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General description Almost all animals and plants synthesize their own vitamin C. There are some exceptions, such as humans and a small number of other animals, including, apes, guinea pigs, the red-vented bulbul, a fruit-eating bat and a species of trout. This has led some scientists, including chemist Linus Pauling to hypothesize that these species either lost (or never had) the ability to produce their own Vitamin C, and that if their diets were supplemented with an amount of the nutrient proportional to the amount produced in animal species that do synthesize their own Vitamin C, better health would result. The species-specific loss in the ability to synthesize ascorbate strikingly parallels the evolutionary loss of the ability to break down uric acid. Uric acid and ascorbate are both strong reducing agents (electron-donors). This has led to the suggestion that in higher primates, uric acid has taken over some of the functions of ascorbate. Vitamin C was first isolated in 1928, and in 1932 it was proved to be the agent which prevents scurvy. Both Charles Glen King at the University of Pittsburgh and Albert Szent-Györgyi (working with ex-Pittsburgh researcher Joseph Svirbely) came to discover what is now known as Vitamin C around April of 1932. Although Szent-Györgyi was awarded the 1937 Nobel Prize in Medicine, many feel King is as responsible for its development if not more so. ** Vitamin C is a weak acid, called ascorbic acid or a salt ascorbate. It is the L-enantiomer of ascorbic acid. The D-enantiomer shows no biological activity. Both are mirror image forms of the same chemical molecular structure (see optical isomers). The active part of the substance is the ascorbate ion, which can express itself as either an acid or a salt of ascorbate that is neutral or slightly basic. Commercial vitamin C is often a mix of ascorbic acid, sodium ascorbate and/or other ascorbates. Some supplements contain in part the D-enantiomer, which is useless and harmless. See the ascorbic acid article for a full description of the molecule's chemical properties. Vitamin C deficiency No bodily organ stores ascorbate as a primary function, and so the body soon depletes itself of ascorbate if fresh supplies are not consumed through the digestive system, eventually leading to the deficiency disease known as scurvy (a form of avitaminosis), which results in illness and death if consumption of vitamin C is not resumed in time. Acute scurvy Acute scurvy is characterized by: Scurvy leads to massive internal hemorrhaging, and is eventually fatal. Scurvy was a common condition among sailors at sea and during the winter season when no fresh fruits or vegetable are available. Functions in the body By far the primary importance of vitamin C is as a reducing agent in the cell. Since the body of the cell is a chemically reducing environment, and the endoplasmic reticulum (ER) is oxidizing, the cell imports dehydroascorbate (oxidized vitamin C) into the ER, and exports vitamin C from the ER, maintaining the important chemical gradient. Daily requirements and dose dependent effects There is continuing debate within the scientific community over the best dose schedule (the amount and frequency of intake) of Vitamin C for maintaining optimal health in humans. Government agency recommended intake levels A balanced diet without supplementation contains enough Vitamin C to prevent acute scurvy in an average healthy adult. For people who smoke, those under stress, and pregnant women it takes slightly more. Recommendations for vitamin C intake have been set by various national agencies as follows: 40 mg per day: Food Standards Agency (UK) 60–95 mg per day, Dietary Reference Intake (DRI), Recommended Daily Allowance (RDA), U.S. Food and Nutrition Board 2004. The U.S. Dietary Reference Intake Tolerable Upper Intake Level (UL) for a 25-year old male is 2,000 mg/day. Vitamin C is recognized to be one of the least toxic substances known to medicine. Its LD50 for rats is 11,900 mg kg-1 *, *, *. Independent dose recommendations Multiple websites exist providing updated links to the extensive and growing literature critical of governmental agency dose recommendations.******* Key arguments include: Some researchers have calculated the amount needed for an adult human to achieve similar blood serum levels as Vitamin C synthesising mammals as follows: 6000-18000 mg per day – Linus Pauling's daily recommendation 6000-12000 mg per day – Thomas Levy, Colorado Integrative Medical Centre recommendation. 3000 mg per day or more during illness or pregnancy (up to 300g for some illnesses) – Vitamin C Foundation's recommendation. * 400 mg per day – Linus Pauling Institute & US National Institutes of Health (NIH) Recommendation. from 3000 mg to 200,000 mg per day based on a protocol described by Robert CathcartRobert F. Cathcart III M.D., Vitamin C, Titrating To Bowel Tolerance, Anascorbemia, and Acute Induced Scurvey, Allergy, Environmental, and Orthomolecular Medicine known as a vitamin C flush wherin escalating doses of Vitamin C are given until diarrhea develops, then choosing the highest dose that does not cause diarrhea (bowel tolerance threshold). High doses (thousands of mg) may result in diarrhea, which is harmless if the dose is reduced immediately. Some researchers claim the onset of diarrhea to be an indication of where the body’s true vitamin C requirement lies. Both Cathcart and Cameron have demonstrated that very sick patients with cancer or influenza do not display any evidence of diarrhea at all until ascorbate intake reaches levels as high as 200 grams (½ pound). However, the biological halflife for vitamin C is quite short, about 30 minutes in blood plasma, a fact which NIH and IM researchers have failed to recognize. NIH researchers established the current RDA based upon tests conducted 12 hours (24 half lives) after consumption. "To be blunt," says Hickey, "the NIH gave a dose of vitamin C, waited until it had been excreted, and then measured blood levels."* There is a strong advocacy movement for large doses of Vitamin C (see Advocacy arguments below), although not all purported benefits are supported by the medical establishment. Many pro-Vitamin C organizations promote usage levels well beyond the current Dietary Reference Intake (DRI). Therapeutic applications and doses Vitamin C is needed in the diet to prevent scurvy, however, from the time it became available in pure form in the 1930s, some practitioners experimented with vitamin C as a treatment for diseases other than scurvy. Colds At least 29 controlled clinical trials (many double-blind and placebo-controlled) involving a total of over 11,000 participants have been conducted into vitamin C and the Common cold. These trials were reviewed in the 1990s and again recently.* The trials show that vitamin C reduces the duration and severity of colds but not the frequency. The data indicate that there is a normal dose-response relationship. Vitamin C is more effective the higher the dose. The vast majority of the trials were limited to doses below 1 g/day. As doses rise, it becomes increasingly difficult to keep the trials double blind because of the obvious gastro-intestinal side effects. So, the most effective trials at doses between 2 and 10 g/day are met with skepticism. Reports from physicians have provided ample clinical confirmation.* The controlled trials and clinical experience prove that vitamin C in doses ranging from 0.1 to 2.0 g/day have a relatively small effect. The duration of colds was reduced by 7% for adults and 15% for children. The studies provide ample justification for businesses to encourage their employees to take 1 to 2 g/day during the cold season to improve workplace productivity and reduce sick days. The clinical reports provide the strongest possible evidence that vitamin C at higher doses is significantly more effective. However, the effectiveness typically comes at the price of gastro-intestinal side effects. It is easy for physicians to minimize these side effects since they cause no lasting harm. Adult patients, however, have proven reluctant to subject themselves to gas and cramping to deliver an unknown benefit (the duration and severity of colds is highly variable so the patient never knows what he/she is warding off). It is well worth the effort of identifying the small subset of individuals who can benefit from high daily doses (>10 g/day) of vitamin C without side effects and training them to regularly take 5 g/day during cold season and to increase the dose at the onset of a cold. The trials proved that vitamin C is more effective for children. Reports from the field confirm the observations in the trials and suggest that children are less prone to vitamin C side effects.* Colds and flu are a serious problem for children. Every time a cold infects a child, its growing mind and body must divert energy from its usual business of growth and development. If the cold is followed by an opportunistic infection, such as bronchitis or ear infection, more energy must be diverted. Colds are the number one trigger for asthma.* Pre-school children in daycare are nearly constantly fighting infections (5-10 per year).* Chronic disease in childhood is believed to sometimes have permanent developmental consequences which can contribute to decreased life expectancy.* Polio Most notable was Fred R. Klenner, a doctor in general practice in Reidsville, North Carolina. He utilized both oral and intravenous vitamin C to treat a wide range of infections and poisons. He published a paper in 1949 that described how he had seen poliomyelitis yield to vitamin C in sufficiently large doses.* No controlled clinical trials have been conducted to confirm effectiveness.* Heart disease Vitamin C is the main of the three ingredients in Linus Pauling's patented preventive cure for heart disease, the other two being the amino acid lysine and nicotinic acid (a form of Vitamin B3). This treatment is not supported by mainstream medical science. Viral diseases, and poisons Orthomolecular medicine and a minority of scientific opinion sees vitamin C as being a low cost and safe way to treat viral disease and to deal with a wide range of poisons. Vitamin C has a growing reputation for being useful in the treatment of colds and flu, owing to its recommendation by prominent biochemist Linus Pauling. In the years since Pauling's popular books about vitamin C, general agreement by medical authorities about larger than RDA amounts of vitamin C in health and medicine has remained elusive. Ascorbate usage in studies of up to several grams per day, however, have been associated with decreased cold duration and severity of symptoms, possibly as a result of an antihistamine effect *. The highest dose treatments, published clinical results of specific orthomolecular therapy regimes pioneered by Drs. Klenner (repeated IV treatments, 400-700+ mg/kg/day **) and Cathcart (oral use to bowel tolerance, up to ~150 grams ascorbate per day for flu), have remained experimentally unaddressed by conventional medical authorities for decades. The Vitamin C Foundation recommends an initial usage of up to 8 grams of vitamin C every 20-30 minutes * in order to show an effect on the symptoms of a cold infection that is in progress. Most of the studies showing little or no effect employ doses of ascorbate such as 100 mg to 500 mg per day, considered "small" by vitamin C advocates. Equally importantly, the plasma half life of high dose ascorbate is approximately 30 minutes, which implies that most high dose studies have been methodologically defective and would be expected to show a minimum benefit. Clinical studies of divided dose supplementation, predicted on pharmacological grounds to be effective, have only rarely been reported in the literature. Essentially all the claims for high dose vitamin C remain to be scientifically refuted. The clinical effectiveness of large and frequent doses of vitamin C is an open scientific question. In 2002 a meta-study into all the published research on effectiveness of ascorbic acid in the treatment of infectious disease and toxins was conducted, by Thomas Levy, Medical Director of the Colorado Integrative Medical Centre in Denver. He claimed that evidence exists for its therapeutic role in a wide range of viral infections and for the treatment of snake bites. Lead poisoning There is also evidence that Vitamin C is useful in preventing lead poisoning, possibly helping to chelate the toxic heavy metal from the body. * Cancer In 2005 in vitro research by the National Institutes of Health indicated that Vitamin C administered in pharmacological concentrations (i.e. intravenous) was preferentially toxic to several strains of cancer cells. The authors noted: "These findings give plausibility to intravenous ascorbic acid in cancer treatment, and have unexpected implications for treatment of infections where H2O2 may be beneficial." This research appeared to support Linus Pauling's claims that Vitamin C can be used to fight cancer.• In 2006 the Canadian Medical Association Journal published in vivo research that demonstrated that intravenous vitamin C can subdue advanced-stage cancer. Cataracts It has been also suggested that Vitamin C might prevent the formation of cataracts. Contraindications A Contraindication is a condition which makes an individual more likely to be harmed by a dose of Vitamin C than an average person. Side-effects Effects of Overdose Vitamin C exhibits remarkably low toxicity. For example, in the rat, the LD50 has been reported as 11900 mg kg-1.• For a 70 kg human, this means that 833,000 mg of vitamin C would need to be ingested to stand a 50% chance of killing the person. However, vitamin C could not result in death when administered orally as large amounts of the vitamin cause diarrhea and are not absorbed.• An extremely large amount of vitamin C would need to be rapidly injected by IV to stand any chance of killing a person. Robert Cathcart, MD, has used intravenous doses of vitamin C of 250 grams and reports that he has had no problems.• The Council for Responsible Nutrition has set an Upper Level (UL) of 2 grams, based on transient diarrhea. Their publication on vitamin C safety notes that "very large doses of vitamin C have been taken daily over the course of many years, and only minor undesirable effects have been attributed with any certainty to the vitamin’s use... Clearly, vitamin C has a low order of toxicity".• Alleged harmful effects Reports of harmful effects of vitamin C tend to receive great prominence in the world's media. As such, these reports tend to generate much debate and more research into Vitamin C. Some of the harmful effects described below have been proven to be unfounded in later studies, while other effects are still undergoing further analysis. Volume 10, pp 293-296, June 2003 Patients with a predispostion to form oxalate stones or those on hemodialysis Sullivan JF, Eisenstein AB. Ascorbic acid depletion in patients undergoing chronic hemodialysis. Am. J. Clin. Nutr. 1970; 23:1339-1341 Deicher R, Horl WH.Vitamin C in chronic kidney disease and hemodialysis patients. Kidney Blood Press Res. 2003;26(2):100-6. should avoid excess use of vitamin C. Conflicts with prescription drugs Pharmaceuticals designed to reduce stomach acid such as the proton pump inhibitors , e.g. Omeprazole, among the most widely-selling drugs in the world, have been found to lower the bio availability of vitamin C by two thirds. Sources of vitamin C Vitamin C is obtained through the diet by the vast majority of the world's population. The richest natural sources are fruits and vegetables, and of those, the camu camu fruit and the billygoat plum contain the highest concentration of the vitamin. It is also present in some cuts of meat, especially liver. Vitamin C is the most widely taken nutritional supplement and is available in a variety of forms from tablets and drink mixes to pure ascorbic acid crystals in capsules or as plain powder. Plant sources Citrus fruits (orange, lemon, grapefruit, lime), tomatoes, and potatoes are good common sources of vitamin C. Other foods that are good sources of vitamin C include papaya, broccoli, brussels sprouts, black currants, strawberries, cauliflower, spinach, cantaloupe, kiwifruit, cranberries and red peppers. Emblica officinalis often referred to as Indian gooseberry or amla, is one of the richest known sources of vitamin C (720 mg/100g of fresh pulp or up to 900 mg/100g of pressed juice.)– it contains 30 times the amount found in oranges. The amount of vitamin C in foods of plant origin depends on: The following table is approximate and shows the relative abundance in different raw plant sources. The amount is given in miligrams per 100 grams of fruit or vegetable (in comparison, one teaspoon of pure vitamin C weighs 4,500 miligrams)... Animal sources
Food preparation It is important to choose a suitable method of food preparation that conserves vitamin C content. When cooking vegetables, one should seek to minimize temperature and duration of cooking and not discard water used in preparation (e.g., by steam cooking or by making soup). Food source vitamin C is identical to that in supplements. The structure of vitamin C is well understood, see ascorbic acid, and there is no difference in benefit between natural and synthetic forms (although fruits and vegetables contain various other nutrients, and vitamin C is not their only health benefit). Recent observations suggest that the impact of temperature and cooking on vitamin C may have been overestimated: It also appears that cooking doesn't necessarily leach vitamin C in all vegetables at the same rate; it has been suggested that the vitamin is not destroyed when boiling broccoli. This may be a result of vitamin C leaching into the cooking water at a slower rate from this vegetable. Copper pots will destroy the vitamin. Some research shows that fresh-cut fruit may not lose much of its nutrients when stored in the refrigerator for a few days. Vitamin C enriched teas and infusions have increasingly appeared on supermarket shelves. Such products would be nonsense if boiling temperatures did indeed destroy vitamin C at the rate it had previously been suggested. It should be noted however that as of 2004 most academics not directly involved in vitamin C research still teach that boiling temperatures will destroy vitamin C very rapidly. Vitamin C supplements Vitamin C is the most widely taken dietary supplement. It is available in many forms including tablets, capsules, drink mix packets, in multi-vitamin formulations and as chemically pure crystaline powder. Tablet and capsule sizes range from 25mg to 1500mg. Vitamin C (ascorbic acid) crystals are typically available in bottles containing 300g to 1 kg of powder (a teaspoon of vitamin C crystals equals 4,500mg). Methods of manufacture (chemical synthesis) 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 more modern Two-Step fermentation process was originally developed in China in the 1960s, uses additional fermentation to replace part of the later chemical stages. Both processes yield approximately 60% vitamin C from the glucose feed. Research is underway at the Scottish Crop Research Institute to create yeast micro organisms to synthesise ascorbic acid in a single fermentation step, a technology which is expected to reduce manufacturing costs considerably. World production of synthesised vitamin C is currently estimated at approximately 110,000 tonnes annually. Main producers today are BASF/Takeda, DSM, Merck and the China Pharmaceutical Group Ltd. of the People's Republic of China. China is slowly becoming the major world supplier as its prices undercut those of the US and European manufacturers. Discovery and history The need to include fresh plant food or raw animal flesh in the diet to prevent disease was known from ancient times. Native peoples living in marginal areas incorporated this into their medicinal lore. For example, infusions of spruce needles were used in the temperate zones, or the leaves from species of drought-resistant trees in desert areas. In 1536, the French explorer Jacques Cartier, exploring the St. Lawrence River, used the local natives' knowledge to save his men who were dying of scurvy. He boiled the needles of the arbor vitae tree to make a tea that was later shown to contain 50 mg of vitamin C per 100 grams. Through history the benefit of plant food for the survival of sieges and long sea voyages was recommended by enlightened authorities. John Woodall, the first appointed surgeon to the British East India Company, recommended the use of lemon juice as a preventive and cure in his book "The Surgeon's Mate" of 1617. The Dutch writer, Johann Bachstrom of Leyden, in 1734, gave the firm opinion that "scurvy is solely owing to a total abstinence from fresh vegetable food, and greens; which is alone the primary cause of the disease." The first attempt to give scientific basis for the cause of scurvy was by a ship's surgeon in the British 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 or sea water, along with their normal rations. In the history of science this is considered to be the first example of a controlled experiment comparing results on two populations of a factor applied to one group only with all other factors the same. The results conclusively showed that citrus fruits prevented the disease. Lind wrote up his work and published it in 1753, in Treatise on the Scurvy. Lind's work was slow to be noticed, partly because he gave conflicting evidence within the book and partly because of social inertia in some elements at the British admiralty who saw care for the well-being of ships' crew as a sign of weakness. There was also the fact that fresh fruit was very expensive to keep on board, whereas boiling it down to juice allowed easy storage but destroyed the vitamin. Ships' captains assumed wrongly that it didn't work, because the juice failed to cure scurvy. It was 1795 before the British navy adopted lemons or lime as standard issue at sea. Limes were more popular as they could be found in British West Indian Colonies, unlike lemons which weren't found in British Dominions, and were therefore more expensive. (This practice led to the nickname limey for British people, especially British sailors.) Captain James Cook had previously demonstrated and proven the principle of the advantages of fresh and preserved foods, such as sauerkraut, by taking his crews to the Hawaiian islands and beyond without losing any of his men to scurvy. For this otherwise unheard of feat, he was awarded a medal by the British Admiralty. So the Navy was certainly well aware of the principle. The cost of providing fresh fruit on board was probably a factor in this long delay. Luxuries or non-standard supplies not provided by the Admiralty were usually provided by the Captains. The name "antiscorbutic" was used in the eighteenth and nineteenth centuries as general term for those foods known to prevent scurvy, even though there was no understanding of the reason for this. These foods include lemons, limes, and oranges; sauerkraut, salted cabbage, malt, and portable soup were employed with variable effect. In 1907, Axel Holst and Theodor Frølich, two Norwegian biochemists studying beriberi contracted aboard ship's crews in the Norwegian Fishing Fleet, wanted a small test mammal to substitute for the pigeons they used. They fed guinea pigs the test diet, which had earlier produced beriberi in their pigeons, and were surprised when scurvy resulted instead. Until that time scurvy had not been observed in any organism apart from humans, and it was considered an exclusively human disease. In the early twentieth century, the Polish-American scientist Casimir Funk conducted research into deficiency diseases, and in 1912 Funk developed the concept of vitamins, for the elements in food which are essential to health. Then, from 1928 to 1933, the Hungarian research team of Joseph L Svirbely and Albert Szent-Györgyi and, independently, the American Charles Glen King, first isolated vitamin C and showed it to be ascorbic acid. In 1928 the arctic anthropologist and adventurer Vilhjalmur Stefansson attempted to prove his theory of how Eskimo (Inuit) people are able to avoid scurvy with almost no plant food in their diet. This had long been a puzzle because the disease had struck European Arctic explorers living on similar high-meat diets. Stefansson theorised that the native peoples of the Arctic got their vitamin C from fresh meat that was raw or minimally cooked. Starting in February 1928, for one year he and a colleague lived on an animal-flesh-only diet under medical supervision at New York's Bellevue Hospital; they remained healthy. In 1933-1934, the British chemists Sir Walter Norman Haworth and Sir Edmund Hirst and, independently, the Polish Tadeus Reichstein, succeeded in synthesizing the vitamin, the first to be artificially produced. This made possible the cheap mass production of vitamin C. Haworth was awarded the 1937 Nobel Prize in Chemistry largely for this work. The synthetic form of the vitamin is identical to the natural form. The Swiss pharmaceutical company Hoffmann-La Roche was the first to mass produce synthetic vitamin C, under the brand name of Redoxon, in 1934. In 1959 the American J.J. Burns showed that the reason some mammals were susceptible to scurvy was the inability of their liver to produce the active enzyme L-gulonolactone oxidase, which is the last of the chain of four enzymes which synthesize ascorbic acid. American biochemist Irwin Stone was the first to exploit Vitamin C for its food preservative properties and held patents on this. He developed the theory that vitamin C was an essential nutrient deficient in humans as a result of a genetic defect that afflicted the whole human race. Vitamin C hypothesis Since its discovery Vitamin C has been considered a universal panacea by some, although this led to suspicions of it being overhyped by others. The fact that man possesses three of the four enzymes that animals employ to manufacture ascorbates in relatively large amounts, has led researchers such as Irwin Stone and Linus Pauling to hypothesize that man's ancestors once manufactured this substance in the body millions of years ago in quantities roughly estimated at 3,000-4,000 mg daily, but later lost the ability to do this through a chance of evolution. If true, this would mean that vitamin C was misnamed as a vitamin and is in fact a vital macronutrient like fat or carbohydrate. Dr. Hickey, of Manchester Metropolitan University, believes that man carries a mutated and ineffective form of the genetic machinery for manufacturing the fourth of the four enzymes used by all mammals to make ascorbic acid. Cosmic rays or a retro virus could have caused this mutation, millions of years ago. In humans the three surviving enzymes continue to produce the precursors to ascorbic acid but the process is incomplete and the body then disassembles them. In the 1960s Nobel-Prize winning chemist Linus Pauling, after contact with Irwin Stone, began actively promoting vitamin C as a means to greatly improve human health and resistance to disease. His book How to Live Longer and Feel Better was a bestseller and advocated taking more than 10,000 milligrams per day. It sold widely and many advocates today see its influence as the reason there was a marked downward trend in US heart disease from the early 1980s onwards. Stone's work also informed the practise of Dr. Robert F. Cathcart III, in the 1970s and 1980s. He applied extremely large doses of ascorbate (300 grams = 0.66 pounds per day) to a wide range of viral diseases with successful results. Cathcart developed the concept of Bowel tolerance, the use of the onset of diarrhea as an indication of when the body's true requirement of ascorbic acid had been reached. He found that seriously ill people could often tolerate levels of tens of grams per day before their tolerance limit is reached. Matthias Rath is a controversial German physician who once worked with Pauling. He is an active proponent and publicist for high dose vitamin C. He has published a theory that deaths from scurvy in humans during the ice age, when vitamin C was scarce, selected for individuals who could repair arteries with a layer of cholesterol. He theorises that, although eventually harmful, cholesterol lining of artery walls would be beneficial in that it would keep the individual alive until access to Vitamin C allowed arterial damage to be repaired. Atherosclerosis is thus a vitamin C deficiency disease. Rath has also argued publicly that high doses of vitamin C can be effectively used against viral epidemics such as HIV, SARS and bird flu. It has been suggested by some advocates that ascorbic acid is really a food group in its own right like carbohydrates or protein and should not be seen as a pharmaceutical or vitamin at all. Chronic scurvy Identified and named by Linus Pauling, "chronic scurvy" or "subclinical scurvy" is a condition of Vitamin C deficiency which is not as easily noticeable as acute scurvy (because chronic scurvy is mostly internal), characterized by micro lesions of tissues (such as that caused by blood pulsing through arteries, which stretches the arterial walls causing them to tear slightly). It is a major contributing factor to cardio vascular disease. The condition is almost entirely preventable with supplementation of larger doses of Vitamin C (8 grams or more per day). Chronic scurvy is commonplace, even in industrialized countries. Regulation There are regulations in most countries which limit the claims on the treatment of disease that can be placed on food, drug, and nutrient product labels. Regulations include: Advocacy arguments Vitamin C advocates argue that there is a large body of scientific evidence that the vitamin has a wide range of health and therapeutic benefits but which they claim have been ignored. They claim the following factors affect the marketing and distribution of Vitamin C, and the dissemination of information concerning the nutrient: See also Sources Books | |||||||||||
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