Zinc

Zinc is essential for DNA synthesis.

Zinc is an essential trace mineral and micronutrient that is found throughout the human body, mainly in the muscles and bone. 1 More than 100 enzymes require zinc in the metabolization of nutrients such as carbohydrates, fatty acids, proteins, and nucleic acids as well as neurotransmitters, 2 3 making zinc essential for DNA synthesis. 4 5 6

Zinc is necessary for normal growth and development during pregnancy, childhood, and adolescence. A dietary restriction in zinc during these periods increases risk of cardiovascular and renal disease in adult life. 7

Zinc is also involved in: 6

  • immunity
  • wound healing
  • sense of taste and smell
  • vision

Zinc is important for prostate gland health and is beneficial when used in the treatment of the following conditions:

  • inflammation 1 8 9
  • acne 1 10
  • atherosclerosis 7 8
  • ADHD 2 11 12
  • myopia (nearsightedness) 13

Zinc and Vitamin D

Vitamin D, specifically vitamin D’s active form (a potent steroid hormone known as calcitriol), exerts its effects on the body by binding to what is called a vitamin D receptor (VDR). Vitamin D receptors are located on the surface of living cells throughout the human body.

DNA interactions

Zinc has been found to modulate steroid hormone receptor-DNA interactions and one of the ways it does so is to bind to VDR, enabling its influence over the activity of vitamin D dependent genes in cells. 14

Calcium metabolism

Zinc is required at the binding site for proper protein expression of VDR. For example, transcription of the target gene calcium-binding protein (CaBP) - also known as Calbindin-D - can be altered if zinc is not present when vitamin D binds to its receptor, leading to improper absorption and utilization of calcium. 15

Immunity

Zinc and vitamin D appear to work together to contribute to proper immune system function. Two key components of immune system response to invading pathogens (bacteria, viruses, fungi) are white blood cells called T cells and neutrophils.

Recent evidence suggests T cells are both zinc and vitamin D dependent. 4 16 17 A deficiency in zinc can impair the generation and maturation of T cells. A deficiency in either vitamin D or zinc can impair T cell functions. 18

Zinc is also required for some of the functions of neutrophils. 4

Bone and muscle

Proper homeostasis between zinc, vitamin D, and other minerals such as calcium and magnesium is necessary to maintain bone and muscle health, 19 including muscle of the myocardium (cardiac muscle). 20 21

Zinc and vitamin D deficiency

Beta-Alanyl-L: -histidinato zinc (AHZ) and zinc acexamate have been shown to have a restorative effect on bone loss, even in states of vitamin D (and calcium) deficiency. 22

Supplementation and diet

Since the body is unable to store zinc, it must be received daily. 6 For best absorption when supplementing, it is best to take zinc in small amounts throughout the day.

The U.S. Food and Nutrition Board (FNB) has determined the following Adequate Intakes (AI) and Recommended Daily Allowances (RDA) for zinc: 6

  • Children under 6 months: 2 mg (AI)
  • Children 6 months-3 years: 3 mg
  • Children 4-8 years: 5 mg
  • Children 9-13 years: 8 mg
  • Adolescents 14-18 years: 9-11 mg
  • Adults: 8-11 mg
  • Pregnant or lactating females: 11-13 mcg

Supplemental forms

Zinc is available in several forms, with the most readily absorbed said to be zinc citrate, zinc acetate, and zinc picolinate. Zinc lozenges are usually in the form of zinc gluconate. Another form, zinc sulfate, is the most likely to cause stomach irritation and zinc oxide is poorly absorbed.

Food sources

Oysters have the highest zinc content of any food.

Zinc is present in several types of foods such as red meat, poultry, beans, and nuts.  Foods with the highest amount of zinc include:

  • oysters
  • beef shanks
  • Alaskan King Crab
  • pork shoulder
  • chicken leg
  • pork tenderloin

At 77 mg per serving, oysters have by far the highest zinc content of any food. 6

Whole grains and legumes contain zinc but they also contain phytates which can bind zinc, impairing absorption. 1 5 6 Zinc from meat products is more bioavailable. Vegetarians will generally require more supplemental zinc per day than non-vegetarians. 6

Zinc Deficiency

Deficiencies of zinc have been linked to numerous conditions, such as:

  • Low birth weight 23
  • Infectious diseases/decreased immunity 8
  • Hypogonadism in males 5 24 25 26
  • Lack of sexual development/delayed puberty 26
  • Growth retardation/dwarfism 26
  • Poor appetite 4 5 27
  • Mental lethargy 5
  • Various skin problems including delayed wound healing, 4 5 27 rough skin, 5 and acne 10

Elevated cholesterol is another condition related to zinc deficiency, with many people being inappropriately placed on cholesterol-lowering drugs while low zinc levels remain uncorrected.

Zinc deficits are known to affect hyaluronic acid levels. (Hyaluronic acid is a water-holding molecule that resides within connective tissue and is abundant in joints, skin, and makes up 80% of the human eye.) Abnormal levels of zinc have been found in those with:

  • cataracts
  • glaucoma
  • macular degeneration, myopia, or retinal detachment

Zinc deficiency is also a factor in the appearance of age-related diseases 8 9 and can cause copper to reach toxic levels in the body.

Zinc deficiency risk factors

Risk factors for zinc deficiency are:

  • Celiac disease 5
  • malabsorption syndrome 5 26
  • chronic renal disease 5 26
  • cirrhosis 5
  • sickle cell disease 5 26
  • malnutrition 26
  • alcoholism 26
  • extensive burns 26
  • infections 28
  • vegetarianism and veganism 8
  • use of diuretics 26
  • use of chelating agents 26

With advancing age and poor synthesis of hydrochloric acid, zinc absorption from foods and supplements is impaired, with very little zinc absorbed from the daily diet. 29

Zinc Toxicity

Risk of zinc toxicity is very low. Side effects such as nausea and vomiting have occurred, though these effects are fleeting and are dose dependent. 1

Chronic administration of high doses of zinc runs risk of abnormally low blood serum copper levels, called hypocupremia. 1

Contraindications

Zinc should not be used with the following medications without first consulting with one’s health care provider:

  • Amiloride (Midamor)
  • Prednisone
  • Cyclosporine
  • other mmunosuppressant medications

Zinc may decrease absorption of two kinds of antibiotics, quinolones and tetracyclines.

Page last edited: 16 August 2011

References

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