If you have the habit of popping vitamin C tablets to help those nasty colds, researchers suggest that you drop it for a much more cost-effective prevention formula - wash your hands often, it keeps germs at bay.
What's more, the researchers said that large doses of vitamin C can prove harmful for humans.
The German Institute for Quality and Efficiency in Health Care (IQWiG) has published information and a quiz on the subject of prevention, helping to separate widespread myths from facts.
For years it was believed that taking vitamin C supplements not only provided protection against colds, but also against cancer, thereby helping people to live longer. An easy-to-understand summary of the research in this area, refuting these beliefs, has now been published on IQWiG's website www.informedhealthonline.org.
"Not only is there no proof that some antioxidants prolong life, but there is some evidence that certain products may even lead to earlier death", says Professor Peter Sawicki, the Institute's Director.
"Positive" news gives people hope, which can quickly spread, become deeply held beliefs.
Professor Sawicki said: "It can be very difficult to accept that these beliefs are myths, but they are not true if further research does not confirm them or the research points to the opposite conclusion."
There are many simple but effective ways to lower the risk of respiratory infections. These include frequently washing your hands with normal soap and water, and not touching your face with your hands.
People who already have a respiratory infection can stop it from spreading by throwing away tissues immediately after using them and not shaking hands with other people.