School of Medicine

For gut microbes, not all types of fiber are created equal

A new study from Washington University School of Medicine in St. Louis shows that beneficial gut microbes thrive when fed specific fiber types. The researchers developed artificial food particles that allow them to measure how different fiber types are processed by human gut bacteria as the fibers transit through the mouse intestine. The artificial food particles consist of magnetic beads with fiber molecules coating the surface. Different colored fluorescent labels allow the researchers to track which fiber type is attached to which bead. (Image: Michael Patnode)

Certain human gut microbes with links to health thrive when fed specific types of ingredients in dietary fibers, according to a new study from Washington University School of Medicine in St. Louis.

The work — conducted in mice colonized with human gut bacteria and using new technologies for measuring nutrient processing — is a step toward developing more nutritious foods based on a strategy of targeted enrichment of key members of gut microbial communities. The researchers identified fibers that selectively increase the abundance of beneficial microbes and tracked down the bioactive components of fibers responsible for their effects. To decipher how members of gut communities compete or cooperate with each other for these fiber ingredients, they also invented a type of artificial food particle that acts as a biosensor for monitoring nutrient processing within the intestine.

The study appears Sept. 19 in the journal Cell.

“We are in the midst of a revolution in food science – where the naturally occurring molecules present in various food staples are being identified using advanced analytic tools,” said senior author Jeffrey I. Gordon, MD, the Dr. Robert J. Glaser Distinguished University Professor, director of the Edison Family Center for Genome Sciences & Systems Biology and leader of the current study. “The resulting encyclopedias of food ingredients are providing an opportunity to understand how gut microbes are able to detect and transform these ingredients to products they use to satisfy their own needs, as well as share with us. Cracking the code of what dietary ingredients beneficial microbes covet is a key to designing foods that enhance health.”

Dietary fiber is known to promote health, but typical Western diets are lacking in high-fiber fruits, vegetables, whole grains and legumes. Fibers contain very diverse and complex collections of molecules. The specific components of various fibers that are used by gut bacteria and confer health benefits are generally not known. Since the human genome possesses a very limited arsenal of genes that break down dietary fiber, and many gut bacterial species are chock full of these genes, people depend on gut microbes to digest fiber.

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