Ask Dr. H: Avoiding colds, without Vitamin C

Question:

I've been taking Vitamin C for years to keep from getting a winter cold, and I think that it does help. A friend of mine thinks that it doesn't really work and it's all in my head. What do you think?

Answer:

The "common cold" is not a single viral respiratory infection, but a group of several viruses that are especially prevalent this time of year. Antibiotics are useless against cold viruses, and the viruses' ability to mutate has so far made it impossible to develop a multi-virus vaccine to prevent infection. That's why we put so much effort into prevention.

The use of Vitamin C for colds has been controversial for decades. In his 1970 book

Vitamin C and the Common Cold

, Nobel Prize winner Linus Pauling wrote that taking 1,000 mg of Vitamin C daily would cut nearly in half the number of colds suffered by most people.

His conclusion was based more on belief than on scientific trials of the type done before medications are approved. Recently, researchers compiled data from 55 studies between 1940 and 2004 that looked at how well doses of at least 200 mg of Vitamin C daily prevented or treated colds, compared with a placebo.

They found that Vitamin C did not keep people from catching colds most of the time. They also found, however, that people who had taken Vitamin C beforehand did not stay sick as long; the effect was particularly noticeable in children. Most of the studies showed that Vitamin C did not help people who waited until after the onset of symptoms, although one large study found that already-sick patients who took 8,000 mg on the first day of their illness got better faster.

In six trials that involved participants exposed to short periods of extreme cold or physical stress (marathon runners, skiers, soldiers), participants got sick 50 percent less often when they took Vitamin C as a preventive measure.

My best tips to prevent catching a cold:

Keep your home well-humidified during winter.

Never let your nose dry out. Use saline nasal spray outside the home to keep it moist.

Wash and disinfect your hands often, and keep them away from your face.

Get enough rest.

Avoid crowds.