Mary Calvagna, MS
Vitamin C, also called ascorbic acid, is a water-soluble vitamin. Water-soluble vitamins are stored in the body in very limited amounts, and are excreted through the urine. Therefore, it is a good idea to have them in your daily diet. Vitamin C is sensitive to light, heat, and air and can be destroyed during food preparation, cooking, or storage.
Vitamin C's functions include:
Smoking increases oxidative stress and metabolic turnover of vitamin C. Therefore, the RDA for smokers is increased by 35 mg/day. For example, if you are a 22-year-old female smoker, your RDA for vitamin C is 110 mg/day.
Intakes of less than 10 mg per day of vitamin C can result in scurvy. Symptoms of vitamin C deficiency include:
The tolerable upper intake level (UL) for vitamin C from dietary sources and supplements combined is:
Because excess vitamin C is excreted in the urine, toxicity is rare. It can happen, though, with several large doses throughout the day. Symptoms of vitamin C toxicity include:
The following populations may be at risk for vitamin C deficiency and may require a supplement:
Free radicals are normal by-products of metabolism, but they can cause chain reactions that result in cell damage. This cell damage can, in turn, increase the risk of chronic diseases, including certain forms of cancer and cardiovascular disease.
Antioxidants have the ability to stop this chain reaction. Vitamin C functions in the body as an antioxidant. Because of this antioxidant capability, vitamin C is being studied for a possible role in prevention of certain conditions like age-related macular degeneration, cataracts, cancer, and cardiovascular diseases. Currently there is not sufficient evidence to recommend vitamin C for any of these conditions.
Many people believe that taking mega-doses of vitamin C will cure a
cold. There is no scientific evidence to support this idea in the general population. However, there may be some preventative benefit in people exposed to extreme physical stress, cold environments, or those not getting enough vitamin C normally. Studies have found that taking vitamin C daily may help slightly reduce the symptoms and the duration of a cold. But taking vitamin C after the onset of the cold does not appear to effect the course of the illness. In addition, a review of studies on vitamin C found that it may be able to prevent and treat pneumonia, particularly in people who do not get enough vitamin C in their diet.
To help increase your intake of vitamin C:
American Dietetic Association
Harvard School of Public Health
Canadian Digestive Health Foundation
Dietitians of Canada
Ascorbic acid. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/. Updated November 7, 2011. Accessed September 19, 2012.
Vitamin C. Office of Dietary Supplements National Institutes of Health.website. Available at: http://ods.od.nih.gov/factsheets/vitaminc.asp. Accessed July 6, 2010.
Vitamin C. Oregon State University Linus Pauling Institute website. Available at: http://lpi.oregonstate.edu/infocenter/vitamins/vitaminC/index.html. Updated December 2009. Accessed September 19, 2012.
Vitamin C (ascorbic acid). University of Maryland Medical Center website. Available at: http://www.umm.edu/altmed/articles/vitamin-c-000339.htm. Updated July 7, 2011. Accessed September 19, 2012.
10/30/2009 DynaMed Systematic Literature Surveillance
http://www.dynamicmedical.com/what.php: Hemila H, Louhiala P. Vitamin C for preventing and treating pneumonia.
Cochrane Database Syst Rev.
Last reviewed September 2012 by Brian Randall, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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