Liquid Iron With Vitamin C

Liquid Iron With Vitamin C

Should You Take Iron With Vitamin C?

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Iron's main role in the body is to transport oxygen and carbon dioxide through the blood. Vitamin C is necessary for growth and repair in your body, and it increases iron absorption. Most people get enough vitamin C from their diet, so taking a vitamin C supplement may not be necessary. If you're at risk of iron deficiency, increasing your intake of iron should be a priority, but consuming vitamin C with iron supplements helps. Children and pregnant women have a high chance of being iron deficient, leading to iron-deficiency anemia. You also need more iron if you have heavy periods or donate blood frequently. If you have symptoms of anemia such as fatigue and cold extremities, please contact your primary care physician.

Vitamin C Improves Iron Absorption

According to a report published in the "International Journal for Vitamin and Nutrition Research" in 2004, vitamin C enhances absorption of iron. Some food contains compounds that inhibit iron absorption, and including vitamin C during these meals helps counteract the inhibiting effect. You must consume vitamin C during at the same time for it to help absorb iron. It doesn't make a difference whether the vitamin C is a supplement (ascorbic acid) or in food. On the other hand, a component in black and pekoe tea binds with iron and reduces the amount your body can absorb, so it's best to avoid drinking tea with your iron supplement.

Getting Enough Iron from Foods

The U.S. National Library of Medicine lists eggs, iron-fortified cereals, beef, liver, oysters, salmon and tuna as some of the best food sources of iron. According to the USDA, pork, clams and oysters contain the highest levels of iron, each containing 7.4 milligrams of iron or more in every 3-ounce serving. Iron in fruits, vegetables, grains and iron supplements is harder to absorb than iron in meat, so supplementing with vitamin C when eating those foods would improve absorption. Keep in mind that men need 8 milligrams of iron daily. Women age 50 and under require 18 milligrams a day and 27 milligrams during pregnancy, while women age 51-plus only require 8 milligrams daily.

Getting Your Vitamin C

Vitamin C deficiency can result in iron deficiency, due to reduced iron absorption. The recommended dietary allowance of vitamin C is 90 milligrams daily for men and 75 milligrams for women. All fruits and vegetables are sources of vitamin C. Some of the most potent fruit sources include citrus, cantaloupe, kiwi, mangoes, papayas, pineapples, watermelons and berries. Vegetables with a high vitamin C content include green vegetables, potatoes, sweet potatoes, tomatoes, red bell peppers and winter squash.

Safety With Taking Supplements

Consult with your doctor before taking any supplements if you're on medication or have a medical condition. Diarrhea and constipation are common side effects of iron supplements. If you take higher doses, nausea and vomiting are potential side effects. Most iron supplements contain 325 milligrams of iron. If you take too much iron, serious side effects can occur. Don't drink milk, take calcium supplements or antacids at the same time you take an iron supplement. To avoid upset stomach and diarrhea, don't take more than 2,000 milligrams of vitamin C supplements in a day. Vitamin C supplements interact with many common medications, such as birth control pills, aspirin, acetaminophen and nonsteroidal anti-inflammatory drugs.

Liquid Iron With Vitamin C

Source: https://www.livestrong.com/article/252558-should-you-take-iron-with-vitamin-c/

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Kebaikan Vitamin C 1000mg Plus Zinc 10mg Tab

Kebaikan Vitamin C 1000mg Plus Zinc 10mg Tab

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These Are The 6 Best Vitamin C Serums For Brighter, Clearer Skin

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There's never a bad time to amp up your skin care regimen's sun protection defenses. Whether you're looking to keep your skin safe from future signs of sun damage or help reduce the appearance of damage that's already been done (aka sun spots), incorporating one of the best vitamin C serums into your beauty routine can help.

In an ingredients list, you'll most likely find vitamin C listed as l-ascorbic acid, which experts agree is the most effective form of vitamin C, along with tetrahexyldecyl ascorbate. You'll also want to pay attention to the concentration level of the vitamin C, as something between 10 and 20 percent is said to be the most stable, and therefore, the most effective when it comes to protecting the skin and improving its overall tone and texture.

While you can certainly apply your vitamin C serum at night, to reap its full sun-protecting benefits, apply it in the morning after cleansing, and before you moisturize and layer on your SPF (which, yes, you still need to wear). You'll also want to be careful about using your vitamin C serum after any cleansers, treatments, or moisturizers that contain salicylic acid, glycolic acid, or retinol, as this can heighten common side effects that come with these ingredients, like burning and redness (especially if you have sensitive skin).

It's also worth noting that vitamin C is a delicate ingredient because it degrades from sun exposure. Because of this, you'll want to store your serum away from the sunlight and be on the lookout for any changes in its color, texture, or smell. A serum packaged in a darker bottle is also ideal, as it helps minimize the product's exposure to sunlight.

Ahead, you'll find six of the best vitamin C serums that are all Amazon user-approved to brighten, protect, and firm your skin.

1

The Best Serum For Vitamin C Newbies

This K-beauty favorite serum contains a mild dose of 5 percent vitamin C to allow your skin to accustom itself with the active ingredient. While that's still enough to notice the brightening and skin tone-evening benefits, the smaller percentage means its also gentler and less likely to irritate skin. Reviewers love its lightweight texture and say a little goes a long way, so you only need a couple of drops. Some have even had luck with using it on their bodies to help fade unwanted scars.

Klairs Freshly Juiced Vitamin C Serum is also an Amazon-user favorite with hundreds of five-star reviews. "I used this product for a few months and then switched to one with a higher percentage of Vitamin C only to find that it didn't work nearly as well," writes one reviewer. "I'm back to using Klairs and am so impressed by the positive change I see in my skin when I use it — it's brighter, smoother, and more even — even though it's a mild product."

The only downside with this serum is that, since it comes in a clear bottle, you'll want to be extra careful with storing it somewhere away from the sun.

2

The Best Vitamin C Serum For Sensitive Skin

If you have sensitive skin, you might have luck with the low-concentration Klairs option, above. But it does contain a few ingredients that some particularly sensitive skin types negatively react to, like propylene glycol. For a super safe, all natural pick, try this all-natural pick from Mad Hippie. It uses vitamin C in the form of sodium ascorbyl phosphate, which is said to cause less irritation and reduce the risk of oxidation. Mad Hippie formulated this serum with other complementary ingredients, like vitamin E and ferulic acid, which both improve and protect the skin from damaging free radicals. And ferulic acid also helps stabilize both vitamins C and E, so that they're even more effective. To keep skin moisturized, hyaluronic acid is included in the formula, while konjac root and chamomile extract work to protect and soothe the skin. There's also a dose of clary sage, which acts as a natural toner and astringent.

"I have very sensitive skin and normally I cannot use vitamin C serums at all," writes a reviewer. "This one does not sting or burn at all." Another user notes, "Within a week or so, I saw a smoother texture to my skin. By the end of the bottle, my skin looked smoother, brighter, and three darker spots on my face [from sun damage] were at least 80 percent lighter."

3

A Vitamin C Serum That Produces An Instant Glow

Yes, all vitamin C serums brighten the skin with continued use, but The Body Shop Vitamin C Skin Boost Instant Smoother also leaves skin glowing directly after you apply it, thanks to the tiny mineral glowing particles it contains. Long-term brightening, protecting, and collagen-boosting effects come from ascorbic acid and the vitamin C-packed camu camu berries that The Body Shop has hand harvested by local collectors on the riverbanks of the Amazon River. Vitamin E provides the skin with more protection against environmental aggressors as it softens, and Community Fair Trade Brazil nut oil further moisturizes the skin. Additionally, dimethicone and glycerin give the serum a smooth texture that helps to blur pores and even out skin tone, making this a great primer, too.

4

The Best Vitamin C Serum For Acne-Prone Skin

This serum might be a bit of a splurge, but its powerful formula means serious results. The brand works with a team of assorted experts to develop each product, including geneticists, biologists, and physicians. For their iS Clinical Pro-Heal Serum Advance+, they developed a vitamin C combo that works for all skin types, including acne-prone. Time-released vitamin C means prolonged antioxidant protection, while vitamins E and A contribute even more antioxidant benefits. iS Clinical included inflammation-reducing zinc sulfate, blemish-preventing kojic acid, and nourishing olive leaf extract to combat signs of acne while helping to prevent future breakouts.

5

The Best Drugstore Vitamin C Serum

For a more affordable option, e.l.f's Beauty Shield Vitamin C Pollution Prevention Serum costs less than $20. Despite its low price, the serum still contains your vitamin C, as well as vitamin E and pomegranate extract, which provides even more vitamin C benefits. You'll also notice glycerin and hyaluronic acid on the ingredients list to leave the skin smooth and moisturized. It's even cruelty-free and vegan, and formulated without parabens, sulfates, or phthalates.

6

The Best Vitamin C Booster Powder

If you're into DIY beauty (or you just want to customize your vitamin C application), a vitamin C booster powder, like the Resurrection Beauty L-Ascorbic Acid Powder, is the perfect choice. This jar solely contains vitamin C in the form of l-ascorbic acid, which is meant to be dissolved in water or witch hazel before being added into your favorite hydrating serum. It can even be added to your nightly moisturizer, sunscreen, or body lotion. Because you're mixing this yourself, you can start with a lower concentration of vitamin C, like 5 percent, and work your way up to 20 percent (the maximum amount recommended) as your skin learns to tolerate it.

Many Amazon reviewers share the different ways they use this powder to make custom treatments. "How terrific to find cosmetic grade vitamin C to make my own solution," one raves. "All skin care experts claim this is the best for anti-aging, however very unstable. This fixes the problem and at an reasonable price. I just mix small batches to last for a week. And in just a few weeks I can see the difference in my skin." Another recommends mixing it with aloe-vera for a skin-soothing and brightening mask.

Bustle may receive a portion of sales from products purchased from this article, which was created independently from Bustle's editorial and sales departments.

Kebaikan Vitamin C 1000mg Plus Zinc 10mg Tab

Source: https://www.bustle.com/p/the-6-best-vitamin-c-serums-16980515

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Iron C Vitamin

Iron C Vitamin

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Key Takeaways

• It's common practice to take vitamin C with iron supplements to help with absorption.
• New research says there's not enough evidence to definitively support a need to take vitamin C with iron in people with iron deficiency anemia.
• You should still avoid taking iron with any food, antacids, or calcium to achieve the best absorption.

According to a new study, people with iron deficiency anemia (IDA) might not need to take supplemental vitamin C along with oral iron supplements to help with absorption, despite longstanding advice to do so.

The standard practice for managing IDA has been for a person to increase dietary sources of iron and take an iron supplement, as well as supplemental vitamin C or foods rich in vitamin C, Nicole DeMasi Malcher, MS, RDN, CDCES, registered dietitian and founder of DeMasi Nutrition, tells Verywell. But now, Malcher confirms that recent data "suggests vitamin C might not be necessary to absorb non-heme [not animal based] iron supplements in the body."

What Is Iron Deficiency Anemia (IDA)?

Iron deficiency anemia (IDA) occurs when the body does not have enough iron. It can be diagnosed with a simple blood test. If untreated, IDA can cause a variety of symptoms, including chronic fatigue, headaches, and an irregular heartbeat.

Anyone can become iron deficient, but some people are more likely to develop the condition. For example, pregnant people are more at risk for developing IDA because iron needs increase throughout pregnancy.

Iron and Vitamin C

Traditionally, healthcare providers have suggested that people take iron along with vitamin C to help create an acidic gastrointestinal environment, which is thought to help dissolve the iron adequately for absorption.

The new study, which was published in the November issue of the Journal of the American Medical Association, notes that there has not been a randomized clinical trial (RCT) to assess whether vitamin C supplements are necessary for patients with IDA taking iron tablets.

The Study

In the randomized clinical trial, 440 adult participants with newly-diagnosed IDA were randomly assigned to two groups. Participants in one group took oral iron supplements (in the form of ferrous succinate) plus vitamin C, and participants in the other took only oral iron supplements.

The participants who were in the iron-only group took 100-milligram (mg) iron tablets every 8 hours for three months. The participants in the iron-vitamin C group took the same dose of iron supplement plus an additional 200 mg of vitamin C.

During the several months of treatment, the researchers periodically evaluated blood samples taken from the subjects to check their iron levels.

Based on their findings, the researchers concluded that taking oral iron supplements alone provided hemoglobin level and iron storage recovery efficacy equivalent to that of oral iron supplemented with vitamin C.

It does not appear that the vitamin C boost offered benefits in terms of iron absorption.

The only possible benefit the researchers observed was that vitamin C might have a positive effect on changes in mean corpuscular volume (MCV)—the measure of the mean size of red blood cells. The researchers thought that the finding could be important because patients with IDA typically have lower than normal MCV values.

Iron Supplements

Iron supplements have been used as a standard practice for treating iron deficiency anemia. The logic behind supplementing with higher doses of iron is that the nutrition gap is filled and the deficiency can be resolved.

There are different forms of iron supplements—including ferrous succinate, the kind used in the recent study—that have been shown to be effective.

While the study suggests that combining iron supplements with vitamin C offers no clinical benefit in terms of iron absorption, other research has found otherwise.

In a 2019 article published in Geriatric Nursing, the author noted that in one study, taking 100 mg of vitamin C with a meal was found to increase iron absorption by 67%.

However, the dose matters when it comes to the data surrounding supplementation. In the recent study, "the participants took 100 mg of iron every 8 hours, which would be 300 mg per day total," Grace Goodwin Dwyer, MS, MA, RD, LDN, a registered dietitian based in Nashville, Tennessee, tells Verywell. "In contrast, people taking over-the-counter iron supplements are probably taking 30 to 60 mg per day if they're following the instructions on the packages on most major brands."

Dwyer says "it would be interesting to see in a follow-up study about how vitamin C applies to lower dosages, like many of our patients are taking."

Dietary Sources of Iron

While taking iron supplements is one way to treat IDA, including food sources of iron in your diet can also help you meet your needs.

There are two main types of iron that come from your diet:

• Heme iron is found in foods like beef and seafood options
• Non-heme iron is found in foods like vegetables, beans, and whole grains. Certain foods are also fortified with non-heme iron.

Heme iron appears to be better absorbed in the body than non-heme iron. Taking vitamin C with non-heme sources of iron may help maximize iron absorption with little risk.

Tips to Support Iron Absorption

If you're supplementing with iron, there are also some things you can do to help ensure that it's properly absorbed and used by your body—or at least, you can avoid doing things that would make it harder for your body to absorb and use the important mineral.

Take Iron Every Other Day

Data published in The Lancet in 2019 suggested that giving iron-depleted women daily iron supplements as divided doses reduced iron absorption. On the other hand, providing iron supplements in single doses on alternate days appeared to optimize iron absorption and might be a preferable dosing regimen.

Choose Your Dietary Sources Wisely

"If you're looking to boost iron absorption in your body through food, it's helpful to focus on animal sources," Dwyer says. This is because of the heme form of the iron that these foods contain. Red meat, chicken, and shellfish can be helpful additions to your diet.

If you follow a vegetarian or vegan lifestyle, know that while there are dietary iron sources that are animal-free, you may need to consider taking a supplement to prevent anemia.

Take Iron On An Empty Stomach

Iron is best absorbed when taken on an empty stomach with a full 8-ounce glass of water or orange juice. If you get an upset stomach, you can take your iron with food or immediately after meals; however, know that taking an iron supplement with food will decrease absorption to 40%.

Avoid Taking Iron With Phytate-rich and/or Polyphenol-rich Foods

You also need to be mindful of the foods and drinks you consume when you take your iron. Absorption of oral iron is inhibited by phytates (which are found in cereals and certain vegetables) and polyphenols (which are found in some vegetables, fruits, cereals, legumes, tea, coffee, and wine).

Tea has been shown to reduce iron absorption by 90%.

Do Not Take Antacids Or Calcium Supplements With Iron

Antacids or calcium supplements can decrease iron absorption and should not be taken at the same time as iron supplements. It is best to space doses of these products out. Take antacids or calcium 12 hours apart from your iron.

Ensure You Are Not Deficient in Copper

Copper is a mineral that plays a key role in helping the body absorb iron. If your copper levels are low, your body might have a hard time absorbing iron.

Consider The Pros and Cons of Taking Vitamin C With Iron

Data appears to be mixed when it comes to the benefits of taking vitamin C with iron to support absorption. If you do choose to take a vitamin C supplement, make sure that you know how much vitamin C is in the product you've chosen.

It appears that vitamin C needs to be taken in a dose of 200 mg to reap the potential benefit.

While taking supplemental vitamin C is low-risk, it's not risk-free. For example, if you don't tolerate the dose, you might experience gastrointestinal symptoms like nausea and diarrhea. You should also know that some prescription and over-the-counter (OTC) medications don't mix with vitamin supplements, including vitamin C. If you're considering trying a supplement, talk to your healthcare provider.

What This Means For You

If you have iron deficiency anemia, your provider might recommend that you increase sources of heme and non-heme iron in your diet, as well as take an iron supplement. But despite the standard practice, you may not need to pair iron with vitamin C to help with absorption. Talk to your doctor before starting any kind of vitamin supplement.

Iron C Vitamin

Source: https://www.verywellhealth.com/vitamin-c-iron-supplement-study-5087131

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How Much Vitamin C Needed For Iron Absorption

How Much Vitamin C Needed For Iron Absorption

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Vitamin A should be an integral part of every person's diet. It plays vital roles in your body by helping to maintain your vision, skin health and even your immune system's ability to work properly. But it's important to consume the right amount; vitamin A can be harmful when your body gets too much of it. Learn more about vitamin A, including what it does, where to find it and what happens when you get too much of it.

Vitamin A is actually a group of fat-soluble vitamins like retinol, retinal and retinyl esters, all of which have various health benefits. Vitamin A is particularly important in the maintenance of vision — especially your ability to see in low light. Your body converts this vitamin to retinal, which combines with other molecules to form rhodopsin. This is the protein principally responsible for your eyes' absorption of light. If you're worried about your vision getting worse over time, make sure you get enough vitamin A. It's a good way to strengthen your sight naturally.

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Consuming sufficient amounts of vitamin A can also work wonders for your immune system. Vitamin A promotes the production of white blood cells, particularly T cells, which eliminate viruses and bacteria from your body. Vitamin A also stimulates the production of special T cells called regulatory T cells. These help to reduce the risk of your body attacking its own healthy cells, which is what happens with some autoimmune diseases. Furthermore, vitamin A fortifies the linings of your respiratory, intestinal and urinary tracts, along with your skin and mucous membranes. It also sends additional immune cells there to prevent bacteria from entering your body and causing an infection.

Vitamin A is also involved in the maintenance of healthy skin by helping immature skin cells age properly into mature skin cells. It reduces sebum production, which can be problematic in oily skin. In fact, Isotretinoin is a common prescription-only vitamin A derivative used as a treatment for acne.

Vitamin A can also contribute to improved bone growth, cell division and cell differentiation. It even promotes reproduction and is a healthy supplement for people who are breastfeeding.

Food Sources of Vitamin A

Vitamin A is quite easy to come by naturally. Many of the most basic staples in our diets — meat, eggs, milk and cheese, for example — are excellent sources of vitamin A. Other specific animal sources have high vitamin A levels as well, such as kidney and liver. However, it's important to note that some of these foods have high cholesterol and saturated fat levels, so be sure to keep a healthy balance of these in your diet if you choose to eat them.

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Vitamin A exists as either preformed vitamin A or as provitamin A carotenoids. Preformed vitamin A is found in animal and dairy sources. Provitamin A carotenoids include beta-carotene and alpha-carotene, which your body converts into vitamin A and other derivatives. Beta-carotene is found in foods like carrots, pumpkins, sweet potatoes, cantaloupes, grapefruits, spinach, broccoli and apricots. As a general rule, the more vibrant the color of a fruit or vegetable is, the more beta-carotene it contains. As a bonus, you won't have to worry about the fat or cholesterol content in these foods.

Side Effects of Too Much Vitamin A

Getting the right amount of vitamin A in your diet shouldn't have any negative side effects. However, a vitamin A deficiency can lead to health issues over time. If you don't get enough vitamin A, you could develop vision problems. Plus, your immune system could weaken, leaving you susceptible to infectious diseases.

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Perhaps even more serious are the side effects of consuming too much vitamin A, also known as hypervitaminosis A. Initially, too much vitamin A can cause headaches, dizziness, nausea and even vomiting. Because vitamin A is fat-soluble, it tends to get stored in your liver if you consume too much of it, which can lead to liver problems and even liver failure. There's also evidence that getting excess vitamin A can cause osteoporosis and bone fractures.

In particular, pregnant people must be careful about their intake of vitamin A, as getting too much vitamin A can cause birth defects. Pregnant people shouldn't eat foods that are high in vitamin A, such as pate and fish liver oil. In general, babies and small children are more sensitive to vitamin A overdoses and deficiencies, so it's important to closely monitor their daily vitamin A consumption, too.

Taking Vitamin A: Daily Dosage Recommendations

According to the Institute of Medicine Food and Nutrition Board, most adult men should consume around 900 micrograms (mcg) of vitamin A per day, and women should have around 700mcg per day. The recommended daily intake is lower (750–770mcg per day) in pregnant people and higher (1200–1300mcg per day) for people who are breastfeeding.

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The daily dosage for children varies with age. From 0 to 6 months, infants should have 400mcg per day, after which they should consume 500mcg per day until they reach the age of 1. Children 1 to 3 years of age should get 300mcg per day, while those from 4 to 8 years of age need 400mcg per day. Those from 9 to 13 years old need 600mcg each day. Daily recommendations for children don't change based on gender.

These dosage requirements are general guidelines. Individuals may have differing daily recommendations for vitamin A, depending on their health status and lifestyle. Most people can get a sufficient amount of vitamin A simply by eating a balanced diet. Consult a doctor before taking any vitamin A supplements or changing from the recommended dosage for your age and sex.

In summary, it's important to be aware of the foods that'll give you an adequate supply of vitamin A. Provided you have a balanced diet, you might not need to take vitamin A supplements. Be aware of foods containing high levels of vitamin A, and avoid eating too much of these, particularly during pregnancy.

Resource Links:

https://medlineplus.gov/vitamina.html

https://bnf.nice.org.uk/treatment-summary/vitamins.html

https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-a/

https://ods.od.nih.gov/factsheets/VitaminA-Consumer/

https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6470929/pdf/nutrients-11-00681.pdf

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Honey C Vitamins Original

Honey C Vitamins Original

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Whether in the form of a fizzy drink or flavored lozenges, cold and flu preventative supplements almost always highlight vitamin C as one of their key ingredients. So, what's so magical about vitamin C? Also known as ascorbic acid, vitamin C is critical to living healthily. Since the human body cannot spontaneously generate this nutrient, vitamin C must instead be absorbed from outside sources, such as vitamin supplements or foods that are naturally rich in it.

Commonly found in cold and flu preventative supplements, vitamin C strengthens and speeds up immune system functionality. Though research does not indicate that vitamin C intake alone can prevent the onset of cold or flu, adequate daily intake may shorten the duration of an infection or lessen the severity of symptoms.

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Vitamin C is crucial for the maintenance of well being. For example, it plays a role in wound healing and helps maintain many essential body tissues. It also acts as a potent antioxidant and can repair damage from free radicals, which are linked to aging effects, and disease vulnerability. Additionally, vitamin C can also prevent anemia, since it helps the body increase absorption of dietary iron, another vital mineral that the body cannot spontaneously create.

Foods that contain high concentrations of vitamin C have been linked with a lower risk of cardiovascular disease, like heart attack and stroke. Vitamin C can also increase levels of nitric oxide, a compound that widens blood vessels and, in turn, lowers blood pressure. In addition, regular intake of vitamin C, along with other vitamins, has been linked to a decreased risk for developing age-related cataracts, a leading cause of visual impairment in the United States.

Common Sources of Vitamin C

Vitamin C can be easily obtained through the many different foods, including:

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• Citrus fruits and juices (orange, grapefruit, lemon, lime and tangerine)
• Berries
• Melons
• Mangoes
• Kiwi
• Tomato
• Broccoli
• Red peppers
• Spinach
• Squash
• Potatoes

Cooking these foods may result in the loss of some of the vitamin content, so it is ideal to ingest them raw, either whole or juiced. Nowadays, there are also numerous packaged food products, like cereals, that have been enriched and fortified with vitamin C, so that the nutrient can be easily obtained.

Vitamin C may also be labeled as "L-ascorbic acid" in supplement form, and most over-the-counter multivitamins contain the recommended daily amount of the vitamin. While it is a good source when an individual is in need of a vitamin C boost, supplements are not meant to replace a diet rich in naturally derived vitamin C.

What Happens When You Have Too Much — or Too Little — Vitamin C?

Vitamin C is a water-soluble vitamin that can be easily flushed out of the body via urination when it is not needed. Therefore, if the main source of vitamin C is from naturally occurring foods, it is near-impossible for excess vitamin C to produce side effects. However, taking excessive concentrated vitamin C supplements may lead to diarrhea or stomach upset.

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Since vitamin C-rich foods are so readily available nowadays, symptoms of inadequate vitamin C intake are also rare in the United States. However, malnourished individuals can experience symptoms of vitamin C deficiency over time, including:

• Weakness
• Fatigue
• Anemia
• Easy bruising
• Joint pain
• Skin breakdown
• Weakened tooth enamel
• Gum inflammation

Severe vitamin C deficiency is referred to as scurvy. Scurvy can be easily treated with increased dietary or supplemental vitamin C. Since vitamin C is crucial in the detoxification of the body, a lack of vitamin C can compromise the immune system and make an individual more susceptible to diseases and infections. Individuals with insufficient vitamin C may find that it takes longer than usual to recover from a cold or a physical wound.

Daily Dosage Recommendations:

The daily dosage recommendation for vitamin C is different for everyone, depending on factors such as gender, age, lifestyle and current health condition. The recommended daily dosage for vitamin C is at least 75 mg daily for women and 90 mg for men. Since people who are pregnant, breast feeding, smoking or using oral contraceptives have a lower blood level of vitamin C than others, larger doses of vitamin C may be needed to achieve optimal results in these individuals. Those who have prior or current medical conditions may also require bigger or smaller dosage levels, as recommended by their healthcare providers.

Resource Links:

• "Vitamin C" via MedlinePlus
• "Vitamin C and Infections" via MDPI
• "Extra Dose of Vitamin C Based on a Daily Supplementation Shortens the Common Cold: A Meta-Analysis of 9 Randomized Controlled Trials" via Hindawi, BioMed Research International
• "Vitamin C" via National Institutes of Health
• "Scurvy" via U.S. Department of Health & Human Services, National Institutes of Health
• "Dietary intake and blood concentrations of antioxidants and the risk of cardiovascular disease, total cancer, and all-cause mortality: a systematic review and dose-response meta-analysis of prospective studies" via The American Journal of Clinical Nutrition
• "Dietary vitamin and carotenoid intake and risk of age-related cataract" via The American Journal of Clinical Nutrition
• "Cardiovascular System" via Department of Anatomy, Seoul National University College of Medicine (via Springer)

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Ginger And Vitamin C

Ginger And Vitamin C

The Benefits of Vitamin B Supplements

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Vitamin B is a crucial resource in your body, yet many people don't consume enough vitamin B with diet alone. Vitamin B vitamins are necessary for both men and women, especially older adults and those with certain medical conditions. Because vitamin B comes in many forms, it can be confusing to figure out exactly how to take for the most health benefits.

Types of Vitamin B Supplements

Vitamin B complex is a supplement that contains a combination of essential B vitamins so you don't have to take multiple pills each day. Some of the most effective vitamin brands include other vitamins as well, such as biotin, zinc, vitamin C and vitamin E. If you only want to take certain B vitamins, look for individual B1, B2, B3, B5, B6 and B12 supplements. If you're pregnant or obese, you need more of these vitamins, but it's good to check with your doctor for specific requirements.

Kidney Health

B Complex is one of the best vitamins for kidney health because each vitamin it contains has an important job. Vitamins B6, B12 and folic acid help prevent anemia, and the other B vitamins, such as riboflavin, thiamine and niacin, turn the food you eat into energy. If you have kidney disease, your vitamin requirements are different than someone who doesn't have it. Vitamin B6 works to make protein and red blood cells, vitamin B12 makes red blood cells and folate maintains nerve cells and assists in making new cells.

Anxiety and Depression

Vitamin B complex vitamins help with depression and anxiety. It's believed that when you're not getting enough B vitamins in your diet, it causes an imbalance in the brain neurotransmitters that create a signal to your brain, leading to depression. Vitamins B3 and B6 added with some folic acid can help improve your mood and reduce anxiety. You can visit your local natural vitamin shop to see what they have, but if you have questions, you should speak to a physician first or do some research to make sure you're taking the right supplements.

Other Conditions

Trials using vitamins B2, B9 and B12 have shown to benefit conditions such as rheumatoid arthritis and osteoarthritis. The reason these B vitamins are the best vitamins for arthritis is because they help reduce inflammation and improve joint mobility. Vitamin B12 is one of the best vitamins for fibromyalgia because low levels of the vitamin in your body can increase symptoms, making your pain and discomfort worse and causing muscle weakness, pins and needles, and unexplained aches and pains. B vitamins are some of the best vitamins to help tinnitus, or ringing in the ear. Many patients who have chronic ringing in their ears are deficient in B12. B vitamins are also the best vitamins for older men and heart health.

What to Buy

What to buy depends on what your body needs. It's helpful to determine your vitamin requirements based on age and sex before increasing your vitamin intake with your diet. Take time to learn about the top 10 vitamin brands and search vitamin company ratings to find something that works best for you. Vitamin E is good as an antioxidant, which protects the cells, so it's another vitamin that is worth considering. Vitamin G is good for improving healing capabilities and reducing inflammation. Vitamin D3 is used for treating and preventing bone disorders by assisting the body in absorbing calcium.

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Equal Plus Vitamin C

Equal Plus Vitamin C

Group of unsaturated nutritional organic compounds

This article is about the family of vitamers. For the form usually used as a supplement, see Retinol.

Chemical structure of retinol, one of the major forms of vitamin A

Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, and several provitamin A carotenoids (most notably beta-carotene).^{[1] [2] [3]} Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system, and for good vision.^{[4] [5]} Vitamin A is needed by the retina of the eye in the form of retinal, which combines with protein opsin to form rhodopsin, the light-absorbing molecule^[6] necessary for both low-light (scotopic vision) and color vision.^[7]

In foods of animal origin, the major form of vitamin A is an ester, primarily retinyl palmitate, which is converted to retinol (chemically an alcohol) in the small intestine. The retinol form functions as a storage form of the vitamin, and can be converted to and from its visually active aldehyde form, retinal.^[3]

All forms of vitamin A have a beta-ionone ring to which an isoprenoid chain is attached, called a retinyl group.^[1] Both structural features are essential for vitamin activity.^[8] The orange pigment of carrots (beta-carotene) can be represented as two connected retinyl groups, which are used in the body to contribute to vitamin A levels.^[3] Alpha-carotene and gamma-carotene also have a single retinyl group, which give them some vitamin activity. None of the other carotenes have vitamin activity. The carotenoid beta-cryptoxanthin possesses an ionone group and has vitamin activity in humans.

Vitamin A can be found in two principal forms in foods:

• Retinol, the form of vitamin A absorbed when eating animal food sources, is a yellow, fat-soluble substance. Since the pure alcohol form is unstable, the vitamin is found in tissues in a form of retinyl ester. It is also commercially produced and administered as esters such as retinyl acetate or palmitate.^[9]
• The carotenes alpha-carotene, beta-carotene, gamma-carotene; and the xanthophyll beta-cryptoxanthin (all of which contain beta-ionone rings), but no other carotenoids, function as provitamin A in herbivores and omnivore animals, which possess the enzyme beta-carotene 15,15'-dioxygenase in the intestinal mucosa to cleave and convert provitamin A to retinol.^[10]

Medical use [edit]

Deficiency [edit]

Vitamin A deficiency is estimated to affect approximately one third of children under the age of five around the world.^[11] It is estimated to claim the lives of 670,000 children under five annually.^[12] Between 250,000 and 500,000 children in developing countries become blind each year owing to vitamin A deficiency, with the highest prevalence in Africa and southeast Asia.^[13] Vitamin A deficiency is "the leading cause of preventable childhood blindness", according to UNICEF.^{[14] [15]} It also increases the risk of death from common childhood conditions such as diarrhea. UNICEF regards addressing vitamin A deficiency as critical to reducing child mortality, the fourth of the United Nations' Millennium Development Goals.^[14]

Vitamin A deficiency can occur as either a primary or a secondary deficiency. A primary vitamin A deficiency occurs among children and adults who do not consume an adequate intake of provitamin A carotenoids from fruits and vegetables or preformed vitamin A from animal and dairy products. Early weaning from breastmilk can also increase the risk of vitamin A deficiency.

Secondary vitamin A deficiency is associated with chronic malabsorption of lipids, impaired bile production and release, and chronic exposure to oxidants, such as cigarette smoke, and chronic alcoholism. Vitamin A is a fat-soluble vitamin and depends on micellar solubilization for dispersion into the small intestine, which results in poor use of vitamin A from low-fat diets. Zinc deficiency can also impair absorption, transport, and metabolism of vitamin A because it is essential for the synthesis of the vitamin A transport proteins and as the cofactor in conversion of retinol to retinal. In malnourished populations, common low intakes of vitamin A and zinc increase the severity of vitamin A deficiency and lead to physiological signs and symptoms of deficiency.^[16] A study in Burkina Faso showed major reduction of malaria morbidity by use of combined vitamin A and zinc supplementation in young children.^[17]

Due to the unique function of retinal as a visual chromophore, one of the earliest and specific manifestations of vitamin A deficiency is impaired vision, particularly in reduced light – night blindness. Persistent deficiency gives rise to a series of changes, the most devastating of which occur in the eyes. Some other ocular changes are referred to as xerophthalmia. First there is dryness of the conjunctiva (xerosis) as the normal lacrimal and mucus-secreting epithelium is replaced by a keratinized epithelium. This is followed by the build-up of keratin debris in small opaque plaques (Bitot's spots) and, eventually, erosion of the roughened corneal surface with softening and destruction of the cornea (keratomalacia) and leading to total blindness.^[18] Other changes include impaired immunity (increased risk of ear infections, urinary tract infections, meningococcal disease), hyperkeratosis (white lumps at hair follicles), keratosis pilaris and squamous metaplasia of the epithelium lining the upper respiratory passages and urinary bladder to a keratinized epithelium. In relation to dentistry, a deficiency in vitamin A may lead to enamel hypoplasia.

Adequate supply, but not excess vitamin A, is especially important for pregnant and breastfeeding women for normal fetal development and in breastmilk. Deficiencies cannot be compensated by postnatal supplementation.^{[19] [20]} Excess vitamin A, which is most common with high-dose vitamin supplements, can cause birth defects and therefore should not exceed recommended daily values.^[21]

Vitamin A metabolic inhibition as a result of alcohol consumption during pregnancy is one proposed mechanism for fetal alcohol syndrome, and is characterized by teratogenicity resembling maternal vitamin A deficiency or reduced retinoic acid synthesis during embryogenesis.^{[22] [23] [24]}

Vitamin A supplementation [edit]

Vitamin A supplementation coverage rate (children ages 6–59 months), 2014^[25]

A 2012 review found no evidence that beta-carotene or vitamin A supplements increase longevity in healthy people or in people with various diseases.^[26] A 2011 review found that vitamin A supplementation of children at risk of deficiency aged under five reduced mortality by up to 24%.^[27] However, a 2016 and 2017 Cochrane review concluded there was not evidence to recommend blanket vitamin A supplementation for all infants less than a year of age, as it did not reduce infant mortality or morbidity in low- and middle-income countries.^{[28] [29]} The World Health Organization estimated that vitamin A supplementation averted 1.25 million deaths due to vitamin A deficiency in 40 countries since 1998.^[30]

While strategies include intake of vitamin A through a combination of breast feeding and dietary intake, delivery of oral high-dose supplements remain the principal strategy for minimizing deficiency.^[31] About 75% of the vitamin A required for supplementation activity by developing countries is supplied by the Micronutrient Initiative with support from the Canadian International Development Agency.^[32] Food fortification approaches are feasible,^[33] but cannot ensure adequate intake levels.^[31] Observational studies of pregnant women in sub-Saharan Africa have shown that low serum vitamin A levels are associated with an increased risk of mother-to-child transmission of HIV. Low blood vitamin A levels have been associated with rapid HIV infection and deaths.^{[34] [35]} Reviews on the possible mechanisms of HIV transmission found no relationship between blood vitamin A levels in the mother and infant, with conventional intervention established by treatment with anti-HIV drugs.^{[36] [37]}

Side effects [edit]

Given that vitamin A is fat-soluble, disposing of any excess taken in through diet takes much longer than with water-soluble B vitamins and vitamin C. This allows for toxic levels of vitamin A to accumulate. These toxicities only occur with preformed vitamin A (retinoid). The carotenoid forms (for example, beta-carotene as found in carrots) give no such symptoms, but excessive dietary intake of beta-carotene can lead to carotenodermia, a harmless but cosmetically displeasing orange-yellow discoloration of the skin.^{[38] [39] [40]}

In general, acute toxicity occurs at doses of 25,000IU/kg of body weight, with chronic toxicity occurring at 4,000IU/kg of body weight daily for 6–15 months.^[41] However, liver toxicities can occur at levels as low as 15,000IU (4500micrograms) per day to 1.4 million IU per day, with an average daily toxic dose of 120,000IU, particularly with excessive consumption of alcohol.^[7] In people with kidney failure, 4000IU can cause substantial damage. Signs of toxicity may occur with long-term consumption of vitamin A at doses of 25,000–33,000IU per day.^[1]

Excessive vitamin A consumption can lead to nausea, irritability, anorexia (reduced appetite), vomiting, blurry vision, headaches, hair loss, muscle and abdominal pain and weakness, drowsiness, and altered mental status. In chronic cases, hair loss, dry skin, drying of the mucous membranes, fever, insomnia, fatigue, weight loss, bone fractures, anemia, and diarrhea can all be evident on top of the symptoms associated with less serious toxicity.^[42] Some of these symptoms are also common to acne treatment with Isotretinoin. Chronically high doses of vitamin A, and also pharmaceutical retinoids such as 13-cis retinoic acid, can produce the syndrome of pseudotumor cerebri.^[43] This syndrome includes headache, blurring of vision and confusion, associated with increased intracerebral pressure. Symptoms begin to resolve when intake of the offending substance is stopped.^[44]

Chronic intake of 1500RAE of preformed vitamin A may be associated with osteoporosis and hip fractures because it suppresses bone building while simultaneously stimulating bone breakdown,^[45] although other reviews have disputed this effect, indicating further evidence is needed.^[1]

A 2012 systematic review found that beta-carotene and higher doses of supplemental vitamin A increased mortality in healthy people and people with various diseases.^[26] The findings of the review extend evidence that antioxidants may not have long-term benefits.

Equivalencies of retinoids and carotenoids (IU) [edit]

As some carotenoids can be converted into vitamin A, attempts have been made to determine how much of them in the diet is equivalent to a particular amount of retinol, so that comparisons can be made of the benefit of different foods. The situation can be confusing because the accepted equivalences have changed.

For many years, a system of equivalencies in which an international unit (IU) was equal to 0.3 μg of retinol (~1 nmol), 0.6 μg of β-carotene, or 1.2 μg of other provitamin-A carotenoids was used.^[46] This relationship is alternatively expressed by the retinol equivalent (RE): one RE corresponded to 1 μg retinol, 2 μg β-carotene dissolved in oil (it is only partly dissolved in most supplement pills, due to very poor solubility in any medium), 6 μg β-carotene in normal food (because it is not absorbed as well as when in oils), and 12 μg of either α-carotene, γ-carotene, or β-cryptoxanthin in food.^[47]

Newer research has shown that the absorption of provitamin-A carotenoids is only half as much as previously thought. As a result, in 2001 the US Institute of Medicine recommended a new unit, the retinol activity equivalent (RAE). Each μg RAE corresponds to 1 μg retinol, 2 μg of β-carotene in oil, 12μg of "dietary" beta-carotene, or 24μg of the three other dietary provitamin-A carotenoids.^[48]

Substance and its chemical environment (per 1 μg)	IU (1989)	μg RE (1989)	μg RAE (2001)
Retinol	3.33	1	1
beta-Carotene, dissolved in oil	1.67	1/2	1/2
beta-Carotene, common dietary	1.67	1/6	1/12
alpha-Carotene, common dietary gamma-Carotene, common dietary beta-Cryptoxanthin, common dietary	0.83	1/12	1/24

Because the conversion of retinol from provitamin carotenoids by the human body is actively regulated by the amount of retinol available to the body, the conversions apply strictly only for vitamin A-deficient humans.^{[ citation needed ]} The absorption of provitamins depends greatly on the amount of lipids ingested with the provitamin; lipids increase the uptake of the provitamin.^[49]

A sample vegan diet for one day that provides sufficient vitamin A has been published by the Food and Nutrition Board (page 120^[48]). Reference values for retinol or its equivalents, provided by the National Academy of Sciences, have decreased. The RDA (for men) established in 1968 was 5000 IU (1500 μg retinol). In 1974, the RDA was revised to 1000 RE (1000 μg retinol). As of 2001, the RDA for adult males is 900 RAE (900 μg or 3000 IU retinol).^{[ citation needed ]} By RAE definitions, this is equivalent to 1800 μg of β-carotene supplement dissolved in oil (3000 IU) or 10800 μg of β-carotene in food (18000 IU).

Dietary recommendations [edit]

The US National Academy of Medicine updated Dietary Reference Intakes (DRIs) for vitamin A, which included Recommended Dietary Allowances (RDAs) and Estimated Average Requirements (EARs), in 2001. For infants up to 12 months there was not sufficient information to establish a RDA, so Adequate Intake (AI) is shown instead. As for safety, tolerable upper intake levels (ULs) were also established. The calculation of retinol activity equivalents (RAE) is each μg RAE corresponds to 1 μg retinol, 2 μg of β-carotene in oil, 12 μg of "dietary" beta-carotene, or 24 μg of the three other dietary provitamin-A carotenoids.^[48]

Life stage group		US RDAs or AIs (μg RAE/day)	Upper limits (UL, μg/day)[IOM 1]
Infants	0–6 months	400 (AI)	500 (AI)
	7–12 months	600	600
Children	1–3 years	300	600
	4–8 years	400	900
Males	9–13 years	600	1700
	14–18 years	900	2800
	>19 years	900	3000
Females	9–13 years	600	1700
	14–18 years	700	2800
	>19 years	700	3000
Pregnancy	<19 years	750	2800
	>19 years	770	3000
Lactation	<19 years	1200	2800
	>19 years	1300	3000

1. ^ ULs are for natural and synthetic retinol ester forms of vitamin A. Beta-carotene and other provitamin A carotenoids from foods and dietary supplements are not added when calculating total vitamin A intake for safety assessments, although they are included as RAEs for RDA and AI calculations.^{[1] [48]}

For U.S. food and dietary supplement labeling purposes, the amount in a serving is expressed as a percent of Daily Value (%DV). For vitamin A labeling purposes 100% of the Daily Value was set at 5,000 IU, but it was revised to 900 μg RAE on 27 May 2016.^{[50] [51]} Compliance with the updated labeling regulations was required by 1 January 2020 for manufacturers with US$10 million or more in annual food sales, and by 1 January 2021 for manufacturers with lower volume food sales.^{[52] [53]} A table of the old and new adult daily values is provided at Reference Daily Intake.

The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. For women and men of ages 15 and older, the PRIs are set respectively at 650 and 750 μg RE/day. PRI for pregnancy is 700 μg RE/day, for lactation 1300/day. For children of ages 1–14 years, the PRIs increase with age from 250 to 600 μg RE/day. These PRIs are similar to the U.S. RDAs.^[54] The EFSA reviewed the same safety question as the United States, and set a UL at 3000 μg/day for preformed vitamin A.^[55]

Sources [edit]

Carrots are a source of beta-carotene

Vitamin A is found in many foods, including the following list.^[56] Conversion of carotene to retinol varies from person to person, and bioavailability of carotene in food varies.^{[57] [58]}

Source	Retinol activity equivalences (RAEs), μg/100g
cod liver oil	30000
liver turkey	8058
liver beef, pork, fish	6500
liver chicken	3296
sweet potato[food 1]	961
carrot	835
broccoli leaf	800
butter	684
kale	681
collard greens frozen then boiled	575
butternut squash	532
dandelion greens	508
spinach	469
pumpkin	426
collard greens	333
ghee	300
cheddar cheese	265
cantaloupe melon	169
bell pepper/capsicum, red	157
egg	140
apricot	96
papaya	55
tomatoes	42
mango	38
pea	38
broccoli florets	31
milk	28
bell pepper/capsicum, green	18
spirulina	3

1. ^ Content in sweet potatoes depend on flesh color.

Metabolic functions [edit]

Vitamin A plays a role in a variety of functions throughout the body,^[4] such as:

• Vision
• Gene transcription
• Immune function
• Embryonic development and reproduction
• Bone metabolism
• Haematopoiesis
• Skin and cellular health
• Teeth
• Mucous membrane

Vision [edit]

The role of vitamin A in the visual cycle is specifically related to the retinal form. Within the eye, 11-cis-retinal is bound to the protein "opsin" to form rhodopsin in rods^[6] and iodopsin (cones) at conserved lysine residues. As light enters the eye, the 11-cis-retinal is isomerized to the all-"trans" form. The all-"trans" retinal dissociates from the opsin in a series of steps called photo-bleaching. This isomerization induces a nervous signal along the optic nerve to the visual center of the brain. After separating from opsin, the all-"trans"-retinal is recycled and converted back to the 11-"cis"-retinal form by a series of enzymatic reactions. In addition, some of the all-"trans" retinal may be converted to all-"trans" retinol form and then transported with an interphotoreceptor retinol-binding protein (IRBP) to the pigment epithelial cells. Further esterification into all-"trans" retinyl esters allow for storage of all-trans-retinol within the pigment epithelial cells to be reused when needed.^[16] The final stage is conversion of 11-cis-retinal will rebind to opsin to reform rhodopsin (visual purple) in the retina. Rhodopsin is needed to see in low light (contrast) as well as for night vision. Kühne showed that rhodopsin in the retina is only regenerated when the retina is attached to retinal pigmented epithelium,^[6] which provides retinal. It is for this reason that a deficiency in vitamin A will inhibit the reformation of rhodopsin, and will lead to one of the first symptoms, night blindness.^[59]

Gene transcription [edit]

Vitamin A, in the retinoic acid form, plays an important role in gene transcription. Once retinol has been taken up by a cell, it can be oxidized to retinal (retinaldehyde) by retinol dehydrogenases; retinaldehyde can then be oxidized to retinoic acid by retinaldehyde dehydrogenases.^[21] The conversion of retinaldehyde to retinoic acid is an irreversible step; this means that the production of retinoic acid is tightly regulated, due to its activity as a ligand for nuclear receptors.^[16] The physiological form of retinoic acid (all-trans-retinoic acid) regulates gene transcription by binding to nuclear receptors known as retinoic acid receptors (RARs) which are bound to DNA as heterodimers with retinoid "X" receptors (RXRs). RAR and RXR must dimerize before they can bind to the DNA. RAR will form a heterodimer with RXR (RAR-RXR), but it does not readily form a homodimer (RAR-RAR). RXR, on the other hand, may form a homodimer (RXR-RXR) and will form heterodimers with many other nuclear receptors as well, including the thyroid hormone receptor (RXR-TR), the Vitamin D₃ receptor (RXR-VDR), the peroxisome proliferator-activated receptor (RXR-PPAR) and the liver "X" receptor (RXR-LXR).^[60]

The RAR-RXR heterodimer recognizes retinoic acid response elements (RAREs) on the DNA whereas the RXR-RXR homodimer recognizes retinoid "X" response elements (RXREs) on the DNA; although several RAREs near target genes have been shown to control physiological processes,^[21] this has not been demonstrated for RXREs. The heterodimers of RXR with nuclear receptors other than RAR (i.e. TR, VDR, PPAR, LXR) bind to various distinct response elements on the DNA to control processes not regulated by vitamin A.^[16] Upon binding of retinoic acid to the RAR component of the RAR-RXR heterodimer, the receptors undergo a conformational change that causes co-repressors to dissociate from the receptors. Coactivators can then bind to the receptor complex, which may help to loosen the chromatin structure from the histones or may interact with the transcriptional machinery.^[60] This response can upregulate (or downregulate) the expression of target genes, including Hox genes as well as the genes that encode for the receptors themselves (i.e. RAR-beta in mammals).^[16]

Immune function [edit]

Vitamin A plays a role in many areas of the immune system, particularly in T cell differentiation and proliferation.^{[61] [62]}

Vitamin A promotes the proliferation of T cells through an indirect mechanism involving an increase in IL-2.^[62] In addition to promoting proliferation, vitamin A (specifically retinoic acid) influences the differentiation of T cells.^{[63] [64]} In the presence of retinoic acid, dendritic cells located in the gut are able to mediate the differentiation of T cells into regulatory T cells.^[64] Regulatory T cells are important for prevention of an immune response against "self" and regulating the strength of the immune response in order to prevent host damage. Together with TGF-β, Vitamin A promotes the conversion of T cells to regulatory T cells.^[63] Without Vitamin A, TGF-β stimulates differentiation into T cells that could create an autoimmune response.^[63]

Hematopoietic stem cells are important for the production of all blood cells, including immune cells, and are able to replenish these cells throughout the life of an individual. Dormant hematopoietic stem cells are able to self-renew, and are available to differentiate and produce new blood cells when they are needed. In addition to T cells, Vitamin A is important for the correct regulation of hematopoietic stem cell dormancy.^[65] When cells are treated with all-trans retinoic acid, they are unable to leave the dormant state and become active, however, when vitamin A is removed from the diet, hematopoietic stem cells are no longer able to become dormant and the population of hematopoietic stem cells decreases.^[65] This shows an importance in creating a balanced amount of vitamin A within the environment to allow these stem cells to transition between a dormant and activated state, in order to maintain a healthy immune system.

Vitamin A has also been shown to be important for T cell homing to the intestine, effects dendritic cells, and can play a role in increased IgA secretion, which is important for the immune response in mucosal tissues.^{[61] [66]}

Dermatology [edit]

Vitamin A, and more specifically, retinoic acid, appears to maintain normal skin health by switching on genes and differentiating keratinocytes (immature skin cells) into mature epidermal cells.^[67] Exact mechanisms behind pharmacological retinoid therapy agents in the treatment of dermatological diseases are being researched. For the treatment of acne, the most prescribed retinoid drug is 13-cis retinoic acid (isotretinoin). It reduces the size and secretion of the sebaceous glands. Although it is known that 40 mg of isotretinoin will break down to an equivalent of 10 mg of ATRA — the mechanism of action of the drug (original brand name Accutane) remains unknown and is a matter of some controversy. Isotretinoin reduces bacterial numbers in both the ducts and skin surface. This is thought to be a result of the reduction in sebum, a nutrient source for the bacteria. Isotretinoin reduces inflammation via inhibition of chemotactic responses of monocytes and neutrophils.^[16] Isotretinoin also has been shown to initiate remodeling of the sebaceous glands; triggering changes in gene expression that selectively induce apoptosis.^[68] Isotretinoin is a teratogen with a number of potential side-effects. Consequently, its use requires medical supervision.

Retinal/retinol versus retinoic acid [edit]

Vitamin A-deprived rats can be kept in good general health with supplementation of retinoic acid. This reverses the growth-stunting effects of vitamin A deficiency, as well as early stages of xerophthalmia. However, such rats show infertility (in both male and females) and continued degeneration of the retina, showing that these functions require retinal or retinol, which are interconvertible but which cannot be recovered from the oxidized retinoic acid. The requirement of retinol to rescue reproduction in vitamin A deficient rats is now known to be due to a requirement for local synthesis of retinoic acid from retinol in testis and embryos.^{[69] [70]}

Vitamin A and derivatives in medical use [edit]

Retinyl palmitate has been used in skin creams, where it is broken down to retinol and ostensibly metabolised to retinoic acid, which has potent biological activity, as described above. The retinoids (for example, 13-cis-retinoic acid) constitute a class of chemical compounds chemically related to retinoic acid, and are used in medicine to modulate gene functions in place of this compound. Like retinoic acid, the related compounds do not have full vitamin A activity, but do have powerful effects on gene expression and epithelial cell differentiation.^[71] Pharmaceutics utilizing megadoses of naturally occurring retinoic acid derivatives are currently in use for cancer, HIV, and dermatological purposes.^[72] At high doses, side-effects are similar to vitamin A toxicity.^{[ citation needed ]}

History [edit]

The discovery of vitamin A may have stemmed from research dating back to 1816, when physiologist François Magendie observed that dogs deprived of nutrition developed corneal ulcers and had a high mortality rate.^[73] In 1912, Frederick Gowland Hopkins demonstrated that unknown accessory factors found in milk, other than carbohydrates, proteins, and fats were necessary for growth in rats. Hopkins received a Nobel Prize for this discovery in 1929.^{[73] [74]} By 1913, one of these substances was independently discovered by Elmer McCollum and Marguerite Davis at the University of Wisconsin–Madison, and Lafayette Mendel and Thomas Burr Osborne at Yale University, who studied the role of fats in the diet. McCollum and Davis ultimately received credit because they submitted their paper three weeks before Mendel and Osborne. Both papers appeared in the same issue of the Journal of Biological Chemistry in 1913.^[75] The "accessory factors" were termed "fat soluble" in 1918 and later "vitamin A" in 1920. In 1919, Harry Steenbock (University of Wisconsin–Madison) proposed a relationship between yellow plant pigments (beta-carotene) and vitamin A. In 1931, Swiss chemist Paul Karrer described the chemical structure of vitamin A.^[73] Vitamin A was first synthesized in 1947 by two Dutch chemists, David Adriaan van Dorp and Jozef Ferdinand Arens.

During World War II, German bombers would attack at night to evade British defenses. In order to keep the 1939 invention of a new on-board Airborne Intercept Radar system secret from German bombers, the British Ministry of Information told newspapers that the nighttime defensive success of Royal Air Force pilots was due to a high dietary intake of carrots rich in vitamin A, propagating the myth that carrots enable people to see better in the dark.^[76]

References [edit]

1. ^ ^{a b c d e} "Vitamin A". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis. January 2015. Retrieved 6 July 2017.
2. ^ Fennema O (2008). Fennema's Food Chemistry. CRC Press/Taylor & Francis. pp. 454–455. ISBN9780849392726.
3. ^ ^{a b c} Blaner WS (2020). "Vitamin A". In BP Marriott, DF Birt, VA Stallings, AA Yates (eds.). Present Knowledge in Nutrition, Eleventh Edition. London, United Kingdom: Academic Press (Elsevier). pp. 73–92. ISBN978-0-323-66162-1.
4. ^ ^{a b} "Vitamin A". MedlinePlus, National Library of Medicine, US National Institutes of Health. 2 December 2016.
5. ^ Tanumihardjo SA (August 2011). "Vitamin A: biomarkers of nutrition for development". The American Journal of Clinical Nutrition. 94 (2): 658S–65S. doi:10.3945/ajcn.110.005777. PMC3142734. PMID 21715511.
6. ^ ^{a b c} Wolf G (June 2001). "The discovery of the visual function of vitamin A". The Journal of Nutrition. 131 (6): 1647–50. doi:10.1093/jn/131.6.1647. PMID 11385047.
7. ^ ^{a b} "Vitamin A". Office of Dietary Supplements, US National Institutes of Health. 26 March 2021. Retrieved 8 August 2021.
8. ^ Berdanier C (1997). Advanced Nutrition Micronutrients. CRC Press. pp. 22–39. ISBN978-0-8493-2664-6.
9. ^ Meschino Health. "Comprehensive Guide to Vitamin A". Archived from the original on 15 May 2013. Retrieved 1 May 2012.
10. ^ DeMan J (1999). Principles of Food chemistry (3rd ed.). Maryland: Aspen Publication Inc. p. 358. ISBN978-0834212343.
11. ^ "Global prevalence of vitamin A deficiency in populations at risk 1995–2005" (PDF). WHO global database on vitamin A deficiency. World Health Organization. 2009.
12. ^ Black RE, Allen LH, Bhutta ZA, Caulfield LE, de Onis M, Ezzati M, Mathers C, Rivera J (January 2008). "Maternal and child undernutrition: global and regional exposures and health consequences". The Lancet. 371 (9608): 243–60. doi:10.1016/S0140-6736(07)61690-0. PMID 18207566. S2CID 3910132.
13. ^ "Fact sheet for health professionals: Vitamin A". Office of Dietary Supplements, National Institutes of Health. 5 June 2013. Retrieved 6 December 2015.
14. ^ ^{a b} "Vitamin A Deficiency", UNICEF. Retrieved 3 June 2015.
15. ^ Also see Akhtar S, Ahmed A, Randhawa MA, Atukorala S, Arlappa N, Ismail T, Ali Z (December 2013). "Prevalence of vitamin A deficiency in South Asia: causes, outcomes, and possible remedies". Journal of Health, Population, and Nutrition. 31 (4): 413–23. doi:10.3329/jhpn.v31i4.19975. PMC3905635. PMID 24592582.
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Further reading [edit]

• Ganguly J (1989). Biochemistry of Vitamin A. Boca Raton, Florida: CRC Press. ISBN9780849368905.
• Litwack G (2007). Vitamin A. Vitamins and Hormones. 75. San Diego, California: Elsevier Academic Press. ISBN978-0-12-709875-3.
• "Vitamin A Supplementation: A Decade of Progress" (PDF). New York: UNICEF. 2007.
• "Investing in the Future: A United Call to Action on Vitamin and Mineral Deficiencies" (PDF). GAIN, Micronutrient Initiative, USAID, The World Bank, UNICEF, Flour Fortification Initiative. 2009.

External links [edit]

• Vitamin+A at the US National Library of Medicine Medical Subject Headings (MeSH)

Equal Plus Vitamin C

Source: https://en.wikipedia.org/wiki/Vitamin_A

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