Vitamin A: Sources, Health Benefits, Deficiency, Side effects, RDA

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.

The most common symptoms of vitamin A deficiency include:

1. Vision issues: such as night blindness and, in extreme cases, complete blindness. [1]
2. Dry or inflamed skin: vitamin A is essential for the creation and repair of skin cells, and its deficiency can lead to skin problems such as dryness, itching, and scaling. [2]
3. Increased susceptibility to infections: vitamin A deficiency can impair immunity, leading to a higher risk of infections, particularly respiratory infections. [3]
4. Difficulty conceiving: vitamin A is important for fertility, and its deficiency can lead to difficulty conceiving. [7]
5. Other symptoms: such as chest infections, Bitot spots (a buildup of keratin in the eyes), and xerophthalmia (a condition where the eyes become very dry and crusted, which may damage the cornea and retina). [4]

Vitamin A deficiency is rare in developed countries, but it can occur in certain populations, such as pregnant women, breastfeeding mothers, infants, and children, especially in developing countries.

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. [5]

Apart from better vision, vitamin A has several other health benefits. Some of the key benefits include:

1. Immune System Support: Vitamin A is important for the normal functioning of the immune system, helping the body fight infections and keeping the immune cells healthy. [6]
2. Reproductive Health: It plays a crucial role in reproductive health, including the normal development of embryos and the maintenance of healthy fetal growth. [7]
3. Cell Growth and Development: Vitamin A is essential for the growth and development of cells, which is important for various physiological processes in the body. [7]
4. Eye Health: In addition to improving vision, vitamin A supports the function of the cornea, which is the protective outer layer of the eye. [8].
5. Reduced Risk of Certain Conditions: Adequate levels of vitamin A may help reduce the risk of conditions such as age-related macular degeneration, infectious diseases, and some eye conditions. [8]

It’s important to ensure that you get enough vitamin A through a healthy and balanced diet, as it is crucial for overall health and well-being.

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 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.

Age Group	Male (mcg RAE/day)	Female (mcg RAE/day)
0-6 months	400	400
7-12 months	500	500
1-3 years	300	300
4-8 years	400	400
9-13 years	600	600
14-18 years	900	700
19+ years	900	700

The table above provides the daily intakes of vitamin A (measured in mcg RAE – Retinol Activity Equivalents) by age and gender, based on the Recommended Dietary Allowances (RDAs) from the National Academies of Sciences, Engineering, and Medicine[3].

Sources:

[1] https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/
[2] https://ods.od.nih.gov/HealthInformation/nutrientrecommendations.aspx
[3] https://www.consumerlab.com/rdas/
[4] https://www.webmd.com/vitamins-and-supplements/vitamins-minerals-how-much-should-you-take
[5] https://health.gov/our-work/nutrition-physical-activity/dietary-guidelines/previous-dietary-guidelines/2015/advisory-report/appendix-e-3/appendix-e-31a4

Vitamin A Foods

Here is a table with the top 10 foods that contain vitamin A per 100 grams, including the DV%:

Food	Vitamin A per 100g	DV%
Sweet Potato	19218 IU	384%
Carrot	16706 IU	334%
Kale	6813 IU	136%
Spinach	46900 IU	938%
Butternut Squash	11155 IU	223%
Red Bell Pepper	3131 IU	63%
Apricot	1926 IU	39%
Cantaloupe	1696 IU	34%
Mango	54 IU	1%
Salmon	59 IU	1%

These values are based on the USDA FoodData Central and other reliable sources. The Daily Value (DV) is based on a recommended daily intake of 5000 IU of vitamin A.

You may want to check this bigger list of 21 Everyday Foods Packed With 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:

• Vitamin A can improve the appearance of wrinkles and sagging, reduce hyperpigmentation and other sun damage, and help address acne.
• It affects the skin in a dose-dependent manner, and both too little and too much vitamin A can have deleterious effects.
• Retinoids, a synthetic form of vitamin A, are used to help clear up severe acne and psoriasis.
• Topical vitamin A is the most studied treatment on the market for aging and acne and is an optimal approach for maintaining healthy skin.

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

• Topical vitamin A is effective for reducing fine wrinkles, splotches, roughness, and treating acne.
• Prescription creams and pills containing retinoids, a synthetic form of vitamin A, are used to help clear up severe acne and psoriasis.

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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