When the Gut Keeps Talking to the Brain
The short answer
Lower abdominal pain one week, epigastric tightness the next, acid rising the week after — the tests come back normal each time, so why does the symptom just keep moving? There is a human study showing that, two years after gastroenteritis had healed, the nerves of the gut remained oversensitive. I look not at quantity but at where the threshold for feeling sits. Weight loss, blood in the stool, or nighttime pain call for a colon examination first.
Contents
Some patients tell me the place of discomfort in their abdomen changes every time.
One time the lower abdomen hurts, another time the epigastrium swells and feels tight, and another time acid rises up.
The tests come back with nothing seriously wrong, every time.
Patients say the symptom keeps changing, so even they cannot get their bearings.
I do not view this as three different diseases.
The Story Between the Gut and the Brain Is Already Familiar
The story of the pathway through which the gut and brain exchange signals — the gut-brain axis — is now widely known. Being tense can cause abdominal pain, and abdominal discomfort can, in turn, shift mood and alertness. The intestinal segment of the vagus nerve contains a large mixture of sensory fibers that carry information from the gut up to the brain. The gut is not only a listener — it is constantly a sender of information as well.
This piece is what comes next. Even after the gut has stopped speaking, the habit of speaking remains.
What Does Not Return Even After It Ends
There are patients whose abdomen remains uncomfortable long after recovering from gastroenteritis. The bacteria are already gone and the inflammation has settled, yet the discomfort remains.
There is a study that checked, in human subjects, whether this was simply a matter of mood.
The excised nerves were still oversensitive, even on a dish.
Having left the body, there was no mind there, no stress, no mood of the day. And yet they were still sensitive. The sensing side itself had already changed to be that way.
I have kept this study in mind for a long time, because it shows that some sensitivity is not a circumstance but a state.
Why It Remains
This resembles the pattern in which the receiving side becomes more sensitive when a signal weakens. When a signal decreases, the receiving side turns up its ear, and if that state lasts long enough, it becomes the new baseline.
It Is a Matter of the Receiving Side, Not the Quantity
So when I see patients like this, I do not suspect the quantity first.
Some patients say acid keeps rising. It is commonly assumed this means there is too much stomach acid. But listening closely, what they describe is closer to queasiness than burning. For such patients, I look not so much at whether the amount produced has increased, but at whether the threshold on the receiving side has dropped.
The same goes for patients who say their abdomen gurgles. Some genuinely have more gas, but others feel the same amount as much larger. These two sound like the same complaint on the surface, but they point to different places.
The Symptom Keeps Moving, Each Time
I return to where this piece began.
When a symptom keeps moving, I also check whether the sensory regulation of one system has shifted along with it. But I do not conclude it is a single disease simply because the location changes. Each time, I re-screen the new symptom for warning signs and check whether it is genuinely connected to the previous one.
Among symptoms that move around like this, some call for testing first. I have noted these separately below.
What Receives First Is Not the Nerve
Between the contents of the gut and the nerves lie the mucosal barrier and various sensory cells. Some stimuli are sensed by epithelial and endocrine cells, which then pass them to nearby nerve endings, and the nerve endings themselves also receive various signals beneath the mucosa.
This is why there is reason to look at the mucosa and its surroundings, not just the nerves alone.
I Direct Medicine at the Mucosa
I do not take the approach of suppressing the nerve into quiet. I take the approach of changing the environment the mucosa sits in.
This is also why I do not explain herbal medicine with the single sentence "it suppresses the nerve." The environment the mucosa sits in, the way the gut moves, and the side that receives the signal — these are three separate layers, and which one carries the most weight differs from person to person.
Because the nervous system has plasticity, sensitivity is not fixed either. But saying it can come back down, and saying how much it comes down for whom, are two different statements.
When Testing Comes First
If weight loss is pronounced, if blood is mixed in, if pain wakes a person at night, if fever accompanies it, if there is anemia, or if a symptom that was never there before appears for the first time after age fifty — there is something that needs checking first. A colon examination comes before anything else.
The mere fact that a symptom moves around cannot settle the matter as a single system's problem. Each newly appeared symptom is checked first, every time.
If the same pattern keeps repeating even after serious disease has been ruled out, then the remaining question is how far the threshold on the receiving side has dropped.
Written by Dr. Heo Ji-young (PhD in Korean Medicine Pathology, Kyung Hee University · former Research Professor of Herbology, Kyung Hee University)
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