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Vitamin A is one of the most important vitamins for the proper functioning of the body. What exactly are its actions in our body and in which cases do we need supplementation? In this article, we are going to explore what is vitamin a, Vitamin A health benefits, Vitamin A sources, its potential side effects, and everything you need to know about this Vitamin.

What is Vitamin A

Vitamin A is a fat-soluble vitamin stored in the liver. There are two types of vitamin A in the diet, the precursor form of the vitamin (retinol) found in meat, fish, poultry, and dairy products, and provitamin A which is found in mainly plant foods (fruits and vegetables).

There are various forms of provitamin A, commonly known as carotenoids. Over 500 carotenoids have been identified in nature which can be converted into vitamin A, but the most common of these is beta-carotene.

Related: Vitamin C: Sources, Health Benefits, Deficiency, Side effects, RDA

Vitamin A Deficiency

Although Vitamin A deficiency is relatively rare in the western world, it is widespread in children in underdeveloped countries and is generally associated with malnutrition.

Symptoms of deficiency include:

  • Impaired vision in the dark (due to reduced sensitivity of the rods in the retina).
  • Dry eyes (may be irreversible) are characterized by simultaneous dryness of the cornea and conjunctiva, ulceration, and liquefaction. The final outcome is a significant reduction in vision and blindness.
  • Dry skin and the presence of a discontinuity in the dermal layers (not a unique indicator of vitamin A deficiency, as other nutrient deficiencies cause similar disorders).
  • Metaplasia and keratinization of cells of the respiratory tract and other organs;
  • Increased susceptibility to respiratory and urinary tract infections;
  • Occasional diarrhea and loss of appetite.

Vitamin A Health Benefits

Vitamin A has many different actions in the body. Most important are:

Better Vision: Many studies have shown that people who take adequate amounts of vitamin A are less likely to develop macular degeneration, cataracts. [1]

Other Vitamin A health benefits include:

  • It is involved in the health of teeth, bones
  • Involved in maintaining the integrity of the skin and cell membrane
  • Participates in the functioning of vision
  • Contributes to reproductive capacity

Vitamin A Side Effects

Vitamin A, being fat-soluble, has the ability to be stored in the body, particularly in the liver. Taking large doses of vitamin A, through diet or supplements, is not desirable. For this reason, it is advisable to take vitamin A supplements under the supervision of a doctor.

Beta-carotene is not stored in the body. However taking large doses can cause a yellow-orange pigmentation on the skin, which returns to normal once it is stopped or ingested.

People with diabetes, liver disease should not take vitamin A without the approval of physicians. In addition, alcoholics and people who smoke should not take beta-carotene supplements.

Both vitamin A and beta-carotene supplementation can increase serum triglyceride levels. [2]

Although Vitamin A is a crucial micronutrient for pregnant women, taking excessive vitamin A intake during pregnancy can be a concern since, when in excess, this micronutrient may exert teratogenic effects in the first 60 days following conception. [3]

Vitamin A: Sources, Health Benefits, Deficiency, Side effects, RDA
– Carrots are geat source of Vitamin A

Vitamin A Daily Requirements

Vitamin A is fat-soluble, so it is recommended to be taken in the presence of a meal with fat. The upper intake for adults is 10,000 IU (3000 mcg) per day, however, it is recommended that men should not exceed 900 mcg and women 700 mcg, respectively, which are the recommended daily intakes.

Here’s a more detailed list of the amount of Vitamin A that people should receive either from food or supplementation.

  • Adult women – 7500 μg (25000 IU)
  • Pregnant women – 2400 μg (8000 IU)
  • Adult men – 9000 μg (29700 IU)
  • Infants – 900 μg (2970 IU)
  • Children 1 – 3 years – 1800 μg (5940 IU)
  • Children 4 – 6 years – 3000 μg (9900 IU)
  • Children 6 – 12 years – 4500 μg (14850 IU)
  • Teenagers – 6000 μg (19800 IU)

Therapeutic dosage should not exceed these limits, except when the patient is under medical supervision. For example, in cystic fibrosis, doses of 1200 – 3300 μg (4000 – 10000 Units) may be given.

Vitamin A Foods

Here’s a list of foods that contain adequate amounts of Vitamin A.

  • Sweet potatoes – Sweet potatoes are arguably the best source of vitamin A. 100 grams provide 384% of our body’s daily requirement. Sweet potatoes are richer in fiber than white and yellow potatoes and have a lower glycaemic index. Because vitamin A is fat-soluble, you’ll absorb it better if you combine the potato with just five grams of olive oil, some avocado, or olives.
  • Liver – 85 grams of roasted liver will provide 444% of your daily requirement. The liver is the main organ in animals and humans where extra vitamin A is stored, so it is the richest animal source of this vitamin. However, liver also contains a lot of saturated fat, so it’s not the top choice of nutritionists – especially compared to the other alternatives on this list.
  • Spinach – is a particularly important source of vitamins A, C, K and folate, and 100g provides 188% of the recommended daily allowance of vitamin A. Combine it with something fatty to help absorb the fat-soluble vitamins.
  • Tuna – Tuna is the king of fish when it comes to vitamin A. Fresh tuna provides 44% of the recommended daily value per 100g.
  • Broccoli – The other dark green vegetable that is high in vitamin A, broccoli provides up to 24% of the recommended daily value per 1/2 cup (boiled), as it is rich in many of the same antioxidants and nutrients as spinach.
  • Carrots – Vitamin A in carrots is present in the form of beta-carotene, a healthy antioxidant. Carrots are extremely rich in beta-carotene and contain 334% of the recommended daily amount of vitamin A per 100g.
  • Melon – Melon is a low-calorie, vegetarian source of vitamin A. 100g can provide you with 68% of your daily requirement.
  • Mango – This delicious tropical fruit is a storehouse of many important nutrients and can be an important addition to a healthy and balanced diet. A medium-sized mango provides about 70% of the daily recommended amount of vitamin A.
  • Tomatoes – Tomatoes are calorie-poor while providing many vitamins and minerals. A medium-sized tomato can provide 20% of our daily vitamin A requirement.
  • Dried Apricots – 10 dried apricots provide us with up to 25% of the body’s recommended daily requirement. Just watch the portions you consume as dried fruit has more sugar and calories than fresh fruit.
  • Pumpkin – Raw or cooked, pumpkin is extremely tasty and nutritious food and is rich in beta-carotene. 100 grams of cooked pumpkin contains 223% of the recommended daily value.
  • Red peppers – Another excellent source of vitamin A. One cup of red peppers can contribute almost 100% of the daily recommended value. Green peppers provide 12% and yellow peppers provide 7%.
  • Low-fat milk – Because it’s fortified, a cup of milk has about 10% of your daily vitamin A requirements. While the amount isn’t particularly high, it’s still a good way to go if you consider that you’re also getting protein, calcium and vitamin D at the same time.
  • Fatty fish – Oily fish is the best option since vitamin A is a fat-soluble vitamin. Salmon, herring and trout are all decent sources. 85g of cooked salmon provides 4% of our daily requirements.
  • Black-eyed peas – Half a cup of this favourite legume provides 13% of the recommended daily value of vitamin A.

Related: Vitamin D: Sources, Health Benefits, Deficiency, Side effects, RDA

Vitamin A Toxicity

A single dose of 300 mg retinol (1 million units) in adults, 60 mg retinol (200000 units) in children, or 30 mg retinol (100000 units) in infants can cause acute toxicity.

Signs and symptoms are usually transient (most commonly occurring about 6 hours after digestion of the acute dose and disappearing after 36 hours) and include:

Severe headache (due to increased intracranial pressure)

  • Mouthalgia
  • Bleeding gums
  • Blindness
  • Confusion
  • Nervousness
  • Blurred vision
  • Hepatomegaly (Enlarged Liver)
  • Irritability

When daily intake is >15 mg retinol (50000 units) in adults and 6 mg (20000 units) in infants and young children, signs of chronic toxicity may occur.

Symptoms may include

  • Dry skin
  • Dermatitis
  • Epidermal rash
  • Disturbances in hair growth
  • Pain in bones and joints
  • Periostosis
  • Cephalalgia
  • Fatigue
  • Insomnia
  • Anorexia
  • Nervousness
  • Vomit
  • Diarrhea
  • Loss Weight
  • Liver enlargement
  • Hepatotoxicity (Liver Toxicity)
  • Increased intracranial pressure
  • Hypercalcemia (due to increased alkaline phosphatase functionality)

The signs and symptoms experienced vary widely from person to person. Most disappear within a week after intake is reduced, but changes in skin and bone remain evident for many months [4].

Vitamin A Pregnancy

Excessive doses of vitamin A appear to cause teratogenesis, although the levels at which this occurs have not been well established.

It is recommended that pregnant women, or women planning to have a child, should not take dietary supplements containing vitamin A (such as fish oils) unless recommended by a doctor. They should also avoid eating excessive foods rich in vitamin A, such as liver, etc.

Important: Vitamin A is essential during pregnancy. But NOT in excessive doses. According to the research paper Vitamin A and Pregnancy: A Narrative Review

Vitamin A is a crucial micronutrient for pregnant women and their fetuses. In addition to being essential for morphological and functional development and for ocular integrity, vitamin A exerts systemic effects on several fetal organs and on the fetal skeleton. Vitamin A requirements during pregnancy are therefore greater. Vitamin A deficiency (VAD) remains the leading cause of preventable blindness in the world.

Vitamin A For Skin

Vitamins are essential for maintaining optimal levels of health, appearance, and function of the skin. Here is what happens when you supply your body with vitamin A:

  • It protects it from the damage of ultraviolet radiation and delays the signs of aging. Most of your vitamin A intake comes from eating foods rich in beta-carotene and provitamin A carotenoids, which are powerful antioxidants. Not only do they fight free radicals that destroy collagen and contribute to the formation of fine lines, wrinkles, and loose skin, but they also reduce the skin’s sensitivity to the sun, providing a kind of natural protection against redness and pigmentation caused by sunlight. [5]
  • It encourages healthy skin cell production. Vitamin A also stimulates fibroblasts – the cells responsible for the growth of tissues that keep skin firm and healthy – in the deep layers of the epidermis.
  • It protects against infections. The skin is an important part of the immune system. It is the first line of defense against bacteria, pollutants, and infections. By promoting cell production, vitamin A helps strengthen this barrier, protecting the skin.
  • It takes care of hair growth. Without enough vitamin A, hair follicles become weak and dry, which leads to thinning and falling hair. By ensuring that you eat enough vitamin A-rich foods, you keep your scalp hydrated and provide it with the necessary nourishment which contributes to the growth of healthy and strong long hair.

Here’s what happens when you apply vitamin A topically:

  • It smooths out wrinkles. Vitamin A in the form of retinol and also retinoic acid used in creams and topical preparations are proven to fight wrinkles and many dermatologists recommend it. Research has shown that these ingredients are able to stimulate collagen production. Retinoids activate the cells responsible for creating new collagen, strengthening the skin, and filling in fine lines beneath the surface so that the skin looks smoother and healthier.
  • Smoothes skin tone and offers radiance. Vitamin A creams can help remove brown spots caused by the sun and enhance the skin’s glow in two ways: First, by increasing and smoothing skin cell production, which helps to remove pigmented, damaged and rough surface cells, allowing light to reflect off the skin more evenly. Secondly, retinoids can block an enzyme required for melanin production, further helping to achieve an even, glowing complexion.
  • It fights acne. Pimples form when pores become clogged with dead skin cells, bacteria, and oily substances providing the perfect breeding ground for Propionibacterium acnes, a common bacteria responsible for the acne problem. Vitamin A creams stimulate cellular reproduction, the same process occurs within the pores themselves, helping to slow down oil production and keep the pores clean.
Vitamin A: Sources, Health Benefits, Deficiency, Side effects, RDA
– Pumpkin and Pumpkin Soup is filled with Vitamin A

Vitamin A For Eyes

Vitamin A helps protect the outer surface of the eye (the cornea) and is important for good vision.

Studies show that eye ointments with vitamin A are effective in treating dry eyes. Indeed, one study showed that inexpensive eye ointments containing Vitamin A are as beneficial as the more expensive eye drops used to treat dry eye syndrome.

Vitamin A eye ointments have also been shown to be beneficial for treating a specific type of eye inflammation known as keratoconjunctivitis of the superior scleral margin [6]. Vitamin A, in combination with other antioxidant vitamins, plays an important role in reducing the risk of age-related macular degeneration (AMD).

Under the auspices of the Age-Related Eye Disease Study (AREDS) conducted by the National Eye Institute, people at high risk of developing the disease who received daily provitamins containing vitamin A (in the form of beta-carotene), vitamin C, vitamin E, zinc, and copper showed a 25% reduction in the risk of calcifying AMD within a 6-year follow-up period.

In addition, it has been shown that the combination of vitamin A and lutein can prolong vision in people suffering from melanocytic retinopathy (RP).

A recent four-year study conducted by researchers at Harvard University School of Medicine and other prominent universities found that people suffering from retinopathy who took daily dietary supplements of Vitamin A (15,000 IU) and lutein (12mg), showed a slowing of peripheral vision loss compared to people who did not take these combination supplements [7].

In early 2011, researchers at Columbia University Medical Center (New York) discovered that a complex, diversified form of vitamin A is likely to slow the development of Stargardt’s disease, an inherited eye disease that causes severe vision loss in young people [8].

When given to mice with the same genetic defect as humans suffering from Stargard’s disease (also known as juvenile macular degeneration), synthetic vitamin A inhibited the development of deposits in the retina known as vitamin A dimmers, which are associated with degenerative mutations and vision loss.

Vitamin A Supplements

Vitamin A is commercially available in supplements in both tablet and capsule form, either in the form of retinol or retinyl palmitate. Here are some of the best Vitamin A Supplements currently in the market.

Vitamin A Vs Retinol

Vitamin A is the general term used to describe the compounds that demonstrate the biological activity of retinol. Vitamin A is fat-soluble. The two main components of vitamin A in foods are retinol and carotenoids.

The term ‘retinoids’ refers to retinol or other natural derivatives such as retinol (retinaldehyde), retinoic acid, and retinyl esters. Retinoids also include synthetic analogs whether or not they exhibit the biological activity of retinol.

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