How fiber prevents diabetes and obesity

January 14, 2014, CNRS
Credit: CNRS

Scientists have known for the past twenty years that a fiber-rich diet protects the body against obesity and diabetes but the mechanisms involved have so far eluded them. A French-Swedish team including researchers from CNRS, Inserm and the Université Claude Bernard Lyon has succeeded in elucidating this mechanism, which involves the intestinal flora and the ability of the intestine to produce glucose between meals. These results, published in the journal Cell on 9 January 2014, also clarify the role of the intestine and its associated microorganisms in maintaining glycaemia. They will give rise to new dietary recommendations to prevent diabetes and
obesity.

Most sweet fruit and many vegetables such as salsify, cabbage or beans are rich in so-called fermentable fibers. Such fibers cannot be digested directly by the but are instead fermented by intestinal bacteria into short-chain fatty acids such as propionate and butyrate, which can in fact be assimilated by our bodies. The of these fibers is well known to researchers: Animals fed a fiber-rich diet become less fat and are less likely to develop diabetes than animals fed a fiber-free diet. Nevertheless, the mechanism behind this effect has until now remained a mystery.

The team headed by Gilles Mithieux, CNRS researcher in the "Nutrition et Cerveau" unit (Inserm / Université Claude Bernard Lyon 1), wondered whether this mechanism could be linked to the capacity of the intestine to produce glucose. The intestine is in fact capable of synthesizing this sugar and releasing it into the blood stream between meals and at night. However, glucose has particular properties: It is detected by the nerves in the walls of the portal vein (which collects the blood coming from the intestine), which in turn sends a nerve signal to the brain. In response, the brain triggers a range of protective effects against diabetes and obesity: the sensation of hunger fades, energy expenditure at rest is enhanced and, last but not least, the liver produces less glucose.

In order to make the connection between fermentable fibers and the production of glucose by the intestine, the researchers subjected rats and mice to diets enriched with fermentable fibers, or with propionate or butyrate. They then observed a strong induction of the expression of genes and enzymes responsible for the synthesis of glucose in the intestine. They showed that the intestine of these animals used propionate as precursor to increase the production of glucose. Mice fed a fat- and sugar-rich diet, but supplemented with fibers, became less fat than control mice and were also protected against the development of diabetes thanks to significantly increased sensitivity to insulin.

How fiber prevents diabetes and obesity

The researchers repeated the experiment with mice whose intestine's ability to produce glucose had been suppressed by genetic engineering. No protective effect was then observed: these mice became fat and developed diabetes like those fed a fiber-free diet. It is therefore the production of glucose by the intestine from propionate and butyrate that is behind the positive effects of fermentable fibers on the organism.

Apart from this previously unknown mechanism, this work sheds light on the role of the which, by fermenting dietary fiber, provides the intestine with precursors to produce glucose. It also demonstrates the importance of the intestine in the regulation of in the body. Finally, these findings should make it possible to propose nutritional guidelines and to highlight new therapeutic targets for preventing or treating and obesity.

Explore further: Researchers observe new mechanism for diabetes resolution

More information: "Microbiota-generated metabolites promote metabolic benefits via gut-brain neural circuits." Filipe De Vadder, Petia Kovatcheva-Datchary, Daisy Goncalves, Jennifer Vinera, Carine Zitoun, Adeline Duchampt, Fredrik Bäckhed, Gilles Mithieux. Cell 9 January 2014

Related Stories

Researchers observe new mechanism for diabetes resolution

July 25, 2013
Though existing research has shown gastric bypass surgery resolves type 2 diabetes, the reason has remained unclear. A research team, led by Nicholas Stylopoulos, MD, Boston Children's Hospital's Division of Endocrinology, ...

Intestinal barrier sleeve shows benefit in rat model of diabetes

October 21, 2013
(HealthDay)—Implantation of a duodenal-endoluminal sleeve (DES) correlates with reductions in body weight (BW) from loss of fat mass, and with improvements in glucose and lipid homeostasis in a rat model of diabetes, according ...

Gut taste mechanisms are abnormal in diabetes sufferers

August 23, 2013
(Medical Xpress)—Researchers at the University of Adelaide have discovered that the way the gut "tastes" sweet food may be defective in sufferers of type 2 diabetes, leading to problems with glucose uptake.

Friends in low places preserve gut health

January 10, 2014
The bacterial communities that live in our intestines should not be considered freeloaders—they contribute substantially to our well-being in a number of ways, including assisting in the breakdown of otherwise indigestible ...

Dietary fibres protect against asthma

January 6, 2014
The Western diet probably has more to do with the asthma epidemic than has been assumed so far because developing asthma is related to the amount of fruit and vegetables consumed. Gut bacteria ferment the dietary fibres contained ...

Recommended for you

Scientists grow human esophagus in lab

September 20, 2018
Scientists working to bioengineer the entire human gastrointestinal system in a laboratory now report using pluripotent stem cells to grow human esophageal organoids.

Study identifies stem cell that gives rise to new bone and cartilage in humans

September 20, 2018
A decade-long effort led by Stanford University School of Medicine scientists has been rewarded with the identification of the human skeletal stem cell.

Researchers identify human skeletal stem cells

September 20, 2018
Human skeletal stem cells that become bone, cartilage, or stroma cells have been isolated from fetal and adult bones. This is the first time that skeletal stem cells, which had been observed in rodent models, have been identified ...

A new app enables a smartphone to ID bacteria in just one hour

September 20, 2018
In a potential game changer for the health care industry, a new cell phone app and lab kit now allow a smartphone to identify bacteria from patients anywhere in the world. With the new app, doctors will be able to diagnose ...

Synthetic sandalwood found to prolong human hair growth

September 19, 2018
A team of researchers led by Ralf Paus of the University of Manchester has found that applying sandalwood to the scalp can prolong human hair growth. In their paper published in the journal Nature Communications, the group ...

Zombie cells found in brains of mice prior to cognitive loss

September 19, 2018
Zombie cells are the ones that can't die but are equally unable to perform the functions of a normal cell. These zombie, or senescent, cells are implicated in a number of age-related diseases. And with a new letter in Nature, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.