Effect of Dietary Fiber on Serum Leptin Level: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Abstract

Abstract Background Dietary fibers may induce satiety through affecting gastro-intestinal and peripheral appetite regulating hormones. Thus, we aimed to investigate the effect of dietary fiber consumption on serum leptin level compared to control diet, in short- and long- term trials, through a systematic review and meta-analysis. Methods We searched PubMed, web of science, Scopus, ProQuest, EMBASE, and Cochrane Library to find randomized controlled clinical trials that evaluated effect of any type of dietary fiber on serum leptin level compared to control diet, until April 2019. Both short-term (1–4 days) and long-term (longer than 2 weeks) studies were selected. Mean differences (MD) of changes in serum leptin level and 95% confidence intervals were extracted from eligible studies, and random effects model was used to analyze data. Results Thirteen studies included the systematic review and 11 entered in the meta-analysis. No significant change was seen in serum leptin level in short-term (MD=0.02, 95% CI; −0.15, 0.20, Tau2=0.0) and long-term studies (MD=−0.10, 95% CI; −0.28, 0.08, Tau2=0.0), followed by fiber consumption. However, this effect was statistically significant in obese participants (MD=−0.36, 95% CI; −0.71, −0.02, Tau2=0.0) in long-term studies. Moreover, we found no significant results in subgroups of baseline serum leptin level, intervention duration, fiber dose, and fiber type. Conclusions This meta-analysis found that taking dietary fiber for long term could lower serum leptin level, just in obese persons. However, further clinical trials are needed in this field to clarify this issue.