Vitamin C


from http://micro.magnet.fsu.edu/micro/gallery.html

The connection between vitamin C (C6H8O6), and cold prevention is unproven, so what is it good for ?
Vitamin C ( ascorbic acid ) is a good, specific reducing agent, meaning that it specializes in giving electrons to the centre (iron) of a molecule (an enzyme known as prolyl oxidase) that plays an important role in producing the protein collagen. Various types of collagen are strong fibers that are found in tendon, skin, corneas, cartilage, in the cardiovascular system and elsewhere in the human body. Hence, the vitamin plays an important role in growth and repair

Vitamin C is also associated with the normal functioning of blood vessels.
Most animals can produce their own vitamin C, but primates, guinea pigs and some fish cannot. We consequently have to obtain the crucial molecule from our diets. Without it we develop scurvy, a disease which causes us to lose strength and develop skin lesions and fragile blood vessels.
As stated previously the RDA is 60 mg. Pregnant women should get 80 mg and lactating women should ingest 100 mg daily. Some people unfortunately believe that there is no toxic level of Vitamin C because of its solubility in water. One gram, however, is considered a toxic dosage (Drugs, Vitamins and Minerals. Henry and al. Fisher,1989).

  • Above 1.0 g, vitamin C destroys vitamin B12 and could cause kidney stones, iron overload and diarrhea .
  • Above 1.5 g , blood copper levels are decreased.
  • Above 2 g, the immune system is impaired and withdrawal symptoms are suffered.

    • When fruits are cooked, much of their vitamin C is oxidized. Ascorbic acid is only stable if its crystals are pure, dry and kept in darkness. Exposed to light and oxygen, ascorbic acid yields electrons and is thus destroyed. In vivo ( in living things), large doses of vitamin A can cause a deficiency of vitamin C.

    Vitamin C also interacts with iron, but in a positive way. If a meal contains 25 to 75 mg of ascorbic acid, the absorption of iron is increased.

    Needless to say, synthetic vitamin C is chemically identical to the vitamin naturally found in fruits and vegetables. Thus supplements are equally effective in preventing scurvy and in acting as a catalyst for the previously mentioned physiological processes. These facts, however, do not exclude the possibility that other compounds found in fruit and not in supplements help accentuate some of Vitamin C' s functions. In Schwartz's March 7 1999 column for the Montreal Gazette, he cites a Cornell study ( no exact reference given , unfortunately )which clearly showed that vitamin C as an integral part of fruit juices was more effective in reducing the formation of carcinogenic nitrosamines in the body than when taken as a supplement. Chlorogenic acid ( C16H18O9 ), supposedly boosts vitamin C activity.
    The Merck Index describes chlorogenic acid as an important factor in plant metabolism. Chlorogenic acid and two of its isomers occur in leaves, fruits and other tissues of dicotyledenous plants (Most commonly eaten fruit are dicots). Like vitamin C, it is a reducing agent . It has long been known as the compound that causes potatoes to blacken when they are cut and exposed to air. (Chem. & Ind. (London) 1958,627) So it is not surprising that it too would attack electron-seeking free radicals. The Vitamin C-chlorogenic acid teamwork reminds us of how numerous carotenoids assist Vitamin A in its physiological role.

    Your Science Home

    Page Maintained by E. Uva; euva@retired.com

    Copyright ©2008