Zinc

Zinc is an essential trace mineral serving as cofactor for more than 300 enzymes and structural component of over 2,000 proteins. It is central to immune function, wound healing, dopamine synthesis, neurotransmitter regulation, and male reproductive function. Serum zinc is an imperfect status marker because circulating levels fluctuate with acute phase response and recent intake; red blood cell zinc or response to a supplementation trial often provides better clinical information.

Clinical evidence supports zinc supplementation in several indications. For ADHD, meta-analysis of 6 RCTs (Talebi et al., 2022) with 489 children shows zinc supplementation reduces ADHD total scores (SMD −0.62, P = .04). Zinc functions as a dopamine transporter (DAT) modulator, which may underlie this effect. In depression, zinc augmentation has shown benefit in partial responders to SSRIs. For immune support, 75mg zinc acetate lozenges within 24 hours of cold onset reduces symptom duration by approximately 33%.

Supplementation at 15-30mg elemental daily is well-tolerated in most adults and appropriate for deficiency repletion or therapeutic indications over 8-12 weeks. Preferred forms include zinc picolinate, bisglycinate, and gluconate, which are better absorbed than sulfate. Zinc competes with copper for intestinal absorption, so chronic dosing above 40mg daily can induce copper deficiency with hematologic and neurological consequences. Protocols exceeding 8 weeks at higher doses should include 1-2mg copper supplementation. Take zinc with food if gastrointestinal upset occurs, and separate from quinolone or tetracycline antibiotics by 2-4 hours.