Previous research has concluded that a high fiber diet protects against obesity and diabetes. However, how a fiber-rich diet protects health was unknown until a recent study by researchers from France and Sweden as published in the journal Cell.
Researchers led by Giles Mithieux of the French National Centre for Scientific research (Centre National de la Recherche Scientifique – CNRS) explain that a high fiber diet rich in foods such as cabbage, beans, and most sweet fruit and vegetables contains fermentable fiber that the intestines cannot digest directly. Gut bacteria instead ferments the fiber into short-chain fatty acids such as butyrate and propionate. The body then absorbs the fatty acids.
In investigating the protective benefits of a high fiber diet against obesity and diabetes, the researchers studied the glucose-producing capabilities of the intestines.
The intestines synthesize glucose and release the substance into the blood stream between meals and at night. The body uses glucose as an energy source including as a primary source of energy for the brain. Glucose also contains certain elements that nerves in the vein that collects blood from the intestines, or the portal wall, detect.
After the glucose-detecting nerve sends a signal to the brain, the brain activates a series of defenses against diabetes and obesity including increased satiety, increased energy expenditure during periods of rest, and less glucose production from the liver.
To determine a connection between glucose production by the intestine and fermentable fibers, the researchers studied rats and mice who were fed either a control diet or a diet supplemented with the fermentable fibers propionate or butyrate.
The mice on the enriched diet, despite eating foods high in both fat and sugar, gained significantly less weight than the mice on the diet unenriched with fermentable fiber. The mice who ate a high fiber diet were also protected against diabetes as a result of increased sensitivity to insulin.
When the researchers then repeated the experiment with mice whose intestines had been genetically engineered to stop producing insulin, the mice gained weight and developed diabetes.
Thus, the protective mechanism of a high fiber diet against obesity and diabetes is the result of the glucose-producing activity of the intestines caused by propionate and butyrate and gut bacteria.
The results of this study may help researchers develop treatments and preventions for obesity and diabetes.
Another recent study also discovered the gut bacteria plays a role in decreasing the risk of asthma. Both of these studies indicate the importance of bacteria in the intestines for overall health.
References
How a Fiber-Rich Diet Protects Against Obesity and Diabetes: http://www.medicalnewstoday.com/articles/271220.php
Microbiota-Generated Metabolites Promote Metabolic Benefits via Gut-Brain Neural Circuits: http://www.cell.com/abstract/S0092-8674(13)01550-X
Image Credits
Kidney Beans: http://www.freeimages.com/photo/1421450
