Vitamins play a key role in converting foods into energy through a process called as metabolism. There are multiple types of vitamins. Each is known for its unique functions and properties. Among these essential nutrients, vitamin A is significant in many ways. Its role spans as wide as boosting your immunity levels, maintenance of retinal health, etc. Lack of this essential vitamin (i.e., deficiency) can lead a lot of side effects; key among such effects is blindness. A well-balanced diet with access to needful amounts of this vitamin can help prevent risks associated with blindness. You may need to know that non-availability of zinc can result in poor absorption of this important vitamin. Thankfully there are many ways by which you can supply your body with needful amounts of vitamin A. Sources include naturally available foods as well as supplements.

Vitamin A is an essential nutrition which is soluble in fats. Many people think that it as a single substance; but, it is a genre of compounds. In the foods you eat, it shows up in two basic forms – (1) as carotenoids and (2) retinyl esters. Carotenoids are available in plentiful quantities in plants-based foods. On the other hand, esters are mainly present in fish, liver as well as dairy products. However, the usable variant of this vitamin is called retinal (or retinoic acid). In order to make use of the vitamins, both the aforesaid forms will need to be converted in your body.

The good news is, as this vitamin is soluble in fats, it can be stored in your tissues. Once stored, it can be used up at a later period of time. But, how is it preserved in the meantime? It is chiefly stored in your liver. The most commonly stored form of this vitamin is known as esters (of the retinyl genre). Your body breaks down such stored esters to a substance called retinol. Once this is broken down, the substance gets bound to specific types of proteins (which serve as retinol-binders). Upon being protein-bound, this essential vitamin is ready for use.

Key functions of vitamin A

This vitamin can do a wide range of functions; its key activities include boosting your immunity levels, development of fetus or boosting fetal health, enabling better eyesight (health of eyes), maintenance of cellular health, etc.

Health of your eyes
Of all the benefits of this vitamin, it is known for its properties to boost your vision. How? It blends with opsin (a kind of protein) to become rhodopsin; this substance plays a very important role in enabling vision in lowlight as well as making your eyes to identity colors. Vitamin A also helps to safeguard the outer part of the eyes, commonly known as cornea. The membrane covering your eyes (called as conjunctiva) also stands to gain with needful supply of vitamin A. It is this membrane which guards your eye while it comes in contact with the inner wall of your eyelid.

Immunity boosting function
T lymphocyte (also termed as T-cells) plays a significant role in guarding your body against possible external attacks and infections. These are white cells of your blood, made in the marrow. These cells are found in your blood as well as tissues. The ubiquitous presence of these cells is needed for protecting your body from likely threats. Vitamin A is required for the growth and availability of these T-cells. Such cells contain special receptors so as to get activated by antigens of any kind.

Works as an effective antioxidant
Vitamin A is known for its antioxidant capabilities; this is the reason why carotenoids-rich vegetables and fruits can help prevent onset of autoimmune conditions such as cancers. Medical research substantiates the role retinoid plays in stopping cancerous growth in ovaries, breasts, urinary bladder, etc. Scientific studies done on two groups of smokers – one group had a pronounced presence of carotene (which is an earlier form of vitamin A) in blood while the other group did not have such high levels of carotene present in their blood.

Final outcome of such studies: The first group – which had a pronounced presence of carotenes in blood – displayed almost 50% lesser risks of mortality due to cancers in their lungs.

In general, many of the benefits of vitamin A can be attributed to the excessive antioxidant properties of carotenoids (a preliminary variant of this vitamin). Vitamin A can thus erect best possible barriers against reactive substances – such as free-radicals – to protect your body from possible stresses, mainly oxidative stress. These stresses are the major reasons for the onset of many ailments such as decline of cognition, cardiac dysfunction, cancers, diabetes, etc.

Foods rich in vitamin A

Among the various sources of vitamin A, those sourced from animal products are easily absorbed than those taken from plant-based sources. Vitamin A sourced from animals is known as performed-vitamin, while those from plant foods are called pro-vitamin-A carotenoid. Also, the extent your body can convert carotenoids into usable vitamins can depend on your diet, genetic make-up, overall wellbeing and drugs or supplements that you may be currently consuming. Those who pursue a strict plant-based diet or nutrition plan (for example – vegans) need to be conscious of this fact.

Sources of performed vitamin A – mainly animal-based products

Foods with high levels of performed vitamin A are cod liver oil, livers of chicken or beef, egg yolk, dairy products such as cheese, butter, cheddar, etc.

Cod liver oil – As the name indicates, this oil is extracted from cod fish’s liver. It is a well-established source of vitamin A as well as vitamin D. Various dietary studies reveal that the oil has nearly 4,000 micrograms of retinol in a standard serving of ~13.5 grams (i.e., one tablespoon). However, you may need to be aware that one tablespoon serves nearly 135% of the daily upper limit of performed vitamin A – i.e., retinol. Daily intake of such levels can result in damages to your liver and may lead to toxic effects. You are hence advised to talk to your doctor or a dietitian before consuming cod liver oil.

Beef – especially, the liver of cow – Liver of a naturally-raised cow has a high level of vitamin A (performed genre) in it. A serving of 3-ounce provides almost 7-times the daily intake value. The only drawback however is the high level of cholesterol present in it. In terms of measurements – a serving of almost 5 grams can help meet your daily fat requirement.

Chicken liver – More than 125% of your daily need for vitamin A can be sourced from an ounce of chicken liver. If you are pregnant, you are advised not to take this food as it may harm your fetus or impair your fetal health. Apart from the proven benefits of vitamin A, nutrients in liver are known to boost the functioning of your kidneys and heart.

Yolk of eggs – Yolk is a low cost source of vitamin A. A large yolk has upto 65 mcg of vitamin A in it. You are advised to stay cautious of likely infections by a bacterial strand called salmonella. It is hence recommended to buy eggs only from certified sources and store eggs in your fridge at an optimal temperature (i.e., at a temperature of 44 degrees Fahrenheit).

Cheese – Made from both cow’s milk and goat’s milk, cheese is loaded with a lot of nutritional values. It is a food item known to have a reasonably high level of vitamin A. One standard-size slice of cheese contains close to 9% of your daily need of this essential vitamin.

Butter – This dairy product has vitamin A in sizeable quantities. A standard serving of one tablespoon (i.e., nearly 13.5 grams) has more than 10% of your daily requirement of vitamin A. The readily usable form – retinol – is packed with a lot of benefits for the health of your eyes, teeth, tissues and skin.

Other rich sources of performed vitamin A include liver of lamb (a serving of 4 ounces can give upto 9-times the daily requirement). Similarly, liver of turkey (4-ounces can yield upto 10-times of your daily need), liver sausages, eel (this is a staple item in Japanese as well as in a few East-Asian cuisines – a fillet of this fish gives as high as 2.5-times the daily intake value), etc. are other richer sources of retinol.

Sources of pro-vitamin A carotenoids – plant-based vitamins

Foods with pronounced levels of pro-vitamin A carotenoids are carrots, tomato, pumpkin, sweet potato, cabbage, spinach, turnip, apricot, kale, parsley, etc.

Carrot – This is a tasty and crunchy root-based vegetable. It is a rich source of beta-carotene, a substance which is a pre-converted form of vitamin A. Apart from these vitamins carrot also has important minerals such as potassium (helps a lot in controlling your blood pressure levels), vitamins B6 (enables energy conversion from foods you consume) and K1 (key to healthier bones as well as timely clotting of blood).

Tomato – It has an antioxidant known as beta-carotene, which gives an orange or yellow color to foods. This substance is a pre-converted form of vitamin A. Once consumed, these antioxidants in tomato soon get converted into this essential vitamin. It also contains other 3 types of carotenoids namely, lycopene (known to possess the highest degree of antioxidant properties among all known carotene substances), lutein (protects your eyes from possible risks of degeneration as you age), alpha-carotene as well as beta-carotene.

Pumpkin – This is a very popular vegetable, grown and harvested in many parts of the world. It is known for its rich presence of vitamins as well as antioxidants. A standard serving of 100 grams of one of its variants can yield as high as 2.5-times the daily recommended intake value of vitamin A. These vitamins are known to prevent autoimmune conditions such as cancers in your mouth, lungs, etc. This vegetable also has beta-carotenes and flavonoids such as lutein; all these help in the conversion and supply of vitamin A to your body.

Pumpkin is also endowed with zea-xanthin – an antioxidant that can safeguard your retina from harmful ultraviolet radiation. Hence, it is a preferred choice for elderly people who are known to live with possible risks of macular degeneration.

Sweet potato – This vegetable is one of the most reliable sources of beta-carotene. This substance is in fact a main reason for the color (orange) of this highly nutritious vegetable. A cup containing 100 grams of sweet potato can provide as high as 3-times your daily need of beta-carotene. This vegetable can also help prevent different types of blindness. Apart from the regular orange colored sweet potato, its purple colored variant also stores a lot of benefits for the health of your eyes.

Cabbage – This is one of the best sources of antioxidants such as beta-carotene, lutein and zea-xanthin. Of all these substances, high levels of beta-carotene help avoid retina related problems (especially, conditions such as macular degeneration). It is also known for its capabilities to stave off risks associated with formation of cataract. The vegetable is also endowed with flavonoids such as quercetin.

Spinach – This leafy food is a powerhouse of nutrients; it has a healthy share of carotenoids in it. A standard serving of 100 grams can provide you with nearly twice the daily dietary needs of vitamin A. In general, your body needs a lot of carotenoids to get them converted into vitamin A. Thanks to the pronounced presence of pre-vitamin carotenoids in spinach; you will never be deprived of vitamin A if you are adding this green and leafy food to your diet regularly!

Turnip – This vegetable also ranks as one of the top sources of carotenoids – a pre-converted form of vitamin A. It is the leaves of this vegetable that can surprise you with its health benefits – available in abundance. A cup (containing about 60 grams) of its greens can serve you as high as 1/3rd of the daily need of pre-vitamin A. The pre-vitamins present in its greens are so easily absorbed than many other forms of carotenoids. As an added benefit, the greens have large quantities of folate; a nutrition to avoid fetal problems and other congenital anomalies.

Apricot – It is another rich source of nutrients to boost the health of your eyes. These include essential nutrients like carotenoids as well as xanthophyll. Apricot is known for its ability to prevent age-based degeneration of eyesight, especially macular repair. It is also included in the diet plan while treating dryness of eyes.

Kale – The excessive amount of chlorophyll may cover the presence of beta-carotene in this leafy vegetable. This is in fact a very rich source of pre-vitamin A. It contains as high as 65% of beta-carotene present in an equal-sized serving of carrots! In terms of real numbers – a cup of 100 grams of raw kale has almost 6 milligrams of pre-vitamin A. The good news is, once cooked – kale releases more beta-carotene; the level often reaches more than 8 milligrams. The not-so good news is – cooking kale robs off some of its other essential nutrients such as polyphenols, vitamin C, etc.

Parsley – This is a widely used aromatic, leafy vegetable. One distinct feature is its low calorific value; only about 2 calories in a serving of nearly 2 tablespoons. However, what distinguishes parsley is the high percentage of vitamin A! Almost 11% to 12% of your daily need for vitamin A can be furnished from a standard serving of 8 grams. Vitamin A present in parsley can help treat skin conditions such as acne as well as improve your immunity levels. It is also known for its strong presence of vitamin C and vitamin K.

Other plant-based sources of vitamin A are collard (another leaf-based vegetable with more than 450 milligrams of vitamin A in a small cup), beet green (half-cupful can yield more than 270 milligrams of vitamin A), etc.

Safe levels of intake of vitamin–A rich foods and dosage limitations

Daily dosage levels of vitamin A recommended for women and men vary to some extent. For men, it stands at 700 mcg and for women it is 900 mcg each day. But, if intake levels breach the upper limit of 3,000 mcg among adults, it can lead to several adverse side effects. Common side effects include drop in appetite, hypersensitivity to solar light, itchiness, problem with eyesight, loss of hair, pain in joints or bones, headache, etc. Excessive intake of vitamin A can also lead to liver injury and other fatal outcomes. Among pregnant women, it may lead to congenital disorders. Safe levels of vitamin A consumption are recommended for both supplementary drugs as well as naturally sourced forms of vitamin A.

Vitamin A supplements

Apart from these foods, your treating doctor may also prescribe a few vitamin supplements to boost the availability of these essential nutrients. For vegans, supplements made from pre-vitamin A forms are usually administered. Among such pre-vitamins, the most widely consumed form is beta-carotene.

You may need to remember that supplements based on beta-carotene are converted into vitamin A. The conversion ratio is expressed by a term called retinol activity equivalents. This index denotes the quantum of vitamins these supplements yield upon being converted. Another note of caution for vegans is – some of these beta-carotene based products may contain beeswax. Hence, a thorough study of the label is important before taking plant-based vitamin A supplements.

Also, while taking these products, you are advised to remember the dosage levels. This becomes essential because a higher dose can lead to likely risks of vitamin A toxicity.


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