A is essential, however, as both an excess and deficiency in this important vitamin have been linked to compromised bone health. One study conducted at the Institute of Gerontology and Geriatrics at the University of Perugia in Italy even found that plasma retinol levels were significantly lower in elderly women with osteoporosis compared to a control group. The results also showed that low levels of retinol were associated with reduced bone mineral density in the femur.

7. Reduces Cholesterol

Cholesterol is a waxy, fat-like substance found throughout the body. Your body needs cholesterol to function properly, as it’s involved in the synthesis of hormones and makes up the foundation of your cell membranes. Too much cholesterol, however, can build up in your blood vessels, causing them to harden and narrow, increasing the risk of heart disease.

Although human studies are limited, some research shows that getting enough vitamin A in your diet may help naturally lower cholesterol levels to optimize heart health. An animal model out of Brazil, for instance, found that supplementing rats with beta-carotene for six weeks was able to significantly slash levels of total cholesterol in the blood.


8. Aids in Reproduction and Development

Vitamin A is crucial when it comes to proper growth and development throughout all stages of life, but it’s also considered one of the best vitamins for women, in particular. A deficiency in this key vitamin is linked to depressed immune function, a higher morbidity and mortality, and even a greater risk of mother-to-child transmission of HIV-1 for pregnant women.

The American Pediatrics Association lists vitamin A as one of the most important micronutrients during pregnancy, especially with regard to lung function and maturation. Beta-carotene is also considered critical in the prevention of developmental disorders for women who are pregnant or breastfeeding.

9. Promotes Tissue Repair

When it comes to tissue repair and cell regeneration, getting enough vitamin A in your diet is key. Besides being vital to promoting proper skin health, some evidence even suggests that this vitamin could aid in wound healing as well.

A study published in Dermatologic Surgery conducted at Drexel University College of Medicine’s Department of Dermatology in Philadelphia, for instance, found that pretreatment with retinoids improved wound healing after undergoing facial resurfacing procedures. Similarly, an animal model published in the Journal of Nutrition concluded that supplementing with different forms of vitamin A in the diet helped increase wound strength in rats following surgery.

10. Prevents Urinary Stones

If you’ve ever experienced urinary stones, you’re likely all too familiar with just how painful they can be. Urinary stones generally form in the kidneys and then slowly grow and develop in the ureters or bladder. They can cause symptoms like frequent urination, abdominal pain, discomfort and hematuria (bloody urine). Left untreated, they can also cause infections and complications and may even require surgical intervention in some cases.

Some research shows that vitamin A may aid in the prevention of urinary stones. In fact, one study out of the National Institute of Nutrition’s Department of Biophysics in India examined the relationship between vitamin A levels and urinary stone formation among children and found that those with low levels of vitamin A had greater levels of calcium oxalate crystals in the urine, indicating a higher risk of urinary stone formation.

Food Sources

Upping your intake of vitamin A foods is the best way to reap the benefits of this important micronutrient. Here are some of the top vitamin A sources to boost your intake and be sure you’re meeting your daily needs:

  1. Winter/butternut squash — 1 cup, cooked cubes: 22,869 international units (457 percent DV)
  2. Sweet potato — 1 medium, cooked potato: 21,907 international units (438 percent DV)
  3. Kale — 1 cup, chopped: 10,302 international units (206 percent DV)
  4. Carrots — 1 medium raw carrot: 10,190 international units (204 percent DV)
  5. Beef Liver — 1 ounce: 8,881 international units (178 percent DV)
  6. Spinach — 1 cup raw: 2,813 international units (56 percent DV)
  7. Dried apricots — 1 ounce: 1,009 international units (20 percent DV)
  8. Broccoli — 1 cup raw: 567 international units (11 percent DV)
  9. Butter — 1 tablespoon: 350 international units (7 percent DV)
  10. Egg yolks — 1 large egg: 245 international units (5 percent DV)

Some other nutritious foods with vitamin A include cod liver oil, green peas, red bell peppers, full-fat raw whole milk, mangoes, tomatoes, cantaloupe, papaya, oatmeal and herbs, such as basil and paprika.

Vitamin A Deficiency

Vitamin A is essential for normal vision as well as proper bone growth, healthy skin, and protection of the mucous membranes of the digestive, respiratory and urinary tracts against infection.

People with long-term malabsorption of fats are more susceptible to developing a vitamin A deficiency. Those with leaky gut syndrome, celiac disease, autoimmune disorders, inflammatory bowel disease, pancreatic disorders or alcohol dependence are also at a higher risk of deficiency.

Vitamin A deficiency has become a public health problem in more than half of all countries, especially in Africa and Southeast Asia, and affects many young children and pregnant women in low-income countries in particular.

This can be a serious problem for children because the lack of vitamin A causes severe visual impairment and blindness and also significantly increases the risk of serious illness, such as infectious diarrhea and measles.

Some of the most common symptoms of a vitamin A deficiency include:

  • Xerophthalmia (dryness of the conjunctiva and cornea)
  • Night blindness
  • Bitot’s spots (buildup of keratin on the conjunctiva)
  • Dry lips
  • Thick or scaly skin
  • Impaired immunity
  • Stunted growth in children


The recommended vitamin A dosage is around 5,000 international units per day for adults and children over the age of four. Keep in mind that an international unit of retinol is equal to about 0.3 μg of RAE (retinol activity equivalents). Similarly, one international unit of beta-carotene from supplements translates to about 0.15 μg of RAE.

By simply upping your intake of fruits and veggies and incorporating a serving or two of vitamin A sources into each meal, it can be easy (and delicious) to meet your daily needs. Try roasting some carrots as a tasty side dish, serving up some kale alongside your main course or baking some butternut squash with a dollop of grass-fed butter to boost your intake even more.

Vitamin A tablets and supplements are also available, but it’s better to get your intake through a variety of food sources rather than through vitamin A supplements. Not only do foods rich in vitamin A supply a greater amount of many of the important nutrients that you need, but some studies have actually found that supplementation with certain forms of vitamin A, such as beta-carotene, may even be linked to a higher risk of cancer in some populations.


Many of the foods rich in vitamin A fit seamlessly into an Ayurvedic diet. Winter squash, for example, is encouraged as a hearty and healthy choice for those looking to lose weight, thanks to its diuretic properties. Sweet potatoes are also known for being highly nourishing and satisfying, plus one of the few foods that works well for all three doshas alike.

Vitamin A foods are also common ingredients used throughout Traditional Chinese Medicine. Kale, for instance, is believed to help strengthen the stomach and promote tissue repair while carrots are said to detoxify, improve vision and strengthen the organs.

Although we now know just how crucial vitamin A is when it comes to growth, development, reproduction and immunity, researchers have only recently begun to uncover the importance of this vitamin over the last 130 years.

Physiologist François Magendie began conducting experiments on dogs in 1816, noting that depriving them of essential nutrients led to higher rates of mortality and corneal ulcers. A few decades later in 1880s, scientists began realizing that there were important, undiscovered nutrients in foods like egg yolks and milk that may be responsible for many of their health-promoting properties.

By 1913, researchers had found that butter and egg yolks, two foods rich in vitamin A, were able to sustain life and support survival in animal models to a greater degree than other types of fat, such as olive oil and lard. In 1932, an organic chemist from Switzerland named Paul Karrer was the first to describe the vitamin A structure, and it was finally isolated just a few years later in 1937.

Since then, a slew of studies have continued to unearth more about the complex relationship between vitamin A and the role that it plays in health, immunity, growth and development.

Risks and Side Effects

High doses of vitamin A may actually do more harm than good. Consuming too much from supplementation or in combination with other antioxidants has been associated with birth defects, lower bone density and liver problems. Vitamin A toxicity can also cause symptoms like jaundice, nausea, loss of appetite, irritability, vomiting and even hair loss.

If you do decide to use vitamin A supplements, make sure to consult with your doctor first, take a low dosage and use supplements from food-based sources if possible. People who drink heavily, smoke, or have kidney or liver disease also should not take vitamin A supplements without talking to a trusted health care professional. Note that vitamin A may also interact with certain medications, including some birth control pills, blood thinners and certain cancer treatments.

Keep in mind that vitamin A is a fat-soluble vitamin and, therefore, needs to be consumed with fat in order to have optimal absorption. A sufficient dietary intake of protein is required for the manufacture of these binding proteins, so inadequate protein intake may result in impaired vitamin A function and deficiency.

Studies have shown that the absorption, metabolism, hepatic release, transport and tissue utilization of vitamin A may depend, in part, on an adequate zinc status. Some studies also suggest that the results of a vitamin D deficiency may be worsened by high supplemental intake of vitamin A.

To prevent issues with vitamin A overdose or hypervitaminosis, opt for food sources and pair them with a well-balanced diet rich in nutrient-dense foods to help maximize your health.

Final Thoughts

  • Vitamin A is a fat-soluble vitamin and antioxidant that’s incredibly important to health.
  • It’s found in many food sources as both retinol and provitamin A carotenoids. Carotenoids must be converted to retinol before they can be used in the body.
  • It benefits skin health, supports immunity, boosts vision, lowers cholesterol and keeps your bones healthy. It’s also necessary for tissue repair and reproduction and may aid in the prevention of cancer and urinary stones.
  • Ideally, try to meet most of your needs through food sources rather than supplementation.
  • By following a balanced, nutritious diet, you can easily take advantage of the many health benefits that this important vitamin has to offer.

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