Named: The Group of People Who May Benefit from Vitamin C to Prevent Colds

Adrian Gombart, Professor of Biochemistry and Biophysics at Oregon State University, noted that this effect was identified in five studies involving people subjected to intense physical exertion. Such exertion is believed to make the body more susceptible to respiratory infections.

“For everyone else, regular vitamin C supplementation has virtually no effect on the frequency of colds. A large Cochrane review of 29 studies involving more than 11,000 people found no preventive effect,” the researchers said.

According to experts, vitamin C may help ease the course of an existing cold if taken regularly in advance. The review found that it reduces the duration of illness by an average of 8% in adults and 14% in children. For a typical seven-day cold, this amounts to approximately half a day and one day, respectively.

Experts also assessed the benefits of other supplements. According to a review of 34 studies, zinc may shorten a cold by approximately two days, although the reliability of this evidence is low. Taking high doses can be harmful: excess zinc has been linked to anaemia and weakened bones.

Experts emphasize that no supplement guarantees protection against colds. Getting enough sleep, maintaining a balanced diet, staying physically active and practising good hygiene can also help reduce the risk of infection.