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 vitamin C, 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 Sources 2 Functions of Vitamin C in the Body 3 Daily Requirement 4 Theraputic Uses

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, blackberries, strawberries, cauliflower, spinach, cantaloupe, and blueberries.

The amount of Vitamin C in fruit depends on the precise variety of the fruit , the soil and climate in which it grew, and the length of time since it was picked. The following table is approximate and shows the relative abundance in different types of fruit.

Table Showing Relative abundance of Vitamin C in Fruits

Fruit	mg vitamin C per 100 grams of fruit
Camu Camu	2800
Rosehip	2000
Acerola	1600
Jujube	500
Baobab	400
Blackcurrant	200
Guava	100
Kiwifruit	90
Longanberry	80
Redcurrant	80
Lychee	70
Persimmon	60
Papaya	60
Strawberry	50
Orange	50
Lemon	40
Melon, cantaloupe	40
Grapefruit	30
Raspberry	30
Tangerine/Mandarin	30
Passionfruit	30
Lime	20
Mango	20
Melon, honeydew	20
Raspberry	20
Tomato	10
Blueberry	10
Pineapple	10
Pawpaw	10
Grape	10
Apricot	10
Plum	10
Watermelon	10
Banana	9
Avocado	8
Crabapple	8
Peach	7
Apple	6
Blackberry	6
Pear	4
Fig	2
Bilberry	1

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:

• skin
• mucous membranes
• teeth
• bones

Vitamin C is also required for synthesis of dopamine, noradrenaline and adrenaline in the nervous system or in the adrenal glands. 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:

• loose teeth
• superficial bleeding
• fragility of blood vessels
• poor healing
• compromised immunity
• mild anaemia

Daily Requirement

The dietary amounts recommended by various authorities are 50-150 mg of ascorbic acid per day. High doses (thousands of mg) are 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 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 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.

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.

Theraputic Uses

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.

It is alleged 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.