Zinc in Nutritional Psychiatry: Associations With Depression, Anxiety, and Neurodevelopmental Disorders and Their Clinical Application

Abstract

Background: Zinc is an essential trace element involved in many enzymatic reactions and neurotransmissi on, and inadequate dietary intake affects a substantial share of the world population. Lower serum zinc has repeatedly been associated with depression severity, a modifiable but overlooked factor in psychiatry. Objective: This review integrates basic, observational, interventional, and meta-analytic evidence on zinc a nd psychiatric symptoms by certainty, clarifying mechanisms, the practical role including blood-test interp retation, and limitations.

Main Text: Zinc may influence mood through the N-methyl-D-aspartate (NMDA) receptor, the zinc-sensi ng receptor GPR39, brain-derived neurotrophic factor pathways, the hypothalamic-pituitary-adrenal axis, a nd inflammation and oxidative stress. Meta-analyses show lower serum zinc in depression, and adjunctive zinc reduces depressive symptoms, though effect sizes are small to moderate and heterogeneous; abnormal ities are also reported in anxiety, attention-deficit/hyperactivity disorder, and schizophrenia but remain inc onsistent. Zinc deficiency and copper excess may also contribute to aggression through distinct pathways, mainly in animal studies. Serum zinc needs careful interpretation: it is redistributed to the liver during infla mmation and varies with hypoalbuminemia, diurnal rhythm, and hemolysis, so it does not directly reflect b rain zinc. Ceruloplasmin, binding most serum copper, rises with inflammation and estrogen, and the coppe r-to-zinc ratio rises with inflammation and aging but is only correlational. Because high-dose zinc induces copper deficiency, zinc, copper, and their ratio should be read with background factors over time. As a pra ctical illustration, we present a woman in her twenties with hypozincemia managed by a morning-zinc, eve ning-iron protocol that separates iron and zinc absorption.

Conclusion: Correcting zinc deficiency and using zinc as an adjunct to standard psychiatric treatment may be reasonable in latent deficiency, treatment resistance, and older adults. Zinc does not replace standard tr eatment, and a biomarker abnormality does not alone indicate improvement. Current evidence does not sup port uniform recommendation; adjunctive use guided by nutritional assessment is warranted.