It’s cold season and products that claim to prevent or significantly shorten colds are flying off the drugstore shelves.
The best strategy to prevent a cold is to wash your hands frequently.
Still, the advertisements for such products are both pervasive and persuasive. But are they worth buying?
Vitamin C and zinc are the supplements used in most of these products. You can buy them in capsules, lozenges, teas or liquids. What does the research show?
Despite over 60 years of clinical studies, there is no definitive proof that large doses of vitamin C can either prevent or lessen the duration of a common cold. In a 2013 review of the available research, the Cochrane Reviews concluded that
The failure of vitamin C supplementation to reduce the incidence of colds in the general population indicates that routine vitamin C supplementation is not justified.
Vitamin C (1000 mg) is the major ingredient of Airborne and Emergen-C. Both are made into fizzy drinks. Airborne also claims to have a “proprietary blend” of minerals and herbs (or even probiotics), but it’s really about the vitamin C. The Food and Drug Administration (FDA) will not allow either product to claim they prevent colds; they can only state they “boost” the immune system. The Emergen-C package has the following generic disclaimer:
This product is not intended to diagnose, treat, cure or prevent any disease. [my emphasis]
Um, why should we buy it, then?
Airborne recommends up to 3000 mg of vitamin C per day; Emergen-C advises no more than 4000 mg per day.
The recommended daily allowance for vitamin C is about 80 mg/day. An 8-ounce glass of orange juice has 97 mg.
Related post: Healthy adults don’t need multivitamins
Doses larger than 2000 mg/day can lead to kidney stones, heartburn, nausea and diarrhea.
Zinc is the main ingredient in Cold-Eeze and Zicam lozenges. Because of positive results in a clinical trial by the Cleveland Clinic Foundation in 1999, both are allowed to claim, respectively, that they “reduce the duration of the common cold” and “get rid of your cold faster.”
How much faster? Half a day.
And to be effective, a zinc supplement must be taken within the first 24-48 hours of a cold, often before the symptoms are really noticeable.
Side effects include nausea and a metallic taste in your mouth.
In 2011, the Cochrane Reviews stated
it is difficult to make firm recommendations about the dose, formulation and duration that should be used.
Not exactly a glowing endorsement.
Bottom line: The facts behind these cold products, to me, do not support their questionable benefits over their cost and possible side effects. I would not spend money on any of them.
Eat a balanced, nutrient-rich diet throughout the year to keep your immune system healthy, and wash your hands!