Zinc

Tier 1 — strong evidence · Immunity · Cold duration

Essential trace mineral involved in 300+ enzymatic reactions, immune defense, wound healing, and testosterone synthesis. The 2024 Ali WHO-commissioned meta-analysis (38 RCTs, PMID 39641338) confirms zinc shortens acute diarrhea duration by 13.27 hours in children. The 2024 Cochrane review (34 studies, 8,526 participants, PMID 38719213) found zinc treatment may reduce cold duration by approximately 2.4 days, though evidence certainty is low-to-moderate and non-serious adverse events (nausea, taste disturbance) were more frequent. The 2025 Cheng NMA (192 trials, PMID 40314175) shows zinc…

Dose: General supplementation: 8–15 mg/day elemental zinc (near or at the RDA). Immune support/deficiency: 15–30 mg/day with food. Acute cold treatment: 75–92 mg/day as acetate or gluconate lozenges for up to 5 days only. Do not exceed 40 mg/day long-term.