fun8stuff said:
oh and by the way, many studies have shown zinc lozenges to be ineffective in treating/prevention colds. The studies that have been positive I have only been weakly positive and they have been with taking the lozenges at the first onset of the cold every 2 hrs for 2 weeks....
http://www.med.umich.edu/pediatrics/ebm/cats/zinc.htm
Your comment inspired me to look up a more definitive review of dietary zinc and health. This one is good:
Walker CF, Black RE. Zinc and the risk for infectious disease. Annu Rev Nutr. 2004;24:255-75.
http://www.ncbi.nlm.nih.gov/entrez/...d&dopt=Abstract&list_uids=15189121&query_hl=6
Here's what it says about zinc and the common cold (the numbers in parentheses refer to references at the end of the article):
Zinc for the treatment of the common cold was first investigated in the early 1980s with the use of zinc gluconate lozenges. Although zinc has been found to inhibit the replication of several rhinoviruses in vitro (41), the same effect in vivo has not been observed; the exact mechanism for how zinc may work in humans is not known. Three systematic review articles summarizing the effects of the first eight clinical trials found that zinc gluconate lozenges have an inconsistent effect on the severity and duration of the common cold (40, 46, 60). Beneficial effects were found in three trials (34, 45, 64), and no benefits were found in five trials (5, 33, 35, 111). Many trials have been criticized for study design problems (34, 111) and small sample sizes (5, 35).
Since these reviews were published there have been mixed results in trials of the use of zinc as a treatment for the common cold. Macknin et al. (58) did not find a difference between the time to resolution of cold symptoms between children receiving 10-mg zinc gluconate lozenges five to six times a day and those receiving placebo for the treatment of the common cold. In a study by Turner (106), prevention and treatment of rhinovirus infection with intranasal zinc gluconate did not prove to be effective (n = 91).
Turner & Cetnarowski (107) assessed the efficacy of zinc acetate and zinc gluconate lozenges among 273 persons challenged with a rhinovirus and among 281 natural cold patients. Among those with artificially induced colds, zinc gluconate significantly reduced the duration of the cold [2.5 days compared to 3.5 days among placebo (p = 0.035)]. No effects on duration were observed among zinc acetate-treated persons, and no effects on severity were observed with either zinc acetate or gluconate. Among those presenting with a natural cold, no effect was observed on duration or severity with zinc acetate or gluconate treatment. Prasad et al. (73) found zinc acetate lozenges to shorten the mean overall duration of cold symptoms (4.5 days in zinc-treated patients compared to 8.1 days in placebo, p < 0.01) and a decreased overall severity of symptoms based on patient scoring. Mossad (63) studied the efficacy of zincum gluconicum nasal gel and found that zinc-treated patients had a significantly shorter duration of illness (4.3 days versus 6.0 days) when compared to placebo (p < 0.005). Zinc may or may not be efficacious for a decline in the severity of, or the complete resolution of, common cold symptoms, but it does not appear to cause any significant adverse effects if used as a lozenge or nasal spray for the treatment of the common cold.