Cardio-Metabolic Effects of Nickel: A Narrative Review

Nickel, a transition metal, is ubiquitous in the environment due to both natural processes and anthropogenic activities. While exposure to nickel has been linked to various adverse health outcomes-including genomic damage, allergic reactions, renal disorders, pulmonary fibrosis, carcinomas of the lung and nasal cavities-its cardiovascular toxicity and metabolic implications remain comparatively underexplored. Recently, a series of cross-sectional analyses utilizing data from the National Health and Nutrition Examination Survey (NHANES) have emerged, providing valuable insights into this issue. Based on the literature from PubMed, this review aims to comprehensively, but narratively summarize clinical observations and database analyses derived from human survey datasets, alongside experimental studies conducted on animal models exposed to varying doses of nickel. Current literature suggests a potential association between nickel exposure, primarily indicated by urinary nickel levels, and cardiovascular as well as metabolic disease variables; however, at low doses, inconclusive findings remain even using the same databases, mainly due to the clinical variables differently used in different studies. Experimental research has demonstrated significant toxic effects of exposure to nickel across multiple organs, including the heart and liver, which seemed significantly associated with oxidative stress and damage. Consequently, this review underscores the urgent need for further investigation utilizing both human data and experimental animal models, particularly focusing on low-level nickel exposure, to elucidate the cardiovascular and metabolic consequences of nickel exposure in humans.