It's a myth that vitamin C will help cure your cold — here's what you should do instead

The INSIDER Summary:

• Vitamin C supplements are touted as a way to "boost" and "support" the immune system.
• But evidence shows they won't help you stave off colds. 
• Taking vitamin C once a cold has already started won't make it go away faster, either. 

Every drugstore is stocked with vitamin C supplements that claim to "support" your immune system. There's a common belief that vitamin C can help you get over a cold faster — or even that it could help you stave off colds in the first place. 

Too bad those beliefs aren't supported by science.

Back in 2007, researchers pooled the results of 29 different studies looking at the effect of vitamin C on colds. They found that taking 200 milligrams of vitamin C every single day — not just on days when you're sick — could make cold symptoms go away about one day sooner. But the benefits ended there. 

The daily supplement regimen did not make people less likely to catch colds, the researchers found. And starting a vitamin C supplement once a cold has already begun didn't work either. The review concluded that it works no better than a placebo.

"After the cold is running its course, [vitamin C] doesn't have any effect," dietitian Andy Bellatti, MS, RD, confirmed to INSIDER. 

So why do so many people believe that vitamin C will help?

Flickr/Mike Mozart

The vitamin-C-for-colds hype originated back in the 1970s, but the concept gained steam in the late 1990s, when a supplement called Airborne hit store shelves. The tablets, developed by a second-grade teacher, contained herbs and a high dose of vitamin C. 

Early marketing materials claimed that Airborne was a "miracle cold buster" and that it could "get rid of most colds in one hour." The company said its claims were backed up by a a double-blind, placebo-controlled study.

But a 2006 ABC News investigation found something different. Turns out the lab that conducted the study was "actually a two-man operation started up just to do the Airborne study," ABC News reported. "There was no clinic, no scientists and no doctors." (By 2008 the company settled a lawsuit and a complaint from the Federal Trade Commission, agreeing to pay back as much as $30 million to its customers over the sketchy claims.)

Airborne is still sold today, and still claims it can "help support your immune system." It's also not alone: Similar supplements featuring vitamin C have popped up, too.

But the evidence shows taking vitamin C isn't going to help your cold very much.

Flickr/Mike Mozart

Plus, vitamin C megadoses of 2,000 milligrams might raise your risk of painful kidney stones, and may give you digestive issues like diarrhea, bloating, and cramps. You're better off fighting colds the old-fashioned way: with fluids and rest.

"If you do have a cold, stay hydrated and get enough rest," Bellatti said. "Don't go to work and pound [vitamin c]."