Trace element dynamics and male fertility: A narrative review on lead, iron, and zinc

Background: Male infertility is an increasing global health concern, with growing evidence highlighting the role of essential trace elements and toxic metals in male reproductive physiology. Zinc and iron are critical for spermatogenesis, redox homeostasis, and endocrine regulation, whereas lead is a persistent environmental contaminant with well-established reproductive toxicity. Escalating industrialization, environmental pollution, and occupational exposures have intensified human contact with these metals, underscoring the need for a transparent and integrative evaluation of their biological and clinical relevance to male fertility. Objective: This narrative review aims to synthesize and critically evaluate current evidence on the effects of lead (Pb), iron (Fe), and zinc (Zn) on male reproductive health, with emphasis on trace element homeostasis, exposure-related reproductive outcomes, and underlying molecular mechanisms. Materials and methods: A structured narrative literature review was conducted using PubMed, Scopus, and Web of Science to identify studies published between January 2000 and December 2025. Titles and abstracts were screened for relevance to trace elements, metal exposure, and male reproductive outcomes. Duplicate records and overlapping datasets were excluded. Full-text articles were assessed based on exposure characterization, methodological rigor, and relevance of fertility-related endpoints. Human clinical and epidemiological studies were prioritized, while animal and in vitro studies were included selectively to support mechanistic interpretation. Results: Human studies consistently associate lead exposure with impaired sperm motility, abnormal morphology, increased DNA fragmentation, and endocrine disruption. Iron demonstrates a concentration-dependent role, supporting mitochondrial function and spermatogenesis at physiological levels, but promoting oxidative stress and hormonal imbalance when dysregulated or excessive. Zinc plays a central role in sperm chromatin stabilization, testosterone biosynthesis, and sperm maturation, with deficiency strongly linked to reduced semen quality and reproductive potential. Conclusion: This review highlights the importance of maintaining trace element balance for male reproductive health. Integration of clinically relevant evidence with mechanistic insights indicates that both toxic metal exposure and imbalance of essential trace elements contribute significantly to male infertility. Clinical and nutritional significance: Optimizing zinc and iron status while minimizing lead exposure may offer practical strategies for improving sperm quality, hormonal regulation, and overall male fertility potential.