Zinc - Mineral

• Method of Action
• Deficiency Symptoms
• Recommended Dietary Allowances

• Properties and Uses
• Toxicity Levels
• Food Sources

Description

The zinc content of the adult human body ranges from 1.4 to 2.5 grams, with the highest concentrations in the bone, liver, kidney, pancreas and muscle tissue.

Zinc is a constituent of many enzymes and is essential for the proper function of these various enzymes. Zinc is essential for the metabolism and structural stability of nucleic acids.

Zinc has been associated with a variety of bodily functions such as the healing of wounds, reproduction, growth, and maintenance of glucose tolerance in the body. All of these functions have been shown to be impaired upon prolonged zinc deficiency.

Method of Action

Zinc is an important metallic constituent of the enzyme carboxypeptidase A, a pancreatic enzyme active in protein degradation. Zinc is found in highest concentration in the liver, with lesser amounts found in the pancreas, kidney, and pituitary gland. Zinc absorption occurs primarily in the small intestine. Zinc-binding ligand molecules act to transport zinc across the mucosal cells of the intestine, where it is picked up by albumin molecules for transport to the liver and other organs.

Zinc is a constituent of the enzyme carbonic anhydrase. This enzyme is, in turn, a constituent of red blood cells and gastric juices, and plays an important role in the deposition of calcium salts in teeth and bones.

The enzyme alcohol dehydrogenase contains zinc and is essential for the conversion of alcohol to an aldehyde, thereby facilitating alcohol metabolism in the liver. The function of this enzyme and its relationship to the development of liver cirrhosis is conspicuously tied to characteristic zinc deficiencies in alcoholic patients.

Zinc is found in other enzymes as well, including lactic dehydrogenase (active in glycolysis), alkaline phosphatase (active in maintaining phosphate levels near bone), and glutamic dehydrogenase (found in blood platelets).

Zinc is important as a structural constituent for RNA proteins and is essential for the proper activity of the RNA synthesizing enzyme RNA polymerase. Zinc also plays a role in metabolism and three dimensional structure of DNA.

Zinc is found in alpha-macroglobulin, an important protein in the body’s immune system. This globulin firmly binds about 30% of plasma albumin, which functions primarily as a transport protein.

Zinc appears to be a cofactor in the synthesis and degradation of collagen, and has effects in reproduction and healing.

Factors which can impair zinc absorption include calcium, fiber, copper, iron, and various diseases, such as Crohn’s disease.

SUMMARY OF METABOLIC FUNCTIONS

• Functions in more than 80 enzymes and hormones

• Essential in RNA and DNA synthesis

• Necessary for growth

• Necessary for release of vitamin A from the liver

Properties and Uses

Zinc supplementation has proven beneficial in the treatment, and sometimes the reversal of various zinc deficiency symptoms. Zinc supplementation has been useful in facilitating expediency in healing wounds and skin lesions suffered by some zinc deficient individuals.

Several other zinc deficiency symptoms, such as mild anemia, diarrhea, depression, and baldness, respond quite well to zinc supplementation.

Zinc supplements, in the form of zinc sulfate, are use to control the symptoms of the hereditary zinc deficient disorder acrodermatitis enteropathica, and are advised for individuals who suffer from chronic alcoholism to help prevent the zinc deficiency characteristic of this disorder.

In patients recovering from post-alcoholic cirrhosis, zinc supplements are an essential constituent of treatment to restore normal liver function.

Zinc is involved in the release of vitamin A from the liver, and in the absence of zinc vitamin A toxicity may occur at considerably lower levels.

In the treatment of the flu or the common cold, large doses of zinc with vitamin A (up to 150,000 I.U. of vitamin A and up to 225 mg of zinc) for a short period of time, (not more than three days) have proven effective. Though the taste may be objectionable, if this is taken sublingually (under the tongue), it is even more effective.

SUMMARY OF THERAPEUTIC FUNCTIONS

• Helps in treatment of rheumatoid and psoriatic arthritis

• Speeds up wound healing process

• Stimulates the immune system

• Reduces tumor growth and aids in cancer treatment

• Helps diabetes by promoting the formation of insulin

Toxicity Levels

Zinc can be toxic if taken in excess of two grams per day. Symptoms of this toxicity include gastrointestinal irritation and vomiting. High zinc consumption may promote copper deficiency due to the antagonistic relationship of these two minerals.

Zinc poisoning can also occur upon ingestion of food that has been stored in galvanized containers.

Recommended Dietary Allowances

RDA for adults 15 mg.

RDA for child/adolescent 10 mg.

RDA for infants 3 to 5 mg.

RDA for lactation 25 mg.

RDA for pregnancy 20 mg.

Food Sources

Summary of Deficiency Symptoms

• Food refining

• Low protein, high carbohydrate diets

• Surgical and physical injury, particularly burns

• Precipitation by phytic acid and phosphate

• Drug treatments such as corticosteroids or oral contraceptives

• Liver and kidney disease

• Diabetes

• Alcoholism

• High intake of cadmium; especially from cigarette smoking

• Pregnancy

• Smoking