Does vitamin C protect against a flu-like infection? – Portal of naturopathic and naturopathic specialists

When a sore throat or a runny nose, some people try to beat the approaching cold with a vitamin C supplement. But does it really help? (Image: bernardbodo /

Vitamin C for the prevention of colds?

During the cold season, you can hear coughing and blowing your nose in many places. A runny nose, watery eyes, or a headache are uncomfortable symptoms of a cold. Some people use supplements containing vitamin C in the belief that they can prevent the flu. But does it really help?

Colds, coughs, headaches: a flu-like infection, the “simple” cold, can be caught several times a year. Some people swear by taking vitamin C supplements to prevent or fight a cold. But does it really bring anything?

Get enough vitamin C from your diet

As the Institute for Quality and Efficiency in Healthcare (IQWiG) explains on its portal “”, a certain amount of vitamin C is essential for health. Most people, however, get completely sufficient amounts in their daily diet. Vitamin C (ascorbic acid) is found for example in fruits and vegetables, especially citrus fruits and berries. Diseases caused by vitamin C deficiency, such as scurvy, are virtually non-existent in this country today.

However, some people take vitamin C supplements every day to prevent illnesses, especially the common cold. Some of these products contain more than one gram of vitamin C, which is more than ten times the recommended daily dose. Because the body cannot store vitamin C, the excess usually ends up in the toilet along with the urine within a few hours. According to the German Federal Institute for Risk Assessment (BfR), a daily intake of 100 milligrams with food is sufficient.

Studies evaluated

Years ago, scientists from the international Cochrane Collaboration research network investigated whether consuming large amounts of vitamin C protects against colds or can alleviate them. To this end, the researchers evaluated controlled studies in which vitamin C was compared with a preparation without the active ingredient (placebo).

According to IGWiG, 29 studies, in which a total of 11,000 adults and children participated, examined whether a regular intake of at least 200 mg of vitamin C protects against colds. Most of the articles tested a dose of 1000 milligrams or more of vitamin C per day. Some of the participants took vitamin C for several years.

Slightly shortened cold duration

Scientific studies have shown that long-term daily intake does not prevent the common cold, but reduces the duration of the common cold by about ten percent. This means, for example, that a cold lasted only nine days instead of ten. In addition, long-term intake of vitamin C may alleviate cold symptoms a bit. These results have also been confirmed by other research groups, especially for children. Adults who only started taking vitamin C when they had a cold did not shorten the duration of the illness.

Preventive effects studied

Some studies have looked at the preventative effects of vitamin C in people briefly exposed to very high levels of physical activity, often in association with cold. These included marathon runners and soldiers doing winter exercises in the mountains. In studies, participants started taking vitamin C as a preventive measure two to three weeks before very intense exercise. According to reports, about half of all colds are preventable.

Hand hygiene prevents infections

But what can really have a preventative effect is good hand hygiene. Due to the corona pandemic, special attention is currently being paid to this. Hands are in constant contact with pathogens, whether through doorknobs, light switches, or objects that many people have touched. This becomes problematic if the germs penetrate further into the mucous membranes via the hands. As explained on the Austrian public health portal “”, Florian Thalhammer of the Clinical Department of Infections and Tropical Medicine at the University of Medicine (MedUni) Vienna estimates that up to 80 percent of all infectious diseases are transmitted through the hands: Colds such as a runny nose or the flu are good examples. Washing your hands massively reduces the risk, as the number of germs can be reduced by over 99 percent. “(Ad)

Author and source information

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This text complies with the requirements of specialized medical literature, medical directives and ongoing studies and has been verified by healthcare professionals.


Institute for Quality and Efficiency in Health Care (IQWiG): Keeps vitamin C healthy ?, (Accessed October 12, 2020),, Austrian public health portal “”: Vitamin C is useless for cold prevention – hand hygiene works! (Accessed October 12, 2020),

Important note:
This article is provided for informational purposes only and should not be used for self-diagnosis or self-treatment. It cannot replace a visit to the doctor.