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Vitamin C

Vitamin C, the L-enantiomer of ascorbic acid, is a water-soluble vitamin used by the body for several purposes. Most animals can synthesize their own ascorbic acid, but some animals, including primates, guinea pigs and humans, cannot. Vitamin C was first isolated in 1928, and in 1932 it was proved to be the agent which prevents scurvy.

Table of contents
1 Discovery and History
2 Sources
3 Functions of Vitamin C in the body
4 Vitamin C Deficiency
5 Daily requirement
6 Therapeutic uses
7 Vitamin C advocacy
8 References
9 External Links

Discovery and History

The need to include fresh plant food 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 pine needles are used in the arctic zone, or the leaves from species of drought resistant trees in desert areas.

Through history the benefit of plant food for the survival of sieges and long sea voyages was recommended by enlightened authorities. In the seventeenth century Richard Woodall, a ship's surgeon to the East India Company, recommended the use of lemon juice as a preventive and cure in his book "Surgeon's Mate" The early eighteenth century Dutch writer, Johannes Bachstrom 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, who at sea in May 1747 provided some crew members with lemon juice in addition to normal rations while others continued on normal rations alone. 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 lemons prevented the disease. Lind wrote up his work and published it in 1753.

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. It was 1795 before the British navy adopted lemon or lime juice as standard issue at sea.

In 1907, Alex Holst and Theodore Frohlich, 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 then 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 was considered a completely human disease.

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 meat and offal 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 and remained healthy.

In the early twentieth century, the Polish American scientist Casimir Funk conducted research into deficiency diseases and in 1912 formulated 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-Gyorgyi, and independently the American Charles Glen King, first isolated vitamin C and showed it to be ascorbic acid.

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 for Chemistry largely for this work.

In 1959 the American J.J. Burns showed that the reason why some mammals were susceptible to scurvy was due to the inability of their livers to produce the active enzyme L-gulonolactone oxidase, which is the last of the chain of four enzymes which synthesise ascorbic acid.


Plant sources

Citrus fruits (lime, lemon, orange, grapefruit) and tomatoes are good common sources of vitamin C. Other foods that are good sources of vitamin C include papaya, broccoli, brussels sprouts, blackcurrants, strawberries, cauliflower, spinach, cantaloupe, and kiwifruit.

The amount of vitamin C in foods of plant origin depends on the precise variety of the plant, the soil and climate in which it grew, the length of time since it was picked, the storage conditions and the method of preparation. Cooking in particular destroys vitamin C.

The following table is approximate and shows the relative abundance in different sources.

Table Showing Relative Abundance of Vitamin C in Principal Fruits and some Raw Vegetables
Fruit Mg vitamin C per 100 grams of fruit Fruit Continued Mg vitamin C per 100 grams of fruit Fruit Continued Mg vitamin C per 100 grams of fruit

CamuCamu 2800 Lemon 40 Grape 10
Rosehip 2000 Melon, cantaloupe 40 Apricot 10
Acerola 1600 Cauliflower 40 Plum 10
Jujube 500 Grapefruit 30 Watermelon 10
Baobab 400 Raspberry 30 Banana 9
Blackcurrant 200 Tangerine/ Mandarin oranges 30 Carrot 9
Guava 100 Passion fruit 30 Avocado 8
Kiwifruit 90 Spinach 30 Crabapple 8
Broccoli 90 Cabbage Raw green 30 Peach 7
Loganberry 80 Lime 20 Apple 6
Redcurrant 80 Mango 20 Blackberry 6
Brussels sprouts 80 Melon, honeydew 20 Beetroot 5
Lychee 70 Raspberry 20 Pear 4
Persimmon 60 Tomato 10 Lettuce 4
Papaya 60 Blueberry 10 Cucumber 3
Strawberry 50 Pineapple 10 Fig 2
Orange 50 Pawpaw 10 Bilberry 1

Animal sources

Most species of animals synthesise their own vitamin C. It is therefore not a vitamin for them. Synthesis in achieved through a sequence of enzyme driven steps, which convert glucose to ascorbic acid. It is carried out either in the kidneys, in reptiles and birds, or the liver, in mammals and perching birds. The loss of an enzyme concerned with ascorbic acid synthesis has occurred quite frequently in evolution and has affected at least some fish, many birds; some bats, guinea pigs and most but not all primates, including Man. The mutations have not been lethal because ascorbic acid is so prevalent in the surrounding food sources.

Table Showing Abundance of Vitamin C in Raw Foods of Animal Origin
Raw animal tissue Mg vitamin C per 100 grams of tissue
Beef liver 31
Oysters 30
Pork liver 23
Calf liver 36

Artificial 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. Main producers are BASF/ Takeda, Roche, Merck and the People's Republic of China.

Functions of Vitamin C in the body

Vitamin C Deficiency

Lack of ascorbic acid in the daily diet leads to a disease called scurvy, a form of avitaminosis that is characterized by:

Daily requirement

The dietary amounts recommended by various authorities are 50-150 mg of ascorbic acid per day. High doses (thousands of mg) are often used, but may result in diarrhea. Any excess of vitamin C is generally excreted in the urine.

In April 1998 Nature reported alleged carcinogenic and teratogenic effects of excessive doses of vitamin C. This was given great prominence in the world's media. However, the effects were noted in test tube experiments and on only two of the 20 markers of free radical damage to DNA, and have not been supported by further evidence from living organisms. Almost all mammals manufacture their own vitamin C in their livers in amounts equivalent to human doses of thousands of milligrams per day. The vitamin is used widely in orthomolecular medicine and no harmful effects have been reported even in doses of 10,000 mg per day or more.

Therapeutic uses

Vitamin C is needed in the diet to prevent scurvy. It also has a reputation for being useful in the treatment of colds and flu. The evidence to support this idea, however, is ambiguous and the effect may depend on the dose size and dosing regime.

Vitamin C advocacy

Fred R. Klenner, a doctor in Reidsville, North Carolina reported in 1949 that poliomyelitis yielded to vitamin C.

Nobel Prize winning chemist Linus Pauling began actively promoting vitamin C in the 1960s as a means to greatly improve human health and resistance to disease.

A minority of medical and scientific opinion continues to see vitamin C as being a low cost and safe way to treat infectious disease and to deal with a wide range of poisons. A megadose of one-half gram per pound of body weight per day of sodium ascorbate salt has been found of theraputic use in both human and veterinary treatments.

A meta-study into the published research on effectiveness of ascorbic acid in the treatment of infectious disease and toxins was conducted, in 2002, by Thomas Levy, Medical Director of the Colorado Integrative Medical Center in Denver. It claimed that overwhelming scientific evidence exists for its therapeutic role.

Some vitamin C advocates hold that the wider adoption of vitamin C for therapeutic use is hindered by the fact that it cannot now be patented, meaning that pharmaceutical companies will be unwilling to fund research or promotion of a substance in which they stand to make little profit and which will compete with some of their own patented medicines.


Thomas Levy (September 2002), Vitamin C, Infectious Diseases, and Toxins , Xlibris Corporation (Paperback). ISBN: 1401069630 (self-published)

External Links