Let’s review and discuss the medical literature, separating myth from fact about which supplements may be beneficial and which may not.
You may have heard that zinc is an effective way to treat a cold. But does the medical literature agree?
The answer is a resounding, yes! According to a meta-analysis that included 13 trials, zinc in any form taken within 24 hours of first symptoms may reduce the duration of a cold by at least one day.
Even more importantly, zinc may significantly reduce the severity of symptoms throughout the infection, thus improving quality of life. The results may be due to an anti-inflammatory effect of zinc.
One of the studies reviewed, which was published in the Journal of Infectious Disease, found that zinc reduced the duration of the common cold by almost 50 percent from seven days to four days, cough symptoms were reduced by greater than 60 percent and nasal discharge by 33 percent.
All of these results were statistically significant. Researchers used 13 grams of zinc acetate per lozenge taken three-to-four times daily for four days. This translates into 50 to 65 mg per day.
The caveat is that not all studies showed a benefit. However, the benefits generally seem to outweigh the risks, except in the case of nasal sprays, which the FDA has warned against.
Unfortunately, all of the studies where there was a proven benefit may have used different formulations, delivery systems and dosages, and there is no current consensus on what is optimal.
According to a review of 29 trials with a combined population of over 11,000, vitamin C did not show any significant benefit in prevention, reduction of symptoms or duration. Thus, there may be no reason to take mega-doses of vitamin C for cold prevention and treatment.
However, in a sub-group of serious marathon runners and other athletes, there was substantial risk reduction when taking vitamin C prophylactically; they caught 50 percent fewer colds.
After review of 24 controlled clinical trials, according to the Cochrane Database, the jury is still out on the effectiveness of echinacea for treatment of duration and symptoms, but the results are disappointing and inconsistent. There are no valid randomized clinical trials for cold prevention using echinacea.
In another randomized controlled trial with 719 patients, echinacea was no better than placebo for the treatment of the common cold.
People with colds need rest – at least that was the theory. However, a 2010 study published in the British Journal of Sports Medicine may have changed this perception.
Participants who did aerobic exercise at least five days per week, versus one or fewer days per week, had a 43 percent reduction in the number of days with colds over two 12-week periods during the fall and winter months.
Even more interesting is that those who perceived themselves to be highly fit had a 46 percent reduction in number of days with colds compared to those who perceived themselves to have low fitness. The symptoms of colds were reduced significantly as well.
What does all of this mean?
Zinc is potentially of great usefulness the treatment and prevention of the common cold. Echinacea and vitamin C may or may not provide benefits, but don’t stop taking them, if you feel they work for you. And, if you need another reason to exercise, reducing your cold’s duration may a good one.