Zinc is one of the essential components of the six enzyme classes present in the body. The mineral helps transmit messages from one cell to the other.
Its deficiency depresses growth, causes appetite loss, skin lesions, and diarrhea, impairs testicular development and reduces immune and cognitive functions. It can lead to dwarfism, delayed puberty, impaired wound healing, and increased susceptibility to infectious disease.
An adult human contains 2 to 3 grams of Zinc. Off this, 0.1% is said to be replenished daily. The replenishment rate determines dietary recommendations for healthy individuals. Its deficiency among people worldwide is estimated to be equal or more than 25%.
The deficiency can occur in people with diets low in bioavailability in food, like red meat and unrefined cereals rich in phytate and dietary fibers. Major manifestations of deficiency include stunted growth and development and an increased incidence of pregnancy complications (Gibson, 1994).
On the other hand, a high zinc intake is also known to lead to copper deficiency. The relationship between zinc and diabetes is suspected and is an area of research (Maret et al., 2006).
In US diets, more than half of it comes from animal food. Vegetarian diets contain legumes, whole grains, nuts, and seeds. While they contain adequate quantities, their bioavailability is restricted due to the phytic acid in these foods. High levels of calcium can also reduce the bioavailability of the mineral.
Zinc deficiency can occur in foods low in bioavailable zinc, like red meat and unrefined cereals rich in phytate and dietary fibers. Major manifestations of zinc deficiency include stunted growth and development and increased pregnancy complications (Gibson, 1994).
High levels of calcium can also reduce the bioavailability of Zinc. Zinc is a non-toxic element. Excessive supplementation can lead to copper deficiency (Sandstead, 1995). The best sources of Zinc are red meats, liver, shellfish, nuts, whole grains, and legumes.
There is strong evidence to support that Zinc, a key constituent of over 300 proteins, may be critical to defense against the initiation and progression of cancer (Ho, 2004).
Additional reading:
Nutrition Facts – a guide to good health