Zinc
Zinc is a trace mineral found in many body tissues of dogs and cats. The mineral is involved in the metabolism of carbohydrates, proteins, lipids, and nucleic acids; without zinc, the metabolism of these nutrients does not function optimally because zinc is a component of certain enzymes (more than 200 enzymes) needed for the metabolism of these nutrients.
Zinc is not only essential for the metabolism of certain nutrients, but it is also involved in the synthesis of proteins, DNA, and RNA; here the mineral acts as a cofactor. Furthermore, zinc is essential for proper cellular immunity and is necessary for reproduction.
The mineral also influences hormone production, particularly testosterone, adrenal corticosteroids, and insulin. The homeostasis – self-regulation – of zinc is regulated through absorption and excretion.
Studies have shown that zinc is present in the outer layer of the skin of mammals. This indicates that the mineral plays a role in skin health and its homeostasis. Zinc is present in keratinocytes – cells found in the outer layer, the epidermis, of the skin – and the mineral is involved in the growth of keratinocytes.
It is well known that vitamin A contributes to eye health, but zinc also plays a role in eye health; zinc is essential for the metabolism of retinal cells. Zinc is also necessary for the taurine content of the retina; zinc helps maintain the taurine level in the retina.
Although the role of zinc alone in reproduction has not been established, studies have shown that a complex of zinc, selenium, folic acid, vitamin E, and omega-3 increases sperm count in male animals. This indicates that these nutrients play a role in reproduction. The importance of zinc in male animal reproduction is well documented, while its role in female animal reproduction is less well known.
Depending on the need for zinc, the body adjusts absorption efficiency. If there is an increased need for zinc, absorption efficiency is increased; if there is a decreased need for zinc, absorption efficiency is reduced.
Zinc is present in both animal and plant materials. Dogs and cats are better able to absorb zinc from animal sources than from plant sources. Absorption of the nutrient mainly takes place in the duodenum, the jejunum – the middle part of the small intestine – and the ileum – the last part of the small intestine.
Certain nutrients affect zinc absorption in the body. When there is an excess of the following nutrients, zinc absorption is reduced: calcium, copper, iron, fibers, and the presence of phytate.
Certain dog breeds have a genetic defect in zinc absorption. These animals have an increased need for zinc.
The presence of specific amino acids, histidine and glutamate, increases zinc absorption.
