What is vitamin A?
Vitamin A is one of the four fat soluble vitamins among vitamin-D, vitamin-E and vitamin-K. Fat soluble vitamins are those which are present in dietary fats and can be stored in the body. These kind of vitamins are also found in plant based foods such as vegetables, nuts and grains but in non active form which means that they need to be converted to an active form by the body for their utilization.
Difference between pre vitamin A and pro vitamin A
There are two main forms of vitamin A in foods and supplements namely Beta carotene(pro vitamin A) and retinol(Pro vitamin A). Beta carotene is called pro vitamin A and is found in foods such as papaya, mango, sweet potato, carrots, pumpkin etc. Retinol on the other hand is called pre vitamin A or preformed vitamin A and it is the active form of this nutrient which is most bioavailable to your body, it is found in foods like Butter, cream, whole milk, egg yolks, fatty meat and liver.
Beta carotene and retinol are not the same thing. Your body uses retinol as the main form of vitamin A because it is the active form of this nutrient. Beta carotene is not directly utilized by the body but it needs to be converted to retinol in the digestive tract. However, the problem is that this conversion process is not very efficient.
12 units of beta carotene makes 1 unit of retinol. In simple words this means that when you eat foods containing pro vitamin A you do not absorb all the vitamin A from them but only some part of it simply because of this low conversion efficiency OR we can also say that foods containing retinol are 12 times more efficient in providing vitamin A as compared to foods containing pre vitamin A. On top of this, many individuals are even very poorer at this conversion. For instance, Beef liver, the richest source of pre vitamin A(retinol) contains 5,400 micro grams of vitamin A per 100g , To get this much amount of retinol you would have to eat 700g of carrots!
So, In conclusion to get enough vitamin A in your diet you should eat foods such as butter, egg yolks, ghee, cream, full fat milk, fatty meat and not just rely on fruits and vegetables.
Why vitamin A is essential?
Although, beta carotene has an major anti oxidant function in the human body which protects against oxidative damage such as during cancer or cardiovascular disease retinol is the main player when it comes to physiological functions of vitamin A.
- Eye health: The most recognized function of vitamin A(retinol) is to maintain the proper health of your eyes. Without vitamin A you cannot see.
- Reproduction: Vitamin A is necessary for the proper functioning of reproduction system in both male and female. In males sperm production is dependent on it and in females maintenance of egg, it’s fertilization and implantation.
- Pregnancy: During pregnancy it is really important for proper development of the child in the womb. Deficiency in this nutrient during pregnancy hampers the development of the placenta and results in growth abnormalities in the child.
- Thyroid health: Vitamin A is also thought to regulates thyroid hormone.
- Regulation of copper: Vitamin A plays a role in supporting iron metabolism by regulating copper in the body. This explains that vitamin A deficiency can also result in problems of iron deficiency such as anemia.
- Immune function: Both beta carotene and retinol have a strong influence on immune function. Beta carotene functions as an anti oxidant to protect against certain cancers, cardiovascular diseases and other kinds of oxidative damage. Retinol on the other hand is vital for mucus secreting glands especially in the respiratory tract which protects against infections.
- Cell Differentiation: Vitamin A is crucial for cell differentiation and growth in almost all cell types in the body.
- Glycoproteins: Vitamin A may also be involved in the synthesis of certain glycoproteins. Glycoproteins are important for cell communication, recognition, aggregation, and adhesion.
Vitamin A deficiency and it’s symptoms
Vitamin A deficiency can cause some serious health conditions especially in pregnant women and growing children.
- Night blindness: Night blindness is the very first sign of vitamin A deficiency in which a person cannot see at night. In xerophthalmia, the conjunctiva becomes dry and the eye is no longer able to form tears. The conjunctiva becomes thickened and wrinkled and the cornea can become ulcerated, which can lead to blindness.
- Infertility in females: In women Vit A deficiency affects the reproductive system in negative way. A women deficient in vitamin a may ovulate but the eggs are likely to degenerate. A deficiency of this nutrient will hamper the development of placenta and implantation of the fertilized egg will not take place or the embryo will die during mid gestation.
- Infertility in males: In males, Vit A deficiency results in poor sperm quality and production.
- Growth abnormalities: Vitamin A deficiency results in growth defects in infant during pregnancy especially in the eyes. The child may end up blind or with poorly developed body. In growing children vitamin A deficiency results in growth deformities and childhood blindness.
- Immune function: Vit A is required for proper function of the mucus secreting glands, which protects us against pathogens or infections.
- Skin and hair damage: Epithelial cells are affected by Vit A deficiency that results into poor skin health, hair loss, damaged hair and other issues related to epithelial cell function.
- Iron deficiency: Iron metabolism is supported by Vit A. Hence, its deficiency can result into iron deficiency anemia.
- Thyroid issues: Vit A has been shown to regulate thyroid hormone. deficiency of this nutrient may result in hypothyroidism.
Food sources of Vitamin A
Beef liver is the richest source of vitamin A, other than that egg yolks, butter, ghee, full fat milk and it’s products, whole cream, cheese, tallow, lard are some excellent sources. In plant based foods Red palm oil is the richest source, sweet potatoes, pumpkin, carrots are great sources of beta carotene.
Vitamin A is a fat soluble vitamin which is crucial for eye health, reproduction, immune function etc. It comes in two dietary forms, provitamin A (beta carotene) which is present in plant based foods and preformed vitamin A (retinol) which is present in animal based foods. Beta carotene is not actual vitamin A since it w needs to be converted to retinol in order to be utilized by the body. Therefore, you should eat retinol rich foods to get adequate vitamin A from your diet.