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Does Vitamin C help with colds?
Nearly all of us have suffered from a cold at least once in our lives. Sneezing and a runny nose are some of the most obvious signs that you’ve caught the common cold. It is often thought that increasing Vitamin C uptake, either by taking supplements or drinking juices, can help fight against colds. Does taking Vitamin C improve a cold once you’ve got it? Or does it help reduce your chances of getting a cold in the first place? We asked 6 experts in nutrition, biochemistry and epidemiology, ‘Does Vitamin C help with colds?’ here is what we found…
Does Vitamin C help with colds?
What are colds and what causes them?
The ‘common cold’ is not just one disease caused by one virus. Professor Harri Hemila, an expert in nutrition and epidemiology from Helsinki University in Finland, says “The common cold is a condition that is defined by symptoms; it is caused by over a hundred different respiratory viruses.” Common cold symptoms include a blocked or runny nose, coughing and sneezing. It is important to keep in mind that not all colds are the same. Dr Hemila says “the viruses have varied between the dozens of vitamin C trials and it is unlikely that the benefit of vitamin C is explained by an effect on just a certain respiratory virus or virus group”
How might Vitamin C help with colds?
Professor Anitra Carr, an expert in Vitamin C from Otago University in New Zealand, says “Research has indicated that vitamin C levels decrease in immune cells during the common cold, and supplementation may help improve the vitamin C status of these immune cells. This could potentially improve their immune functions.”
What is the evidence that Vitamin C helps fight a cold once you get it?
Several studies have investigated whether Vitamin C helps fight colds. Some of these studied are called ‘controlled trials’. Professor Hemila explains that controlled trials are where “study participants are divided to two groups equally. One group is administered vitamin C and the other group is the control group which is administered an ineffective placebo.” He goes on to describe how “in 31 placebo-controlled studies, regular vitamin C administration reduced common cold duration in adults on average by 8%, and in children by 14%. Based on these 31 studies, there is very strong evidence that vitamin C is better than placebo in alleviating colds.”
Professor Carr agrees, saying “Yes – vitamin C can help with colds. Meta-analysis (comparison of multiple studies) of vitamin C for the prevention and treatment of the common cold has indicated that supplementation with ?200 mg/d of vitamin C can decrease the duration and severity of the common cold.”
Interestingly, reaching for supplements after you’ve already started sneezing might not help you. Dr Ms Carol Haggans, an expert in nutrition from the National Institutes of Health, says “vitamin C supplements taken on a regular basis appear to reduce the duration of the common cold and the severity of its symptoms. But if someone starts taking vitamin C after they come down with a cold, it doesn’t appear to help.”
What is the evidence that Vitamin C helps prevent you catching a cold?
Ms Haggans says “For most people, vitamin C supplements don’t reduce the likelihood of coming down with a cold. However, vitamin C at doses of 250 mg – 1,000 mg/day might help reduce the risk of colds in people exposed to extreme physical stress such as marathon runners, skiers, and soldiers in subarctic areas.”
Should I start taking Vitamin C to prevent bad colds?
Many studies have found that only some people might see a positive effect from regularly taking Vitamin C. Ms Haggans adds that “Vitamin C supplements might also be helpful in people who get marginal amounts of vitamin C, such as chronic smokers and older adults.”
Professor Jens Lykkesfeldt, an expert in pharmacology and Vitamin C from Copenhagen University in Denmark, says “Some evidence suggest that regular vitamin C supplementation can shorten the duration and frequency of common colds ... However, the effect is limited in individuals that get a balanced diet and are sufficient in vitamin C.”
Professor Hemila summarises that “Although placebo-controlled trials have unambiguously shown that regularly administered vitamin C is better than placebo for alleviating the common cold, the practical significance is still an open question and further research is needed. We do not know what is the best dose and how much benefit we would get from the best dosages.”
For most people, taking regular Vitamin C won’t help prevent you catching a cold. However, it could help you fight a cold once you’ve got it.
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