At the first signs of a cold, many of us have probably poured a big glass of O.J. on the assumption that loading up on vitamin C is a surefire way to kick just about any bug. Modern-age nose-blowers may also reach for “immunity boosters” like Airborne and Emergen-C to cure the sniffles — but does vitamin C, and the supplements that tout its benefits, really work to prevent (or cure) the common cold?
Out in the Cold — Why It Matters
Researchers have been studying the role vitamin C plays in preventing and treating the common cold for more than 60 years . While research abounds, most experts say there is still little proof that increasing vitamin C intake will help cut down on sick days.
Still, the research isn't conclusive. One study did find that taking a daily vitamin C supplement reduced the frequency of catching a cold . Another study found that vitamin C made a big difference in preventing colds among people exposed to brief periods of intense cold or “extreme” physical exercise (like skiers, military personnel, and marathon runners), but not among the general population . And another study suggests upping vitamin C intake could reduce the severity and duration of a cold — and hopefully erase the need for that economy-size tissue box .
So it looks like some vitamin C, which is found naturally in superfoods like oranges, bell peppers, and strawberries, certainly won't do us any harm. But what about the massive doses of vitamin C found in products like Airborne and Emergen-C?
Created by a schoolteacher in 1997 (guess she was sick of germy kids), each tablet of Airborne contains 1,000 mg of vitamin C (equivalent to 11 glasses of O.J.) along with zinc, vitamins A and E, selenium, and a blend of herbs including ginger and Echinacea. Emergen-C also contains 1,000 mg of vitamin C (1667% of the daily recommended value) and recommends users take it up to two times daily. Each serving also includes B vitamins, zinc, and electrolytes, which is why it claims to enhance energy (without the caffeine crash). While neither of them outright say they can prevent or cure colds (anymore!), the mega doses of vitamin C are generally the reason many cold-sufferers are sniffling their way to the supplement aisle.
Too Much of a "Good" Thing? — The Answer/Debate
While there are no product-specific studies testing Airborne and Emergen-C’s effectiveness in preventing and treating the common cold, research looking at the common cold and ingredients like vitamin C and zinc can give us some insight into the efficacy of these products.
As we've shown, the research on vitamin C as a sickness-fixer is mixed, though many professionals maintain that it's not an effective treatment for the sniffles. Studies on zinc also remain pretty inconclusive: Multiple studies suggest zinc isn't an effective treatment for the common cold, although one study did conclude that at high doese, zinc can be an effective remedy for the sniffles   . Obviously, more research is needed before anyone goes around touting zinc as the latest miracle cure.
So it looks like taking these immunity boosters is likely neither seriously beneficial nor harmful. But there are still a few things to consider before overdoing it on the fizzy drinks. Too much vitamin C, for example, can cause diarrhea, nausea, and stomach cramps (the National Institutes of Health [NIH] suggest that adults consume no more than 2,000mg of the vitamin each day). Similarly, too much vitamin A (which is often included in these immune boosters) might do more harm than good. In excess doses (defined by the NIH as more than 10,000 IU per day) can cause dizziness, nausea, headaches, coma, and (in rare cases) death. In other words, it is possible to have too much of a good thing.
So when it comes to catching a bug (and hopefully squashing it!) this cold season, it’s probably best to save money on the hype and listen to the classic recommendations. That means get lots of sleep, keep hands clean, and cook up some chicken soup.
While regularly consuming adequate amounts of vitamin C may help reduce the frequency of catching colds, there is little evidence that it can actually help prevent or treat sickness once it's already set it.
Photo by Cris Magliozzi
Originally posted December 19, 2011. Updated March 6, 2013.
What are your go-to cold remedies? Share them in the comments below!