Many people increase their vitamin C intake in a bid to boost their immune systems, but research now claims the idea of using supplements to combat colds is a myth.
Analysis of 30 studies involving more than 11,000 people has found no evidence to show that, for the average person at least, taking additional vitamin C can stop the sniffles.
In fact, only people under immense physical stress, such as soldiers, marathon runners and skiers, get any benefits, the research added.
Scientists claim these people are 50% less likely to catch a cold if they take daily vitamin C.
But generally, it appears that the protection provided by the supplements is so minute it is not worth the effort or expense.
Intense debate has surrounded the beneficial effects of vitamin C since it was discovered around 70 years ago.
US Nobel Prize-winning chemist Dr Linus Pauling championed the chemical in his book, Vitamin C and the Common Cold.
In it, he encourages people to take 1,000mg daily to lead a healthier life, but current guidelines recommend a daily intake of about 60mg.
Just one 220ml glass of orange juice contains more than that - about 97mg.
Professor Harri Hemila, from the Department of Public Health at the University of Helsinki, said: "It doesn't make sense to take vitamin C 365 days a year to lessen the chance of catching a cold."
The new analysis appears in The Cochrane Library, published by the Cochrane Collaboration, an international organisation that evaluates medical research.
Related story: Vitamin C campaigners support supplement
The Cochrane Collaboration
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