Vitamin C

Vitamin C

Vitamin C is also known as ascorbic acid. It has antioxidant properties and protects foods from oxidation, and it is required for all cell metabolism. It is read-ily destroyed by heat, air, and alkalies, and it is easily lost in cooking water.

Functions.Vitamin C is known to preventscurvy.This is a disease char-acterized by gingivitis (soft, bleeding gums and loose teeth); flesh that is easily bruised; tiny, pinpoint hemorrhages of the skin; poor wound healing; sore joints and muscles; and weight loss. In extreme cases, scurvy can result in death. Scurvy used to be common among sailors, who lived for months on bread, fish, and salted meat, with no fresh fruits or vegetables. During the middle of the eighteenth century, it was discovered that the addition of limes or lemons to their diets prevented this disease.

Vitamin C also has an important role in the formation of collagen, a pro-tein substance that holds body cells together, making it necessary for wound healing. Therefore, the requirement for vitamin C is increased during trauma, fever, and periods of growth. Tiny, pinpoint hemorrhages are symptoms of the breakdown of collagen.

Vitamin C aids in the absorption of nonheme iron (from plant and ani-mal sources and less easily absorbed than heme iron) in the small intestine when both nutrients are ingested at the same time. Because of this, it is called an iron enhancer.

Vitamin C also appears to have several other functions in the human body that are not well understood. For example, it may be involved with the forma-tion or functioning of norepinephrine (a neurotransmitter and vasoconstrictor that helps the body cope with stressful conditions), some amino acids, folate, leukocytes (white blood cells), the immune system, and allergic reactions.

It is believed to reduce the severity of colds because it is a natural antihista-mine, and it can reduce cancer risk in some cases by reducing nitrites in foods.

Vitamin C is absorbed in the small intestine.

Sources.The best sources of vitamin C are citrus fruits, melon, strawber-ries, tomatoes, potatoes, red and green peppers, cabbage, and broccoli.

Requirements.Vitamin C is measured in milligrams. Under normal cir-cumstances, an average female adult in the United States requires 75 mg a day and an average male 90 mg. In times of stress, the need is increased. Regular cigarette smokers are advised to ingest 125 mg or more a day.

It is generally considered nontoxic, but this has not been confirmed. An excess can cause diarrhea, nausea, cramps, an excessive absorption of food iron, rebound scurvy (when megadoses are stopped abruptly), and possibly oxalate kidney stones.

Deficiency.Deficiencies of vitamin C are indicated by bleeding gums, looseteeth, tendency to bruise easily, poor wound healing, and, ultimately, scurvy.