VITAMINS: Vitamin C (Ascorbic Acid)

Functions of Vitamin C
Deficiency of Vitamin C
People with an increased risk of Vitamin C deficiency
Clinical uses Vitamin C
Recommended Daily Allowance of Vitamin C
Food sources of Vitamin C
Toxicity of Vitamin C
References

Vitamin C (Ascorbic Acid)

Functions of Vitamin C

Essential for healthy teeth, gums & Bones.
Helps heal wounds, scar tissue, & Fractures.
Prevents scurvy.
Builds resistance to infection.
Aids in the prevention & treatment of the common cold.
Gives strength to blood vessels.
Aids in the absorption of iron.
Is required for the synthesis of collagen, the intercellular "cement" which holds tissues together.
Is also one of the major antioxidant nutrients. It prevents the conversion of nitrates (from tobacco smoke, smog, bacon, lunch meats, & some vegetables) into cancer-causing substances. According to Dr. Lines Pauling, the foremost authority on Vitamin C, Vitamin C will decrease the risk of getting certain cancers by 75%.

Deficiency of Vitamin C

Vitamin C deficiency causes scurvy, which is characterized by swollen, bleeding gums, loosening of the teeth, capillary hemorrhaging, including bleeding into joints, tender and painful extremities, poor wound healing, weakness and fatigue, and psychological disturbances.

People with an increased risk of Vitamin C deficiency

Smokers (NB. each cigarettes robs us of approx 25 mg of vitamin C).
City dwellers or anyone subject to pollution.
Heavy drinkers.
Women on the pill.
People who take aspirin, antibiotics, anti-arthritic drugs.
Those under stress.
Athletes.
The elderly.

Clinical uses Vitamin C

Prevention and treatment of scurvy is the only established use of vitamin C.
Effects of vitamin C on wound healing, blood pressure, colds and immune function are still under investigations.

Recommended Daily Allowance of Vitamin C

Increased intake of vitamin C is recommended for stress situations such as trauma, infection, strenuous exercise, or elevated environmental temperatures. The requirement in smokers may be 100 mg/day. Recent kinetic analyses suggest that intakes of 150-200 mg/day, but below 400 mg/day, obtained from the diet, may offer the most benefit in normal, healthy individuals.

Food sources of Vitamin C

The best food sources of vitamin C are citrus fruits, berries, melons, tomatoes, potatoes, green peppers and leafy green vegetables. Vitamin C is sensitive to air, heat and water, so it can easily be destroyed by prolonged storage, overcooking and processing of foods.

Toxicity of Vitamin C

Megadoses of vitamin C of 1000-2000 mg have commonly been associated with gastrointestinal disturbances (nausea, abdominal cramps and diarrhea). In general, megadoses of vitamin C should be avoided in individuals with a history of renal stones due to oxalate formation or hemochromatosis or other diseases related to excessive iron accumulation. Excess vitamin C may predispose premature infants to hemolytic anemia due to the fragility of their red blood cells. In healthy individuals, it appears that megadoses of up to 1000 mg/day of vitamin C are well tolerated and not associated with any consistent adverse effects. Concern of its pro-oxidant properties is stimulating renewed interest in its potential long-term toxicity.

References

Harris, J. R. (1996) Ascorbic Acid: Biochemistry and Biomedical Cell Biology. Subcellular Biochemistry, vol. 25, Plenum Press, NY.
Weber, P., Bendich, A. & Schalch, W. (1995) Vitamin C and human health. A review of recent data relevant to human requirements. Internat. J. Vit. Nutr. Res. 66: 19-30.
Rumsey, S. C. & Levine, M. (1998) Absorption, transport and disposition of ascorbic acid in humans. J. Nutr. Biochem. 9: 116-130.