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CAS Number: 50-81-7
Molecular Weight: 176.12
Beilstein: 84272
EC Number: 200-066-2
MDL number: MFCD00064328
APPLICATIONS
Vitamin C is used to prevent and treat scurvy.
Moreover, Vitamin C is an essential nutrient involved in the repair of tissue, the formation of collagen, and the enzymatic production of certain neurotransmitters.
Vitamin C is required for the functioning of several enzymes and is important for immune system function.
Vitamin C also functions as an antioxidant.
Vitamin C is used as a food additive, browning inhibitor, flavor stabilizer, dough modifier and color stabilizer.
Deficiency of Vitamin C is associated with scurvy. L-ascorbic acid stimulates immune response and is implicated in the synthesis of collagen, carnitine and neurotransmitters.
Vitamin C has been used:
-as a component in osteogenic differentiation medium
-in MesenCult medium for the differentiation of bone marrow stromal cells
-as a standard for vitamin C assay
-to prevent trihalomethanes formation potential (THMFP).
Vitamin C, also known as ascorbic acid, has several important functions.
These include:
-helping to protect cells and keeping them healthy
-maintaining healthy skin, blood vessels, bones and cartilage
-helping with wound healing
-Lack of vitamin C can lead to scurvy.
Vitamin C (ascorbic acid) is a nutrient your body needs to form blood vessels, cartilage, muscle and collagen in bones.
Vitamin C is also vital to your body's healing process.
Vitamin C is an antioxidant that helps protect your cells against the effects of free radicals — molecules produced when your body breaks down food or is exposed to tobacco smoke and radiation from the sun, X-rays or other sources.
Free radicals might play a role in heart disease, cancer and other diseases.
Vitamin C also helps your body absorb and store iron.
Because your body doesn't produce vitamin C, you need to get it from your diet.
Vitamin C is found in citrus fruits, berries, potatoes, tomatoes, peppers, cabbage, Brussels sprouts, broccoli and spinach.
Vitamin C is also available as an oral supplement, typically in the form of capsules and chewable tablets.
Most people get enough vitamin C from a healthy diet.
Vitamin C deficiency is more likely in people who:
-Smoke or are exposed to secondhand smoking
-Have certain gastrointestinal conditions or certain types of cancer
-Have a limited diet that doesn't regularly include fruits and vegetables
-Severe vitamin C deficiency can lead to a disease called scurvy, which causes anemia, bleeding gums, bruising and poor wound healing.
If you take vitamin C for its antioxidant properties, keep in mind that the supplement might not offer the same benefits as naturally occurring antioxidants in food.
The recommended daily amount of vitamin C is 90 milligrams for adult men and 75 milligrams for adult women.
Vitamin C is needed for the growth and repair of tissues in all parts of your body.
It is used to:
-Form an important protein used to make skin, tendons, ligaments, and blood vessels
-Heal wounds and form scar tissue
-Repair and maintain cartilage, bones, and teeth
-Aid in the absorption of iron
Vitamin C is one of many antioxidants.
Antioxidants are nutrients that block some of the damage caused by free radicals.
Free radicals are made when your body breaks down food or when you are exposed to tobacco smoke or radiation.
The buildup of free radicals over time is largely responsible for the aging process.
Free radicals may play a role in cancer, heart disease, and conditions like arthritis.
The body is not able to make vitamin C on its own.
It does not store vitamin C.
It is therefore important to include plenty of vitamin C-containing foods in your daily diet.
For many years, vitamin C has been a popular household remedy for the common cold.
Research shows that for most people, vitamin C supplements or vitamin C-rich foods do not reduce the risk of getting the common cold.
However, people who take vitamin C supplements regularly might have slightly shorter colds or somewhat milder symptoms.
Taking a vitamin C supplement after a cold starts does not appear to be helpful.
Vitamin C has a definitive role in treating scurvy, which is a disease caused by vitamin C deficiency.
Beyond that, a role for vitamin C as prevention or treatment for various diseases is disputed, with reviews reporting conflicting results.
A 2012 Cochrane review reported no effect of vitamin C supplementation on overall mortality.
It is on the World Health Organization's List of Essential Medicines.
Scurvy
The disease scurvy is caused by vitamin C deficiency and can be prevented and treated with vitamin C-containing foods or dietary supplements.
It takes at least a month of little to no vitamin C before symptoms occur.
Early symptoms are malaise and lethargy, progressing to shortness of breath, bone pain, bleeding gums, susceptibility to bruising, poor wound healing, and finally fever, convulsions and eventual death.
Until quite late in the disease the damage is reversible, as healthy collagen replaces the defective collagen with vitamin C repletion.
Treatment can be oral supplementation of the vitamin or by intramuscular or intravenous injection.[9] Scurvy was known to Hippocrates in the classical era.
The disease was shown to be prevented by citrus fruits in an early controlled trial by a Royal Navy surgeon, James Lind, in 1747, on board HMS Salisbury.
From 1796 onward, lemon juice was issued to all Royal Navy crewmen.
Infection
Research on vitamin C in the common cold has been divided into effects on prevention, duration, and severity.
A Cochrane review which looked at at least 200 mg/day concluded that vitamin C taken on a regular basis was not effective in prevention of the common cold.
Restricting analysis to trials that used at least 1000 mg/day also saw no prevention benefit.
However, taking vitamin C on a regular basis did reduce the average duration by 8% in adults and 14% in children, and also reduced severity of colds.
Another review of adult trials with daily supplementation also reported shorter duration and less severe symptoms.
A subset of trials in adults reported that supplementation reduced the incidence of colds by half in marathon runners, skiers, or soldiers in subarctic conditions. Another subset of trials looked at therapeutic use, meaning that vitamin C was not started unless the people started to feel the beginnings of a cold.
In these, vitamin C did not affect duration or severity.
An earlier review stated that vitamin C did not prevent colds, did reduce duration, did not reduce severity.
The authors of the Cochrane review concluded that:
"The failure of vitamin C supplementation to reduce the incidence of colds in the general population indicates that routine vitamin C supplementation is not justified … Regular supplementation trials have shown that vitamin C reduces the duration of colds, but this was not replicated in the few therapeutic trials that have been carried out.
Nevertheless, given the consistent effect of vitamin C on the duration and severity of colds in the regular supplementation studies, and the low cost and safety, it may be worthwhile for common cold patients to test on an individual basis whether therapeutic vitamin C is beneficial for them."
Vitamin C distributes readily in high concentrations into immune cells, has antimicrobial and natural killer cell activities, promotes lymphocyte proliferation, and is consumed quickly during infections, effects indicating a prominent role in immune system regulation.
The European Food Safety Authority found a cause and effect relationship exists between the dietary intake of vitamin C and functioning of a normal immune system in adults and in children under three years of age.
Several studies found ascorbate to have specific antiviral effects in which it inactivates the RNA or DNA of viruses or in the assembly of the virus.
COVID-19
According to ClinicalTrials.gov, as of early 2021 there were 50 completed or ongoing COVID-19 clinical trials including vitamin C as a treatment.
A meta-analysis of six published trials was published in October 2021.
Treatments were either oral or intravenous. Dose ranged from 50 mg/kg/day to 24 g/day.
Reported outcomes were mortality, hospitalization duration, intensive care duration and need for ventilation.
From the Conclusion: "The present meta-analysis showed that administration of vitamin C did not have any effect on major health outcomes in COVID infected patients, in comparison to either placebo/standard therapy.
Sub-group analysis also revealed that irrespective of its dosage, route of administration and disease severity, it didn't have discernible benefit in such patients. Hence, larger prospective randomized trials are needed in order to evaluate the effect of isolated vitamin C administration, separately for both vitamin C replete and deplete individuals."
During March through July 2020, vitamin C was the subject of more US FDA warning letters than any other ingredient for prevention and/or treatment of COVID-19.
As of April 2021, the National Institutes of Health (NIH) COVID-19 Treatment Guidelines stated that "there are insufficient data to recommend either for or against the use of vitamin C for the prevention or treatment of COVID-19."
Cancer
There are two approaches to the question of whether vitamin C has an effect on cancer.
First, within the normal range of dietary intake without additional dietary supplementation, are people who consume more vitamin C at lower risk for developing cancer, and if so, does an orally consumed supplement have the same benefit?
Second, for people diagnosed with cancer, will large amounts of ascorbic acid administered intravenously treat the cancer, reduce the adverse effects of other treatments, and so prolong survival and improve quality of life?
A 2013 Cochrane review found no evidence that vitamin C supplementation reduces the risk of lung cancer in healthy people or those at high risk due to smoking or asbestos exposure.
A second meta-analysis found no effect on the risk of prostate cancer.
Two meta-analyses evaluated the effect of vitamin C supplementation on the risk of colorectal cancer.
One found a weak association between vitamin C consumption and reduced risk, and the other found no effect from supplementation.
A 2011 meta-analysis failed to find support for the prevention of breast cancer with vitamin C supplementation, but a second study concluded that vitamin C may be associated with increased survival in those already diagnosed.
Under the rubric of orthomolecular medicine, "Intravenous vitamin C is a contentious adjunctive cancer therapy, widely used in naturopathic and integrative oncology settings."
With oral administration absorption efficiency decreases as amounts increase.
Intravenous administration bypasses this.
Doing so makes it possible to achieve plasma concentrations of 5 to 10 millimoles/liter (mmol/L), which far exceed the approximately 0.2 mmol/L limit from oral consumption.
The theories of mechanism are contradictory.
At high tissue concentrations ascorbic acid is described as acting as a pro-oxidant, generating hydrogen peroxide (H2O2) to kill tumor cells.
The same literature claims that ascorbic acid acts as an antioxidant, thereby reducing the adverse effects of chemotherapy and radiation therapy.
Research continues in this field, but a 2014 review concluded: "Currently, the use of high-dose intravenous vitamin C [as an anticancer agent] cannot be recommended outside of a clinical trial."
A 2015 review added: "There is no high-quality evidence to suggest that ascorbate supplementation in cancer patients either enhances the antitumor effects of chemotherapy or reduces its toxicity.
Evidence for ascorbate's anti-tumor effects was limited to case reports and observational and uncontrolled studies."
Cardiovascular disease
In 2017, an independent study evaluating 15,445 participants found no evidence to show vitamin C decreases the risk cardiovascular disease.
These results supported one 2013 review which found no evidence that antioxidant vitamin supplementation reduces the risk of myocardial infarction, stroke, cardiovascular mortality, or all-cause mortality (it did not provide subset analysis for trials that just used vitamin C).
However, another 2013 review found an association between higher circulating vitamin C levels or dietary vitamin C and a lower risk of stroke.
A 2014 review found a positive effect of vitamin C on endothelial dysfunction when taken at doses greater than 500 mg per day.
The endothelium is a layer of cells that line the interior surface of blood vessels.
Brain function
A 2017 systematic review found lower vitamin C concentrations in people with cognitive impairment, including Alzheimer's disease and dementia, compared to people with normal cognition.
The cognitive testing, however, relied on the Mini-Mental State Examination, which is only a general test of cognition, indicating an overall low quality of research assessing the potential importance of vitamin C on cognition in normal and impaired people.
A review of nutrient status in people with Alzheimer's disease reported low plasma vitamin C, but also low blood levels of folate, vitamin B12, and vitamin E.
Other diseases
Studies examining the effects of vitamin C intake on the risk of Alzheimer's disease have reached conflicting conclusions.
Maintaining a healthy dietary intake is probably more important than supplementation for achieving any potential benefit.
A 2010 review found no role for vitamin C supplementation in the treatment of rheumatoid arthritis.
Vitamin C supplementation does not prevent or slow the progression of age-related cataract.
A systematic review reported that low intake and low serum concentration was associated with greater progression of periodontal disease.
DESCRIPTION
Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in various foods and sold as a dietary supplement.
Vitamin C is used to prevent and treat scurvy.
Moreover, Vitamin C is an essential nutrient involved in the repair of tissue, the formation of collagen, and the enzymatic production of certain neurotransmitters.
Vitamin C is required for the functioning of several enzymes and is important for immune system function.
Vitamin C also functions as an antioxidant.
Most animals are able to synthesize their own vitamin C.
However, apes (including humans) and monkeys (but not all primates), most bats, some rodents, and certain other animals must acquire it from dietary sources.
There is some evidence that regular use of supplements may reduce the duration of the common cold, but it does not appear to prevent infection.
It is unclear whether supplementation affects the risk of cancer, cardiovascular disease, or dementia.
Vitamin C may be taken by mouth or by injection.
Vitamin C is generally well tolerated.
Large doses may cause gastrointestinal discomfort, headache, trouble sleeping, and flushing of the skin.
Normal doses are safe during pregnancy.
The United States Institute of Medicine recommends against taking large doses.
Vitamin C was discovered in 1912, isolated in 1928, and, in 1933, was the first vitamin to be chemically produced.
Vitamin C is on the World Health Organization's List of Essential Medicines.
Vitamin C is available as an inexpensive generic and over-the-counter medication.
Partly for its discovery, Albert Szent-Györgyi and Walter Norman Haworth were awarded the 1937 Nobel Prizes in Physiology and Medicine and Chemistry, respectively.
Foods containing vitamin C include citrus fruits, kiwifruit, guava, broccoli, Brussels sprouts, bell peppers, Potatoes and strawberries.
Prolonged storage or cooking may reduce vitamin C content in foods.
Vitamin C is one of the most commonly supplemented nutrients.
Although Vitamin C is probably best known for its importance to immunity, vitamin C research has revealed multiple other functions within the body.
In the 1920s, vitamin C was first identified by the prospective Nobel laureate Albert Szent-Györgyi from Szeged University in Hungary, who unravelled the role of this essential vitamin for the treatment and prevention of scurvy resulting from vitamin C deficiency.
Before its discovery, around 50% of sailors developed scurvy, a condition now recognised as associated with vitamin C deficiency.
It was noted that scurvy could be ameliorated by the consumption of citrus fruits, especially limes, during sea voyages and so lemon or lime juice became part of sailors’ daily rations.
Vitamin C is water soluble, which is an important factor in its function.
Vitamin C is also known as ascorbate or ascorbic acid.
BIOLOGY
Significance
Vitamin C is an essential nutrient for certain animals including humans.
The term vitamin C encompasses several vitamers that have vitamin C activity in animals.
Vitamin C salts such as sodium ascorbate and calcium ascorbate are used in some dietary supplements.
These release ascorbate upon digestion.
Ascorbate and ascorbic acid are both naturally present in the body, since the forms interconvert according to pH.
Oxidized forms of the molecule such as dehydroascorbic acid are converted back to ascorbic acid by reducing agents.
Vitamin C functions as a cofactor in many enzymatic reactions in animals (including humans) that mediate a variety of essential biological functions, including wound healing and collagen synthesis.
In humans, vitamin C deficiency leads to impaired collagen synthesis, contributing to the more severe symptoms of scurvy.
Another biochemical role of vitamin C is to act as an antioxidant (a reducing agent) by donating electrons to various enzymatic and non-enzymatic reactions.
Doing so converts vitamin C to an oxidized state - either as semidehydroascorbic acid or dehydroascorbic acid.
These compounds can be restored to a reduced state by glutathione and NADPH-dependent enzymatic mechanisms.
In plants, vitamin C is a substrate for ascorbate peroxidase.
This enzyme utilizes ascorbate to neutralize excess hydrogen peroxide (H2O2) by converting it to water (H2O) and oxygen.
Deficiency
Vitamin C blood serum levels are considered saturated at levels > 65 μmol/L (1.1 mg/dL), achieved by consuming amounts which are at, or above, the Recommended Dietary Allowance, while adequate levels are defined as ≥ 50 μmol/L.
Hypovitaminosis in the case of vitamin C is defined as ≤ 23 μmol/L and deficiency occurs at ≤ 11.4 μmol/L.
For those 20 years of age or above, data from the U.S. 2003-04 NHANES survey showed mean and median serum concentrations of 49.0 and 54.4 μmol/L, respectively.
The percent of people reported as deficient was 7.1%.
Scurvy is a disease resulting from a deficiency of vitamin C.
Without this vitamin, collagen made by the body is too unstable to perform its function and several other enzymes in the body do not operate correctly.
Scurvy is characterized by spots on and bleeding under the skin, spongy gums, 'corkscrew' hair growth, and poor wound healing.
The skin lesions are most abundant on the thighs and legs, and a person with the ailment looks pale, feels depressed, and is partially immobilized.
In advanced scurvy there are open, suppurating wounds, loss of teeth, bone abnormalities and, eventually, death.
Notable human dietary studies of experimentally induced scurvy were conducted on conscientious objectors during World War II in Britain and on Iowa state prisoners in the late 1960s to the 1980s.
Men in the prison study developed the first signs of scurvy about four weeks after starting the vitamin C-free diet, whereas in the earlier British study, six to eight months were required, possibly due to the pre-loading of this group with a 70 mg/day supplement for six weeks before the scorbutic diet was fed.
Men in both studies had blood levels of ascorbic acid too low to be accurately measured by the time they developed signs of scurvy.
These studies both reported that all obvious symptoms of scurvy could be completely reversed by supplementation of only 10 mg a day.
People in sepsis or septic shock may have micronutrient deficiencies, including low levels of vitamin C.
PHARMACOLOGY
Vitamin C – specifically, in the form of ascorbate – performs numerous physiological functions in the human body by serving as an enzyme substrate or cofactor and an electron donor.
These functions include the synthesis of collagen, carnitine, and neurotransmitters; the synthesis and catabolism of tyrosine; and the metabolism of microsome.
During biosynthesis, ascorbate acts as a reducing agent, donating electrons and preventing oxidation to keep iron and copper atoms in their reduced states.
Vitamin C functions as a cofactor for the following enzymes:
Three groups of enzymes (prolyl-3-hydroxylases, prolyl-4-hydroxylases, and lysyl hydroxylases) that are required for the hydroxylation of proline and lysine in the synthesis of collagen.
These reactions add hydroxyl groups to the amino acids proline or lysine in the collagen molecule via prolyl hydroxylase and lysyl hydroxylase, both requiring vitamin C as a cofactor.
The role of vitamin C as a cofactor is to oxidize prolyl hydroxylase and lysyl hydroxylase from Fe2+ to Fe3+ and to reduce it from Fe3+ to Fe2+.
Hydroxylation allows the collagen molecule to assume its triple helix structure, and thus vitamin C is essential to the development and maintenance of scar tissue, blood vessels, and cartilage.
Two enzymes (ε-N-trimethyl-L-lysine hydroxylase and γ-butyrobetaine hydroxylase) that are necessary for synthesis of carnitine.
Carnitine is essential for the transport of fatty acids into mitochondria for ATP generation.
Hypoxia-inducible factor-proline dioxygenase enzymes (isoforms: EGLN1, EGLN2, and EGLN3)
Dopamine beta-hydroxylase participates in the biosynthesis of norepinephrine from dopamine.
Peptidylglycine alpha-amidating monooxygenase amidates peptide hormones by removing the glyoxylate residue from their c-terminal glycine residues.
This increases peptide hormone stability and activity.
CHEMISTRY
The name "vitamin C" always refers to the l-enantiomer of ascorbic acid and its oxidized forms, such as dehydroascorbate (DHA).
Therefore, unless written otherwise, "ascorbate" and "ascorbic acid" refer in the nutritional literature to l-ascorbate and l-ascorbic acid respectively.
Ascorbic acid is a weak sugar acid structurally related to glucose.
In biological systems, ascorbic acid can be found only at low pH, but in solutions above pH 5 is predominantly found in the ionized form, ascorbate.
All of these molecules have vitamin C activity and thus are used synonymously with vitamin C, unless otherwise specified.
Numerous analytical methods have been developed for ascorbic acid detection. For example, vitamin C content of a food sample such as fruit juice can be calculated by measuring the volume of the sample required to decolorize a solution of dichlorophenolindophenol (DCPIP) and then calibrating the results by comparison with a known concentration of vitamin C.
INDUSTRIAL PRODUCTION
Vitamin C is produced from glucose by two main routes.
The Reichstein process, developed in the 1930s, uses a single pre-fermentation followed by a purely chemical route.
The modern two-step fermentation process, originally developed in China in the 1960s, uses additional fermentation to replace part of the later chemical stages.
The Reichstein process and the modern two-step fermentation processes use sorbitol as the starting material and convert it to sorbose using fermentation.
The modern two-step fermentation process then converts sorbose to 2-keto-l-gulonic acid (KGA) through another fermentation step, avoiding an extra intermediate.
Both processes yield approximately 60% vitamin C from the glucose feed.
In 2017, China produced about 95% of the world supply of ascorbic acid (vitamin C), which is China's most exported vitamin, having total revenue of US$880 million in 2017.
Due to pressure on Chinese industry to discontinue burning coal normally used for vitamin C manufacturing, the price of vitamin C rose three-fold in 2016 alone to US$12 per kg.
HISTORY
Scurvy at sea
In the 1497 expedition of Vasco da Gama, the curative effects of citrus fruit were known.
Later, the Portuguese planted fruit trees and vegetables in Saint Helena, a stopping point for homebound voyages from Asia, which sustained passing ships.
Authorities occasionally recommended plant food to prevent scurvy during long sea voyages.
John Woodall, the first surgeon to the British East India Company, recommended the preventive and curative use of lemon juice in his 1617 book, The Surgeon's Mate.
In 1734, the Dutch writer Johann Bachstrom gave the firm opinion, "scurvy is solely owing to a total abstinence from fresh vegetable food, and greens."
Scurvy had long been a principal killer of sailors during the long sea voyages.
According to Jonathan Lamb, "In 1499, Vasco da Gama lost 116 of his crew of 170; In 1520, Magellan lost 208 out of 230;...all mainly to scurvy."
James Lind, a British Royal Navy surgeon who, in 1747, identified that a quality in fruit prevented scurvy in one of the first recorded controlled experiments.
The first attempt to give scientific basis for the cause of this disease was by a ship's surgeon in the Royal Navy, James Lind. While at sea in May 1747, Lind provided some crew members with two oranges and one lemon per day, in addition to normal rations, while others continued on cider, vinegar, sulfuric acid or seawater, along with their normal rations, in one of the world's first controlled experiments.
The results showed that citrus fruits prevented the disease. Lind published his work in 1753 in his Treatise on the Scurvy.
Fresh fruit was expensive to keep on board, whereas boiling it down to juice allowed easy storage but destroyed the vitamin (especially if boiled in copper kettles).
It was 1796 before the British navy adopted lemon juice as standard issue at sea.
In 1845, ships in the West Indies were provided with lime juice instead, and in 1860 lime juice was used throughout the Royal Navy, giving rise to the American use of the nickname "limey" for the British.
Captain James Cook had previously demonstrated the advantages of carrying "Sour krout" on board, by taking his crews to the Hawaiian Islands without losing any of his men to scurvy.
For this, the British Admiralty awarded him a medal.
The name antiscorbutic was used in the eighteenth and nineteenth centuries for foods known to prevent scurvy.
These foods included lemons, limes, oranges, sauerkraut, cabbage, malt, and portable soup.
In 1928, the Canadian Arctic anthropologist Vilhjalmur Stefansson showed that the Inuit avoid scurvy on a diet of largely raw meat.
Later studies on traditional food diets of the Yukon First Nations, Dene, Inuit, and Métis of Northern Canada showed that their daily intake of vitamin C averaged between 52 and 62 mg/day, comparable with the Estimated Average Requirement.
DISCOVERY
Vitamin C was discovered in 1912, isolated in 1928 and synthesized in 1933, making it the first vitamin to be synthesized.
Shortly thereafter Tadeus Reichstein succeeded in synthesizing the vitamin in bulk by what is now called the Reichstein process.
This made possible the inexpensive mass-production of vitamin C.
In 1934 Hoffmann–La Roche trademarked synthetic vitamin C under the brand name Redoxon and began to market it as a dietary supplement.
In 1907 a laboratory animal model which would help to identify the antiscorbutic factor was discovered by the Norwegian physicians Axel Holst and Theodor Frølich, who when studying shipboard beriberi, fed guinea pigs their test diet of grains and flour and were surprised when scurvy resulted instead of beriberi.
By luck, this species did not make its own vitamin C, whereas mice and rats do.
In 1912, the Polish biochemist Casimir Funk developed the concept of vitamins.
One of these was thought to be the anti-scorbutic factor. In 1928, this was referred to as "water-soluble C", although its chemical structure had not been determined.
From 1928 to 1932, Albert Szent-Györgyi and Joseph L. Svirbely's Hungarian team, and Charles Glen King's American team, identified the anti-scorbutic factor.
Szent-Györgyi isolated hexuronic acid from animal adrenal glands, and suspected it to be the antiscorbutic factor.
In late 1931, Szent-Györgyi gave Svirbely the last of his adrenal-derived hexuronic acid with the suggestion that it might be the anti-scorbutic factor.
By the spring of 1932, King's laboratory had proven this, but published the result without giving Szent-Györgyi credit for it.
This led to a bitter dispute over priority.
In 1933, Walter Norman Haworth chemically identified the vitamin as l-hexuronic acid, proving this by synthesis in 1933.
Haworth and Szent-Györgyi proposed that L-hexuronic acid be named a-scorbic acid, and chemically l-ascorbic acid, in honor of its activity against scurvy.
The term's etymology is from Latin, "a-" meaning away, or off from, while -scorbic is from Medieval Latin scorbuticus (pertaining to scurvy), cognate with Old Norse skyrbjugr, French scorbut, Dutch scheurbuik and Low German scharbock.
Partly for this discovery, Szent-Györgyi was awarded the 1937 Nobel Prize in Medicine, and Haworth shared that year's Nobel Prize in Chemistry.
In 1957, J.J. Burns showed that some mammals are susceptible to scurvy as their liver does not produce the enzyme l-gulonolactone oxidase, the last of the chain of four enzymes that synthesize vitamin C.
American biochemist Irwin Stone was the first to exploit vitamin C for its food preservative properties.
He later developed the theory that humans possess a mutated form of the l-gulonolactone oxidase coding gene.
In 2008, researchers at the University of Montpellier discovered that in humans and other primates the red blood cells have evolved a mechanism to more efficiently utilize the vitamin C present in the body by recycling oxidized l-dehydroascorbic acid (DHA) back into ascorbic acid for reuse by the body.
The mechanism was not found to be present in mammals that synthesize their own vitamin C.
SOURCES OF VITAMIN C
Food
Fruits and vegetables are the best sources of vitamin C.
Citrus fruits, tomatoes and tomato juice, and potatoes are major contributors of vitamin C to the American diet.
Other good food sources include red and green peppers, kiwifruit, broccoli, strawberries, Brussels sprouts, and cantaloupe.
Although vitamin C is not naturally present in grains, it is added to some fortified breakfast cereals.
The vitamin C content of food may be reduced by prolonged storage and by cooking because ascorbic acid is water soluble and is destroyed by heat.
Steaming or microwaving may lessen cooking losses.
Fortunately, many of the best food sources of vitamin C, such as fruits and vegetables, are usually consumed raw.
Consuming five varied servings of fruits and vegetables a day can provide more than 200 mg of vitamin C.
Good sources include:
-citrus fruit, such as oranges and orange juice
-peppers
-strawberries
-blackcurrants
-broccoli
-brussels sprouts
-potatoes
All fruits and vegetables contain some amount of vitamin C.
Fruits with the highest sources of vitamin C include:
-Cantaloupe
-Citrus fruits and juices, such as orange and grapefruit
-Kiwi fruit
-Mango
-Papaya
-Pineapple
-Strawberries, raspberries, blueberries, and cranberries
-Watermelon
Vegetables with the highest sources of vitamin C include:
-Broccoli, Brussels sprouts, and cauliflower
-Green and red peppers
-Spinach, cabbage, turnip greens, and other leafy greens
-Sweet and white potatoes
-Tomatoes and tomato juice
-Winter squash
Some cereals and other foods and beverages are fortified with vitamin C.
Fortified means a vitamin or mineral has been added to the food.
The best food sources of vitamin C are uncooked or raw fruits and vegetables.
Cooking vitamin C-rich foods or storing them for a long period of time can reduce the vitamin C content.
Microwaving and steaming vitamin C-rich foods may reduce cooking losses.
Exposure to light can also reduce vitamin C content.
Choose orange juice that is sold in a carton instead of a clear bottle.
Dietary supplements
Supplements typically contain vitamin C in the form of ascorbic acid, which has equivalent bioavailability to that of naturally occurring ascorbic acid in foods, such as orange juice and broccoli.
Other forms of vitamin C supplements include sodium ascorbate; calcium ascorbate; other mineral ascorbates; ascorbic acid with bioflavonoids; and combination products, which contains calcium ascorbate, dehydroascorbate, calcium threonate, xylonate and lyxonate.
A few studies in humans have examined whether bioavailability differs among the various forms of vitamin C.
Another study found no differences in plasma vitamin C levels or urinary excretion of vitamin C among three different vitamin C sources: ascorbic acid and ascorbic acid with bioflavonoids.
These findings, coupled with the relatively low cost of ascorbic acid, led the authors to conclude that simple ascorbic acid is the preferred source of supplemental vitamin C.
LARGE DOSES
Vitamin C megadosage is a term describing the consumption or injection of vitamin C in doses comparable to or higher than the amounts produced by the livers of mammals which are able to synthesize vitamin C.
The theory behind this, although not the actual term, was described in 1970 in an article by Linus Pauling.
Briefly, his position was that for optimal health, humans should be consuming at least 2,300 mg/day to compensate for the inability to synthesize vitamin C.
The recommendation also fell into the consumption range for gorillas - a non-synthesizing near-relative to humans.
A second argument for high intake is that serum ascorbic acid concentrations increase as intake increases until it plateaus at about 190 to 200 micromoles per liter (µmol/L) once consumption exceeds 1,250 milligrams.
As noted, government recommendations are a range of 40 to 110 mg/day and normal plasma is approximately 50 µmol/L, so 'normal' is about 25% of what can be achieved when oral consumption is in the proposed megadose range.
Pauling popularized the concept of high dose vitamin C as prevention and treatment of the common cold in 1970.
A few years later he proposed that vitamin C would prevent cardiovascular disease, and that 10 grams/day, initially (10 days) administered intravenously and thereafter orally, would cure late-stage cancer.
Mega-dosing with ascorbic acid has other champions, among them chemist Irwin Stone and the controversial Matthias Rath and Patrick Holford, who both have been accused of making unsubstantiated treatment claims for treating cancer and HIV infection.
The mega-dosing theory is to a large degree discredited. Modest benefits are demonstrated for the common cold.
Benefits are not superior when supplement intakes of more than 1,000 mg/day are compared to intakes between 200 and 1,000 mg/day, and so not limited to the mega-dose range.
The theory that large amounts of intravenous ascorbic acid can be used to treat late-stage cancer is - some forty years after Pauling's seminal paper - still considered unproven and still in need of high quality research.
However, a lack of evidence has not stopped individual physicians from prescribing intravenous ascorbic acid to thousands of people with cancer.
SIDE EFFECTS
Serious side effects from too much vitamin C are very rare, because the body cannot store the vitamin.
However, amounts greater than 2,000 mg/day are not recommended.
Doses this high can lead to stomach upset and diarrhea.
Large doses of vitamin C supplementation are not recommended during pregnancy.
They can lead to shortage of vitamin C in the baby after delivery.
Too little vitamin C can lead to signs and symptoms of deficiency, including:
-Anemia
-Bleeding gums
-Decreased ability to fight infection
-Decreased wound-healing rate
-Dry and splitting hair
-Easy bruising
-Gingivitis (inflammation of the gums)
-Nosebleeds
-Possible weight gain because of slowed metabolism
-Rough, dry, scaly skin
-Swollen and painful joints
-Weakened tooth enamel
-A severe form of vitamin C deficiency is known as scurvy.
This mainly affects older, malnourished adults.
SYNONYMS
ascorbic acid
ascorbate
Antiscorbutic factor
Vitamin C
L-Threoascorbic acid
