Effect of Increasing Red Meat Intake on Iron Status in Adults with Normal and Suboptimal Iron Status: A Systematic Literature Review and Meta-Analysis of Intervention Studies.

Context: Iron deficiency is the most prevalent nutrient deficiency globally. There is increasing interest in the use of food-based approaches for improving and maintaining iron status.

Objective: A systematic literature review was conducted to identify, critically-appraise, and meta-analyze data from intervention studies that investigated the effect of increasing red meat intake on iron status in adults.

Data Extraction: The search was conducted using the PubMed, Web of Science, Scopus, Embase, Cochrane, SPORTDiscus, and Google Scholar databases, as well as other supplementary search strategies up to October 2024. Inclusion criteria for reviewed articles were participants who were adults aged 18 to 70 years, interventions that involved ≥4 weeks of increased red meat intake, included a suitable control condition, and measured at least 1 biomarker of iron status. The initial search yielded 5212 articles, with 10 articles (n = 397 participants) meeting the inclusion criteria.

Data Analysis: The effect of intervention on markers of iron status were analyzed using a meta-analytic multivariate model, and the potential moderating effect of multiple variables were considered. The final meta-analysis included 42 effects (k) for serum ferritin (k = 25) and hemoglobin (Hb; k = 17) concentrations. Interventions involving increasing red meat intake had no significant effect on serum ferritin concentrations (raw mean change difference [RMCD] = 1.87 μg L-1; 95% CI, -0.73 to 4.48; t = 1.619; P = .139) but did have a positive effect on Hb concentrations (RMCD = 2.36 g L-1; 95% CI, 0.71 to 4.02; t = 3.297; P = .011). Moderator analysis revealed a positive effect of increasing red meat intake on serum ferritin concentrations when the intervention lasted at least 8 weeks (RMCD = 2.27 μg L-1; 95% CI, 0.87 to 3.67), and longer than 16 weeks (RMCD = 5.62 μg L-1; 95% CI, 0.67 to 10.6).

Conclusions: Increasing red meat intake can improve iron status as indicated by increases in serum ferritin and Hb concentrations, but the extent to which such increases are clinically meaningful remains to be established.

Systematic Review Registration: PROSPERO registration No. CRD42023479349.