Vitamin C (Ascorbic Acid)
Overview
The primary function of vitamin C is the manufacturing of a protein substance called collagen. Collagen is a very integral protein in the structures that contain it since it provides a structural foundation and holds our body together. Structures that contain collagen include cartilage, connective tissue, ligaments, and tendons. Thus, vitamin C is important for wound repair, healthy gyms, and the prevention of easy bruising. Vitamin C also has a critical role in such things as immune function, the manufacture of certain nerve transmitting substances and hormones, and absorption and utilization of other nutritional factors. Vitamin C is an important nutritional antioxidant as well.
The C stands for citrus, where the vitamin is found. The physical characteristics include its weak stability; it is a weak acid, easily oxidized in air, and sensitive to heat and light. Since it is contained in the aqueous part of fruits and vegetables, it is easily lost during the cooking preparation process. Loss is minimized when vegetables such as broccoli or Brussels sprouts are cooked in a double boiler instead of water. If copper is present in the water or cookware, loss of vitamin C is also diminished.
Ascorbic acid was not isolated from lemons until 1932, when scurvy was prevalent. Scurvy, first described by Aristotle in 450 BC, is a syndrome that is characterized by lack of energy, gum inflammation, tooth decay, and bleeding problems. In the 1700s, there were a high percentage of sailors with the British navy and other fleets that died from scurvy. Research James Lind discovered that lemon juice cures and prevents the devastating and deadly disease. The ships then implementing a practice where lime was carried for the sailors to consume on a daily basis in order to maintain good health (these sailors later became more popularly known as “limeys”).
Ascorbic acid is readily absorbed from the intestines; usually about 80%-90% of it is absorbed. It is used by the body within 2 hours and usually out of the blood within 3 to 4 hours. In stressful conditions, as well as with alcohol and tobacco abuse, it is more readily used up. The level of vitamin C in the blood of smokers is much lower than nonsmokers with similar intake. Other situations and substances that may reduce absorption or increase its excretion include fever, viral illness, antibiotics, cortisone, aspirin, and other pain medicines, environmental toxins (such as DDT, petroleum products, or carbon monoxide), exposure to heavy metals such as lead, mercury, or cadmium. Sulfa antibiotics also increase elimination of vitamin C from the body by 2 to 3 times.
Some ascorbic acid is stored in high concentrations within some parts of the body. These include the adrenal glands, (about 30 mg), the pituitary, the brain, the eyes (especially the retinas), the ovaries, and the testes, a total of about 30 mg per pound of body weight. The recommended amounts vary widely than those of any other nutrient. Sources range from 60 mg, or in those with deficiencies, up to 50 to 100 grams to treat various conditions (mainly viral illnesses). People commonly take 2 or 3 grams a daily for maintenance and cold prevention. Even without any serious health conditions, vitamin C requirements vary as much as threefold or fourfold between different people.
Sources
Citrus fruits, including oranges, lemons, limes, tangerines, and grapefruits, are the best known sources of vitamin C. The fruits with the highest natural concentrations are citrus fruits, rose hips, acerola cherries, followed by papayas, cantaloupes and strawberries. Rich vegetable sources include red and green peppers, broccoli, brussel srpouts, tomatoes, asparagus, parsley, dark leafy greens, and cabbage. Normally, there is not much available in whole grain, seeds, and beans, but when sprouted, their vitamin C content shoots up.
Vitamin C supplements are usually made from rose hips, acerola cherries, peppers, or citrus fruits. It also can be synthesized from corn syrup, which is high in dextrose. Synthetic ascorbic acid is usually made from food sources, though it can be concentrated for higher doses than natural extracts.
Functions
One important function of vitamin C is the maintenance and formation of collagen. Collagen, as mentioned before helps with wound healing but also maintains healthy blood vessels. Ascorbic acid works as a coenzyme to convert proline and lysine to hydroxyproline and hydroxylysine, both very integral to the collagen structure.
Vitamin C also helps with the metabolism of tyrosine, folic acid, and tryptophan. Troyptophan is converted in the presence of ascorbic acid to 5-hydroxytryptophan, which forms serotonin, an important brain chemical. Vitamin C helps folic acid convert to its active form, tetrahydrfolic acid to form neurotransmitter substances.
It also has an important characteristic as an antioxidant vitamin, which means that it helps prevent oxidation of water-soluble molecules that could create free radicals, which may generate cellular injury and disease. Vitamin C is recycled back and forth between its reduced and oxidized form/
Ascorbic acid also has some detoxifying qualities and helps reduce the side effects of such drugs as cortisone, aspirin, and insulin. It also reduces the toxicity of heavy metals lead, mercury, and arsenic.
New research continues to show the value of vitamin C in immune system stimulation. Ascorbic acid may activate neutrophils, which are the most prevalent white blood cells and work as the frontline defense than other white blood cells. It also boosts the production of lymphocytes, which are the white blood cells tantamount in antibody production and coordination of immune cell function.
Uses
There are several clinical and nutritional uses for ascorbic acid. Ascorbic acid is usually used for the common cold. There are also some applications to prevention of cancer, though more research is needed.
Vitamin C also has been used to withdraw those with drug addictions to such substances as narcotics, alcohol, caffeine, and even sugar. High level ascorbic acid may decrease the withdrawal symptoms. Vitamin C, through its antioxidant effects, may reduce the effects of pollution. There are also some laxative qualities and may help with constipation problems. In those with iron definenciey, vitamin C helps with the absorption of iron. It also helps diabetics improve the utilization of blood sugar.
Vitamin C also may have a role in the prevention and treatment of atherosclerosis and reducing the risks of heart disease and its devastating results. It has been shown to lower platelet aggregation, which is an important factor in reducing the formation of platelet and clots.
Deficiency and toxicity – Vitamin C is non toxic for the most part. It is not stored in the body readily and most excess amounts are rapidly eliminated through the urine. Anything excessive would cause diarrhea, but only with a high amount of vitamin C. Other side effects include nausea, dysuria, and skin sensitivities. With very high amounts of vitamin C, hemolysis can occur. There is also some concern with causing kidney stones, though it is very rare.
As far as deficiency, the main one is scurvy, as mentioned before. Early symptoms of scurvy are likely to happen in infants in a phenomenon known as “rebound scurvy.” This occurs when babies born to mothers take higher doses of vitamin C than necessary. Since vitamin C crosses the placenta, the infants will get used to a higher dose of ascorbic acid in utero so much, that feel deficient unless breasted with taking the seam amount of vitamin C during pregnancy.
The symptoms of scurvy occur due to the lack of ascorbic acid on collagen formation. The first sign of depletion may be related to vitamin C’s other functions. Early bruising and tiny hemorrhages in the skin, general weakness, loss of appetite, and poor digestion may occur. As the symptoms may progress, nose bleeds, sore and bleeding gum, anemia, joint tenderness, and swelling may occur. The loss of collagen may lead to bone brittleness contributing to fragile bones.
Requirements
We only need 10 to 20 mg to prevent scurvy, which is contained in a single portion of most fruits or vegetables. Infants need about 35 mg, about 50 mg between ages 1 and 14 and 60 mg afterwards are the suggested minimum.
References
- Alan H. Pressman and Sheila Buff.(2007). The Complete Idiot's guide to vitamins and minerals. New York : Alpha Books
- Brewer, S. (2010). The essential guide to vitamins, minerals and herbal supplements. London : Right Way
- Elson M. Haas, Md & Buck Levin, Phd, Rd.(2006). Staying Healthy with Nutrition: The Complete Guide to diet and nutritional medicine. Berkeley, Calif. : Celestial Art
- Holford, P. (2004). The optimum nutrition bible. London : Piatkus
- Holford, P & Lawson, S.(2008). Optimum Nutrition Made Easy How to achieve optimum health. London : Piatkus
- Lieberman, S. & Bruning, N. (2003). The Real Vitamin & Mineral Book. New York : Avery
- Rodale Health Books.(2009). Healing with vitamins : the best nutrients to slow, stop, and reverse disease. Emmaus, Pa. : Rodale
- Royston, A.(2003). Vitamins and minerals for a healthy body. Oxford : Heinemann Library
- The National Research Council.(1989). Recommended Dietary Allowances, 10th ed, National Academy of Sciences
- Werbach, M. (1993). Nutritional Influences on Illness. 2nd ed. Los Angeles: Third Line Press
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