A diet of fiber-rich foods, such as fruits and vegetables, reduces the risk of developing diabetes, heart disease and arthritis. Indeed, the evidence for fiber’s benefits extends beyond any particular ailment: Eating more fiber seems to lower people’s mortality rate, whatever the cause.
That’s why experts are always saying how good dietary fiber is for us. But while the benefits are clear, it’s not so clear why fiber is so great. “It’s an easy question to ask and a hard one to really answer,” said Fredrik Bäckhed, a biologist at the University of Gothenburg in Sweden.
He and other scientists are running experiments that are yielding some important new clues about fiber’s role in human health. Their research indicates that fiber doesn’t deliver many of its benefits directly to our bodies.
Instead, the fiber we eat feeds billions of bacteria in our guts. Keeping them happy means our intestines and immune systems remain in good working order.
In order to digest food, we need to bathe it in enzymes that break down its molecules. Those molecular fragments then pass through the gut wall and are absorbed in our intestines.
But our bodies make a limited range of enzymes, so that we cannot break down many of the tough compounds in plants. The term “dietary fiber” refers to those indigestible molecules.
