Red meat intake and its influences on inflammation and immune function biomarkers in human adults: a systematic review and meta-analysis of randomized controlled trials and observational studies

Red meat intake (RMI) is implicated in promoting inflammation and compromising immune function. We conducted a systematic review and meta-analysis assessing how RMI influences inflammation and immune function biomarkers in adults with any health status. Twenty-two randomized controlled trials (RCTs; 1152 adults) and 10 observational studies (OBS; 438,925 adults) were included from literature published through May 2024 using PubMed, Scopus, CINAHL, and Cochrane databases. Sufficient data were obtained for meta-analyses of blood C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), leptin, and adiponectin. Overall, greater total RMI led to higher CRP across 18 RCTs (weighted mean difference 0.23, 95% CI 0.08–0.39). Subgroup analyses indicated similar findings for participants diagnosed with, but not without, cardiometabolic diseases; unspecified or mixed RMI, but not unprocessed RMI; studies without, but not with, energy restriction; and RMI ≥, but not Registry and registry number for systematic reviews or meta-analyses: PROSPERO CRD42021256264