Is Zinc Effective Against Colds?

Zinc is a “flu-fighter” that “keeps your immune system in working order,” AARP told its members last winter.


But taking zinc didn’t prevent colds or other respiratory infections in five studies that gave 10 mg to 20 mg of zinc—alone or as part of a multivitamin—or a placebo to some 2,560 mostly older adults every day for seven months to two years. (The DV for zinc is 15 mg.)

In a sixth trial, though, the 24 adults at a senior center in Detroit who were given 45 mg of zinc every day for a year were 67 percent less likely to get sick than the 25 adults who got a placebo.

Why the discrepancy? “Many of the elderly were zinc deficient,” says researcher Ananda Prasad of Wayne State University in Detroit. “We gave them more zinc and had them take it between meals to increase its absorption.” But Prasad’s study has yet to be repeated.

Zinc lozenges are more likely to help. In some studies, sucking on at least 75 mg of zinc from lozenges every day at the first sign of a cold cut its duration—though not its severity—by up to two days.

Sources: J. Am. Geriatr. Soc. 55: 35, 2007; BMJ 331: 324, 2005; JAMA 288: 715, 2002; Complement. Ther. Clin. Pract. 15: 91, 2009; Arch. Intern. Med. 159: 748, 1999; Am. J. Clin. Nutr. 85: 837, 2007; Cochrane Database Syst. Rev. 6: CD001364, 2013.


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3 Replies to “Is Zinc Effective Against Colds?”

  1. I have used zinc loxenges for the last ten or so years to combat colds or other respiratory infections and been very successful. I have 7.5 mg in my daily vitamins, but whenever I feel a cold coming on with beginning symptoms of a scratchy throat or watery eyes, etc. I immediately such on zinc lozenges I buy at health food stores (not the candy type at regular stores). I usually take about two at first, then another in a few hours, about three a day, for about three days or until all symptoms disappear. I haven’t had a cold in tears, of course, knock in wood, right!! the symptoms never get worse, they all eventually disappear in a day or two.

  2. the discrepency could be due to the fact that the different studies didn’t use the same form of zinc. According to my research zinc acetate is the most effective for flu and cold followed by zinc gluconate to a lesser degree. The problem with zinc acetate is the taste…awful from what I found out even though I never used it myself since cold doesn’t seem to be able to get a grab on me.

    1. From the Nutrition Action Heathletter: The six trials, including the one with Detroit seniors, were looking at whether taking zinc pills once a day would prevent colds.

      Zinc lozenges are used to treat a cold once it has started. A 2013 review by the Cochrane Collaboration, a network of international scientists that conducts rigorous asssessments of the evidence for medical therapies, found that zinc gluconate and zinc acetate lozenges cut the duration of colds by about the same amount.

      Cochrane Database Syst Rev. 2013 Jun 18;6:CD001364.
      doi: 10.1002/14651858.CD001364.pub4.
      Zinc for the common cold.
      Singh M1, Das RR.

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