Vitamin C is also known as ascorbic acid which, in chemical terms, is a sugar essential for biochemical functions in the human body. It is the only water-soluble vitamin that is not part of the B complex. Since it is water-soluble, vitamin C cannot be stored in the body and fresh supplies are needed daily from food. Vitamin C is the least stable vitamin and is very sensitive to oxygen. Potency can be lost or reduced through exposure to heat, light or air.
Despite the fact that it is so widely researched, vitamin C has so many functions that their extent is not fully understood. It is clear, however, that the human body cannot survive without this nutrient.
Vitamin C is measured in milligrams (mg).
The most common food sources of vitamin C are citrus fruits such as oranges, lemons, limes and grapefruits. Richest natural sources are acerola cherries, rose hips, plums, blackcurrants, guavas, strawberries and gooseberries.
Vegetables such as parsley, broccoli, greens, tomatoes, sprouts, green peppers and watercress also contain significant quantities of vitamin C. Although potatoes contain only low levels of the nutrient, because they are often eaten in such high quantities they can provide a useful contribution to intake of the vitamin.
Vitamin C is known to be involved in at least 300 processes and is generally recognised to have a wide range of therapeutic uses.
Key roles include:
- the maintenance of healthy connective tissue and bones
- the production of collagen
- the regulation of cholesterol metabolism; the control of histamines
- the functioning of the adrenal glands
Vitamin C is the least stable of the water-soluble vitamins. It is easily destroyed by oxidation, i.e. exposure to air, light, heat and water and storage. Processing and cooking can substantially reduce the vitamin C content of foods. Pressure cooking, steaming or boiling for a short time with a small amount of water and using the freshest possible vegetables will help to ensure that the maximum amount of the nutrient is retained.
Deficiency symptoms of vitamin C can be varied. In the elderly or ill, the symptoms of scurvy can still be observed. They include bleeding, easy bruising, swollen gums and dry, scaly skin. Other signs of less serious deficiency include depression, hysteria, lack of resistance to infection, the appearance of little blood spots called petechiae under the skin’s surface, muscle and joint pain and loose teeth.
Certain sections of the population may be more at risk of deficiency because of an increased requirement for the nutrient:
- Pregnant and lactating women.
- The elderly, who may consume low levels of fresh fruit and vegetables and who require additional vitamin C for the production of collagen.
- Athletes and those in demanding, stressful situations, because of their depleted levels of vitamin C in the adrenal glands.
- Heavy drinkers of alcohol
- Those taking certain drugs on a regular basis, including steroids, aspirin, antibiotics, corticosteroids or the contraceptive pill
- People who have undergone or are preparing for surgery may benefit from increased intake of vitamin C to assist in the healing process.
Bioflavonoids are a group of substances which always occur naturally with vitamin C and which enhance its activity. They are biochemical substances that work synergistically but also in their own right.
Richest sources are citrus fruits (the skin and the pulp), apricots, cherries, grapes, green peppers, tomatoes and broccoli. Unlike vitamin C they are very stable, even in processed foods.Vitamin C is also linked with fat-soluble vitamins such as the powerful antioxidants A and E and with some B vitamins because of its protective effect over these nutrients.