Can Vitamin C Prevent or Treat Cold Symptoms?

Vitamin C has been studied for many years as a possible treatment for colds, or as a way to prevent colds. But findings have been somewhat inconsistent. Overall, experts have found little to no benefit for vitamin C preventing or treating the common cold.

In a July 2007 study, researchers wanted to discover whether taking 200 milligrams or more of vitamin C daily could reduce the frequency, duration, or severity of a cold. After reviewing 60 years of clinical research, they found that when taken after a cold starts, vitamin C supplements do not make a cold shorter or less severe. When taken daily, vitamin C very slightly shorted cold duration -- by 8% in adults and by 14% in children.

But researchers found the most effect on people who were in extreme conditions, such as marathon runners. In this group, taking vitamin C cut their risk of catching a cold in half.

So what does all this mean?

The average adult who suffers with a cold for 12 days a year would still suffer for 11 days a year if that person took a high dose of vitamin C every day during that year.

For the average child who suffers about 28 days of cold illness a year, taking daily high-dose vitamin C would still mean 24 days of cold illness.

When vitamin C was tested for treatment of colds in 7 separate studies, vitamin C was no more effective than placebo at shortening the duration of cold symptoms.