Inulin is a non-digestible carbohydrate found naturally in many plant, fruit and grain foods, and is also widely used as an ingredient in functional foods. Some of these natural sources include artichokes, asparagus, onions and leeks, bananas, agave, yams, chicory root, or garlic, among others. The Microbiome, Nutrition and Health group of the Institute of Agrochemistry and Food Technology (IATA), a center of the Higher Council for Scientific Research (CSIC), has evaluated in mice how the interaction between the intestinal microbiota and inulin, a soluble dietary fiber, generates a compound that helps alleviate non-alcoholic steatohepatitis (NASH), a liver disease characterized by inflammation and fat accumulation (hepatic steatosis), frequently associated with obesity and type 2 diabetes, which in more advanced stages s can lead to liver cirrhosis.
Dietary fibers are complex carbohydrates that nourish our intestinal microbiota, and support the symbiotic relationship that exists with the human organism. These fibers cannot be completely broken down by the digestive enzymes present in the intestine, and it is the bacteria that live there that ferment the fibers. This interaction generates metabolites that help regulate intestinal transit and thus reduce the risk of metabolic diseases, such as diabetes or obesity.
The researchers Yolanda Sanz, Alejandra Flor and Marta Olivares have carried out an exhaustive review of bibliographic data where they have analyzed how inulin, a soluble fiber that is fermented by the intestinal microbiota, could help prevent the progression of non-alcoholic steatohepatitis (NASH). To do this, these scientists have evaluated the evidence of a study that compares the effect of a soluble fiber, inulin, and an insoluble fiber, cellulose, in mice with non-alcoholic steatohepatitis. The results, which have been published in Nature Microbiology, show that inulin is more effective than cellulose in reducing fat accumulation and fibrosis, as well as reducing inflammation and oxidative stress, characteristic symptoms of NASH.
Bacteria, metabolite minifactories
The metabolites produced from bacteria during the fermentation process have a wide range of effects and uses in nature. The studies reviewed by the authors add to the growing evidence supporting the role of metabolites produced by intestinal bacteria in improving diet-related diseases.
In this case, the fermentation of inulin by the intestinal bacterium Parabacteroides distasonis led to the production of pentadeconoic acid, which helped reduce hepatic steatosis and inflammation. This finding complements recent studies that show that this bacterium could contribute to the reduction of weight gain, hyperglycemia, and fat accumulation in obese mice.
Inulin is more effective than cellulose in attenuating fat accumulation and fibrosis, as well as reducing inflammation and oxidative stress, characteristic symptoms of NASH
“Treatments with inulin, P. distasonis or pentadeconoic acid, the result of the interaction between dietary fiber and the bacteria, protect mice against NASH. These treatments could restore the function of the intestinal barrier”, state the authors.
“In humans, however, these effects depend on more variables than those studied in mice, such as the ability of each individual’s microbiota to metabolize specific fibers or each person’s lifestyle,” they maintain. “Nevertheless, this study exemplifies the value of tracking nutrient flows between the microbiota and the human host organism to design diets that modulate the gut microbiota, enhancing the desired microbial functions and thus helping to mitigate metabolic diseases with increasing prevalence,” they highlight.
Source: CSIC
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