Vitamin A Benefits Explained Scientifically
Vitamin A is the generic term for a group of fat-soluble compounds highly important for human health.
They’re essential for many processes in your body, including maintaining healthy vision, ensuring the normal function of your immune system and organs and aiding the proper growth and development of babies in the womb.
It’s recommended that men get 900 mcg, women 700 mcg and children and adolescents 300–600 mcg of vitamin A per day (1).
Vitamin A compounds are found in both animal and plant foods and come in two different forms: preformed vitamin A and provitamin A.
Preformed vitamin A is known as the active form of the vitamin, which your body can use just as it is. It’s found in animal products including meat, chicken, fish and dairy and includes the compounds retinol, retinal and retinoic acid.
Provitamin A carotenoids — alpha-carotene, beta-carotene and beta-cryptoxanthin — are the inactive form of the vitamin found in plants.
These compounds are converted to the active form in your body. For example, beta-carotene is converted to retinol (an active form of vitamin A) in your small intestine (2).
Here are 6 important health benefits of vitamin A.
1. Protects Your Eyes From Night Blindness and Age-Related Decline
Vitamin A is essential for preserving your eyesight.
The vitamin is needed to convert light that hits your eye into an electrical signal that can be sent to your brain.
In fact, one of the first symptoms of vitamin A deficiency can be night blindness, known as nyctalopia (3).
Night blindness occurs in people with vitamin A deficiency, as the vitamin is a major component of the pigment rhodopsin.
Rhodopsin is found in the retina of your eye and extremely sensitive to light.
People with this condition can still see normally during the day, but have reduced vision in darkness as their eyes struggle to pick up light at lower levels.
In addition to preventing night blindness, eating adequate amounts of beta-carotene may help slow the decline in eyesight that some people experience as they age (4).
Age-related macular degeneration (AMD) is the leading cause of blindness in the developed world. Though its exact cause is unknown, it’s thought to be the result of cellular damage to the retina, attributable to oxidative stress (5).
The Age-Related Eye Disease Study found that giving people over the age of 50 with some eyesight degeneration an antioxidant supplement (including beta-carotene) reduced their risk of developing advanced macular degeneration by 25% (6).
However, a recent Cochrane review found that beta-carotene supplements alone won’t prevent or delay the decline in eyesight caused by AMD (7).
Summary Eating adequate amounts of vitamin A prevents the development of night blindness and may help slow the age-related decline of your eyesight.
2. May Lower Your Risk of Certain Cancers
Cancer occurs when abnormal cells begin to grow or divide in an uncontrolled way.
In observational studies, eating higher amounts of vitamin A in the form of beta-carotene has been linked to a decreased risk of certain types of cancer, including Hodgkin’s lymphoma, as well as cervical, lung and bladder cancer (10, 11, 12, 13).
Similarly, vitamin A supplements haven’t shown the same beneficial effects (16).
At the moment, the relationship between vitamin A levels in your body and cancer risk is still not fully understood.
Still, current evidence suggests that getting adequate vitamin A, especially from plants, is important for healthy cell division and may reduce your risk of some types of cancer (20).
Summary Adequate vitamin A intake from whole plant foods may reduce your risk of certain cancers, including Hodgkin’s lymphoma, as well as cervical, lung and bladder cancer. However, the relationship between vitamin A and cancer is not fully understood.
3. Supports a Healthy Immune System
Vitamin A plays a vital role in maintaining your body’s natural defenses.
This includes the mucous barriers in your eyes, lungs, gut and genitals which help trap bacteria and other infectious agents.
It’s also involved in the production and function of white blood cells, which help capture and clear bacteria and other pathogens from your bloodstream.
Summary Having enough vitamin A in your diet helps keep your immune system healthy and function at its best.
People with this condition develop painful spots and blackheads, most commonly on the face, back and chest.
These spots occur when the sebaceous glands get clogged up with dead skin and oils. These glands are found in the hair follicles on your skin and produce sebum, an oily, waxy substance that keeps your skin lubricated and waterproof.
Though the spots are physically harmless, acne may have a serious effect on people’s mental health and lead to low self-esteem, anxiety and depression (24).
The exact role that vitamin A plays in the development and treatment of acne remains unclear (25).
This would increase your risk of acne by making it more difficult for dead skin cells to be removed from hair follicles, leading to blockages.
Some vitamin-A-based medications for acne are now available with a prescription.
Isotretinoin is one example of an oral retinoid that is effective in treating severe acne. However, this medication can have serious side effects and must only be taken under medical supervision (28, 29).
Summary The exact role of vit A in the prevention and treatment of acne is unclear. Yet, vitamin-A-based medications are often used to treat severe acne.
However, eating enough vitamin A is also necessary for proper bone growth and development, and a deficiency in this vitamin has been linked to poor bone health.
Additionally, a recent meta-analysis of observational studies found that people with the highest amounts of total vitamin A in their diet had a 6% decreased risk of fractures (30).
Yet, low levels of vita A may not be the only problem when it comes to bone health. Some studies have found that people with high intakes of vitamin A have a higher risk of fractures as well (31).
Even so, these findings are all based on observational studies, which cannot determine cause and effect.
This means that currently, the link between vitamin A and bone health is not fully understood, and more controlled trials are needed to confirm what has been seen in observational studies.
Bear in mind that vitamin A status alone does not determine your risk of fractures, and the impact of the availability of other key nutrients, like vitamin D, also plays a role (32).
Summary Eating the recommended amount of vit A may help protect your bones and reduce your risk of fractures, though the connection between this vitamin and bone health is not fully understood.
Likewise, animal studies have suggested that vitamin A deficiency in females can impact reproduction by reducing egg quality and affecting egg implantation in the womb (33).
In pregnant women, vitamin A is also involved in the growth and development of many major organs and structures of the unborn child, including the skeleton, nervous system, heart, kidneys, eyes, lungs and pancreas.
Therefore, many health authorities recommended that women avoid foods that contain concentrated amounts of vitamin A, such as pâté and liver, as well as supplements containing vitamin A during pregnancy.
Summary Adequate amounts of vit A in the diet are essential for reproductive health and the healthy development of babies during pregnancy.
Vit A is a fat-soluble vitamin, which is stored in your body. This means that excess consumption can lead to toxic levels.
Hypervitaminosis A is caused by consuming too much preformed vitamin A through your diet or supplements containing the vitamin.
Symptoms can include nausea, dizziness, headaches, pain and even death.
Though it can be caused by excessive intake from the diet, this is rare compared to overconsumption from supplements and medications.
Additionally, eating a lot of provitamin A in its plant form doesn’t carry the same risks, as its conversion to the active form in your body is regulated (37).
Summary Eating high amounts of the active form of vit A from animal foods, medications or supplements can be toxic. Excessive consumption of provitamin A from plant foods is unlikely.
Vitamin A is vital for many important processes in your body.
It’s used to maintain healthy vision, ensure the normal functioning of your organs and immune system, as well as establishing normal growth and development of babies in the womb.
Both too little and too much vitamin A could have negative effects on your health.
The best way to ensure you get the balance right is to consume vitamin-A-rich foods as part of your normal diet and avoid supplementing with excessive amounts.