Probiotics and Their Functional Role in Mitigating Antinutrient Effects In Vivo—A Systematic Review and Meta‐Analysis

ABSTRACT Antinutrients like phytic acid and oxalates reduce mineral bioavailability by forming insoluble complexes with iron, zinc, and calcium. Probiotic supplementation may counteract these effects through enzymatic activity (e.g., phytase, oxalate decarboxylase) and microbiota modulation. This PRISMA‐based meta‐analysis evaluated 27 in vivo studies (chickens, mice, rats) published between 2005 and 2025. Controlled trials assessing probiotic effects on mineral absorption under antinutrient‐rich diets were analyzed using random effects models, expressed as standardized mean differences (SMD) with 95% confidence intervals (CI). Probiotic supplementation may enhance selected markers of mineral bioavailability across animal models (broiler, mouse, and rats), although the certainty of evidence was low and between‐study heterogeneity was substantial. In broiler chickens, probiotics increased hepatic iron (SMD = 2.05; CI: 0.91–3.20) and liver ferritin levels (SMD = 2.85; CI: 0.90–4.80). In rat models of hyperoxaluria, probiotics reduced renal calcium oxalate deposition (SMD = 0.77; p = 0.0001), though the impact on urinary oxalate levels was not significant (SMD = 0.20). In mouse models, the interventions demonstrated improved gut microbiota diversity without significant alterations in total body weight (SMD = 0.02). Based on low‐certainty evidence from heterogeneous animal studies, probiotic supplementation may improve selected mineral‐bioavailability outcomes and may reduce calcium oxalate deposition under antinutrient‐rich conditions. These findings should be interpreted cautiously. Further well‐designed, species‐specific studies using standardized interventions and outcome measures are needed before firm conclusions can be drawn.