Vitamin C is one of the most important antioxidants. Vitamin C safeguards the water-soluble substances in the body from damage by free radicals. Free radicals are molecules with an unpaired electron—they are hungry for another electron.
Free radicals are unstable and react quickly with other compounds. Normally, free radicals attack the nearest stable molecule, “stealing” its electron, as seen in Figure 2-3. This attack is known as oxidative stress. When the “attacked” molecule loses its electron, it can become a free radical itself, beginning a chain reaction that can continue. If this chain reaction continues, it can disrupt a living cell.
Free radicals occur normally during metabolism. Also, the body’s immune system purposefully creates them to neutralize viruses and bacteria. Other sources of free radicals and other oxidative stresses include environmental factors such as pollution, hard radiation, cigarette smoke, and certain pesticides.
Figure 2-4 Vitamin C as an antioxidant.
Vitamin C is unusual in that it can neutralize a free radical without becoming a free radical itself. As seen in Figure 2-4, vitamin C can donate one or two hydrogen atoms to neutralize a free radical. The electrons from the hydrogen atoms neutralize the free radicals to prevent a free radical chain reaction. After donating two hydrogen atoms with their electrons, vitamin C can normally be reactivated with the addition of two hydrogen atoms. Vitamin C with its two hydrogen atoms is called ascorbic acid and is in a state of readiness to perform antioxidant actions.
Vitamin C is called dehydroascorbic acid when it has lost its two hydrogen atoms. Dehydroascorbic acid needs to be recharged before acting as an antioxidant. Vitamin C is stable both with and without its extra hydrogen atoms. Vitamin C can protect many indispensable molecules in the body, such as proteins, fats, carbohydrates, and nucleic acids (DNA and RNA), from damage by free radicals.
The protection of DNA from oxidative damage is one way that vitamin C can help reduce the risk of cancer. Vitamin C also has a role in regenerating vitamin E and beta-carotene after they have performed their antioxidant functions. Iron is absorbed in the intestines with the help of vitamin C. Vitamin C assists the absorption of iron by protecting the iron from oxidation.
Antioxidant Roles of Vitamin C
Protects Protein and DNA.
Regenerates vitamin E and beta-carotene.
Aids absorption of iron.
Inhibits the formation of nitrosamines.
Nitrates are present in many common foods. These nitrates can be transformed into cancer-causing nitrosamines in the intestines if vitamin C is lacking. There is evidence that vitamin C may inhibit the formation of cancer-causing nitrosamines from nitrate and may reduce the carcinogenicity of preformed nitrosamines.
Vitamin C neutralizes the nitrosamines by working as an antioxidant and donating electrons. Meats are often cured with nitrates and may contain nitrosamines. Nitrosamine content can be high in fried bacon, cured meats, beer, tobacco products, and nonfat dry milk.
More about C-Vitamin:
0 comments