Abstract
Non-viable probiotics have been increasingly studied as a safer and more stable alternative to live probiotics to manage obesity and metabolic disorders. But efficacy across strains, doses, and treatment durations is still unknown. This systematic review and meta-analysis included 40 eligible controlled animal studies to quantify the effects of inactivated probiotics (by heat or sonication) on obesity-related outcomes in high-fat diet-induced obese rodent models. Our analysis showed a significant reduction in final body weight and total fat mass with supplementation of inactivated probiotics, whereas weight gain showed a favorable but non-significant decrease. Fasting blood glucose, fasting insulin and HOMA-IR were significantly improved as well indicating improved glycemic control. The results of the lipid profile showed a significant decrease in total cholesterol. Triglycerides and LDL cholesterol showed a favorable but not a significant decrease and HDL cholesterol was not significantly affected. Liver enzymes showed a significant reduction in ALT and a favorable, but not significant, reduction in AST. Subgroup analyses revealed treatment strain, duration, and dosage as moderators of specific outcomes. Treatment-specific effects differed across metabolic domains. Findings from these preclinical models support the potential of inactivated probiotics against obesity-related metabolic dysfunction; however, heterogeneity was observed for several outcomes. For each outcome, Egger's regression tests were applied separately to identify publication bias or other small-study effects specific to outcomes. Nevertheless, these preclinical data justify the translation of inactivated probiotics interventions into clinical research in obesity-related disorders.