Trouble in Both Stomach and Intestines: Can Irritable Bowel Syndrome Affect the Stomach Too?

The gastrointestinal tract in our body is not merely an organ for digesting food. It constantly exchanges signals with the brain through a highway directly linking them, known as the gut-brain axis. Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder that occurs when a problem arises in communication along this gut-brain axis. In particular, when upper gastrointestinal symptoms are also present, the traffic congestion along this highway can be seen as even more severe. Psychological factors such as stress or anxiety stimulate the brain to secrete neurotransmitters and hormones, including serotonin and cortisol, which directly affect the motility and sensitivity of the stomach and intestines. For example, stress may alter the gastric emptying rate or increase gastric acid secretion to cause epigastric pain or dyspepsia, or it may excessively promote or suppress intestinal peristalsis to cause diarrhea or constipation. It resembles a severe traffic jam where vehicles can neither travel downward from above nor flow properly below. In addition, patients with IBS often experience leaky gut syndrome, in which intestinal barrier permeability increases and imbalances arise in the gut microbiota, or microbiome. This triggers inflammatory responses in the gut, producing visceral hypersensitivity where the enteric nervous system becomes overly sensitive. Extreme discomfort and pain can be felt from minor stimuli that normally would not cause pain. Because these changes can manifest across the entire gastrointestinal tract, complex patterns develop in which upper symptoms such as epigastric pain and abdominal distension appear alongside lower abdominal pain, constipation, and diarrhea. Ultimately, irritable bowel syndrome can be understood not simply as an issue of the intestines alone, but as an overall bodily imbalance arising from complex entanglements among delicate interactions between the brain and gut, nervous system regulation, and the gut environment. Therefore, rather than trying to resolve only one or two isolated symptoms, an overall approach to restoring bodily balance is essential.