Sensitive stomach: fullness, upper abdominal pain and Helicobacter

Healthy state

The stomach is more than a bag. When you eat, its upper part relaxes to make room, while the lower part grinds the food and passes it to the small intestine in portions. Nerves tell the brain how full it is. Normally we only feel a pleasant sense of fullness.

The stomach does three things. It stores: during eating its upper part relaxes via a nerve reflex (accommodation), so there is room without a rise in pressure. It grinds and portions: the lower part kneads the chyme, and the pylorus lets only small particles of a few millimetres through. And it empties: a normal meal takes about two to four hours. Fat and protein in the small intestine signal back via hormones that things should go slower, so the small intestine is not overwhelmed. Between meals the cleaning wave (MMC) moves leftovers on about every 90 to 120 minutes. It only starts when you are fasting; constant snacking interrupts it.

Experts call upper abdominal symptoms dyspepsia. If endoscopy finds no cause such as an ulcer, it is called functional dyspepsia. It is common. The Rome V criteria Rome V criteria Internationally used criteria with which experts classify IBS, functional constipation and stomach complaints based on symptoms. Rome V (2026) is the current version; it replaced the Rome IV criteria of 2016. More in the chapter “The gut-brain axis” distinguish two forms: postprandial distress syndrome, with fullness after meals and early satiety, and epigastric pain syndrome, with pain or burning below the breastbone. The two often occur together.

Helicobacter pylori is a bacterium that settles in the stomach lining. It causes inflammation and ulcers and increases the risk of stomach cancer. The Maastricht VI consensus regards it as an infectious disease that should be treated.

How common Helicobacter pylori is varies greatly from country to country. People usually catch it in childhood, often within the family. Most carriers never have symptoms. The bacterium survives the acid by making ammonia with an enzyme called urease and so creating a protective pocket. In some carriers the long-lasting inflammation leads to ulcers, and in a few, over many years, to stomach cancer.

Disrupted state: causes and effects

In functional dyspepsia the stomach often does not expand properly when eating, empties more slowly or reacts more sensitively to stretching, acid and fat. Stress, earlier gut infections and mild inflammation in the duodenum also play a role. Bloating and IBS Irritable bowel syndrome Recurring abdominal pain linked to bowel movements, without tests finding another cause. Today it is understood as a disorder of gut–brain interaction. More in the chapter “The gut-brain axis” symptoms are often added.

Another player is the duodenum directly behind the stomach. In some affected people it shows mild inflammation with more immune cells and a slightly more permeable lining, and the small intestine then reacts more strongly to acid and fat coming from the stomach. This fits the observation that symptoms often begin after a gut infection. Symptoms that occur mainly after eating point more to emptying and stretch, while pain or burning in the upper abdomen even when fasting points more to acid sensitivity.

Helicobacter can cause the same symptoms. People who are treated more often have fewer symptoms: in a meta-analysis Meta-analysis An analysis that combines the results of several studies. It is only as good as the studies it includes. of 18 trials, about 15 people had to be treated for one additional person to improve markedly. That sounds like little, but treatment also lowers the risk of ulcers and stomach cancer.

On testing for Helicobacter: a breath test Breath test After drinking a sugar solution, hydrogen and methane in the breath are measured several times. This can reveal sugar intolerances and signs of bacterial overgrowth. More in the chapter “Gut tests: what they show and what they do not” and a stool test show an active infection. A blood test for antibodies only shows that the body met the bacterium at some point and is poorly suited to checking whether treatment worked. So that the test is not falsely negative, acid blockers should be paused for about two weeks and antibiotics for about four weeks beforehand, which you discuss with your doctor. Treatment usually combines several antibiotics with an acid suppressant over 10 to 14 days. In many regions the germs are often insensitive to some antibiotics, especially clarithromycin, so guidelines follow the local situation. The antibiotics change the gut flora Microbiome, gut microbiota The community of all microbes in the gut, mainly bacteria, plus viruses, fungi and archaea. Most live in the colon. More in the chapter “Building microbial diversity” temporarily; that is no reason to skip treatment, because it lowers the risk of ulcers and stomach cancer.

Not every upper abdominal pain comes from the stomach. Gallstones cause cramping pain at the top right, often after a fatty meal. The pancreas, coeliac disease Coeliac disease An autoimmune disease in which gluten damages the lining of the small intestine. It is diagnosed with a blood test and usually a biopsy while you are still eating gluten. More in the chapter “Lactose, fructose, gluten: making sense of intolerances”, reflux and many medications, such as painkillers, iron or metformin, can cause similar symptoms. Delayed stomach emptying (gastroparesis Gastroparesis Delayed gastric emptying without a mechanical obstruction, with nausea, vomiting, early satiety and fullness. More in the chapter “Gastroparesis: when the stomach empties too slowly”) stands out when undigested food is vomited hours after eating. Rarely the heart is behind it: pressure in the upper abdomen on exertion, especially in women and people with diabetes, should be checked by a doctor.

Differences between people: women are somewhat more often affected, and in children and teenagers upper abdominal complaints often go together with stress and school. Stress acts via the vagus nerve Vagus nerve The tenth cranial nerve and the most important nerve of the rest-and-digest system. It connects the brainstem and the abdominal organs; most of its fibres tell the brain what is happening in the gut. More in the chapter “The vagus nerve: the data line between belly and head” and stress hormones directly on stomach emptying and sensitivity. New symptoms from about age 60, by contrast, should be taken more seriously than in younger people. You can observe for yourself: do the symptoms come during eating, afterwards or when fasting? At night? After fat, coffee or stress? These notes help your doctor classify the form and choose the right treatment.

Warning signs such as difficulty swallowing, repeated vomiting, anaemia, weight loss or stomach cancer in the family call for an endoscopy. The North American guideline also recommends it from age 60 for new symptoms; the age limit differs between countries.