Emotions like fear and disgust could lead to more acidic stomach pH

Do you find your stomach rumbling at times you are afraid or panicked? According to a team of scientists from the Sapienza University of Rome, this happens because intense emotions like fear, horror, disgust, and shock have the power to change the pH of your stomach.

In a recently published study (not yet peer-reviewed), the researchers reveal a “deep-body physiology of emotions.” They propose that gastrointestinal (GI) signals share a strange connection with the emotions a person feels. 

For instance, if a person is experiencing a threatening situation, then according to the study, the pH of their gut will drop down, and the stomach will become acidic. Interestingly, similar findings were also reported 190 years ago by William Beaumont, a US army surgeon who is also known as the father of Gastric Physiology.

“Our findings about the link between pH acidity of the stomach and perceived emotions (disgust, fear, and happiness) are in line with the anecdotal reports described by Beaumont in 1833,” the study authors note. 

Validating the connection between your emotions and stomach

The study authors performed an interesting experiment involving 31 men who were mentally and physically fit and had no health issues. The average age of the subjects was 24 years, and each of them was given a smart pill. 

The pill was a battery-powered device that contained sensors for monitoring gut activity from the inside. All the participants were asked to swallow it, and as they did, the smart pill started collecting data related to the pH and temperature of the participants’ digestive systems.   

Meanwhile, on the outside, the participants were asked to watch different video clips featuring different types of emotional content expressing happiness, sadness, fear, and disgust. Each clip was nine-second long, and in between these clips, the participants were also shown emotionally neutral content.

The subjects were then asked to fill out a questionnaire in which they wrote about the emotions they felt after watching each video clip. After going through these responses along with the data collected by the smart pills, the study authors noticed that when participants experienced emotions like fear or disgust —- pH decreased and acidity increased in their stomachs.

They further found that the breathing rate went up when the subjects felt sad. The authors finally concluded that strong emotions are found to be associated with increased gastrointestinal sensations. “Our findings support somatic theories of emotions, suggesting that specific patterns of physiological signals are linked to unique emotional states,” said the researchers.

“In conclusion, we believe that the present findings have the potential to open new avenues for studying the unexplored influences of the neurobiology of the gastrointestinal system on typical and atypical emotional processes,” they further added.

The findings are indeed eye-opening. However, these are based on an experiment involving only a small number of male participants. This is the biggest limitation of this research, and therefore, future studies involving a large number of both male and female participants need to be done. 

The study is published on the preprint website bioRxiv.