Association of Selenium Levels with Neurodegenerative Disease: A Systemic Review and Meta-Analysis.

BACKGROUND: Neurodegenerative diseases (NDs) have posed significant challenges to public health, and it is crucial to understand their mechanisms in order to develop effective therapeutic strategies. Recent studies have highlighted the potential role of selenium in ND pathogenesis, as it plays a vital role in maintaining cellular homeostasis and preventing oxidative damage. However, a comprehensive analysis of the association between selenium and NDs is still lacking. METHOD: Five public databases, namely PubMed, Web of Science, EMBASE, Cochrane and Clinical Trials, were searched in our research. Random model effects were chosen, and Higgins inconsistency analyses (I2), Cochrane's Q test and Tau2 were calculated to evaluate the heterogeneity. RESULT: The association of selenium in ND patients with Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD) was studied. A statistically significant relationship was only found for AD patients (SMD = -0.41, 95% CI (-0.64, -0.17), p < 0.001), especially for erythrocytes. However, no significant relationship was observed in the analysis of the other four diseases. CONCLUSION: Generally, this meta-analysis indicated that AD patients are strongly associated with lower selenium concentrations compared with healthy people, which may provide a clinical reference in the future. However, more studies are urgently needed for further study and treatment of neurodegenerative diseases.

Selenium Status in Patients with Chronic Liver Disease: A Systematic Review and Meta-Analysis.

BACKGROUND: The potential role of selenium in preventing chronic liver diseases remains controversial. This meta-analysis aimed to summarize the available evidence from observational studies and intervention trials that had evaluated the associations between body selenium status and chronic liver diseases. METHODS: We comprehensively searched MEDLINE, Embase, Web of Science, and Cochrane Library from inception to April 2021. The study protocol was registered at PROSPERO (CRD42020210144). Relative risks (RR) for the highest versus the lowest level of selenium and standard mean differences (SMD) with 95% confidence intervals (CI) were pooled using random-effects models. Heterogeneity and publication bias were evaluated using the I2 statistic and Egger's regression test, respectively. RESULTS: There were 50 studies with 9875 cases and 12975 population controls in the final analysis. Patients with hepatitis (SMD = -1.78, 95% CI: -2.22 to -1.34), liver cirrhosis (SMD = -2.06, 95% CI: -2.48 to -1.63), and liver cancer (SMD = -2.71, 95% CI: -3.31 to -2.11) had significantly lower selenium levels than controls, whereas there was no significant difference in patients with fatty liver diseases (SMD = 1.06, 95% CI: -1.78 to 3.89). Moreover, the meta-analysis showed that a higher selenium level was significantly associated with a 41% decrease in the incidence of significant advanced chronic liver diseases (RR = 0.59, 95% CI: 0.49 to 0.72). CONCLUSION: Our meta-analysis suggested that both body selenium status and selenium intake were negatively associated with hepatitis, cirrhosis, and liver cancer. However, the associations for fatty liver diseases were conflicting and need to be established in prospective trials.