By Jennifer Copley (Last Updated 24 July 2009)
Vitamin C (Ascorbic acid) is a potent antioxidant that is critical to the health of blood vessels, muscles, and bones, as well as the formation of collagen and the ability to absorb iron. Despite its involvement in many aspects of health, research has yielded mixed results regarding vitamin C’s ability to cure or prevent colds.
Older Studies of Vitamin C’s Efficacy in Preventing or Curing Colds
There have been numerous studies conducted into Vitamin C’s preventative and curative effects. Some of the more notable ones include the following:
- A review of clinical trials found only a very slight reduction in colds with vitamin C supplementation, but a significant reduction in severity of symptoms with Vitamin C compared to a placebo in most studies (Chalmers, 1975).
- In a 15-week study of 448 subjects, the experimental group took 500 mg of vitamin C each week and 1,500 mg daily on the first day of an illness followed by 1,000 mg over the next 4 days. Overall, the vitamin group experienced less severe symptoms and spent approximately 25% fewer days indoors due to illness than the placebo group (Anderson et al., 1975).
- A twin study found that younger children who received supplements of vitamin C had colds with less severe symptoms and shorter duration than the comparison group, though no significant treatment effect was found for older children (Miller et al., 1977).
Recent Research Review of Vitamin C’s Effects on Colds
WebMD reports that a recent review of research conducted over the past 60 years indicates that regular daily vitamin C intake may slightly shorten the duration of colds when they occur (8% for adults and 14% for children). However, taking vitamin C only after a cold starts probably does nothing to reduce the severity or duration for most people.
Overall, the evidence suggests that vitamin C does not prevent colds for most people, but it may provide a protective effect for those whose bodies are subjected to extreme conditions (i.e., cold temperatures, intense physical exertion) such as marathon runners, skiers, and soldiers in harsh climates. For those experiencing physical stressors, it was found that regular supplementation with vitamin C cut their likelihood of coming down with colds by about 50%.
Although research findings for vitamin C’s effects on colds have been inconsistent, they do suggest that while ascorbic acid probably won’t do much prevent illness for anyone whose body isn’t subjected to extreme conditions, regular intake may reduce the total number of sick days and the magnitude of symptoms. As for prevention, athletes and those whose jobs involve physical stress are the ones most likely to benefit from supplementation.
Other Benefits of Vitamin C
Even if vitamin C only shaves one day off a cold for most people, that’s one extra day to feel good and be more productive, so it’s probably worthwhile, given the additional health benefits ascorbic acid can provide.
Vitamin C is important for a variety of health concerns, ranging from the healing of wounds and burns to helping prevent cancer, stroke, and age-related macular degeneration (in conjunction with vitamin E, zinc, and beta-carotene). While most research indicates that megadoses aren’t necessary for optimum health, a regular daily intake of vitamin C, preferably through dietary sources, can provide a number of health benefits.
This article is not intended as a substitute for medical consultation or care. Health concerns should be referred to a qualified medical practitioner.
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- Anderson, T.W.; Beaton, G.H.; Corey, P.; & Spero, L. (1975). “Winter Illness and Vitamin C: The Effect of Relatively Low Doses.” Canadian Medical Association Journal, 112(7): 623-826.
- Chalmers, T.C. (1975). “Effects of Ascorbic Acid on the Common Cold: An Evaluation of the Evidence.” American Journal of Medicine, 58: 532-536.
- Higdon, J., PhD., Reviewed by Frei, B., PhD. (2006). “Vitamin C.” Linus Pauling Institution Micronutrient Information Center. LPI.OregonState.edu.
- Hitti, M. (28 June 2005). “Vitamin C May Not Fight the Common Cold.” WebMD.com.
- Miller, J.Z.; Nance, W.E.; Norton, J.A.; Wolen, R.L., Griffith, R.S., & Rose, R.J. (1977). “Therapeutic Effect of Vitamin C: A Co-Twin Control Study.” Journal of the American Medical Association, 237(3): 248-251.
- University of Maryland Medical Center. (2009). “Vitamin C (Ascorbic Acid).” UMM.edu.
- WebMD.com. (Reviewed by Smith, M.W., MD, 18 December 2007). “Vitamin C for the Common Cold.”