zinc deficiency

Zinc and body Metabolism

Category : Mineral

Zinc was discovered to be essential for the growth of living organisms in 1869. The suspicion that zinc deficiency occurs in man is relatively recent. Since 1963, zinc has gained a greater recognition for its role in human health and has stimulated extensive research. Zinc is involved in numerous aspects of cellular metabolism. Zinc, supports your healthy immune system, is necessary to synthesize DNA/RNA, is essential for wound healing. Zinc is found in cells throughout the body. It is needed for the body’s defensive (immune) system to properly work. It plays a role in cell division, cell growth, wound healing, and the breakdown of carbohydrates. Zinc is also needed for the senses of smell and taste. During pregnancy, infancy, and childhood the body needs zinc to grow and develop properly. It also seems as if zinc helps to control the oil glands, and is also required for the synthesis of protein and collagen – which is great for wound healing and a healthy skin.

The effects of zinc are based on its involvement in more than 300 enzymatic reactions, in which it acts as a co-factor on the one hand and as an integral component on the other. When it is present in the active centre of enzymes, it increases their reactivity. Many electron-transferring enzymes make use of the ability of zinc to form various stages of oxidation. Zinc-dependent enzymes are the part of intermediate metabolism of carbohydrates, lipids, amino-acids and nucleic acids, as well as porphyrine biosynthesis. Some metabolic enzymes (e.g. carboxypeptidase A and B, aminopeptidase, alkaline phosphates) as well as dehydrogenase, which is required to break down alcohol, require zinc to function

As it forms part of enzyme catalysis, this trace element is also involved in the anti-oxidative mechanisms. In addition, zinc is involved in the regulation of the acid/alkaline balance. Synthesis of the retinol-binding protein (RBP) in the liver depends on zinc, as does the retinol dehydrogenase reaction in the visual cycle. The immunomodulatory effects of zinc deserve special mention. Ultimately, the synthesis of testosterone and thus the development and maturing of the male sex organs and spermatogenesis also take place with the involvement of zinc.

Distribution in human body
In an average human body, there is about 2 to 3 grams of zinc. Most of this is found in the muscle tissue and the bone. The highest concentration of zinc is found in the choroid of the eye and optic nerve, followed by the prostate, bone, liver and kidneys, muscles (zinc content varies with colour and function of muscles), heart, spleen, testes, brain, and adrenals. The skin also has a high concentration of zinc and can often be a sensitive indicator of zinc status. A zinc deficiency can adversely affect any of these organs.

zinc2Source of Zinc
Zinc is present in a variety of foods that many people consume daily. High-protein foods contain high amounts of zinc. Beef, pork, and lamb contain more zinc than fish. The dark meat of a chicken has more zinc than the light meat. Some other food sources that contain zinc are some seafood, whole grains, fortified cereals, beans, nuts and dairy products. Fruits and vegetables are not good sources, because the zinc in plant proteins is not as available for use by the body as the zinc from animal proteins. Therefore, low-protein diets and vegetarian diets tend to be low in zinc. The absorption of zinc tends to be higher in diets high in animal protein, as opposed to those rich in plant protein. An element present in whole grains, breads, cereals and legumes called phytate can also work to decrease zinc absorption.

Conditions Associated with Zinc Deficiency
Though the actual amount of zinc necessary to support the human body is quite small, its effects on the body are astronomical. Zinc deficiency is characterized by growth retardation, loss of appetite, and impaired immune function. In more severe cases, zinc deficiency causes hair loss, diarrhea, delayed sexual maturation, impotence, hypogonadism in males, and eye and skin lesions. Weight loss, delayed healing of wounds, taste abnormalities, and mental lethargy can also occur. Many of these symptoms are nonspecific and often associated with other health conditions; therefore, a medical examination is necessary to ascertain whether a zinc deficiency is present.

One of the most serious manifestations of zinc deficiency is seen in acrodermatitis enteropathica, a genetic disorder that occurs in children. Serum and hair zinc levels are both found low in children with this condition and who respond well to zinc supplementation. This condition is associated with an absolute zinc deficiency. Zinc deficiency has been found in patients with lupus erythematosus, scleroderma, psoriasis, skin blemishes and rashes, and slow wound healing.

Sickle Cell Anemia
Zinc deficiency is seen in people suffering from sickle cell anemia. It has been found that in sickle cell disease excessive calcium accumulates within the red blood cells contributing to their deformity. Zinc has proven beneficial due to its effect of decreasing calcium infiltration into the erythrocytes.

Zinc deficiency is seen in people suffering from sickle cell anemia. It has been found that in sickle cell disease excessive calcium accumulates within the red blood cells contributing to their deformity. Zinc has proven beneficial due to its effect of decreasing calcium infiltration into the erythrocytes.

Zinc has an antiviral effect, particularly on many forms of rhinoviruses. It has been found to affect poliovirus in high concentrations. The antiviral effects of zinc have been found to be even more effective when given in conjunction with vitamin A, and magnesium. Zinc deficiency is associated with a decrease in immune response and increased susceptibility to viral infections.

zinc2Virus Disturbance
Relative deficiencies of zinc can cause visual changes known as dyschromatopsia, a disturbance of the red/green color axis characterized by an inability to distinguish easily between certain shades of greens and blues. Dyschromatopsia is commonly seen in individuals with low tissue zinc to copper ratios.

Factory Contributing to Zinc
Drugs can produce a zinc deficiency by suppressing absorption, increasing excretion, or interfering with zinc synergists, such as vitamin B6 and magnesium. Etham-butal and isoniazid, antituberculer drugs, and di-iodohydroxyquin used for entamoeba histolytica, contribute to zinc deficiency. They particularly affect the eyes and can produce atrophy of the optic nerve, optic neuritis, and blindness. Nialamide and isocarboxazid are MAO inhibitors and are used as antidepressants. They are known to cause visual disturbances due to their antagonistic effect upon zinc metabolism. These drugs act by producing a sympathomimetic effect and therefore probably contribute to an absolute zinc deficiency. Antiinflammatories such as corticosteroids and diuretics such as thiazides are commonly used medications that can also adversely affect zinc status. Alcohol is known to produce a diuresis of zinc and increase iron absorption or retention. Diets high in phytates also decrease zinc absorption. Mineral 28

Table 1: Recommended Dietary Allowances (RDAs) for Zinc