Bamboo shoot fiber prevents obesity in mice by modulating the gut microbiota

Abstract

Dietary fiber has been shown to prevent high-fat diet induced obesity through modulating the gut microbiota; however, quality difference in fiber type is largely unknown. We performed a 6 week study on C57BL/6J mice fed a macronutrient matched high-fat diet with different fiber types including cellulose (HFC), bamboo shoot fiber (HFBS) and several other commonly consumed fibers. Our results showed that the HFBS group exhibited the lowest weight gain among all diet groups and had improved lipid profiles and glycemic control compared with the HFC group. As revealed by 16S rRNA gene sequencing, loss of diversity in the gut microbiota induced by the HFC diet was largely prevented by the HFBS diet. Moreover, compared with the HFC diet, the HFBS diet resulted in markedly increased relative abundance of Bacteroidetes and strong inhibition of Verrucomicrobia, two divisions strongly correlated with body weight. In conclusion, the present study provides evidence of a quality difference among different types of dietary fibers and shows that bamboo shoot fiber is the most effective in suppressing high-fat diet induced obesity. Our findings indicate that bamboo shoot fiber is a potential prebiotic fiber which modulates the gut microbiota and improves host metabolism.

Figure 1. Bamboo shoot fiber prevented body weight gain in C57 BL/6J mice fed a high-fat diet for 6 weeks.

Evolution of body weight gain of mice on (a) different dietary fibers, (b) or fiber mixes with different proportions of bamboo shoot fiber with inulin. (c) Relative body weight gain at week 6. Data are expressed as the percentage of body weight gain relative to the initial body weight (%). LF, low fat diet; High-fat diets with 10% fiber: cellulose (HFC), wheat fiber (HFW), soybean fiber (HFS), inulin (HFI), bamboo shoot fiber (HFBS), and mixed bamboo shoot fiber and inulin with ratios of 2:1 (HFBSI33), 3:1 (HFBSI25), and 9:1 (HFBSI10). Data are expressed as mean ± SEM of fifteen mice. **p < 0.01, ***p < 0.001, vs. mice fed LF diet. ^#p < 0.05, ^###p < 0.001, vs. mice fed HFC diet.

Figure 2. Bamboo shoot fiber reduced fat mass accumulation in high-fat diet fed mice.

(a) Representative photographs of mice. The weight of white adipose tissue (WAT): (b) subcutaneous, (c) parametrical, (d) perirenal, and (e) mesenteric. (f) Adipocyte morphology was assessed by H&E staining (200×). (g) Daily food intake. (h) Daily energy intake. (i) Food efficiency. LF, low fat diet; HFC, high-fat diet with cellulose; HFBS, high-fat diet with bamboo shoot fiber. Data are expressed as mean ± SEM (eight mice for each group). *p < 0.05, **p < 0.01, ***p < 0.001, vs. mice fed LF diet. ^##p < 0.01, ^###p < 0.001, vs. mice fed HFC diet.

Figure 3. Bamboo shoot fiber prevented hepatic lipid accumulation.

(a) Liver weight (% of body weight). (b) Lipid content in liver. (c) Hepatic TG. (d) Hepatic TC. (e) Expression of lipid metabolism related genes (PPARα, Mttp, Fabp1 and Scd1) in liver. Data are expressed as mean ± SEM (eight mice for each group). *p < 0.05, **p < 0.01, ***p < 0.001, vs. mice fed LF diet. ^#p < 0.05, ^##p < 0.01, ^###p < 0.001, vs. mice fed HFC diet. LF, low fat diet; HFC, high-fat diet with cellulose; HFBS, high-fat diet with bamboo shoot fiber.

Figure 4. Bamboo shoot fiber modulated the structure and diversity of the gut microbiota.

(a) Principal coordinate analysis (PCoA) and (b) Sample clustering results of the unweighted UniFrac distances of microbial 16S rRNA sequences from the V3-V4 region in cecal contents at week 6. (c) Alpha diversity analysis at the OTU level calculated on denoised sequences of mouse cecal microbiota. Six mice for each group. LF, low fat diet; HFC, high-fat diet with cellulose; HFBS, high-fat diet with bamboo shoot fiber.

Figure 5. Bamboo shoot fiber modulated the composition of the gut microbiota.

(a) Phylum-level, (b) family-level, and (c) genus-level taxonomic distributions of the microbial communities in cecal contents determined by next generation sequencing. Data are expressed as mean ± SEM (six mice for each group). LF, low fat diet; HFC, high-fat diet with cellulose; HFBS, high-fat diet with bamboo shoot fiber. *p < 0.05, **p < 0.01, ***p < 0.001, vs. mice fed LF diet. ^#p < 0.05, ^##p < 0.01, ^###p < 0.001, vs. mice fed HFC diet.