Zinc is an essential trace element for humans, animals and plants. It is vital for many biological functions and plays a crucial role in more than 300 enzymes in the human body. The adult body contains about 2-3 grams of zinc. Zinc is found in all parts of the body: it is in organs, tissues, bones, fluids and cells. Muscles and bones contain most of the body’s zinc (90%). Particularly high concentrations of zinc are in the prostate gland and semen. Among all the vitamins and minerals, zinc shows the strongest effect on our all-important immune system. Zinc plays a unique role in the T-cells. Low zinc levels lead to reduced and weakened T-cells which are not able to recognize and fight off certain infections. An increase of the zinc level has proven effective in fighting pneumonia and diarrhea and other infections. Zinc can also reduce the duration and severity of a common cold.