| Table of contents |
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2 Sources 3 Functions of Vitamin C in the body 4 Daily requirement 5 Therapeutic uses 6 References 7 External Links |
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 ships 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 ships 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 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 in the years 1928 to 1933 the Hungarian biochemist 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 artificial 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.
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 and the method of preparation. Cooking in particular destroys vitamin C.
The following table is approximate and shows the relative abundance in different sources.
Discovery and History
The need to include fresh plant food in the diet to prevent disease was known intuitively from ancient times although has often been overlooked. 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. Sources
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.
| 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.
| 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 approx. 60% vitamin C from the glucose feed.
Main producers are
BASF/ Takeda , Roche, Merck, People's Republic of China.
Functions of Vitamin C in the body
As a participant in hydroxylation, vitamin C is needed for the production of collagen in the connective tissue. These fibres are ubiquitous throughout the body; providing firm but flexible structure. Some tissuess have a greater percentage of collagen, including:
Vitamin C is also needed to synthesise carnitine, important in the tranfer of energy to the cell mitochondria.
It is a strong antioxidant.
Lack of ascorbic acid in the daily diet leads to a disease called scurvy, a form of avitaminosis that is characterized by:
In April 1998 Nature reported alleged carcinogenic and teratogenic effects of excessive doses of vitamin C. This was given a great deal of prominence in the world's media. The effects were noted in test tube experiments, and on only two of the 20 markers of free radical damage to DNA. They 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 mg 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.
Fred R. Klenner, M.D., of 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. SARS and rabies are reported to respond to massive dosages.
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 MD Medical Director of the Colorado Integrative Medical Center in Denver. It concluded that overwhelming scientific evidence exists for its therapeutic role.
It is possible that the wider adoption of vitamin C for therapeutic use is hindered by the fact that it cannot now be patented. This makes pharmaceutical companies 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 profitable patented medicines.