Zinc is an element that plays vital roles in a body. It is an essential cofactor for more than 3,000 protein reactions. Zinc has 18 EFSAapproved health claims; more than any other ingredient. Claims are related to metabolism, protein synthesis, cognition and vision. Zinc also contributes to the maintenance of normal bones, hair, nails, skin and the normal function of the immune system. However, there's huge differences between the bioavailability of zinc salts when seeking local effect in the throat. Zinc acetate has been found to be the most effective salt when used locally to kill bacteria and viruses in the mouth cavity, and to shorten the duration of the common cold.
Dr Harri Hemila, adjunct professor of Helsinki University, has published metaanalysis of seven randomised zinc studies where zinc acetate and zinc gluconate has been studied on the treatment of the common cold. In three studies, the used form of zinc was acetate and colds were about 40% shorter. In four studies, they used zinc gluconate and flus were shortened by 28%. On average, flus were 33% shorter.
In five studies, the dosages of zinc were 80-92mg a day, and in two of them dosages were 192mg and 207mg a day. There was no evidence that over 100mg dosages would be more efficient but the daily dosage should be at least 75mg zinc - 80-100mg a day being the reasonable dosage. People suffering from commoncold symptoms should start taking zinc acetate tablets as soon as the first symptoms - like congested nose, cough or sore throat - occur. Tablets should be sucked slowly so that they remain in the mouth for at least 20 minutes.
The effect of zinc acetate is based on its ability to rapidly dissolve to the so-called ionic, active form. If zinc is not released, the local effect is not achieved. The product should not contain ascorbic acid because it binds zinc and prevents its release from salt. Based on the evidence, zinc acetate is the best form in lozenges. Still, the mechanism of action is not fully assured, but zinc contributes to the normal function of the immune system, which defends body from viruses and bacteria. Zinc is needed for development, differentiation and activity of white blood cells.
One apple-flavoured Vitatabs zinc acetate lozenge contains 15mg of zinc. For a common cold, one should slowly suck six tablets a day - one tablet every two to three hours. A few days or one week's course is usually enough to relieve symptoms and shorten the duration of flu. The taste of free zinc is distinctive but inevitable in the sense of local action.
Although the recommended daily intake of zinc is 10mg a day and the upper tolerable level is 25mg a day, taking higher zinc amounts temporarily is generally considered safe. However, a high dosage may cause stomach upset and nausea. A special warning emphasising short-term use is written on the product's label. Children, pregnant women and elderly people should not exceed the daily recommendations without a doctor's advice.