Caused by airborne viruses, the common cold is characterized by a runny nose, sore throat, headache and sneezing. Fortunately symptoms are usually short-lived and are usually alleviated with over-the-counter cold medicines and rest. High-dose vitamin C has a long history of use in the treatment and prevention of the common cold. However, evidence to support its use is mixed. Get medical advice before taking high doses of this vitamin to treat a cold.
Properties and Potential Benefits
Vitamin C, also known as ascorbic acid, is a water-soluble antioxidant. It plays a role in several physiological and biochemical processes, including collagen synthesis, protein metabolism and immune function. It may play a role in the treatment and prevention of several conditions, including cardiovascular disease, cataracts and cancer. According to the Office of Dietary Supplements, high-dose vitamin C supplements may help to prevent a cold or shorten its duration, although it may not be of any help if you start using it once you already have a cold.
Dosage
Fruits and vegetables are a rich source of vitamin C. It is also available as a dietary supplement in tablets or capsule form. You can also buy effervescent vitamin C tablets that dissolve in water if you don't like swallowing pills. RxList notes that a daily dose of 1 to 3 g has been studied in scientific research for the treatment of the common cold. Check with your doctor or pharmacist that it is safe for you to take this amount of vitamin C.
Scientific Evidence
Evidence to support the use of vitamin C in the prevention and treatment of the common cold is mixed. The results of five-year trial, published in the January 2006 issue of the "European Journal of Clinical Nutrition," found that vitamin C supplementation significantly reduced the frequency of the common cold but that it did not help to reduce the severity of an existing cold. In contrast, an analysis of data from 30 clinical trials, published in the July 2007 "Cochrane Database of Systematic Reviews" concluded that vitamin C supplements do not reduce the incidence of the common cold in the general population. However, the authors add that it may be beneficial for people in certain subgroups, for example those that live in cold environments.
Safety Considerations
RxList states have vitamin C is safe for most people but adds that it might cause mild side effects, including stomach cramps, headache, heartburn and vomiting. The more vitamin C you take, the more likely you are to experience these effects. Taking more than 2,000 mg daily may increase the risk of kidney stones. Do not take more than 120 mg per day if you are pregnant. High-dose vitamin C is contraindicated in several conditions, including cancer, diabetes and blood-iron disorders. It may interact with other drugs you are taking, including cholesterol-lowering drugs and aspirin.
References
- University of Maryland Medical Center: Common Cold
- Office of Dietary Supplements: Vitamin C
- RxList: Vitamin C
- "European Journal of Clinical Nutrition"; Effect of Vitamin C on Common Cold: Randomized Controlled Trial; S. Sasazuki, et al.; January 2006
- "Cochrane Database of Systematic Reviews";Vitamin C for Preventing and Treating the Common Cold; R.M. Douglas, et al.; July 2007
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