Pomelo Peel Fiber Regulates Lipids and Obesity in High Fat Diet-Fed Mice by Regulating the Intestinal Microflora

This study intended to investigate the efficacy of dietary fiber in preventing obesity and regulating the intestinal microflora. C57BL/6 mice were fed D12492 high-fat diet supplemented with pomelo peel, insoluble dietary fiber (IDF) from pomelo peel or soluble dietary fiber (SDF) from pomelo peel. Those fed a maintenance diet or the high-fat diet served as normal control and obesity control groups, respectively. The feeding period lasted for 67 days. The changes in food intake, body mass, blood biochemical indexes, visceral indexes and intestinal microflora of the mice were observed during the feeding period. The results showed that compared with the obesity control group, body mass, serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels, epididymal fat coefficient and Lee’s index decreased by 4.9%, 8.3%, 14.29%, 0.44% and 2.54% in the IDF group, decreased by 5.1%, 11.4%, 21.21%, 0.60% and 2.47% in the SDF group, but increased by 1.3%, 7.4%, 12.5%, 0.96% and 1.27% in the pomelo peel group, respectively. The concentration of HDL-C increased by 0.52%, 0.78% and 5.44% in the IDF, SDF and pomelo peel groups, respectively. Moreover, dietary fiber from pomelo peel increased the relative abundance of Bacteroidetes and Lachnospiraceae_NK4A136_group, and decreased the relative abundance of Firmicutes, Desulfobacterota and Deferribacterota. Therefore, both SDF and IDF from pomelo peel have a significant effect on preventing obesity and lowering blood lipids, probably not by inhibiting food intake but rather by increasing the relative abundance of Bacteroidetes and Lachnospiraceae_NK4A136_group, and decreasing the relative abundance of Desulfobacterota and Deferribacteres. The increase in the relative abundance of Firmicutes is not significantly correlated with body mass, but significantly positively correlated with HDL-C and negatively correlated with LDL-C, which is beneficial to lipid control. The increase in the relative abundance of Bacteroidetes is significantly negatively correlated with body mass, TC and HDL-C levels, and significantly positively correlated with LDL-C levels, which is conducive to body mass control, but not blood lipid control. Hence, the effects of Bacteroidetes and Firmicutes on body mass and blood lipids need to be further studied. Pomelo peel dietary fiber can increase body mass and LDL-C levels by increasing food intake, but also significantly increase HDL-C levels. Similarly, its benefits in controlling body mass and blood lipids need to be further confirmed.