Vitamin C and the Common Cold

Sliced citrus fruit
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For years people have claimed that vitamin C will cure the common cold. There has been much speculation that it can shorten or prevent colds as well. So what does the evidence show?

There has been quite a bit of research in this area but the evidence is not exactly clear-cut. Some studies have shown positive results while others have not, but the overall consensus is that there is no real proof that vitamin C will prevent or cure a cold.

 

Taking Routine Supplements for Cold Prevention

Researchers who reviewed dozens of studies on the effects of vitamin C on the common cold found that taking vitamin C routinely won't prevent colds in the general public. 

Those who seem to benefit most from taking vitamin C are people who have a vitamin C deficiency and highly trained athletes and military personnel. The studies performed on athletes and military personnel who are in very good physical shape and experience extreme conditions showed that taking vitamin C reduced their risk of catching a cold by 50%. However, these results have not been replicated in the general public. This means similar studies have been conducted with "regular" people and the results were not the same.

Taking Routine Supplements to Reduce Cold Symptoms or Duration

Some studies have shown that people who get the recommended amount of vitamin C on a regular basis may experience a slightly shorter duration if they get a cold.

The same effect does not hold true in studies where people started taking larger doses of Vitamin C only after they started to feel sick. 

However, the risks are low and it's possible that taking vitamin C could work for you. Some people do feel it helps them even though large-scale studies have failed to prove that it works for a majority of people.

 

Want to Try It Anyway?

If you want to take vitamin C to help your immune system, it is best to get it through your diet instead of supplements. Foods high in vitamin C include:

  • Citrus fruits and juices
  • Green and red peppers
  • Strawberries
  • Tomatoes
  • Broccoli
  • Dark leafy greens
  • Sweet and white potatoes
  • Cantaloupe
  • Raspberries, blueberries and cranberries
  • Watermelon
  • Brussels Sprouts
  • Pineapple
  • Cabbage

The recommended daily values of vitamin C for adult males is 90 mg/day and for adult females is 75 mg/day. Taking more than 500 mg at one time will not provide any benefit because the body cannot store it. Don't waste your money on supplements that contain greater than 500mg of Vitamin C, your body will just get rid of it.

People with kidney disease should avoid vitamin C supplements. Excessive amounts of vitamin C can cause upset stomach and diarrhea in anyone.

The Bottom Line

Vitamin C probably may not help you avoid a cold, but eating a diet that includes foods high in vitamin C is good for your body because it helps boost your immune system and aids in the absorption of iron.

Unless you have kidney problems, taking Vitamin C supplements is inexpensive and carries few risks or side effects. Some people do find that it helps with their cold symptoms and it may be worth a try to see if it works for you. 

Sources:

Hemilä, H; Chalker, E. "Vitamin C for Preventing and Treating the Common Cold". Cochrane Acute Respiratory Infections Group 31 Jan 13. The Cochrane Library. 12 Jun 15. 

”Vitamin C.” Medline Plus 01 Dec 08. National Institutes of Health. 13 Dec 08.

”Vitamin C and colds.” Medline Plus 15 May 12. National Institutes of Health. 09 Aug 12.

"Common Cold." Medline Plus 8 Jan 12. National Institutes of Health. 09 Aug 12.

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