Thought for Food Blog

Zinc and the Human Body

Zinc is an essential trace element for all forms of life, in fact in their article ‘Zinc Deficiency: A Special Challenge’, published in The Journal of Nutrition, K. Michael Hambidge and Nancy F. Krebs argue it is of ‘exceptional biologic and public health importance.’

Zinc deficiency affects about two billion people in the developing world and is associated with many diseases. In children it causes growth retardation, delayed sexual maturation, infection susceptibility and diarrhea, contributing to the death of about 800,000 children worldwide per year.

Zinc and Minerals | IFIS Publishing

Nearly 300 different metalloenzymes depend on zinc for their ability to catalyse vital chemical reactions. Among the classes of enzymes with zinc metalloenzymes are oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases.

Enzymes with a zinc atom in the reactive center, such as alcohol dehydrogenase in humans, are widespread in nature. Consumption of excess zinc can cause ataxia, lethargy and copper deficiency.

The vast majority of zinc is absorbed by the small intestine though a transcellular process with the jejunum being the site with the greatest transport rate, i.e. the active transport of nutrients across epithelial cells.

Zinc plays an important role in the structure of proteins and cell membranes because of its ability to stabilize thiol groups and phospholipids and to quench free radicals. Zinc influences all immune cell subsets. However, it is particularly important in the maturation and function of T cells, or T lymphocytes, because it is an essential cofactor for the thymus hormone, thymulin.

Zinc finger proteins – small protein structural motifs that can coordinate one or more zinc ions to help stabilise their folds – have been found to regulate gene expression by acting as transaction factors.

Zinc also contributes to cell signalling and has been found to influence the release of hormones and nerve impulse transmission.

In their article, Antioxidant-Like Properties of Zinc in Activated Endothelial Cells, Bernhard Hennig et al argue that:

zinc can act as an endogenous protective factor against atherosclerosis by inhibiting the oxidation of LDL by cells or transition metals'

Although not yet tested as a therapy in humans, an article ‘Direct intra-tumoral injection of zinc-acetate halts tumor growth in a xenograft model of prostate cancer’ published in the Journal of Experimental & Clinical Cancer Research by Maulik R Shah et al, indicates that zinc may preferentially kill prostate cancer cells. Due to the fact that zinc navigates its way naturally to the prostate and because the prostate is accessible with relatively non-invasive procedures, its potential as a chemotherapeutic agent in this type of cancer has shown promise.

However, in their article, published in the Journal of the National Cancer Institute, Michael F. Leitzmann et al have demonstrated that prolonged use of zinc supplements in excess of the recommended dosage may actually increase the chance of developing prostate cancer, also likely due to the natural build-up of this heavy metal in the prostate.

Zinc is an essential component of a healthy diet. However, excess dietary zinc might lead to potential increased health risks. A balanced diet in relation to zinc-content – the Recommended Dietary Allowance (RDA) for a 32 year old male is 11mg and 8mg for a 32 year old female – is therefore likely to represent the best approach for a healthy lifestyle in the developed and developing world.

(Image Credit: Dominic Morel at www.freeimages.com)



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