In a study published in the journal Gut Microbes, researchers from Kyoto University, Tokyo University of Agriculture and Technology, and Noster have reported the mechanisms of bacteria-derived fibres in supporting gut health and metabolism and preventing obesity.
Probiotic foods such as miso and kimchi are rich in bacteria that keep the gut and body healthy. A complementary food group known as prebiotics (mainly fibrous foods) serve as fuel for these bacteria to thrive. However, the exact mechanisms which make prebiotics favourable for our health is unclear. A research collaboration between Ikuo Kimura (Kyoto University), Miyamoto Junki (Tokyo University of Agriculture and Technology), Hidenori Shimizu (Noster Inc), and colleagues has recently elucidated how prebiotics derived from a specific type of bacteria can do so.
Lactic acid bacteria, such as Leuconostoc mesenteroides (L. mesenteroides), are used in the fermentation process of fermented foods such as kimchi, sauerkraut, and pickles. One of the fibrous metabolites of L. mesenteroides is exopolysaccharide (LmEPS). The researchers thus focused their study on the potential role of LmEPS as a prebiotic fibre. EPS, which was produced in large quantities by L. mesenteroides was first isolated and its chemical structure was analysed.
A combination of probiotic and prebiotic foods could be the best way to promote well-being
Now, short-chain fatty acids (SCFAs), another metabolic byproduct of gut-bacteria, are known to have favorable effects such as the synthesis of gut hormones. Therefore, after feeding mice an LmEPS-rich diet, corresponding changes in levels of SCFAs in the blood and intestines were first evaluated. These mice did indeed have high SCFA levels, suggesting that EPS promoted the synthesis of SCFAs in their gut bacteria. The team then found that the increased levels of SCFAs led to reduced spikes in blood glucose levels in these mice. These changes, however, were minimal with L. mesenteroides administration alone, suggesting that LmEPS was the main facilitator.
To then investigate the effects of LmEPS on host energy homeostasis, 4-week-old mice were fed a high-fat diet (HFD) supplemented with either LmEPS or cellulose as a non-fermented fibre (control) for 12 weeks and changes in body weight were measured. At 12 weeks, LmEPS-fed mice had considerably lower body weight and fat mass than mice fed a control diet. Finally, alterations in the gut bacterial composition of LmEPS-fed mice were scrutinised. Using 16S rRNA amplicon sequencing, the team found that the abundance of Bacteroidetes and Verrucomicrobia, increased whereas Firmicutes decreased. In particular, Bacteroides and Bacteroidales S24-7 group efficiently produced SCFAs from LmEPS in the intestine.
This study reveals the physiological outcomes which make certain prebiotic foods beneficial. A combination of probiotic and prebiotic foods could also be the best way to promote well-being. ''Our findings reveal an important mechanism that accounts for the effects of diet, prebiotics, and probiotics on energy homeostasis,'' conclude the researchers. What's more, LmEPS can be explored further as a preventative strategy against lifestyle-related diseases such as diabetes or obesity.
