Oral rehydration therapy is however not the solution for prevention of diarrhoea.ORS does not reduce the duration nor the risk of persistent diarrhea. Additional therapy is required. Zinc in child health
The importance of the role of zinc in human health has been known since long. Zinc is essential for more than 300 enzymes, structural proteins and hormones. It is needed for diverse physiological processes and metabolic functions including many aspects of the immune system. (1)

Lack of zinc is associated with atrophy of the thymus, a gland which has a role in the maturation of lymphocytes, and the function of "T" lymphocytes is especially vulnerable to deficiency of this mineral. Zinc deficiency is associated with a reduction in delayed type hypersensitivity, and other immune responses mediated by T cells.
In zinc deficiency there is an imbalance in the production of T helper cells with different functions; there is a shift from T cells (Th1) which have a predominately cellular function and are important in the defense against viral and intracellular pathogens in favour of T cells (Th2) which are involved in the production of antibodies. (2)
On the other hand in experimentally induced zinc deficiency in animals there is also a reduction in the production of antibodies and in the function of the natural killer cells. Further studies will elucidate the role of zinc in the immune system and increase our understanding of how and when this mineral can be best used to prevent and treat infection.
Zinc is also needed for cell replication and is thus essential for the regeneration of the intestinal mucosa, the healing of wounds and the turnover of epithelial cells necessary to maintain healthy skin. The combination of these essential functions explains why zinc plays such an important part in the protection against infections.