Dietary Medium-Chain Triacylglycerols versus Long-Chain Triacylglycerols for Body Composition in Adults: Systematic Review and Meta-analysis of Randomized Controlled Trials

Objective: To assess the effect of replacing dietary long-chain triacylglycerols (LCTs) with medium-chain triacylglycerols (MCTs) on body composition in adults. Methods: We conducted a meta-analysis of randomized controlled trials (RCTs), to determine whether individuals assigned to replace at least 5g of dietary LCTs with MCTs for a minimum of 4 weeks show positive modifications on body composition. We systematically searched, through July 2013, the CENTRAL, EMBASE, LILACS, and MEDLINE databases for RCTs that investigated the effects of MCT intake on body composition in adults. Two authors independently extracted data and assessed risk of bias. Weighted mean differences (WMDs) were calculated for net changes in the outcomes. We assessed heterogeneity by the Cochran Q test and I-2 statistic and publication bias with the Egger's test. Prespecified sensitivity analyses were performed. Results: In total, 11 trials were included, from which 5 presented low risk of bias. In the overall analysis, including all studies, individuals who replaced dietary LCT with MCT showed significantly reduced body weight (WMD, -0.69kg; 95% confidence interval [CI], -1.1 to -0.28; p = 0.001); body fat (-0.89kg; 95% CI, -1.27 to -0.51; p < 0.001), and WC (-1.78cm; 95% CI, -2.4 to -1.1; p < 0.001). The overall quality of the evidence was low to moderate. Trials with a crossover design were responsible for the heterogeneity. Conclusion: Despite statistically significant results, the recommendation to replace dietary LCTs with MCTs must be cautiously taken, because the available evidence is not of the highest quality.