Medical Reviewed by Dr. Shanmukha Priya, M.Phil and Ph.D. in Food Science and Nutrition
From protecting your eyesight to keeping your skin smooth, Vitamin A performs crucial functions in the human body. It is also important for fetal development in pregnant mothers. However, poor dietary lifestyle leads to Vitamin A deficiency.
Dietary modifications will be made and in case of severe deficiency, supplements will be provided to reverse the Vitamin A deficiency.
In this article, we bring you all about Vitamin A – its deficiency, cause, food source and Vitamin A toxicity.
What is Vitamin A?
Vitamin A is a fat-soluble vitamin that ensures a healthy immune function, promotes cell growth and is responsible for eye health. This vitamin is of two types.
While the first type is retinoids, the second type is called beta-carotene. Retinyl esters and retinol, the preformed Vitamin A (first type), occurs in animal products like fish, liver, meat and dairy. The provitamin A, carotenoids, can be found in plant-based foods like vegetables, fruits and oils.
Apart from food sources, Vitamin A can be obtained from supplementary medications too.
Retinoic acid and retinal are the active forms of Vitamin A and the body must convert the preformed Vitamin A and provitamin A to the former to use it. Since this Vitamin is a fat-soluble vitamin, the body stores it in the liver for later use.
Benefits of Vitamin A
Vitamin A performs a number of functions in the human body and the important functions are listed below.
1. Keeps the eyes healthy
Vitamin A preserves the eyesight and it converts the light that touches the eye into an electrical signal that is sent to the brain. Night blindness (nyctalopia) and xerophthalmia are the first signs of Vitamin A deficiency. This is because; their eyes find it difficult to pick the low-level light during the night.
Eating adequate beta-carotene can help slow down eyesight declination that few may experience due to age.
2. Enhances Immunity
Vitamin A maintains the body’s immunity and strengthens its natural defence system. This Vitamin protects the mucous barriers in the eyes, gut, genitals and lungs. This barrier helps trap infectious agents and bacteria.
Vitamin A also helps with the function and production of WBC (white blood cells) which will help the body clear the bacteria from the bloodstream. Vitamin A deficiency can make the person prone to catching infections and can delay the recovery if they fall sick.
Studies reveal that reversing Vitamin A deficiency in children affected by malaria or measles has shown to reduce the risk of them dying from these diseases. This is especially in developing countries where these diseases are common. 
3. Helps with reproduction and growth
Vitamin A is essential for the maintenance of a healthy reproductive system in males and females. It supports embryo development and normal growth during pregnancy.
Studies on rats have revealed that Vitamin A deficiency can affect the growth of sperm cells. Likewise, in females, Vitamin A deficiency can reduce the quality of the egg and affect the egg implantation in the womb.
4. Good for the bones
Apart from Vitamin D, Vitamin A is also essential for the growth and maintenance of bones. People with Vitamin A deficiency are prone to fractures.
It is important to note that Vitamin A alone is not enough to determine fracture risks. The intake of other essential nutrients and Vitamin D also plays a role here.
5. Keeps the skin healthy
Vitamin A deficiency can cause acne. According to certain studies, this deficiency can cause the overproduction of the keratin protein in the hair follicles which can lead to acne. However, the correlation between Vitamin A and acne is still unclear.
6. Can reduce the risk of developing certain cancers
However, Vitamin A obtained through plants is only associated with reduced cancer risks and not animal foods. Likewise, Vitamin A supplements have not exhibited any benefits for cancer.
It is worth mentioning that the relation between Vitamin A levels in the body and reduced cancer risk remains inconclusive.
Vitamin A deficiency
A survey conducted by the National Nutrition Monitoring Bureau (NNMB, 2006) reported a prevalence of 61 % of subclinical VAD at the national level
Vitamin A deficiency is common in developing countries since people living in these countries have very limited access to both animal and plant food sources of Vitamin A.
When left untreated, Vitamin A can cause health complications. According to the World Health Organization (WHO), Vitamin A deficiency is the cause of preventable blindness in kids across the globe.
This deficiency increases the risk of patients dying from diarrhoea and measles.
To boot, Vitamin A deficiency also increases the risk of pregnant women developing anaemia and may even die due to other complications. Vitamin A deficiency also affects the foetus negatively by slowing its development and growth. 
While the above are severe complications, some of the milder symptoms include acne and hyperkeratosis – both are skin issues.
People who are at risk of developing Vitamin A deficiency include patients suffering from cystic fibrosis, premature infants, pregnant and lactating women. This is more prevalent in developing countries.
Symptoms of Vitamin A deficiency
One of the foremost symptoms of Vitamin A deficiency is impaired vision since Vitamin A is directly related to eye health. Apart from this, other symptoms include skin issues, weakened immunity and impaired reproductive function.
Below are some of the other common symptoms of Vitamin A deficiency.
1. Dry eyes and skin
Vitamin A is involved in repairing and creating skin cells. Lack of Vitamin A can cause eczema – a condition where the skin becomes inflamed, itchy and dry. Studies have revealed that Vitamin A supplements have shown positive effects on treating eczema. 
As mentioned earlier, Vitamin A and eye health are directly related. Severe Vitamin A deficiency can lead to blindness or can dry the corneas. In fact, dry eyes are one of the foremost signs of Vitamin A deficiency.
The good news is this condition can be improved by taking Vitamin A supplements. Likewise, a study revealed that Vitamin A supplements reduced the chances of developing dry eyes by 63% in children and infants.
2. Infertility and the inability to conceive
Vitamin A plays a vital role in the reproduction of both women and men and also fetal development.
If you are unable to conceive, then Vitamin A deficiency may be one of the reasons and you and your partner should get checked for the same.
Another study has revealed that high oxidative stress can be a reason behind infertility in men. Since Vitamin A is a nutrient that is loaded with antioxidant, Vitamin A supplements can improve this condition.
3. Skin issues
Several studies have linked Vitamin A deficiency and acne. Vitamin A can be applied topically (ointments) or taken orally (supplements) to treat this condition.
Before taking oral medications, one should know about its side effects and how it will interact with other medications if you are taking. To be safe, it is best to consult your doctor first.
4. Night Blindness
A severe case of Vitamin A deficiency can cause night blindness and high prevalences were reported in developing countries.
In a study, Vitamin A (through supplements and foods) were given to women suffering some night blindness for six weeks. By the end of the study, the condition improved by 50%.
5. Delayed wound healing
Vitamin A deficiency can delay wonder healing after an injury or surgery. Vitamin A is responsible for collagen creation – a component that is important for healthy skin.
A study conducted on rats revealed that taking Vitamin A orally improves collagen production. Another research on rats suggested that topical application of Vitamin A on skin prevented wounds caused by diabetes.
It is worth mentioning that the study conducted on humans exhibited similar results.
6. Infection in throat and chest
If you are experiencing recurrent infections in the throat and chest, it may be due to Vitamin A deficiency. However, the results are mixed behind this theory.
While one study conducted on Ecuadorian children revealed that children taking Vitamin A experienced fewer infections in respiratory, another set of studies revealed that Vitamin A supplements can increase the respiratory infections.
7. Delayed development in children
Vitamin A is essential for the proper development of the body and the lack of it can hinder the development, especially in children.
Studies conducted on developing nations revealed that Vitamin A supplements, along with other essential nutrients can positively impact growth.
A study conducted on Indonesian children reported that participants who tool Vitamin A supplements for four months grew 0.39 centimetres more than the children who were given placebo.
Food sources of Vitamin A
Vitamin A can be obtained from both plant and animal foods. The best food sources of Vitamin A are,
- Fortified milk
- Fortified breakfast cereal
- Cod liver oil
Apart from the above-mentioned foods, Vitamin A can be found in vegetables and fruits that are rich in orange and yellow colour.
And other beta-carotene sources include spinach, broccoli and very dark green and leafy vegetables. It is important to note that vegetable sources of Vitamin A do not have fat and therefore, for better absorption, it should be taken with fat.
It is noteworthy that the above-mentioned meat sources are high in cholesterol and fat and therefore should be eaten with moderation for better health.
Vitamin A toxicity or Hypervitaminosis A
As much as Vitamin A is vital for the human body, excessive intake can cause harm too. While Vitamin A toxicity (Hypervitaminosis A) is rare, it is not unheard of.
The RDA (Recommended Daily Allowance) of Vitamin A for men is 900 mcg and for women is 700 mcg. This can be effortlessly achieved by eating a wholesome diet.
An adult should not consume more than 3000 mcg of Vitamin A in a day or it will lead to toxicity. Therefore, it is best to check with your healthcare professional before taking Vitamin A supplements.
Taking excess Vitamin A while pregnant can be harmful to the baby. Therefore, expectant mothers should avoid foods that have a high amount of Vitamin A and should take supplements only after consulting their doctor. Likewise, studies have revealed that excess intake of Vitamin A can also lead to fractures. 
The side effects of severe Vitamin A toxicity include,
- Itchy skin
- Disturbed vision
- Vomiting and nausea
- Dry skin
- Damage to the liver
- Decreased/poor appetite
- Pain in bones and joints
- Hair loss
- Sensitivity to sunlight
From taking care of the eyes to keeping the skin healthy and ensuring proper human development, Vitamin A plays multiple crucial roles.
Though Vitamin A deficiency is rare once developed it can cause various health complications. Supplements can correct the deficiency but one should ensure that they don’t overdo it and develop Vitamin A toxicity, which is also quite dangerous.
Before resorting to supplements, it is very important to talk to your doctor about the dosages and quantity you should take.
It is very vital for the body to have adequate levels of Vitamin A to function properly. Our daily recommended dose can be easily attained by eating a well-balanced diet that is loaded with fresh vegetables, nuts and lean meat and using appropriate cooking methods.
Remember, when you eat healthy and wholesome foods, deficiencies can easily be avoided.
Happy and healthy eating!