Zinc

Historically, zinc’s role in human nutrition became appreciated in the mid-20th century. Traditional nutrient wise: populations with low zinc diets historically had higher rates of growth retardation, immune dysfunction, skin and wound-healing problems (though much of this is modern nutritional epidemiology rather than “herbal tradition”). In more practical uses: zinc metal and alloys have been used for centuries (e.g., coinage, galvanising), but for nutritional/health uses the recognition is relatively recent.

• Element: Zinc (Zn) atomic number 30, typical oxidation state +2 (Zn²⁺) in biological systems.
• In the human body, zinc is bound to proteins, enzymes, transported by specific transporters (ZIP and ZnT families) rather than free.
• Storage/distribution: The adult human body contains about 2–3 g of zinc. It is a cofactor for many metalloenzymes, and structural element (e.g., zinc finger proteins) in gene regulation

• Cofactor role: Zinc is an essential constituent of numerous enzymes (hundreds to >300) involved in DNA/RNA synthesis, protein synthesis, cell division, metabolism of carbohydrate, lipid, protein.
• Structural/regulatory role: Zinc finger proteins, cellular signalling, gene expression regulation, immune cell differentiation and function.
• Immune modulation & antioxidant role: Zinc influences immune responses (innate & adaptive), inflammatory markers, antioxidant defences (e.g., part of superoxide dismutase enzyme systems) and supports mucosal barrier integrity.
• Metabolic/endocrine role: Zinc is required for insulin storage and function in pancreatic beta-cells, influences carbohydrate metabolism, lipid metabolism, reproductive hormone biology.
• Homeostasis and transport: Special transporter proteins (ZIPs, ZNTs) regulate zinc absorption, distribution, excretion. Zinc cannot be stored in large quantities, so dietary intake is required regularly.

1. Immune function / Inflammation:

• A meta-analysis of RCTs (35 trials, ~1,995 participants) found that zinc supplementation significantly reduced inflammatory biomarkers (CRP, hs-CRP) and increased CD4 levels. A recent review states zinc modulates immune cell signalling and barrier integrity.

2. Growth, Child health and Mortality:

• In children under five, zinc supplementation (≥10 mg/day) significantly reduced all-cause mortality by ~16% in one umbrella review of 43 articles. In meta-analysis of children under 5, zinc supplementation reduced all-cause mortality by ~16% (SRR 0.84) and more in certain subgroups.

3. Metabolic health glycaemic control, lipid profile:

• In people with type 2 diabetes, meta-analysis of 20 RCTs: zinc supplementation significantly reduced fasting blood glucose (WMD ~-19.66 mg/dL) and HbA1c (WMD −0.43) compared to control. Another meta-analysis found zinc supplementation decreased triglycerides, VLDL, total cholesterol, fasting glucose, HbA1c in 1,141 participants across 20 studies. PubMed

4. Mucosal and barrier health (gut, epithelium):

• Zinc plays a key role in intestinal mucosal repair, brush-border enzyme activity, absorption of water/electrolytes and supports defence against diarrhoeal disease.

5. Reproductive health:

• A review found zinc has important roles in human reproduction from spermatogenesis to egg development, embryo/fetal growth, and placental development.

6. Wound healing and skin health:

• Zinc contributes to collagen synthesis, tissue repair, and is structurally important in skin integrity. (See review: “Physiological and medicinal zinc”).

7. Cancer, aging, DNA repair:

• Research indicates zinc deficiency impairs DNA repair, influences carcinogenesis, and zinc involvement in over 3000 proteins underscores its broad role in cellular integrity.

8. Other uses

• The umbrella review also reported associations of higher dietary zinc intake with lower risk of digestive tract cancers, depression, type 2 diabetes. PubMed Summary: Zinc is multi-functional, with strong evidence especially in immune health, growth/child health, metabolic endpoints (glucose / lipids), barrier/mucosal integrity, and reproduction.

• According to StatPearls/NCBI: Zinc supplements above the UL (40 mg/day in adults) are contraindicated in well-nourished pregnant and lactating women unless supervised.
• Individuals with existing high zinc status may risk toxicity if supplemented inappropriately. Use caution in individuals with impaired renal/liver function, since trace element metabolism may be affected (although more specific data vary).
• For people on diets high in phytates (e.g., high cereal/legume diets) absorption may be poor; likewise malabsorption states may need different strategy.

• Mild side effects (especially with high doses) include gastrointestinal distress: nausea, vomiting, abdominal cramps, diarrhea.
• Long-term high intake of zinc can lead to copper deficiency, iron deficiency, or anemia. Loss of sense of smell has been reported with intranasal zinc formulations (though those are off-label/different context).
• High zinc intake (>UL) may impair immune function paradoxically.
• Beware of zinc toxicity: although zinc is relatively low-toxicity, very high doses (tens of grams) can be harmful.

• Copper: High zinc intake reduces copper absorption; thus zinc and copper supplementation often need balancing.
• Iron: High zinc may interfere with iron absorption; competition among minerals in the gut.
• Antibiotics: Zinc may interfere with absorption of certain antibiotics (e.g., tetracyclines, quinolones) when taken concomitantly; recommended to separate dosing by 2–3 hours.
• Non-steroidal anti-inflammatory drugs (NSAIDs): Some articles suggest zinc may interfere with NSAID absorption/effects (as referenced in a health-media article) but stronger clinical data may be limited.
• Herbs/adaptogens: No major well-documented interactions specific to adaptogens, but because zinc influences many enzyme systems, caution is warranted when combining high-dose zinc with herbs that affect mineral metabolism (e.g., licorice, ginseng, whole-food concentrate blends) until more data are available.
• Multivitamin/mineral formulations: Since many contain zinc + copper + iron, careful to avoid excess zinc or imbalance of minerals. Tip: Because zinc competes with other minerals for absorption, it's best taken with food, and complementary nutrients (like copper) may need monitoring if high-dose zinc supplementation is used.

• Zinc Intakes and Health Outcomes: https://pubmed.ncbi.nlm.nih.gov/35211497
• Meta-analysis of zinc supplementation in under-five children mortality: Effect of zinc supplementation on mortality in under 5-year children https://pubmed.ncbi.nlm.nih.gov/34120246
• The Efficacy of Zinc Supplementation Alone or in Combination for Improving Pregnancy: https://pubmed.ncbi.nlm.nih.gov/40836314
• **Effects of Zinc Supplementation on Cardiometabolic Risk Factors: https://pubmed.ncbi.nlm.nih.gov/31494808
• Meta-analysis on immune factors: https://pubmed.ncbi.nlm.nih.gov/33356467
• Review on zinc in human nutrition: https://pubmed.ncbi.nlm.nih.gov/34382897

While many benefits of zinc are supported by high-quality evidence (especially in deficiency states, child health, immune/metabolic outcomes), supplementation in well-nourished adults may have more modest effects and requires caution. The absorption and bioavailability of zinc depend on dietary factors (phytates, calcium, iron, protein) and form of zinc (sulfate, gluconate, picolinate, chelate) this means that even if intake is adequate, functional deficiency may occur if absorption is poor. Zinc has a narrow margins of safety with respect to other trace minerals (especially copper), so long-term high dose zinc supplementation should monitor mineral balance. The “optimal dose” for a given individual depends on age, sex, life-stage (pregnancy, lactation), baseline zinc status, diet, comorbidities and concurrent medications.