ZINC (Zn)

General - trace mineral; immune stimulator mineral;

• Adult body contains about 2 or 3 grams of zinc;
• Dietary zinc - copper ratios need to be carefully balanced;
• Involved in many physiological processes;
• History: essentiality for rats established in 1934; in swine in 1955; Zn deficiency identified in humans in 1961; RDA set in 1974;

Nutrition

• Sources: best: oysters, herring, clams; good: pumpkin seeds, cheddar cheese, liver, meat; fair: wheat germ, whole grains, eggs, nuts, chicken, peas, carrots; poor: refined, processed foods;
• Supplements: zinc salts, acid salts, amino-acid chelates, multi-mineral, multi-mineral-vitamin formulations;
• Absorption from entire small intestine, duodenum, jejunum & illeum; taken to liver by portal vein, attached to albumin;
• Improved by: histidine, with which zinc complexes for absorption; glutathione; deficiency enhances uptake; human breast milk;
• Antagonized by: calcium & iron; copper competes with zinc for absorption; phytic acid in diets high in cereal grains may bind zinc & interfere with absorption; oxalate, coffee & tea inhibit absorption; tetracycline interferes with absorption;
• Storage: relatively high zinc concentrations found throughout the body; highest concentration found in eye and ear; about 20% of the body’s zinc is found in the skin; elevated concentrations of zinc in kidneys, liver; in males, high zinc concentrations in prostate gland & sperm;
• Excretion: largest amount through intestine & feces, but kidney, skin & sweat & semen also lose appreciable amounts of zinc; rapid turnover of zinc in cancer, healing of burns & growth spurts of infancy & adolescence;
• Metabolism: large amounts of zinc lost in sweat during exercise & by anxiety;
• Interactions: thiazide diuretics, EDTA, penicillamine & cortisone increase zinc excretion; high levels of zinc may interfere with selenium absorption; high zinc may decrease copper & iron in body;

Functions of zinc

• • Co-factor in over 80 zinc-containing metallo-enzyme reactions in all cells, tissues & organs; also
  has non-enzymatic roles;
  • Necessary for vitamin A metabolism & night vision;
  • Necessary for insulin’s ability to function;
  • Plays important role in stabilizing membranes;
  • Involved in growth, cell division & synthesis of nucleic acids & protein; required for manufacture
  of polysomes, on which proteins are synthesized; necessary for synthesis of intracellular
  microtubules, important for movement of phagocytic immune cells;
  • Necessary for synthesis of nucleic acids DNA & RNA (DNA & RNA polymerases); part of
  enzyme which breaks down RNA (RNAase);
  • Co-factor in alpha-macroglobulin, an immune system protein; required for thymus gland function;
  activates serum thymic factors; zinc also has direct anti-viral activity;
  • Necessary for essential fatty acid metabolism in the production of hormone-like prostaglandins,
  that regulate platelet stickiness, arterial muscle tone (blood pressure), tissue inflammation, sodium
  and water balance & immune function;
  • Necessary for the senses of taste & smell, the biochemistry of vision & normal function of nerves;
  • Necessary for brain development & for adult brain function; zinc-deficient brain cells shrink;
  • Necessary for skin, hair and fingernail protein (keratin & chitin) metabolism;
  • Involved in enzymes that synthesize & degrade collagen;
  • Necessary for development, maturation & maintenance of primary & secondary male sex organs,
  as well as sperm formation;
  • Involved in all reproductive processes in women, including ovulation, birthing & lactation;
  • Necessary for bone and joint metabolism;
  • Essential for wound healing;
  • Part of protein-digesting enzymes in pancreatic juice;
  • Helps remove CO2 from tissues & eliminate CO2 through lungs; helps maintain acid-base
  balance;
  • Necessary for removing ammonia (NH3) from body;
  • Required for production of HCl in stomach, essential for protein digestion;
  • Required for maintenance of the cardiovascular system;
  • Necessary for carbohydrate metabolism & alcohol detoxification in liver;
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Quantities

• Measurement: milligrams; inability to taste a solution of Zn SO4 indicates zinc deficiency;
• Optimum: (SONA) average ranges from 12 to 20 mg/day;
• Individual optimum needs to be determined for each individual case; requirement influenced by
type of diet, age, climate, activity level (sweating loses large amounts), trauma & illness;
• Minimum: (DRI) 8 mg/day for female; 11 mg/ day for male;
• Less than RDA: no official figures; estimates suggest 60% of population;
• Deficiency from soil deficiencies of zinc, widespread in North America; dietary intake of zinc
reflects soil zinc & is marginal in many people; imbalance in Zn/copper ratio; poor dietary
practices; use of refined & processed foods from which zinc has been removed; slimming diets;
excessive alcohol use; vegetarianism; exposure to toxic metals such as cadmium & inorganic
copper from water pipes; acute & chronic stress; injury;
• Decreased intake, decreased absorption, decreased utilization, increased loss & increased
requirement;
• Symptoms include: joint pain; stretch marks on skin of hips, thighs, abdomen, breasts & shoulder
girdle; infertility; impaired growth, sexual development & sexual function; loss of taste
(hypogeusia) & appetite (anorexia); slowed wound healing; birth defects; atherosclerotic plaque
formation; hypercholesterolemia; acne & other skin disorders; poor fingernail formation & white
spots on fingernails; proneness to infections; behavioural problems including hyperactivity,
schizophrenia & perceptual dysfunction; genetic zinc deficiency (inability to absorb) results in
acrodermatitis enteropathica: whole body rash, infections, diarrhoea, retardation; retarded growth;
can be fatal if untreated; cured by high doses of zinc;
• Impaired DNA synthesis; impaired RNA synthesis; impaired polysome production; impaired
protein synthesis, cell replication, night vision and retinal function; impaired phagocytic function,
cellular immunity, humoral immunity & immune cell intercommunication;
• Decreased albumin synthesis; impaired glucose metabolism; decreased insulin response;
disordered prostaglandin activity; decreased testosterone; lowered white cell, T-lymphocyte &
serum thymic factor activity; lowered resistance to infection & auto-immune disease; abnormal
retinal pigments; decreased collagen synthesis; decreased platelet aggregation;
• Toxicity: fever, nausea, vomiting from acute doses of 2,000 mg;
• Long-term intake of more than 180 mg/day impairs immune function & may result in copper
deficiency, anaemia & low levels of neutrophil white blood cells (neutropenia);
• Excess zinc may result in gastrointestinal irritation & adverse changes in HDL/LDL ratios;

Therapy with zinc

• Zinc is best known for its effectiveness in treating enlarged & inflamed prostate glands, common
in older men;
• Zinc is useful for treating pubertal acne & other skin conditions due to increased Zn requirement
for the production of sex hormones;
• Zinc can speed wound healing, surgical trauma & burns (along with vitamins C & E);
• Helps prevent development of stretch marks on breast and abdominal skin of pregnant & breastfeeding
women; supports normal development of the unborn child;
• Used to treat anorexia nervosa, part of which may involve loss of taste & smell, (foods taste like
sawdust);
• Useful for supplementing the diets of vegans, that tend to both be Zn-deficient & high in phytates
which may bind zinc;
• Helpful in treatment of macular degeneration, that results in blindness;
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• Helps prevent & heal conditions of recurrent infections & colds;
• Can help prevent alcohol-induced cirrhosis of the liver;
• Part of nutritional program used to prevent & treat cardiovascular disease;
• Part of nutritional treatment of Hodgkin’s disease, leukemia & cancer;
• Helpful in treatment of diabetes, pancreatic insufficiency of insulin production;
• Useful in reducing the swelling & pain of arthritis, especially rheumatoid;
• Useful to prevent absorption and help excretion of heavy metals lead, mercury & cadmium; useful
in cadmium-caused male infertility;
• High zinc levels may be useful in removing iron in iron toxicity;
• Part of balanced program of nutrition for health & life extension;
• Synergists: vitamins C & E for healing; vitamins A, C & E & essential fatty acids for acne & skin
conditions; complete & balanced nutritional program for all conditions;