Zinc fights colds, but dosing and recommendations unknown
In a systematic review carried out by Cochrane review researchers, zinc was found to help fight colds.
Though the study confirmed zinc has benefits for reducing severity and length of cold symptoms, researchers still are hesitant to make any recommendations about its use.
What the scientists did find out is zinc lozenges and syrup taken within a day before cold symptoms appear are beneficial. After a week, cold symptoms disappeared in groups of people using zinc, compared to those given placebo in the review that included 15 trials, involving 1,360 people. The study is a follow-up of reviews conducted in 1999, with the addition of newer trials. The scientists looked at 15 studies altogether.
"This review strengthens the evidence for zinc as a treatment for the common cold," said lead researcher Meenu Singh of the Post Graduate Institute of Medical Education and Research in Chandigarh, India. "However, at the moment, it is still difficult to make a general recommendation, because we do not know very much about the optimum dose, formulation or length of treatment."
Rashmi Das, MD, of the Post Graduate Institute of Medical Education and Research in Chandigarh, India who also worked n the review, zinc can also have unwanted side effects that include bad taste and nausea, again compared to those using placebo in the trial reviews.
The authors write, "Given that some formulations (especially lozenges) produced side effects and not all formulations may be effective, the use of zinc to treat common cold symptoms is presently advised with caution."
Though the review shows zinc can help the common cold, the amount and duration of supplementation is still not known. The scientists aren't even sure how it works, but think it may block replication of the virus in the lining of the nose, or epithelium that harbors the rhinovirus.
In the study, zinc supplementation resulted in fewer days lost from work. Children given the mineral in lozenges and syrups for five months had fewer colds, took less time off from school and needed fewer antibiotics.
According to the National Institutes of Health, zinc is essential for cellular metabolism and plays a role in immunity. The body does not store zinc, making it essential to focus on regular daily intake. You can get zinc from a variety of foods that include beans, nuts, poultry, whole grains, oysters, pork, beef, chicken leg and fortified cereals and dairy.
Though the study adds clarity to the role of zinc for boosting immunity and fighting the common cold, more research needs to be done before optimum dosing or recommendations for its use could be provided.