Noster Microbiome research: Fibrous fuel: Prebiotic fibers can keep the body's metabolism in check to improve gut-environment and suppress obesity

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23 Mar, 2023, 07:26 GMT

KYOTO, Japan, March 23, 2023 /PRNewswire/ -- In a study recently published in the journal Gut Microbes, researchers from Kyoto University, Tokyo University of Agriculture and Technology, and Noster Inc. report the mechanisms of bacteria-derived fibers in supporting gut health and metabolism and preventing obesity.

An illustration of the beneficial effects of L. mesenteroides-derived EPS in the composition of the gut microbiome

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 favorable 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 fiber. EPS, which was produced in large quantities by L. mesenteroides was first isolated and its chemical structure was analyzed.

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 fiber (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 scrutinized. 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.

Background

Probiotics and prebiotics: Probiotics are a class of bacteria, yeast, and other microbes which are beneficial to the body. These microbes typically reside within tissues such as the gut, urinary tract, and lungs and play roles in digestion, synthesizing vitamins, and keeping harmful bacteria at bay. Given these important functions, probiotics can also be supplemented in the body through fermented foods such as yogurt, Japanese pickles and kimchi, which keeps the gut healthy.

Prebiotics are fibers derived from non-digestible plants such as asparagus. These are carbohydrates that pass along the gut without being digested by the human body but serve as nourishment for the probiotics to flourish. In this study, the researchers show that exopolysaccharide, a bacteria-derived prebiotic also has many health-related benefits. Such compounds can be used to create prebiotic supplements that can target specific disease conditions.

Reference

Junki Miyamoto, Hidenori Shimizu, Keiko Hisa, Chiaki Matsuzaki, Shinsuke Inuki, Yuna Ando, Akari Nishida, Ayano Izumi, Mayu Yamano, Chihiro Ushiroda, Junichiro Irie, Takane Katayama, Hiroaki Ohno, Hiroshi Itoh, Kenji Yamamoto, Ikuo Kimura. Host metabolic benefits of prebiotic exopolysaccharides produced by Leuconostoc mesenteroides. Gut Microbes, Jan 2023