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Vitamin C for the Common Cold

At the very first sign of cold symptoms, many people reach right for a bottle of vitamin C supplements. Vitamin C for the common cold is such a widely accepted treatment that we seek it out in lots of products, such as fortified juices, cough drops, and tea.

Vitamin C was first touted for the common cold in the 1970s. But despite its widespread use, experts say there's very little proof that vitamin C actually has any effect on the common cold.

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What Is Vitamin C?

Vitamin C is an important vitamin and antioxidant that the body uses to keep you strong and healthy. Vitamin C is used in the maintenance of bones, muscle, and blood vessels. Vitamin C also assists in the formation of collagen and helps the body absorb iron.

Vitamin C is found naturally in vegetables and fruits, especially oranges and other citrus fruits. This key vitamin is also available as a natural dietary supplement in the form of vitamin C pills and vitamin C chewable tablets.

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 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.

Is Vitamin C Safe to Take?

In general, vitamin C is safe to take when ingested through food sources such as fruits and vegetables. For most people, taking vitamin C supplements in the recommended amounts is also safe. The RDA or recommended daily allowance is 90 mg for men and 75 mg for women. High doses of vitamin C (greater than 2000 milligrams per day for adults) may cause kidney stones, nausea, and diarrhea.

If you're unsure about taking vitamin C for colds, talk to your health care provider. 

WebMD Medical Reference

Reviewed by Roy Benaroch, MD on June 20, 2012
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