Zinc
Zinc is a trace mineral present 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—that are needed to metabolize these nutrients.
Zinc is not only essential for the metabolism of certain nutrients; it is also involved in the synthesis of proteins, DNA, and RNA, where the mineral acts as a cofactor. In addition, zinc is essential for the proper functioning of cellular immunity and is necessary for reproduction.
The mineral also influences the production of hormones, particularly testosterone, adrenal corticosteroids, and insulin. Zinc homeostasis—self-regulation—is regulated through absorption and excretion.
Studies have shown that zinc is present in the outermost layer of the skin of mammals. This demonstrates that the mineral plays a role in skin health and its homeostasis. Zinc is present in keratinocytes—cells found in the outermost layer, the epidermis, of the skin—and the mineral is involved in the growth of keratinocytes.
It is generally 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 needed for the taurine content of the retina; zinc helps maintain adequate taurine levels in the retina.
Although the individual role of zinc in reproduction has not been established, studies have shown that a combination of zinc, selenium, folic acid, vitamin E, and omega-3 increases sperm count in male animals. This demonstrates that the nutrients mentioned above play a role in reproduction. The importance of zinc in the reproduction of male animals is well established; its role in the reproduction of female animals is less well understood.
Depending on the need for zinc, the body adjusts its absorption efficiency. When there is an increased need for zinc, absorption efficiency increases; when there is a reduced need for zinc, absorption efficiency decreases.
Zinc is present in both animal and plant matter. Dogs and cats are better able to absorb zinc from animal matter than from plant matter. Absorption of the nutrient takes place mainly in the duodenum, the jejunum—the middle section of the small intestine—and the ileum—the final section of the small intestine.
Certain nutrients affect zinc absorption in the body. When there is an excess of the following nutrients, zinc absorption decreases: calcium, copper, iron, fiber, and the presence of phytate.
Certain dog breeds have a genetic abnormality affecting zinc absorption. These animals have an increased need for zinc.
The presence of specific amino acids, histidine and glutamate, increases zinc absorption.
