Depression was linked to lower blood zinc and iron in observational studies
A review found differences in mineral levels between people with major depression and healthy controls; it did not test supplementation.
Based on the published abstract. The full paper may contain additional methods, results and limitations.
The 30-second takeaway
Across observational studies, people with major depression had lower blood levels of zinc and iron than healthy controls. Copper was higher in the initial analysis, but its overall evidence was inconclusive. These are differences in blood measurements, not evidence that taking supplements treats depression or that mineral levels caused the disorder.
The included studies were observational, and results varied between studies. The abstract cannot establish why blood levels differed or whether changing them improves symptoms.
What researchers found
Serum zinc: standardized mean difference
Major depression versus healthy controls; 95% CI -0.78 to -0.46. Timing of blood measurements was not reported in the abstract.
What the difference means
The reported zinc result is expressed on a standardized scale, rather than as a blood concentration. It describes a difference between groups and cannot, on its own, show whether an individual has a deficiency.
Why the minerals differ
The authors detected signs of publication bias for zinc and copper. After adjustment, zinc and iron remained statistically significant, whereas the conclusion treated copper as unresolved. This makes the minerals' evidence patterns different.
The original publication
Association between serum levels of essential elements (copper, zinc, and iron) and major depressive disorder: a systematic review and meta-analysis.
Davarinejad O, Nasseri Z, Mansouri B
Rev Environ Health · 2026
- PubMed ID
- 41263185
- Record checked
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