July 20, 2022
Faculty of Pharmacy, Keio University
A research group at Keio University has discovered that two different sugars utilized by gut bacteria act synergistically on specific gut microbes to suppress high-fat diet-induced obesity. This research is the work of a group led by Professor Yun-Gi Kim, primarily involving Sawako Tomioka (then a master's student at the Graduate School of Pharmaceutical Sciences, Keio University) and Natsumi Seki (then a Project Assistant Professor at the Faculty of Pharmacy, Keio University).
Indigestible and non-absorbable carbohydrates, such as dietary fiber, are not absorbed by the body and instead serve as nutrients for gut bacteria. For this reason, they are called Microbiota-Accessible Carbohydrates (MACs). MACs are known to improve the gut environment, contributing to health maintenance and disease prevention. Although there is a wide variety of MACs, the specific properties of each—that is, the different effects each MAC has on the gut environment and host physiological functions—have not been analyzed in detail.
L-arabinose is a monosaccharide found in the fiber of grains such as corn, rice, and wheat, and it is poorly absorbed in the small intestine. L-arabinose is also known to inhibit the activity of sucrase, an enzyme involved in the digestion of sucrose.
This study revealed that when L-arabinose and sucrose are consumed simultaneously, both function as MACs. They act synergistically on specific gut bacteria to boost the production of acetate and propionate—short-chain fatty acids known as beneficial gut microbial metabolites—thereby suppressing high-fat diet-induced obesity. Furthermore, it was newly discovered that L-arabinose and sucrose activate different metabolic pathways for acetate production by gut bacteria.
Sugar, which is primarily composed of sucrose, is widely used in cooking and other applications, but its excessive consumption increases the risk of obesity. This study suggests that consuming L-arabinose along with foods high in sucrose may not only suppress the digestion and absorption of sucrose but also improve the gut environment through the synergistic action of the two sugars, potentially suppressing obesity.
Consuming dietary fiber, a representative MAC, is one way to improve the gut environment, but the functional differences among various MACs have not been examined in detail. This study has shown that multiple MACs can exert cooperative and synergistic effects to improve the gut environment, and that each MAC affects gut bacteria (the environment) differently. These findings also suggest the possibility of building a personalized gut environment by consuming appropriate MACs.
The results of this research were published in the online edition of the international academic journal "Cell Reports" on July 19, 2022 (US Eastern Standard Time).
For the full press release, please see below.