Role of Zinc in Human Metabolic Processes

Reference from the joint report of FAO/WHO expert consultation on Human Vitamin and Minerals verbatim. 

Zinc is present in all body tissues and fluids. The total body zinc content has been estimated to be 30 mmol (2 g). Skeletal muscle accounts for approximately 60 percent of the total body content and bone mass, with a zinc concentration of 1.5–3 μmol/g (100-200 μg/g), for approximately 30 percent.

1. Hambidge, K.M. 1987. Zinc. In: Trace elements in human and animal nutrition. Mertz, W., ed. 5th, Vol. 1., p.1-137. Orlando, Florida, Academic Press, Inc. 

Zinc concentration of lean body mass is approximately 0.46 μmol/g (30 μg/g). Plasma zinc has a rapid turnover rate and it represents only about 0.l percent of total body zinc content. This level appears to be under close homeostatic control. High concentrations of zinc are found in the choroid of the eye 4.2 μmol/g (274 μg/g) and in prostatic fluids 4.6-7.7 mmol/l (300-500 mg/l) (1).

Zinc is an essential component of a large number (>300) of enzymes participating in the synthesis and degradation of carbohydrates, lipids, proteins, and nucleic acids as well as in the metabolism of other micronutrients. Zinc stabilises the molecular structure of cellular components and membranes and contributes in this way to the maintenance of cell and organ integrity.

2. Shankar, A.H. & Prasad A.S. 1998. Zinc and immune function: the biological basis of

altered resistance to infection. Am. J. Clin. Nutr., 68(suppl.): 447S-463S

Furthermore, zinc has an essential role in polynucleotide transcription and thus in the process of genetic expression. Its involvement in such fundamental activities probably accounts for the essentiality of zinc for all life forms. Zinc plays a central role in the immune system, affecting a number of aspects of cellular and Humoral immunity (2). The role of zinc in immunity was reviewed extensively by Shanglar et al.

1. Hambidge, K.M. 1987. Zinc. In: Trace elements in human and animal nutrition. Mertz, W., ed. 5th, Vol. 1., p.1-137. Orlando, Florida, Academic Press, Inc.

The clinical features of severe zinc deficiency in humans are growth retardation, delayed sexual and bone maturation, skin lesions, diarrhoea, alopecia, impaired appetite, increased susceptibility to infections mediated via defects in the immune system, and the appearance of behavioural changes (1). 

The effects of marginal or mild zinc deficiency are less clear. A reduced growth rate and impairments of immune defence are so far the only clearly demonstrated signs of mild zinc deficiency in humans. Other effects, such as impaired taste and wound healing, which have been claimed to result from a low zinc intake, are less consistently observed.