The RDA (recommended daily amount) of Zinc for a typical adult is approx 10mg daily. It is present in most food but notable food with a high concentration of it include oysters, beef and sesame seeds.It is used by the body in cellular respiration and there are approx 100 enzymes in the body that require zinc1. It also has roles in the enzymes involved in the immune system, protein synthesis and wound healing.
It is taken into the body as the Zn2+ ion. The average human body will contain approx 2g of zinc and it is most concentrated in the brain, muscle, bones, liver and kidneys 2.
A defficiency of zinc in the diet can lead to supressed growth.
Sources / references:
1 http://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/ accesed on 26th May 2011
2 http://en.wikipedia.org/wiki/Zinc#Biological_role accessed on 26th May 2011