Key Source: FoundMyFitness 

Takeaways

• Zinc homeostasis is important for many facets of human health.
  • Immune function, protein synthesis, wound healing, DNA synthesis, and cell division.
• Most people get enough zinc.
  • If not: DNA damage, immune dysregulation, etc.
• Zinc supplementation can be effective way to boost immune system.
  • Fight illnesses such as the common cold, pneumonia, acne, and metabolic disorders.
• No good biomarkers for zinc status.
• Eat:
  • Animal products such as beef, poultry, and shellfish.

Key Observations

• Primary source:
  • Animal products such as beef, poultry, and shellfish.
  • US adults obtain about 12 mg of zinc per day.
• Requirement.
  • Varies according to age, sex, and life stage of healthy people.
  • Lowest need in infancy.
  • Steadily increases into adulthood.
  • Pregnancy and breastfeeding: role in growth, development, and immune response.
• Zinc deficiency.
  • Uncommon in developed nations.
  • Estimated 2 billion people worldwide have low intake.
  • Vegetarians and vegans may be at a higher risk of developing zinc deficiency (no meat).
  • Alcoholics are at risk (decreases absorption, increases excretion).
• Biomarkers.
  • Tough, concentration fluctuates as much as 20% over 24 hour period.
• Absorption.
  • Average absorbed amount about 20-30% of intake.
  • Body adjusts the percentage of zinc absorption to maintain its exact needs.
  • Absorbed in the jejunum, the second portion of the small intestine.
  • Bound to albumin, passed into general circulation.
  • Cannot enter cells without a transporter.
  • Uptake of zinc into cells requires an ionophore.
    • A molecule that can transport ions across a lipid membrane.
• Presence in the body.
  • About 2-3 grams.
  • Skeletal muscles (60%), bones (30%), rest spread throughout.
  • Inside the cell: 50% cytoplasm, 30-40% nucleus, 10% membrane.
• Bioavailability.
  • Affected by the co-ingestion of other dietary components.
  • Phytates and iron can inhibit zinc absorption.
    • Phytate: a natural substance primarily found in seeds, nuts, legumes, and grains.
    • Can reduce zinc absorption by half.
    • Fermentation can lower impact of phytates.
  • Protein can increase zinc absorption.
    • Absorption from animal proteins up to 46% greater than from a plant protein.
• DNA damage.
  • Zinc is a cofactor and component of proteins involved in gene regulation, DNA repair, signal transduction, and antioxidant defense.
  • p53, which guides DNA damage response mechanisms, requires zinc for proper function.
  • Zinc deficiency is thought to promote oxidative stress and DNA damage.
• Immune function.
  • T cells.
    • Zinc deficiency can cause T cell dysregulation and decrease total T cell numbers.
    • T cells are in part regulated by the zinc-dependent hormone thymulin.
  • Viruses.
    • Inhibitors of RNA viruses.
    • Requires zinc + ionophore.
  • Inflammation.
    • Prevents excess inflammatory signals mediated by the innate immune system.
• Age related immune dysregulation.
  • People older than 65 have an intake of zinc less than half the recommended amounts.
  • Factor in aged-associated inflammation and immune dysfunction.
• Pneumonia.
  • Pneumonia: inflammatory lung infection that impairs respiratory function.
  • Zinc may reduce duration and severity.
• Common cold.
  • Zinc lozenges may be beneficial in reducing the duration of the common cold.
• Brain.
  • Early on: required for function of enzymes and proteins necessary for neurogenesis.
  • Zinc also plays a role in regulating communication between neurons.
• Metabolic regulation.
  • Improve glucose regulation in people with diabetes.
  • May not be effective in healthy individuals without metabolic diseases.
  • Zinc plays a major role in insulin biosynthesis.
  • Effects on HDL and LDL vary.
• Safety.
  • Excess dosage associated with both acute and chronic toxicity.
• Supplements.
  • Zinc gluconate and zinc sulfate appear to be absorbed better than zinc oxide.
  • Most effective when taken without food (due to impact of phytates).