Minerals - Zinc (Zn)

Question 1

Zinc (Zn)

Answer 1

• Zinc is the most abundant intracellular trace element (the body contains 2 g of Zn)
• Zn is a co-factor in over 200 metalloenzymes involved in catalytic, structural and regulatory functions; such as:
  o Superoxide dismutase (SOD) – antioxidant
  o Alcohol dehydrogenase – breakdown of alcohol (increased alcohol intake = increased zinc demand)
  o Carboxypeptidase – digestive proteins
  o Other enzymes involved in haem synthesis, folate absorption and DNA/RNA synthesis

Question 2

Food sources

Answer 2

• The highest food source of zinc is Oysters.With nuts, seeds, whole grains, meat and other shellfish also containing good amounts.
• Vegetables vary in Zn content depending on the soil quality
  Key food sources / per 100g:
  Nuts and seeds e.g. sesame, Brazil, pecans / 10.25 mg
  Grains e.g. rye flour, oats, amaranth, wheat / 5.62 mg
  Legumes e.g. adzuki, Chickpeas (garbanzo) / 1.77 mg
  Shellfish e.g. oysters, crabs, lobster, clams / 33.24 mg
  Meet e.g. calf’s liver, beef, lamb / 5.45 mg

Question 3

Functions: Reproduction

Answer 3

Functions: Reproduction
* Production of sex hormones (Increased zinc usage during adolescence)
* Required for spermatogenesis
* Inhibits 5a-reductase (e.g. inhibits the conversion of testosterone to the more potent androgen DHT)
Therapeutic uses:
* Infertility (Male and female)
* Erectile dysfunction
* Low testosterone

Question 4

Functions: Endocrine

Answer 4

Functions: Endocrine
* Needed for T4 to T3 conversion
Therapeutic uses:
* Thyroid Health

Question 5

Functions: Cell proliferation

Answer 5

Functions: Cell Proliferation
* Needed for cell proliferation (E.g. in the skin) and differentiation
* Required for DNA binding proteins involved in gene expression
* Aids tight junctions (i.e. in the skins/GIT)
Therapeutic uses:
* Wound healing
* Acne
* Cancer
* Cirrhosis
* Burns

Question 6

Functions: Sensory function

Answer 6

Functions: Sensory function
* Sense of taste and smell (taste buds contain Zn-containing enzymes)
* Support vision and hearing
Therapeutic uses:
* Poor taste/vision
* Olfactory issues
* Tinnitus

Question 7

Functions: Immunity and antioxidant

Answer 7

Functions: Immunity and antioxidant
* An important antioxidant
* Increases phagocyte, Natural killer cell, T- and B-cell activity
* Anti-inflammatory (decreases inflammatory cytokines e.g. interleukin-6/ TNF-a)
* Anti-viral activity: inhibits replication
Therapeutic uses:
* Frequent infections
* Inflammation
* Cardiovascular disease

Question 8

Functions: Digestion

Answer 8

Functions: Digestion
* Need it to the production of HCl
* Used to create a pancreatic enzymes
Therapeutic uses:
* Week digestion
* Hypochlorhydria (low stomach acid)

Question 9

Absorption

Answer 9

• Zn Absorption ranges from 20 - 40% depending on the bioavailability of the food source
• Protein generally enhances absorption (with the exception of casein protein (in dairy) which inhibits Zn) but phytates in plants form a complex with Zn and inhibit absorption:
  o Phytates are highest in whole grains, legumes, nuts and seeds (phytate level can be reduced by soaking, sprouting and fermenting)
• Excess Ca, Cu and non-haem Fe may also inhibit Zn absorption (e.g. simultaneous intake of milk or cheese can decrease Zn absorption)
• Note: Zn supplementation antagonizes Cu absorption

Question 10

Deficiency

Answer 10

• Deficiency is fairly common and can be caused by malabsorption, a diet high in phytates or low intake of Zn-rich foods
• Groups at an increased risk: older adults, alcoholics, pregnant women and athletes

Question 11

Signs and symptoms of deficiency

Answer 11

• Poor sense of taste and smell
• Recurrent infections, delayed wound healing
• Skin disorders (e.g. acne), dandruff, white spots on fingernails
• Infertility (male and female) and low libido
• Signs of weak digestion (e.g. bloating, fatigue)

Question 12

Supplementation

Answer 12

• When using Supplementation, the best absorbed form appears to be Zn picolinate but Zn citrate, Zn acetate and Zn glycinate are also well-absorbed
• Typical supplemental dosage is between 15 - 25 mg/day and it’s advised to take with food, as taken on an empty stomach can cause stomach upset

Question 13

Toxicity

Answer 13

• Long-term intakes in excess of the TUL (40 mg) may lead to Cu deficiency, and for this reason supplement manufacturers often include 1-2mg Cu

Question 14

Zinc functions

Answer 14

Reproduction
Endocrine
Cell proliferation
Sensory functions
Immunity and antioxidant
Digestion