You know what fiber's good for—to keep things moving smoothly downstairs. But it's not just for staying regular. Fiber can boost the number of beneficial bacteria in your gut, too. That's according to a study in the Journal of Nutrition. [Seema Hooda et al.,"454 Pyrosequencing Reveals a Shift in Fecal Microbiota of Healthy Adult Men Consuming Polydextrose or Soluble Corn Fiber"]

Researchers gave 20 men a daily snack bar to munch on. The bars had 21 grams of either polydextrose or soluble corn fiber—two fibers commonly added to cereal, pancake mixes and breakfast bars. After two weeks researchers took stool samples, and sequenced the DNA of bacteria living in them.

Turns out that extra fiber upped populations of Faecalibacterium—an anti-inflammatory bug that may protect the gut against inflammatory bowel syndrome. Fiber also increased the numbers of lactobacillus—the beneficial microbe in yogurt and probiotics. The researchers say these friendly bacteria may thrive when you eat fiber because you're supplying the bugs with what they prefer to eat.

Most Americans get only about 15 grams of fiber a day—half the recommended value. So instead of focusing on probiotics, to add new bacteria to your gut, the researchers say why not eat prebiotics like fiber, to feed the good guys already living there?

—Christopher Intagliata

[The above text is a transcript of this podcast.]