Zinc Decreases Severity and Length of the Common Cold.
Americans spend over one billion dollars annually on nonprescription treatments for coughs and colds, including antipyretics, antihistamines, cough preparations, and decongestants in various combinations. Although these agents may help the symptoms of colds and flu to subside gradually, they do not address the underlying condition, including immune and nutrition status. Also, many of the agents used conventionally for colds and flu may cause unwanted side effects such as insomnia, hyper-excitability, dry mouth, constipation, drowsiness, or interact with prescription medications. As an alternative to standard over-the-counter cold remedies, different preparations of the herb echinacea are well marketed.
Zinc is necessary for the functioning of over 300 different enzymes and, as such, it plays a vital role in an enormous number of biological processes. Zinc is widely distributed in microorganisms, plants, and animals. In humans, the highest concentrations of zinc are found in the liver, pancreas, kidneys, bone, and muscles. Zinc is highly concentrated in parts of the eye, prostate gland, sperm, skin, hair, and nails. Zinc helps regulate a wide variety of immune system functions and it may stimulate anti-viral activity. Because of these benefits, it has been studied for use as a treatment for the common cold. The best dietary sources of zinc are lean meats, liver, eggs, and seafood (especially oysters). Whole grain breads and cereals are also good sources of zinc.
Researchers published a review in the Cochrane Library assessing the effect of zinc on common cold symptoms. The review consisted of 15 randomized, double-blind, placebo-controlled trials involving over 1,360 people. The selection criteria was using zinc for at least five consecutive days to treat, or at least five months to prevent the common cold. The results were people who took zinc – as syrup, lozenges or tablets within 24 hours of symptom onset – experienced reduction in severity and length of the illness. One week after the onset of the cold, more people who took zinc reported their cold was resolved in comparison to those who did not take zinc. They also found that children who took zinc syrup or lozenges for five months or more experienced fewer colds, fewer missed school days and needed fewer antibiotics. Overall adverse events, bad taste and nausea were higher in the zinc group. The authors concluded zinc as a potential remedy in reducing occurrence, severity and duration of the common cold but because zinc may produce side effects it is difficult to recommend dose, formulation and duration of treatment.1