Mediterranean Diet Reduces Inflammation in Adults: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Abstract

CONTEXT: Inflammation and oxidative stress play pivotal roles in the pathogenesis of chronic diseases, such as cardiovascular disease (CVD), diabetes, and neurodegenerative disorders. The Mediterranean diet (MD) has shown promise in mitigating these factors, but results across studies have been inconsistent. OBJECTIVE: Given the lack of clear evidence regarding the effects of an MD on inflammatory and oxidative stress biomarkers, we carried out a systematic review and meta-analysis to assess its true impact. DATA SOURCES: A systematic review and meta-analysis was conducted on randomized controlled trials (RCTs) to evaluate the effects of the MD on biomarkers of inflammation and oxidative stress, and a comprehensive search across PubMed, Web of Science, and Scopus, and a hand-search up to July 2024 was performed. DATA EXTRACTION: After removing duplicates and screening titles and abstracts, eligible records were retrieved. For unavailable full texts, authors were contacted, and unresponsive cases were excluded. Data extracted included author, year, country, group sizes, mean age, health conditions, intervention details and duration, outcomes, and statistical measures (means, SDs, and changes). DATA ANALYSIS: 33 RCTs involving 3476 participants were included. Significant reductions were observed for high-sensitivity C-reactive protein (hs-CRP), interleukin (IL)-6, and IL-17 in the MD group in comparison to a control diet. However, no significant effects were noted for CRP, IL-10, tumor necrosis factor-alpha, or total antioxidant capacity. Subgroup analyses revealed stronger effects for specific age groups and intervention durations. In participants aged <60 years, with intervention durations <12 weeks, and in individuals with CVD, IL-6 was reduced significantly following the MD regimen. CONCLUSION: The MD can significantly improve certain inflammation biomarkers, particularly hs-CRP, IL-6, and IL-17, supporting its potential role in reducing inflammation-related risks. However, further high-quality studies will be essential to confirm these findings. SYSTEMATIC REVIEW REGISTRATION: PROSPERO no. CRD42024613719.