Vitamin A has several benefits for humans. Its effect on several stages of life.
First, let’s see about vitamin A.
Vitamin A is a generical term for many related compounds. Retinol (alcohol) and retinal (an aldehyde) also known as vitamin A.
Retinal can be converted by the body to retinoic acid (RA), the form of vitamin A known to affect gene transcription.
Retinol, Retinal, RA, and related compounds are known as a retinoid. β- Carotene and other carotenoids that can be converted by the body into retinol are referred to as provitamin A carotenoids.
You may already know the retina is located in the back of the eye. When light passes through the lens, it is sensed by the retina. Then it converted to a nerve impulse by the brain. Retinol transported to the retina via circulation and accumulates in retinal pigment epithelial cells. Then retinol is esterified to form a retinyl ester, which can be stored. When needed, retinyl esters can break apart (hydrolyzed). Then, change into a form that can be oxidized.
This form can be shuttled across the interphotoreceptor matrix to the rod cell, where it tied up to a protein called opsin to form the visual pigment rhodopsin. It’s also known as Visual purple. Rod cells with rhodopsin can detect very small amounts of light. Which making them important for night vision.
When light absorption happened early form of retinal transforms into another form known as “all-trans-retinal” and results in its release. This process related to the cascade of events. Also, it’s leading to the generation of an electrical signal to the optic nerve. After the nerve impulse generated by the optic nerve, it delivers to the brain where it can be converted as a vision.
Once release “all-trans-retinal” converted to “all-trans-retinol”, which can transport to the retinal epithelial cell thereby completing the visual cycle. Insufficient retinol available to the retina results in impaired dark adaptation known as “Night Blindness”.
A form of retinoic acid act as hormones to affect gene expression. Thereby it influences numerous physiological processes. Two chemical forms of RA are transported to the nucleus of the cell-bound to cytoplasmic retinoic acid-binding proteins. Within the nucleus, RA binds to retinoic acid receptor proteins. Specifically, one form of RA binds to retinoic acid receptors (RARs). Another form of RA binds to retinoid X receptors (RXRs). These RAR and RXR, respectively, allow the complex to regulate the rate of gene transcription, influencing the synthesis of certain proteins.
RXRs may also form a heterodimer with thyroid hormone receptors (THRs) or vitamin D receptors (VDRs). In this way, vitamin A with other chemical forms may interact to influence gene transcription.
Through the stimulation and inhibition of transcription of specific genes, RA plays a major role in cellular differentiation, the specialization of cells for highly specific physiological roles. Many of the physiological effects attributed to vitamin A appear to result from its role in cellular differentiation.
3. Help for Good Immunity
Vitamin A work as an anti-infective vitamin. Therefore, it is essential for the normal functioning of the immune system. As we know, skin and mucosal cells function as a barrier and form the body’s first line of defense against infection. Also, retinol and its metabolites are necessary to maintain the integrity and function of these cells.
Vitamin A and RA play the main role in the development and differentiation of white blood cells, such as lymphocytes. Lymphocytes play critical roles in the immune response. Activation of T lymphocytes, the major regulatory cells of the immune system, appears to require all-trans-RA binding of RARs.
4. Affect In Growth and Development
Vitamin A excess and deficiency of vitamin A are known to cause birth defects. Retinol and RA are essential for embryonic development. During fetal development, RA functions in limb development and formation of the heart, eyes, and ears. In addition, RA has been found to regulate the expression of the gene for growth hormone. These benefits of vitamin A are most important for human growth.
5. Help for Red Blood Cell Production
Red blood cells, similar to all blood cells, are derived from precursor cells called stem cells. Stem cells depend on retinoid for normal differentiation into red blood cells.
In addition, vitamin A appears to facilitate the moving of iron from storage sites to the developing red blood cell for incorporation into hemoglobin. Hemoglobin carries oxygen in red blood cells.
6. For Nutrient Interactions
Vitamin A deficiency may cause an increase in iron-deficiency anemia. Therefore, vitamin A supplementation also prescribe for iron-deficiency anemia. And also improves iron nutritional status among children and pregnant women. The combination of iron and vitamin A, supplemental help to reduce anemia more effectively than either taking iron or vitamin A supplemental alone.
7. Help For Cancer Prevention
Lung Cancer Prevention
According to current experiments shows increasing retinol intake helps to decrease the risk of lung cancer. However, the effects of retinol may be different for nonsmokers than smokers.
Breast Cancer Prevention
Researches have found that Retinol and its metabolites can reduce the growth of breast cancer cells in vitro. However, studies of dietary about retinol intake in humans have not confirmed this. There is evidence in humans that increased intake of preformed vitamin A or retinol reduces breast cancer risk.
8. Use as a Disease Treatment
As well as retinoid is used to treat several conditions, including retinitis pigmentosa, acute promyelocytic leukemia, and various skin diseases.
However, it is important to know that treatment with high doses of natural or synthetic retinoids overrides the body’s own control process. Also, there are potential side effects and toxicities related retinoid therapies.
In addition, as mentioned earlier, excessive retinoid compounds cause birth defects. Thus, women expected to become pregnant should avoid treatment with these medications. Retinoid is very long-acting side effects. Also, birth defects reported occurring months after discontinuing retinoid therapy. It’s not good to use the retinoid contains drugs without medical supervision.
9. Use to treat severe acne
Both natural and synthetic retinoids used to treat disorders of the skin. Etretinate and acitretin are retinoids useful in the treatment of some special conditions in the skin. Another chemical form of vitamin A, use to treat severe acne.
10. Give a more youthful complexion
In addition, retinoids affect the transcription of skin growth factors and their receptors. We store vitamin A in our skin cells almost exclusively as in an ester form as Retinyl Palmitate and sometimes Retinyl Acetate and Retinyl Propionate. These ester forms of Vitamin A can be gradually released through the above pathway way to become Retinoic acid.
Therefore, a combination of Vitamin A, make powerful antioxidants and flavonoids help to restore skin cells. It results in a more youthful complexion with a smoother texture and healthy glow.
11. Help to Keep Healthy Bones
Vitamin A is vital in the bone remodeling process because osteoblasts and osteoclasts have nuclear receptors for retinoic acid. Besides, vitamin A deficiency in animals leads to changes in bone by increasing bone thickness.
However, excess vitamin A intakes from retinol and serum retinol are related to lower BMD and higher fracture risk, but low intakes as well.
Recommended Dietary Allowance of Vitamin A
- Children – 400 – 600 µg / day
- Women – 750 µg /day
- Pregnant Women – 1000 µg / day
- Lactation – 1200 µg / day
- Men – 750 – 1000 µg / day
To gain these benefits of vitamin A you need to know about Vitamin A rich foods.
Vitamin A-Rich Foods
- Sweet Potatoes
- Iceberg Lettuce
- Butternut Squash
- Whole Milk
- Turkey Liver
- Beef Liver
- Dried Apricots
- Dried Basil
- Cod Liver Oil
Vitamin A has several benefits related to the human body. Taking excessive supplements of vitamin A and also the deficiency may cause problems in your daily life.
Therefore it’s better to take Vitamin A from the food sources which rich in Vitamin A.
Then without any problem, you can gain these benefits of vitamin A.
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