Scientists at the Sapienza University of Rome found that feelings of fear and disgust increase the acidity of gastric juice. Medical research published stores bioRxiv.
The gastrointestinal tract plays an important role in the emotional reactions of the body. For example, a malfunction in the gut microbiome can exacerbate symptoms of depression and vice versa. However, it is not entirely clear how the environment in which microbes live in the digestive tract changes when different emotions are felt.
In their study, the scientists used sensors that measure acidity, temperature, and pressure as it passes through the human digestive tract when ingested. The authors recruited a group of 31 volunteers with no health problems. All participants swallowed “smart” pills. The scientists also measured the electrical activity of the digestive tract muscles externally. They recorded other physiological reactions of the body.
The volunteers were then asked to watch a series of videos that evoked different emotions such as happiness, fear, sadness and disgust. There were four viewing sessions in total, and at the end of each viewing session, participants filled out a questionnaire on how they perceived the video.
Scientists have found that when fear and disgust are felt, the digestive system releases lower pH stomach acid. The more disgust or fear the volunteers experienced, the lower the pH was.
“With this type of data, we can better model not only how our healthy bodies work, but also people with conditions. Future studies, including those involving more diverse groups of volunteers, will be needed to generalize the results, the scientists said.