Exploring the boundaries between epigenetics and religiosity/spirituality: a systematic review

BACKGROUND: Associations between religiosity/spirituality (R/S) and health are well documented, but underlying mechanisms remain poorly understood. This review examined epigenetic and related molecular pathways that may underlie these associations. METHODS: EMBASE, PubMed, Web of Science, and Scopus were searched through 8 January 2025. Eligible studies assessed at least one R/S variable, construct, or intervention and gene-expression-related outcomes, including DNA methylation (DNAm), histone modifications, microRNAs, noncoding RNAs, or protein-level changes. Results were narratively synthesized. Risk of bias was assessed using Joanna Briggs Institute tools. RESULTS: Thirty-six studies were included, totaling 43,671 participants. Nineteen were cross-sectional, 22 were conducted in the United States, 23 involved community populations, and 10 included clinical samples. Overall, 39 instruments or measurement approaches assessed R/S. Outcomes included inflammatory, stress-related, lipid-related, and gene-regulatory markers, including C-reactive protein (CRP), interleukin-6, cortisol, lipid profile, DNAm, and messenger RNA. Findings were heterogeneous, with consistent inverse associations for CRP and a tendency toward lower cortisol with higher R/S, while other outcomes were mixed. DISCUSSION: The evidence suggests a potential beneficial epigenetics influence of R/S. However, methodological weaknesses, heterogeneity, limited longitudinal evidence, and small samples limit interpretation. Future studies require prospective designs, standardized measures, large samples, and confounding control. PROTOCOL REGISTRATION: www.crd.york.ac.uk/prospero identifier is CRD42022327728.