What is Vitamin A?
Along with other minerals, vitamins, and other compounds, vitamin A is an essential micronutrient. Your body cannot manufacture it; therefore, it must be included in your diet (1).
Vitamin A is a fat-soluble vitamin, which signifies that apart from the oral route it can also be absorbed via the skin.
Although vitamin A is considered a singular nutrient it’s the name for a group of fat-soluble compounds. Its many forms are also referred to as retinoids; retinol, retinoic acid, retinal, and retinyl esters are some of them.
Many components of the body, including the eyes, skin, and immune system, require this nutrient for optimal growth and function.
Many foods like fruits, vegetables, and seafood, include it. Plants include a group of compounds known as carotenoids. In the body, some can be restored to vitamin A.
This vitamin is most typically used to treat vitamin A deficiency. It’s also used to treat acne, cataracts, delayed growth in children, infections, and a variety of other ailments.
Vitamin A won’t grant you superhuman night vision or eliminate your need for contact lenses, but it will help you maintain good eye health.
Vitamin A also promotes white blood cell formation and activity, aids in bone remodeling, maintains healthy endothelial cells (those that line the body’s internal surfaces), and regulates cell growth and division, which is necessary for reproduction.
What are The Food Sources of Vitamin A?
Friends, two types of vitamin A are found in the human diet. These are:
Preformed vitamin A
It is found in animal products such as meat, fish, poultry, and dairy foods.
Provitamin A
These are also known as precursors to vitamin A and are found in plant-based foods such as vegetables and fruits. The most common type of these is beta-carotene.
This vitamin is also available in dietary supplements. It usually comes in the form of preformed vitamin A (retinyl palmitate or retinyl acetate), provitamin A (beta-carotene), or a combination of preformed and provitamin A.
Evidence suggests that eating a variety of vitamin A-rich foods is beneficial for the human body.
Main food sources of Vitamin A or vitamin A-rich foods are:
- Green leafy vegetables (like spinach, kale, broccoli),
- Vegetables that are orange and yellow (like carrots, pumpkin, sweet potatoes, and other summer squash, winter squash),
- Fish oils,
- Red bell peppers,
- Beef liver
- Mango,
- Cantaloupe,
- Tomatoes,
- Dairy products,
- Eggs, and
- Fortified foods.
Although the health benefits of vitamin A supplementation are less obvious, fruits and vegetables, in particular, are preventive against some diseases.
Animal products, fortified meals, and vitamin supplements all contain preformed vitamin A. Carotenoids are generally existing pigments based in plants.
Retinol (preformed vitamin A) is added to many breakfast cereals, drinks, dairy products, and other foods.
Beta-carotene, lutein, lycopene, and zeaxanthin are found in many fruits and vegetables, as well as some supplements.
What are The 7 Uses and Health Benefits of Vitamin A?
This vitamin is very beneficial for your health. The main 7 uses and health benefits of Vitamin A are as under:
1) Vitamin A is a Potent Antioxidant
Alpha-carotene, beta-carotene, and beta-cryptoxanthin are Provitamin A carotenoids and have potent antioxidant properties.
Carotenoids fight with free radicals, which are highly reactive molecules and can harm your body by creating oxidative stress (2). This oxidative stress has been linked to many chronic diseases like diabetes, heart disease, cancer, and cognitive decline (3).
So friends, diets that are high in carotenoids are linked with a decreased risk of many of these conditions, such as heart disease, diabetes, and cancer.
2) Vitamin A is Essential for Eye Health & May Prevents Macular Degeneration
This vitamin is very essential to vision and eye health.
One of the first few symptoms of vitamin A deficiency is night blindness.
According to researchers, retinol not only creates the pigments in the retina of your eye but is also integral for good vision mainly night vision, and your eye’s whole health.
Sufficient dietary intake of vitamin A also helps to prevent certain eye diseases, like night blindness, and age-related macular degeneration (AMD).
Studies have shown that higher blood levels of alpha-carotene, beta-carotene, and beta-cryptoxanthin were associated with a 25% to 35% lower risk of advanced AMD (4). This lower risk is associated with carotenoid nutrients’ protection of macular tissue by lowering levels of oxidative stress.
3) It May Lower the Risk of Cancer
Due to their antioxidant properties, adequate intake of carotenoids, carotene, and vitamin A may protect against certain types of cancer.
A study conducted on 10,000 adults has shown that the risk of dying from lung cancer in smokers was significantly decreased to 46% and 61% with the highest blood levels of alpha-carotene and beta-cryptoxanthin, respectively, than non-smokers with the lowest intake of these nutrients (5).
In vitro studies reveal that retinoids may inhibit the growth of certain cancer cells, such as breast, bladder, and ovarian cancer (6)
4) Vitamin A boosts Your Immune System
By stimulating responses that defend your body from infections and illnesses, vitamin A impacts your immune health.
It is involved in the formation of certain cells, such as B- and T-cells, which play important roles in immune responses that guard against disease.
Vitamin A plays a key role in immune function, including cell-mediated immunity, innate immunity, and humoral antibody immunity. Thus, deficiency of this vitamin may lead to increased levels of pro-inflammatory molecules that lower immune system response and function (7).
5) Vitamin Promotes Fertility and Fetal Development
Vitamin A is crucial for both female and male reproduction because it plays a role in egg and sperm development.
This vitamin is also essential for placental health; and the growth and development of the embryo (8).
Hence, vitamin A is important to maternal and fetal health and also to those who are trying to conceive.
6) It May Prevent Diabetes
Various studies have revealed that people are less likely to suffer from impaired glucose tolerance and diabetes with sufficient levels of vitamin A.
7) Vitamin A Benefits for Skin
Vitamin A plays an important role in the overall health of your skin. When you consume this vitamin, your liver converts it to retinol.
When it is applied topically to the skin, then it is absorbed and the skin stops being overly dry. This is due to the reason that retinol is a key ingredient that encourages the production of new skin cells (9).
Persistent deficiency of vitamin A results in xerosis and follicular hyperkeratosis (excess keratin in the hair follicles on the skin) (9).
Vitamin A has the following benefits for the skin:
a) It May Slow Down The Signs Of Aging
This vitamin can be applied topically on the skin or you can also include it in your diet.
It is a potent antioxidant and supports collagen production. This helps to reduce wrinkles, fine lines, and saggy skin, which can be caused because of collagen damage.
b) It May Protect Against Skin Infection
Your skin is the first line of defense against bacteria, pollutants, and several other infections.
Vitamin A encourages the production of new skin cells and strengthens your skin.
Thus, it helps to fight skin infections.
c) Vitamin A May Help Reduce Acne
Retinoic acid is a major ingredient of Isotretinoin, a drug used to treat acne (10). Isotretinoin also benefits from sebum regulation, and thus also helps to treat acne.
d) Vitamin A may Promote Wound Healing
This vitamin may repair the skin from everyday damage
Vitamin A also boosts the growth of fibroblasts, skin cells, and other skin tissues. It also promotes collagen synthesis.
Retinol, retinoic acid, and retinal acid, which are derivatives of vitamin A, play an important role in the growth of skin cells (9).
When your body is deficient in vitamin A, your skin gets weakened and is more prone to wounds.
e) It May Provide Photoprotection
This vitamin absorbs certain UV radiation and has a photoprotective action on your skin.
Vitamin A is the parent compound of retinyl esters, and these esters work on the epidermis and absorb ultraviolet radiation (11). This helps to protect your skin from sun damage.
How to Use Vitamin A?
These are the guidelines to use vitamin A
You should follow the directions on the packaging or your doctor’s prescription for Vitamin A.
Do not transcend the suggested dosage or use it for longer than the recommended time.
Any usage instructions that come with your medicine should be carefully read and followed, or follow your doctor’s guidance.
If you don’t understand something, consult with your doctor or pharmacist.
Daily Recommended Dose of Vitamin A
The daily recommended dose of Vitamin A varies from person to person based on their sex, age, and physical condition.
Females need more Vitamin A during pregnancy and while breastfeeding.
This vitamin is available in several forms, and the vitamin A content in foods is often measured as retinol activity equivalents (RAEs).
| 1 mcg of retinol | |
| One RAE is equal to | 12 mcg of beta-carotene from food |
| 2 mcg of beta-carotene from supplements | |
| 3.33 international units (IU) of vitamin A |
The list below has the information regarding the proper daily dosage of Vitamin A:
- Adult men: 900 mcg per day
- Adult women: 700 mcg per day
- Pregnant women: 750-770 mcg per day
- Breastfeeding women: 1300 mcg per day
- Infants, aged 0-6 months: 400 mcg per day
- Infants, aged 7-12 months: 500 mcg per day
- Children, aged 1-3 years: 300 mcg per day
- Children, aged 4-8 years: 400 mcg per day
- Children, aged 9-13 years: 600 mcg per day
- Children, aged 14-18 years: 900 mcg per day for males and 700 mcg for females
What are the Side Effects of Vitamin A?
When consumed in doses of less than 10,000 units (or 3,000 mcg) per day, vitamin A is probably safe.
Preformed vitamin A (retinol or retinyl ester) and provitamin A are the two types of vitamin A (carotenoids). Symptoms of deficiency and excess of vitamin A are of many types.
Only preformed vitamin A is included in the maximum daily dose. When used in doses larger than 10,000 units (3,000 mcg) per day, preformed vitamin A may be dangerous.
Topical application of Vitamin A on the skin is usually harmless for a short period.
The risk of side effects may increase with higher doses. Prolonged high-dose use can have substantial negative effects on health, including brain health.
High oral doses of vitamin A have also been linked to an increased risk of osteoporosis and hip fracture, mainly in older adults and postmenopausal women.
High doses of vitamin A in children can cause severe sleepiness, child’s growth issues, and loss of consciousness.
Special Warnings
Pregnancy and Breast-Feeding
When used daily, a recommended dose of vitamin A is considered safe. Larger doses may be harmful and may cause birth abnormalities.
However, if you are pregnant, you should seek medical counsel before taking this vitamin.
Although some amount of vitamin A is required for a baby’s normal growth, excessive amounts can cause birth abnormalities.
You may have to consume a prenatal vitamin manufactured especially for pregnant women. Animal liver, some fortified breakfast cereals, and nutritional supplements all contain vitamin A in various forms.
Children
The maximum amount of vitamin A that children can safely consume is determined by their age. When taken orally in excessive doses, it may be harmful to youngsters.
Irritability, diarrhea, drowsiness, and other health issues may occur when excessive doses are taken.
Excessive use of alcohol
Alcohol use may exacerbate vitamin A’s possibly damaging effects on the liver.
Fat Related Disease
Vitamin A is not properly absorbed by people who have disorders that impede fat absorption. Celiac illness, jaundice, short gut syndrome, pancreatic disease, cystic fibrosis, and liver cirrhosis are among these conditions.
Liver Disease
Too much of this vitamin may exacerbate liver illness. If you have liver illness, avoid using vitamin A pills.
Malnutrition
Taking vitamin A supplements may result in an excess of this vitamin in the body in persons with severe protein deficiency.
Zinc deficiency
Vitamin A deficiency symptoms could be caused by a zinc shortage. To improve this disease, a mix of vitamin A and zinc supplements may be required.
Symptoms of Deficiency and Excess of Vitamin A
Vitamin A is an important nutrient that is mandatory to intake to live a healthy life. But its excessive consumption is also harmful. You can see some particular symptoms in case of deficiency or excess of vitamin A in your body.
What are the 10 Symptoms of Deficiency of Vitamin A?
10 symptoms of deficiency of vitamin A are as under:
1. Dry Eye
Vitamin A takes good care of our eyes. The deficiency of it can lead to some eye problems like dry eyes and complete blindness. A dry eye is a condition where our eyes become dry due to being unable to produce enough tears. The condition is known as Xerophthalmia. Complete blindness gets caused due to the drying cornea.
2. Night Blindness
Night blindness is another eye issue that can be faced due to a severe deficiency of vitamin A. It is a condition under which a person can’t see well at night or in less light.
3. Delayed or Stunted Growth
Lack of vitamin A can show a problematic symptom of stunted growth in children. As it is mandatory for the physical development of the human body, children should always receive this vitamin to grow well.
4. Dry Itchy Skin
Vitamin A plays a major role in protecting your skin health as well. The deficiency of it can make your skin dry and itchy.
It helps create new skin cells and also repairs the damaged ones. It also decreases the inflammation caused by multiple skin issues. Eczema can be caused due to a deficiency of vitamin A.
5. Infertility
Vitamin A aids in reproduction in both men and women. The lack of this vitamin can lead to infertility in both men and women.
Deficiency of it may cause trouble in the way of conceiving.
Vitamin A also helps in the proper development of the embryo.
6. Acne
Vitamin A helps in skin development. It also fights again various types of skin inflammation.
So, when the deficiency of vitamin A occurs, the person starts getting acne and its breakouts.
7. Frequent infections
A person having vitamin A deficiency may face frequent infections as their immunity will not be strong enough to fight against the pathogens. These infections usually happen in the throat and chest sections of the human body.
8. Slower wound healing
It helps in faster wound healing. It also promotes collagen creation in your body. Collagen keeps your skin healthy.
Thus, a deficiency of vitamin A can make your wounds heal slowly.
9. Keratinisation
Keratinisation is a process in which the cells of the urinary, respiratory, and gastrointestinal tracts get filled with keratin. The process produces dead cells that structure tough forms within the tracts.
10. Bitot’s Spot
In this health condition, keratin builds up in the conjunctiva of the human eyes. Bitot’s spot can be triangular, oval, or irregular in shape. These spots are a sign of Vitamin A deficiency and are associated with the drying of the cornea.
How Does The Deficiency of Vitamin A Get Diagnosed?
An eye check-up by an experienced doctor can reveal that you have vitamin A deficiency.
Your medical history may also help in the diagnosis.
Sometimes, a blood test is suggested to know the amount in your blood. The normal range of vitamin A in the blood is from 15 to 60 mcg/dL (i.e. micrograms per deciliter), so anything below 15 mcg/dL is considered deficient.
Early diagnosis of vitamin A deficiency can prevent long-term consequences like blindness from developing.
What are The Reasons Behind Vitamin A Deficiency?
There can be multiple reasons behind vitamin A deficiency in the human body.
The main reason behind this is malnutrition. Vitamin A deficiency is prevalent in South Asian as well as African countries.
Infections like measles can cause the symptoms of its deficiency to worsen.
Some gastrointestinal diseases may interfere with the absorption of vitamin A in adults. These diseases are:
- Celiac disease
- Pancreatic insufficiency
- Bile duct disorder
- Minimal food intake, like due to an eating disorder
- Giardiasis
- Liver Cirrhosis
- Duodenal bypass
Orlistat is a drug used by people who want to lose weight, but this drug may reduce the body’s ability to absorb fat-soluble vitamins such as vitamin A; and thus increase the risk of vitamin A deficiency.
What are the Symptoms of Vitamin A toxicity or Excess of vitamin A or hypervitaminosis A?
Vitamin A is very important for overall health, but too much of it can be dangerous. Consumption of too much Preformed vitamin A can lead to vitamin A toxicity and this condition is also called Hypervitaminosis A.
To prevent toxicity of vitamin A you shouldn’t exceed its tolerable upper limit (UL) is 10,000 IU (3,000 mcg) for adults.
As you know vitamin A is fat-soluble, it is stored in your body and can reach harmful levels over time.
Its excessive consumption can lead to serious side effects and can even be fatal if eaten at extremely high doses.
Its toxicity is usually linked to excessive supplement intake or treatment with certain medications, such as Isotretinoin.
Based on the severity of the condition, it is divided into two types, acute and chronic.
Acute vitamin A toxicity occurs over a short time period when a single, excessively high dose of this vitamin is ingested, whereas chronic toxicity can occur with long-term ingestion of its supplements 10 times higher than the recommended daily dose (RDA) (12).
The most common side effects of chronic vitamin A toxicity frequently referred to as hypervitaminosis A are:
- Sunlight sensitivity
- Nausea and vomiting
- Poor appetite
- Vision disturbances
- Joint and bone pain
- Headache
- Liver damage
- Confusion
- Jaundice
- Hair loss
- Dry skin
- Jaundice
- Itchy skin
- Delayed growth
Though less commonly, acute vitamin A toxicity is linked with more severe symptoms, like increased cranial pressure, liver damage, and even death.
Vitamin A toxicity can also negatively affect maternal and fetal health and may lead to teratogenic effects (13).
The tolerable upper limit (UL) for vitamin A applies to animal-based food sources of vitamin A and its supplements.
However, a high intake of dietary carotenoids is not linked with toxicity, although studies link beta-carotene supplements with an increased risk of heart disease and lung cancer in smokers (14).
Hence, always consult with your doctor before taking vitamin A supplements.
What is the Diagnosis and Solution of Hypervitaminosis A (or Toxicity of Vitamin A)?
Hypervitaminosis A can be diagnosed through blood tests.
Decreasing the amount of vitamin A intake in your diet, or stop consuming its supplements can normalize levels of this vitamin in your body.
Conclusion
Vitamin A is a fat-soluble nutrient that is very essential for your well-being and is vital to eye health, immune function, reproduction, and fetal development.
Both its deficiency and overconsumption can make your body face multiple health issues.
This vitamin is easily available both in natural sources and medicinal forms. Its daily consumption is mandatory to stay healthy.
References:
1) What is vitamin A and why do we need it?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3936685/
2) Free radicals, antioxidants and functional foods: Impact on human health
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249911/
3) Oxidative Stress: Harms and Benefits for Human Health
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5551541/
4) Intakes of Lutein, Zeaxanthin, and Other Carotenoids and Age-Related Macular Degeneration During 2 Decades of Prospective Follow-up
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5119484/
5) Serum carotenoid levels and risk of lung cancer death in US adults
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4317899/
6) Vitamin A, Cancer Treatment and Prevention: The New Role of Cellular Retinol Binding Proteins
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4387950/
7) Effect of vitamin A deficiency on the immune response in obesity
https://pubmed.ncbi.nlm.nih.gov/22369848/
8) Vitamin A in Reproduction and Development
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257687/
9) Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2699641//
10) The use of isotretinoin in acne
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2835909/
11) Vitamin A Exerts a Photoprotective Action in Skin by Absorbing Ultraviolet B Radiation
https://www.jidonline.org/article/S0022-202X(15)30495-4/fulltext
12) Hypercalcaemia Secondary to Hypervitaminosis A in a Patient with Chronic Renal Failure
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4655642/
13) WHO Guideline: Vitamin A Supplementation in Pregnant Women. Geneva: WHO, 2011; WHO Guideline: Vitamin A Supplementation in Postpartum Women. Geneva: WHO, 2011
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3648723/
14) Beta-carotene and lung cancer in smokers: a review of hypotheses and status of research
https://pubmed.ncbi.nlm.nih.gov/20155614/
Disclaimer: This article is intended for informational purposes only. Any information associated with this article should not be considered as a substitute for prescriptions suggested by local healthcare professionals.
Recommended Articles:
1) Zinc (Zn): Uses, Benefits, Food Sources, & Side Effects