|
|
 |
|
|
|
| |
Vitamin C
(Ascorbic Acid)
|
| |
| Introduction |
Back to Top |
| Vitamin C corrects the world's oldest known nutritional deficiency, the disease scurvy. It was first isolated by Albert Szent Gyorgyi in 1928. Today, scientists know that humans are one of the few species that cannot manufacture vitamin C in the body. Humans must depend on diet or nutritional supplements as the source of this vitamin.
Vitamin C is a water soluble vitamin that is stored in many tissues throughout the body, but the adrenal glands contain the highest concentration.
The best sources of vitamin C are fresh fruits, especially citrus fruits, strawberries, cantaloupe and currants. Fresh vegetables, especially Brussels sprouts, collard greens, lettuce, cabbage, peas, and asparagus are also good sources.
Because of its acid content, physicians recommend taking a buffered form of vitamin C if you are taking it in higher doses.
|
 |
| Reported Uses |
Back to Top |
|
Vitamin C has been heavily researched for its role in a long list of functions in the body. First, it is involved with the production of collagen and elastin, which are necessary for the health of skin, tendons, joints, bones, teeth and blood vessels. Second, vitamin C functions as an antioxidant, thus helping to limit damage to the body from free radicals. It also enhances the antioxidant activity of vitamin E. Low levels of vitamin C during chemotherapy increases the chance of side effects.(1)
Next, vitamin C is important for production of the hormones that help the body respond to physical stress. Also, vitamin C may reduce some inflammatory reactions because it possesses anti-histamine activity. Finally, vitamin C can help the body rid itself of heavy metal toxins like mercury, lead, cadmium and nickel.
Vitamin C has an equally long list of targeted clinical applications. To begin, vitamin C can support immunity to a variety of illnesses.(2) Studies suggest that the severity and duration of the common cold may be lessened with vitamin C when taken in moderately high doses.(3) In a recent study there were fewer colds and recovery was faster with the individuals taking vitamin C.(4) Scientists have also found some immune-boosting benefits for patients with the AIDS virus.(5)
Vitamin C's role as an antihistamine may help reduce allergy symptoms.(6) Vitamin C deficiency has also been linked to a higher risk of asthma, and supplementation may reduce asthma symptoms.(7, 8) Deficiency has also been associated with cervical dysplasia.(9)
Vitamin C also has a number of applications for the treatment and prevention of chronic diseases. First, studies suggest supplementation may reduce atherosclerotic plaque.(10) It may also increase HDL cholesterol levels (the so-called “good” cholesterol) while helping prevent the conversion of LDL, or “bad” cholesterol to a more harmful form.(11, 12) A study involving 153 people with coronary artery disease and low HDL (good) cholesterol questioned these benefits. The antioxidants vitamin C, vitamin E, beta-carotene and selenium were added to cholesterol treatment of simvastatin and niacin and continued to show improvement over placebo, but decreased the benefits seen on HDL cholesterol measurements from simvastatin and niacin without the antioxidants.(13)
Bone loss and decreases in bone mineral density is inevitable as we age. It is important to slow this process, maintain strong healthy bones and thus decrease the risk of bone fractures. According to the National Osteoporosis Foundation, over half of Americans older than 50 have low bone mineral density and 80% of them are women.(14) Especially when used with other therapies, numerous studies have supported the use of vitamin C to help support bone mineral density.(15, 16, 17, 18) One study found that there was an increased risk of polyarthritis in those with lower dietary intakes of fruits and vegetables, and vitamin C.
Also, studies suggest that long term vitamin C supplementation may reduce the risk of many kinds of cancer.(20) Low vitamin C intake may increase chances of diabetes(21, 22) and that vitamin C may support overall health in diabetics.(23)
A small study investigated the role of vitamin C in the circulation of smokers. The participants ingested 2 grams of vitamin C and the blood flow was measured. The results showed that blood flow was significantly better in the non-smokers than the smokers. After the vitamin C, the blood flow increased in the smokers, but not in the non-smokers.(24)
|
|
| Dosage Info |
Back to Top |
| Dosage Range |
|
Most Common Dosage |
|
Dosage Forms |
| 60-2,000mg daily.(25, 26) Some therapeutic applications may go much higher.(27) |
250mg daily. |
Capsules, tablets, liposomal sprays, effervescent tablets, bulk powder, and injectables (Rx only). |
| |
|
|
| Toxicities & Precautions |
Back to Top |
| Be sure to tell your pharmacist, doctor or other health care providers about any dietary supplements you are taking. There may be a potential for interactions or side effects. |
General
This dietary supplement is considered safe when used in accordance with proper dosing guidelines. |
Health Conditions
If you have liver disorders or gout, talk to your doctor before taking this dietary supplement. |
Side Effects
Occasional side effects reported with large doses of this dietary supplement include diarrhea. Approximately 15 percent of people taking moderately high doses of vitamin C experience abdominal gas, bloating, and cramping. Because large doses may also interfere with some medical tests(28), advise your doctor if you are taking vitamin C. It may be necessary to reduce the dose of this dietary supplement to stop the diarrhea. Tell your doctor if these side effects become severe or do not go away. |
Pregnancy/Breast-Feeding
To date, the medical literature has not reported any adverse effects related to fetal development during pregnancy or to infants who are breast-fed. Proper nutrition is essential during pregnancy for the healthy development of the fetus. Numerous vitamins and minerals are a vital part of proper nutrition. If you are pregnant, think you might be pregnant, trying to get pregnant, or breast-feeding an infant, talk to your healthcare professional about supplementing your diet with appropriate vitamins and minerals. |
Age Limitations
To date, the medical literature has not reported any adverse effects specifically related to the use of this dietary supplement in children. Vitamins and minerals are an essential part of proper growth and development. Talk to your healthcare professional about the appropriate use of vitamins and minerals in children. Do not use any vitamin or mineral in children under 2 years of age unless first discussed with your healthcare professional. |
|
| Footnotes |
Back to Top |
1 Kennedy DD, Tucker KL, Ladas ED, Rheingold SR, Blumberg J, Kelly KM. Low antioxidant vitamin intakes are associated with increases in adverse effects of chemotherapy in children with acute lymphoblastic leukemia. Am J Clin Nutr. Jun2004;79(6):1029-36.
View Abstract
2 Anderson R. The Immunostimulatory, Anti-inflammatory and Anti-allergic Properties of Ascorbate. Adv Nutr Res. 1984;6:19-45.
3 Pauling L. How to Live Longer and Feel Better. New York: W.H. Freeman and Company; 1986:118-21.
4 Van Straten M, Josling P. Preventing the common cold with a vitamin C supplement: a double-blind, placebo-controlled survey. Adv Ther. May2002;19(3):151-9.
View Abstract
5 Cathcart RF 3rd. Vitamin C in the Treatment of Acquired Immune Deficiency Syndrome (AIDS). Med Hypotheses. Aug1984;14(4):423-33.
View Abstract
6 Levine MA, Pollard HB. Hydrocortisone Inhibition of Ascorbic Acid Transport by Chromaffin Cells. FEBS Lett. 1983;158(1):134-38.
View Abstract
7 Hatch GE. Asthma, Inhaled Oxidants, and Dietary Antioxidants. Am J Clin Nutr. Mar1995;61(3 Suppl):625S-30S.
View Abstract
8 Bielory L, et al. Asthma and Vitamin C. Ann Allergy. Aug1994;73(2):89-96.
View Abstract
9 Romney SL, et al. Plasma Vitamin C and Uterine Cervical Dysplasia. Am J Obstet Gynecol. Apr1985;151(7):976-80.
View Abstract
10 Willis GC. Serial Arteriography in Atherosclerosis. Can Med Assoc J. 1954;71:562-68.
11 Jialal I, et al. Physiologic Levels of Ascorbate Inhibit the Oxidative Modification of Low Density Lipoprotein. Atherosclerosis. Jun1990;82(3):185-91.
View Abstract
12 Rezaian GR, Taheri M, Mozaffari BE, Mosleh AA, Ghalambor MA. The salutary effects of antioxidant vitamins on the plasma lipids of healthy middle aged-to-elderly individuals: a randomized, double-blind, placebo-controlled study. J Med Liban. Jan2002;50(1-2):10-3.
View Abstract
13 Cheung MC, Zhao XQ, Chait A, Albers JJ, Brown BG. Antioxidant supplements block the response of HDL to simvastatin-niacin therapy in patients with coronary artery disease and low HDL. Arterioscler Thromb Vasc Biol. Aug2001;21(8):1320-6.
View Abstract
14 National Osteoporosis Foundation. Disease Statistics. Available at: http://www.nof.org/osteoporosis/stats.htm. Accessed Jul2002.
15 Morton DJ, Barrett-Connor EL, Schneider DL. Vitamin C supplement use and bone mineral density in postmenopausal women. J Bone Miner Res. Jan2001;16(1):135-40.
View Abstract
16 Hall SL, Greendale GA. The relation of dietary vitamin C intake to bone mineral density: results from the PEPI study. Calcif Tissue Int. Sep1998;63(3):183-9.
View Abstract
17 Wang MC, Luz Villa M, Marcus R, Kelsey JL. Associations of vitamin C, calcium and protein with bone mass in postmenopausal Mexican American women. Osteoporos Int. 1997;7(6):533-8.
View Abstract
18 Leveille SG, LaCroix AZ, Koepsell TD, Beresford SA, Van Belle G, Buchner DM. Dietary vitamin C and bone mineral density in postmenopausal women in Washington State, USA. J Epidemiol Community Health. Oct1997;51(5):479-85.
View Abstract
NO footnote for fnID:
20 Block G. Epidemiologic Evidence Regarding Vitamin C and Cancer. Am J Clin Nutr. Dec1991;54(6 Suppl):1310S-314S.
View Abstract
21 Zhang C, Williams MA, Frederick IO, et al. Vitamin C and the risk of gestational diabetes mellitus: a case-control study. J Reprod Med. Apr2004;49(4):257-66.
View Abstract
22 Bates CJ, Lean ME, Mansoor MA, Prentice A. Nutrient intakes; biochemical and risk indices associated with Type 2 diabetes and glycosylated haemoglobin, in the British National Diet and Nutrition Survey of people aged 65 years and over. Diabet Med. Jul2004;21(7):677-84.
View Abstract
23 Sinclair AJ, et al. Low Plasma Ascorbate Levels in Patients with Type 2 Diabetes Mellitus Consuming Adequate Dietary Vitamin C. Diabet Med. Nov1994;11(9):893-98.
View Abstract
24 Teramoto K, et al. Acute effect of oral vitamin C on coronary circulation in young healthy smokers. Am Heart J. Aug 2004;148(2):300.
View Abstract
25 Hemila H. Vitamin C supplementation and common cold symptoms: factors affecting the magnitude of the benefit. Med Hypotheses. Feb1999;52(2):171-8.
View Abstract
26 Douglas RM, Chalker EB, Treacy B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2000;(2):CD000980.
View Abstract
27 Daniel TA, Nawarskas JJ. Vitamin C in the prevention of nitrate tolerance. Ann Pharmacother. Oct2000;34(10):1193-1197.
View Abstract
28 Mitch WE, et al. Effect of large oral doses of ascorbic acid on uric acid excretion by normal subjects. Clin Pharmacol Ther. Mar1981;29(3):318-21.
View Abstract
|
|
|
|
|
|
|
|
