The trillions of microbes in our guts connect the food we eat to the rest of our body, playing crucial roles in stress and health. Some dietary fibers in our food are digested by these microbes to generate signaling molecules.

Millions of people worldwide struggle from stress and associated burdens. A group of researchers from the Translational Research Center in Gastrointestinal Disorders in Belgium tested whether dietary fiber could modify our stress responses. These fibers are converted to signaling molecules called short-chain fatty acids (SCFAs), that may attenuate stress.

For one week, 66 healthy male subjects were given a pill containing the amount of fatty acids found in either 10 or 20 grams of fiber, or a placebo. Before they received their treatment or placebo, participants were stressed to get a baseline measurement.  To stress out these subjects, researchers used a common experimental paradigm that combined social and physical aspects of stress. Participants kept their hand submerged in cold water for two minutes, while being closely watched. They were told that their facial expressions were monitored. Afterwards, the researchers took blood samples to look at the stress hormone cortisol, as well as SCFAs at different points after the stress.

They discovered that the greater the dose of fatty acids a person received, the smaller the cortisol-stress response (meaning, that person had less cortisol in their blood in response to the stressful event), and the more SCFAs in their blood.

This study shows that eating more fiber could attenuate the acute stress response. Future studies on this topic could establish a dietary intervention that doctors could prescribe to lower high blood pressure associated with stress.