Sources of Vitamin A
In this article, I will explain about sources of Vitamin A and Vitamin A Benefits. Vitamins are essential for a healthy body. There is a long list that contains Sources of Vitamin A and I have listed all foods that are rich in Vitamin A.
Vitamin A for a for Healthy Body-Vitamin A Benefits
- 1 Vitamin A for a for Healthy Body-Vitamin A Benefits
- 2 What are vitamins?
- 3 Vitamin A
- 4 Sources of Vitamin A:
- 5 Forms of Vitamin A And Their Absorption:
- 6 Effect on Bones:
- 7 Effect on Metabolism:
- 8 Effect on Epithelial Tissues:
- 9 Complications due to vitamin A deficiency:
- 10 Yellow, Orange Fruits and Vegetables:
- 11 Benefits of Vitamin A
- 12 Final Words About sources of Vitamin A
- 13 About the Author:
Growing up and realizing how important our diet is for our health led us all to the idea that vitamins are a component of our diet that helps in proper growth and functioning, which is certainly correct. They are integral for most of the body functions and their deficiencies can cause severe disorders. Vitamins are basically organic compounds that should be taken in through diet because they can’t be synthesized by our body. Vitamins actually come from vita, means vital or life and amine, which refers to as amino acids as they were originally thought to contain amines in their structure. We must eat healthy and Nutrition rich food. Read sources of Vitamin A for details. Read here about Calcium Containing Foods.
What are vitamins?
“Vitamins are organic compounds essential in very small amounts for supporting normal physiological function.”
We’re well aware of the types of vitamins, that are divided into two major groups
- Fat-soluble vitamins
- Water-soluble vitamins
Now, fat-soluble (kind of vitamins that show more affinity towards lipids as compared to water), they are characterized as Vitamin A, D, E and K. While water soluble (kind of vitamins that are easily soluble in water) they are characterized as vitamin B complex and C.
Here we’re going to discuss major fat-soluble vitamin, Vitamin A and sources of Vitamin A.
Fat-soluble unknown factors present in milk that were not fats, proteins and carbohydrates were found by Fredrick Gowland Hopkins, an English biochemist in the year 1912. After this a scientist from Yale University, Elmer McCollum discovered these unknown factors while researching dietary fats. In 1920, they were referred to as Vitamin A.
Vitamin A exists in three different active forms,
- Retinoic acid
- Antixerophthalmic factor
- Anti-infective factor
- Growth factor
Those chemical agents are known (retinoic acid) that inhibits pathogenic drying of the membrane lining the eyelids or the membranes that are covering eyeballs.
They mostly prevent infections of eyes.
They help in the growth of males and female reproductive organs and also they are required in germ cells production.
It is also known as Vitamin A2, which is basically a derivative of retinal. It is found in the liver of fish present in freshwater.
Properties of Vitamin A:
- It’s a fat-soluble yellowish color oil in appearance.
- It is rapidly oxidized with less biological activities in the presence of oxygen.
- It is quite stable in the absence of oxygen.
- Its activity is destroyed by excessive heating.
- It is quite sensitive to ultraviolet light.
- In human body, vitamin A shows cis-trans isomerism.
Sources of Vitamin A:
Here I have listed all major sources of Vitamin A
Vitamin A is found in a versatile range of foods. There are obviously two major divisions through which we can obtain this vitamin.
- Animal source: fish liver oil, milk, butter, egg yolk, kidney, cheese, cream, and muscles. We can obtain performed vitamin A (retinol and its esterified form called as retinyl ester) from animal sources.
- Plant source: leafy green vegetables such as spinach, kale, broccoli, cantaloupe and etc. orange and yellow vegetables like carrot, turnips, potato, tomato, tomato products, pumpkins, fortified cereals and some vegetable oils. They are also classified as provitamin A.
Forms of Vitamin A And Their Absorption:
- Retinyl esters of diet are hydrolyzed by pancreatic esterase in the intestine to give and free fatty acids(FFA).
- B-carotene from plant sources is oxidatively converted into two molecules of vitamin a.
- Retinol is re-esterified within the intestinal mucosal cells and then incorporated into chylomicrons formation.
- Rest of their transport is same as of triglycerides and other fat-soluble vitamins. Firstly, they are absorbed in lymph because they are soluble in the fat medium, then transported to the blood through carrier proteins and then they are transported to the liver and fatty tissues for storage.
Storage of Vitamin A:
The primary form of storage of vitamin A is Retinyl ester and are stored in hepatic stellate cells. So we can see that the major portion of reserved vitamin A is found in the liver but it is only in normal conditions or dietary intake, in some situations they may also present in;
- Breasts of lactating women
- Adrenal glands
Physiological Functions of Vitamin A:
There are few physiological functions of vitamin a, give below;
- Role in vision
- Effect on bones
- Role in metabolism
- Effect on epithelium
Role in Vision:
The role of vitamin a in the process of vision was first elucidated by George Wald, this whole event occurs in the cyclic process known as Rhodopsin cycle or Wald visual cycle. The retina of our eyes contain two types of cells,
- Rod cells: involved in dim light vision
- Con cells: involved in bright light vision
The human eye has 10 million rods cells and con cells half of their number which means 5 million. Animals like cats and owls for which night vision is more necessary they contain more number or rod cells. Aldehydic Cis form of vitamin a that is called as cis-retinal, present in retina combines with opsin protein to form a conjugated protein called rhodopsin which is essential for night vision. In the presence of light rhodopsin is hydrolyzed into opsin and all-trans-retinal. This conversion occurs through a cyclic process give as:
By this whole cycle, the person is able to see in dim light. Some of the vitamin a may get lost during the process but it is immediately replaced by a new one from vitamin a stores in our body. But if it’s not supplied properly, the situation may get worse, for example, night blindness. Read here about What Causes Obesity?
Effect on Bones:
Vitamin a helps in bone development, so its deficiency may cause the deformation of skull bones which can cause nerve degeneration and eventually paralysis. Read here about Signs of Malnutrition and what causes malnutrition.
Effect on Metabolism:
Mitochondria works properly in the optimum concentration of vitamin a, so when glucocorticoid is biologically synthesized the optimum levels of vitamin a is necessary if interrupted it can inhibit the formation of glycogen from lactate and glycerol. Vitamin a deficiency or excess both can cause destructive effects by the interruption in oxidative phosphorylation. Here is the list of Iron Rich Foods.
Effect on Epithelial Tissues:
Vitamin a is important to maintain healthy epithelial tissues and this is because that retinal and retinoic acid are required to prevent keratin synthesis (a hard infusible fibrous protein which is responsible for making of nails, claws, fangs and horny surfaces) because when its deficiency occurs epithelial cells start producing this protein keratin on skin giving it a rough texture or appearance, this condition is called as keratinization. Deatils about Celiac Disease is given here.
Complications due to vitamin A deficiency:
Vitamin a deficiency occurs due to inadequate intake, fat malabsorption or liver malabsorption. It can cause different diseases which can lead to monopolies and disabilities, for example,e paralysis and xerophthalamia. Some of these diseases are given below.
- Corneal ulcers
- Keratinized urinary tract epithelium
Pathologic dryness of the cornea and conjunctiva of the eye which mostly occurs due to the severe deficiency. Wrinkling and dryness of cornea occurs making it difficult to see properly. If it remains untreated for too long it can cause corneal ulcers and eventually blindness. It is present in developing countries at the alarming rate while in developed countries it is found rarely. It is a progressive disease; night blindness is one of the earliest symptoms of this disease. Bitot’s spots (the white colored lesions on the cornea) may start forming that are deposits of tissues in the conjunctiva of the eye. It can be cured at its early stages but taking vitamin a rich food like carrots, leafy greens, poultry, eggs and orange yellow fruits and vegetables.
It occurs due to the deficiency of vitamin a. it’s a disorder of epithelium and vitamin a is essential of healthy epithelia of cornea and conjunctiva just as it is important for other epithelial surfaces of the body. Deficiency in vitamin a leads to atrophic changes take place in mucosal surfaces, losing goblets cells and these goblet cells are replaced by keratinized stratified squamous epithelium as a result cornea breaks down and liquefies causing a condition called keratomalcia. Refer to the list for sources of Vitamin A.
Both xerophthalamia and keratomalcia can get worse and cause ‘CORNEAL ULCERS’.
Keratin is a protein which gives roughness to the skin, it constitutes nails, hoofs, feathers, hair and it also makes outer layer of skin. Keratinization occurs due vit a deficiency in respiratory, GI, and urinary tracts. Its causes drying, follicular formation and scaling of skin. Its more severe for the patients of younger age. Mortality rate may reach up to 50% due to deficiency of vitamin a in children.
Prevention and cure through diet:
Prevention can be best done by diet, food you ingest is the best way to keep a person healthy. When taking unhealthy food can lead to huge amount of disorders then healthy foods can help to improve body health significantly. We have discussed the animal and plant sources earlier but now we will jump right into their separate description. As we know leafy green vegetables are rich in fiber and vitamin a. for example broccoli, kale, lettuce, collard greens, chard, lettuce, spinach, colocasia leafs, and etc.
A leafy green vegetable, very useful for weight loss and optimum health, rich in carbohydrates(71%), proteins(20%), fats(9%) and other nutrients, their measurements in 1 cup serving is given as;
- Proteins: 3.71 g
- Carbohydrates: 11.20 g
- Dietary fibers: 5.15 g
- Total fat: 0.64 g
- Total calorie: 54.60
Amount of vitamin A in its composition: 2414.88 IU (international units)
- They contain vitamin A in them in the form of retinoid and carotenoids (beta carotene, lutein ad zeaxanthin)
- Calcium, sodium, zinc, fluoride, iron, magnesium, phosphorus, potassium, sodium, copper, chromium, chloride all these minerals are also present in 1 serving of broccoli in micrograms.
- It also contains Omega 3 and omega 6 fatty acids in 0.19g and 0.08g respectively.
- Its glycemic load is three on the scale of 0-250.
- Its most benefiting factor is that it is very low in cholesterol and saturated fat.
- Total vitamin A obtained from 100g of broccoli is 623 IU.
Collard greens belong to family cruciferae and these vegetables are called as cruciferous vegetables. They have amazing health benefits. Their 10 servings per week are recommended normally. One cup or one serving of finely chopped and cooked, 190g of collard greens contain 63 calories. And they have a very low load on glycemic index. It helps in cancer prevention because they improve three systems of our body 1) inflammatory and anti-inflammatory response, 2) detoxification system, 3) antioxidant system. Collard are rich source of vitamin k but a good source of vitamin A too. Fiber, calcium, choline, vitamin B12, B6, iron, copper, vitamin E, vitamin C and manganese.
A very good source of dietary fibers, vitamin K, vitamin A, magnesium, phosphorus, iron, folate, calcium, potassium, copper, manganese, vitamin B6, proteins, riboflavin and thiamin. They have very low glycemic load, saturated fatty acids and extremely low cholesterol content. 72 % carbohydrates, 16 % proteins and 12 % fats, all of this in one serving which can contain 67-70g of chopped kale. It contains fairly large amount of antioxidants (that help in prevention of cancer) for e.g. kaempferol and flavonoids quercetin. They also contain cardioprotecive, anti-inflammatory, anti-viral, anti-depressant, substances. Vitamin k is required for blood clotting and kale is its richest source.
It can also be used to lower cholesterol which in turn reduces the risk of cardio vascular diseases, because elevated cholesterol levels are one of the major risk factors of CVD and many other chronic diseases. Lutein and zeaxanthin, are types of carotenoids that help in protection of eye, kale has abundance of these nutrients. Kale gives the feeling of fullness and its significantly low in calories, high in fibers so it could be a very good weight reducing food. Due to its many positive outcomes kale is considered as one of the most nutritious and healthiest food item on planet.
Yellow, Orange Fruits and Vegetables:
It’s a melon kind of a fruit. Rich in vitamin A (in carotenoid form) and vitamin C. one serving of diced cantaloupe will contain 78g of food in which will have 54 calories. Sodium 26mg, total carbs 14g, dietary fibers 2g, sugars 12g, proteins 2g, cholesterol 0g. Vitamin A is 106 % , vitamin C 96 % , calcium and iron 2 2 %. It can provide you with anti-oxidants, electrolytes and phytochemicals. As we already know that antioxidant can help in the prevention of cancer and cantaloupe have anti-oxidizing agents in it so that means it could be given as a diet to the person on the risk of cancer. They also protect body from free radical attack that can damage body in different ways.
Vitamin A of cantaloupe can also help in healthy vision, fresh skin, anti-inflammatory response and improving immunity. The most significant function of cantaloupe is to act as an antioxidant, and their rind is nowadays used to extract an enzyme called superoxide dismutase (SOD). It protects the human body from oxidative stress. Cantaloupe seeds produce omega 3 fatty acids. They are the best natural source of antioxidants. Best sources of Vitamin A.
Carrots are one of the most commonly and widely used healthy vegetable. It helps in reducing weight and improving vision. One serving of raw diced carrots consisting of 100g contain 41 calories. This edible root vegetable constitutes of 88 % water and 12 % other nutrients which are 9.6g carbohydrates, 0.9g proteins, 4.7g sugar, 2.7g fiber and 0.2g fats which is mainly omega 6 fatty acids. Glycemic index for carrot ranges from 16-60 which varies for different forms like chopped, cooked, pureed and etc. Refer to the list that contains sources of Vitamin A.
Soluble fibers are present in carrot in the form of pectin which delays the digestion of starch and other sugars by giving a feeling of fullness for this reason it could be used for weight loss purposes. They also help in the regulation of normal flora of the gut that help in improving health and keeping body away from different diseases. Cellulose and lignin are two major insoluble fibers found in carrot in addition to hemicellulose. They improve normal bowl movement of the gut and protect it from situations like constipation. Carrots are the major reservoir of beta-carotene. They help in vision, immunity, skin/epithelial cell differentiation and reproduction. Retinal improves vision while retinoic acid is involved in growth and cellular differentiation.
Carrots contain biotin which is also called as vitamin H helps in metabolism of different macronutrients like proteins and fat. It also contains potassium, vitamin K and vitamin B6 which regulate other mechanisms like BP control and blood clotting, bone health and energy conversion respectively. Carrots reduces the risk of different kinds of cancers like stomach and colon cancer, in women who have slightly increased level of carotenoids circulating in the blood have low risk of breast cancer. Another important health benefit carrot provides is lowering the blood cholesterol level. It also promotes eye health and lowers the risk of age related muscular degeneration.
An egg is a cascade full of nutrients. It contains 7 gram proteins, 5 gram fat, out of which 1.6g are saturated, vitamins (mostly vitamin A), minerals and rich iron. An egg provides you with 75 calories. Vitamin A is essential for eye health and its most easily acceptable form for the body is retinol which is found abundantly in eggs, liver, milk and milk products. They help in vision, cell differentiation and proliferation improves immune function and proper growth. Eggs also contain zeaxanthin and lutein. Eggs are high in cholesterol but that doesn’t mean that they shouldn’t be taken in our diet. A normal adult and kid should take it in their diet because it contains high-quality proteins and cholesterol in it.
It is a deep yellowish, orange colored squash plant with ribbed patterns on it. It is the richest natural source of vitamin A. one serving or 100g of chopped and cooked pumpkin contains 20 calories while without boiling its 26 calories. It is a healthy source of phosphorus and vitamin A. 2g sugar, 1.1g dietary fibers, 4.9g carbohydrates and 8,513 IU vitamin A. Minerals like iron, magnesium, zinc, vitamin E, vitamin B5 are also present. Pumpkins have a very good quantity of fibers in them that’s why they help in weight loss, regulating normal cholesterol levels and prevention of cardiovascular problems. It basically contains the alpha-carotene form of vitamin A, which is readily converted into retinol after entering the body and we already know that it is known for maintaining healthy, smooth, glowing skin.
Milk and milk products:
Milk is basically a complete health package or food item. We will discuss calories and the nutrients of whole milk because this is most easily and widely available form everywhere. 100g of whole milk gives 61 calories with 3.2g proteins, round about 3g of fats out of which 1.9g is saturated fat, 4.8g carbohydrates majorly lactose. Other than these three macronutrients, vitamin A (162 IU), D and B12, calcium, sodium, potassium and magnesium are also present. Vitamin A in Milk has uncountable benefits for health. Its makes bone and teeth strong, improves vision, brain health, regulate immune system to perform better functions, makes skin in fact generally all epithelial tissues soft. It also acts as an antioxidant, which protects body from cancer and other chronic diseases.
Calcium and phosphorus work together to maintain healthy bone mass, due to this reason many doctors recommend milk intake to a patient suffering from some bone disorder. Milk products like, butter, cheese, skimmed milk, yogurt, Greek yogurt, sour cream, milk powder, ice creams, kefir and etc. they also have functions similar to the whole milk given above.
Mango is one of the sweetest fruits. It also contains vitamin A in considerably good quantity. Mango provides with 60 calories/ 100g. Almost 16 g carbohydrates, 14g sugar, 1.6g of dietary fibers, 0.8g proteins, potassium, magnesium, sodium is present in it. 21% vitamin A, in form of carotenoids(beta-carotenoid) which gives them the yellow color. They help to prevent age-related degeneration of eyes and muscles, asthma, cancer by its antioxidant property. It is beneficial to make skin clean and fair. It helps to regulate the digestive system and prevent constipation. Read sources of Vitamin A for detail. Read here about Vitamin C Foods.
Beef liver is the richest source of vitamin A, the performed source of vitamin A to be exact. It contains a high quantity of cholesterol in it too so it shouldn’t be consumed in large portions in the diet. Its most important function is to strengthen the immune system and intracellular transport. Vitamin B12 Foods.
Benefits of Vitamin A
Vitamin A’s most important function or benefit is to improve immune system because it effects epithelial and mucosal linings of the eyes, respiratory, urinary, gastrointestinal tracts of our body. I have listed all major sources of Vitamin A above. It is required for differentiation and growth of white blood cells that are the main part of the immune system. Read here about Foods for Vitamin E.
Vitamin A in aldehyde form that is retinal helps in the distinguishing dark and light, thus improving night vision they regulate the vision cycle. They fight against cataracts, muscular degeneration, glaucoma and other age-related eye diseases. Vitamin A effectively maintains bone and teeth health by strengthening them. They play important role in replacing old and worn tissues with newer, fresh, healthy ones. Antioxidant activity of vitamin A helps in reducing oxidative stress by combating free radicals which in turn eliminates the risks of cancer.
Toxicity of Vitamin A
Now if we talk about the toxicity of this particular vitamin A is called as hypervitaminosis. Read carefully all the major sources of Vitamin A. Excessive intake of vitamin A can be chronic and acute. It can cause pain in bone, changes in vision and skin while chronic hypervitaminosis can cause liver damage, it can be diagnosed by blood test through which body’s vitamin A levels could be checked. It is caused by excessive dietary supplementation or due to any pharmacological treatment like isotretinoin for acne. Symptoms of toxicity are; vomiting, nausea, pain in bones, drowsiness, blurry vision, dizziness, dry skin, brittle or cracked nails, poor appetite and mouth ulcers. These symptoms are different in infants, which include soft skull bones, confusion, bulging of eyes mostly eyeballs, all this may end with coma.
Richest sources of vitamin A and their calories:
|Food items||Serving||Calories||Amount of vitamin A (IU)||Benefits|
|Beef liver||100g||165||17,997 IU||Immune system and vision.|
|Pumpkin||100g||26||8,513 IU||Skin, weight loss because of high fiber content and regulates cholesterol level.|
|Egg||100g||155||520 IU||Cell differentiation and proliferation, vision and immune system.|
|Milk (whole)||100g||61||162 IU||Epithelial tissues, brain health , vision and skin.|
|Broccoli||100g||34||623 IU||Weight loss, maintain blood pressure, bone health and immune system.|
|Kale||100g||49||9,990 IU||Works as an antioxidant that can help to prevent cancer, anti-inflammatory response, helps in lowering cholesterol and prevents CVD.|
RDA of Vitamin A
- 900 micrograms for men.
- 700 micrograms for women.
- 1200-1300 RAE for lactating women.
- Less than 700 micrograms for infants and kids less than 14.
Final Words About sources of Vitamin A
I hope that after reading this article on sources of Vitamin A, you will have better knowledge of Vitamin A Benefits and foods that are rich in Vitamin A.
About the Author:
My name is Maheen Ejaz, a student of BS in Human Nutrition and Dietetics. The sole purpose behind the writing of this article is making it easier for common people to know about the vitamins, especially vitamin A. I discussed every little thing in simplest ways so that it would definitely provide you with the greater understanding about the topics.
What motivated me to write an article was my interaction with a patient who was suffering from night blindness and I had to tell them completely about vitamin A deficiency, a literate person always tries to know everything behind his sufferings and ease. So, it is basically just a simple attempt to facilitate people out there trying to know a bit more about what benefits his or her health and what could inflict a negative effect. I hope my effort will be useful to you all. Thank you.
“From the bitterness of disease, man learn the sweetness of health”.