Does zinc aid in wound healing?

Zinc is a crucial micronutrient, present in small amounts in the human body, less than 50 mg/kg. It is vital for the body's health due to its critical roles in growth and development, bone metabolism, the central nervous system, immune function, and wound healing, which is the focus of this article.

Zinc is a vital cofactor for the function of over 10% of proteins encoded by the human genome, representing no less than 3,000 proteins and enzymes. Zinc-dependent proteins play numerous indispensable roles within cells, such as transcriptional regulation, DNA repair, cell death, metabolic processing, regulation of the extracellular matrix (ECM), and antioxidant defence.

It should be noted : this trace element cannot be stored by the body. Therefore, to reap its benefits, regular consumption of zinc-rich foods is essential. The food richest in zinc is the oyster, but there are others such as offal, red meat, wholemeal bread and eggs. The vast majority of zinc present in the human body is stored in skeletal muscles (60%), but reserves are also present in the bones (30%), skin (5%), liver and other organs (2 to 3%).

Zinc is particularly important for the skin. The skin contains a relatively high zinc content (approximately 5% of the body content), primarily associated within the epidermis (50-70 μg/g of dry weight). Due to its abundance in the epidermis, it is observed that a slight zinc deficiency results in rough skin and an alteration in wound healing.

Studies dating back to 1970 and earlier have demonstrated the significance of zinc concentrations in wound healing in patients suffering from thermal injuries or exposed to surgical stress.

From as early as the 1970s, the benefits of zinc supplementation have been reported in critically ill patients, severe burn victims, subcutaneous abscesses, minor surgery, and bedsores. Wound healing, inflammation, and immune response are intimately linked to each other. Over the years, it has been demonstrated that zinc is capable of modulating both innate and adaptive immune functions. Zinc alters immune responses in a multitude of ways, ranging from myeloid-derived cells and inflammatory signalling to lymphocyte differentiation and antibody production.

In this regard, certain wound care protocols recommend a daily supplementation of elemental zinc, such as zinc sulphate or zinc gluconate, to accelerate healing. The maximum tolerable intake, defined as the highest daily dose unlikely to have adverse effects on health, is 40 mg of zinc. Nausea, vomiting, diarrhoea, headaches, and cramps are some of the symptoms of zinc toxicity, beyond this 40 mg limit.