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:
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:
Choose My Plate—Department of Agriculture
Eat Right—American Dietetic Association
Canadian Digestive Health Foundation
Dietitians of Canada
Ascorbic acid. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated July 7, 2016. Accessed July 21, 2016.
Vitamin C. Office of Dietary Supplements National Institutes of Health website. Available at: https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional. Updated February 11, 2016. Accessed July 21, 2016.
Vitamin C. Oregon State University Linus Pauling Institute website. Available at: http://lpi.oregonstate.edu/mic/vitamins/vitamin-C. Updated January 14, 2014. Accessed July 21, 2016.
Vitmin C deficiency. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated April 27, 2010. Accessed July 21, 2016.
10/30/2009 DynaMed Systematic Literature Surveillance
http://www.ebscohost.com/dynamed: Hemila H, Louhiala P. Vitamin C for preventing and treating pneumonia.
Cochrane Database Syst Rev.
Last reviewed July 2016 by Michael Woods, MD
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