The role of obesity in altering the effects of short chain fatty acids (SCFA) on metabolic hormone regulation: A systematic review and meta-analysis

Abstract

Background

Current studies suggest that supplementing SCFA producers may have beneficial effects in preventing and treating obesity. Plasma SCFAs play a significant role in modulating metabolic hormones, thereby positively influencing metabolism. This review explores the connection between plasma SCFAs and metabolic hormones associated with obesity.

Methods

We collected data from PubMed, EBSCO, and EMBASE using MESH keywords [(short-chain fatty acids) AND (overweight OR obesity OR obese) AND (GLP-1) OR (glucagon-like peptide 1) OR (insulin) OR (ghrelin) OR (leptin) OR (PYY)]. Studies published between 2012 and 2024 were included, involving both genders, filtered for human studies, and published in English. Studies without full-text access were excluded. Risk of bias was assessed using the ROB-2 tool for clinical trials and the Joanna Briggs Institute (JBI) Critical Appraisal Tools for cohort and cross-sectional studies. This study was registered in PROSPERO with the number CRD42021284687.

Results

We identified 52 studies, comprising a total of 3,552 overweight or obese individuals, including adults (aged 18–78 years) and adolescents (aged 11–12 years), that met the inclusion criteria. These studies reported on circulating SCFAs, GLP-1, PYY, insulin, leptin, and ghrelin. We found no significant differences in acetate (-2.05 [-37.54, 33.44]), propionate (-0.17 [-3.28, 2.93]), butyrate (-0.23 [1.46, 1.00]), GLP-1 (-0.36 [-1.36, 0.64]), or insulin (1.71 [-9.65, 13.06]) between the placebo and intervention groups in the clinical trials. However, PYY levels showed a significant difference (-0.91 [-1.64, -0.71]) in the placebo compared to the intervention group. Methodological variations prevented us from assessing leptin and ghrelin levels, as well as analyzing observational studies related to SCFAs and metabolic hormones. The impact of dietary fiber, SCFA infusion, prebiotic supplementation, and dietary modifications varied concerning GLP-1, PYY, and insulin. We hypothesize that the characteristics of the intervention and participant variability regarding obesity and its comorbidities influenced the study outcomes.

Conclusion

The dietary intervention had no effect on plasma SCFAs and metabolic hormones, considering obesity-related conditions. We recommend that future research investigate mediating variables when exploring the association between plasma SCFAs and metabolic hormones in obesity.