The stomach: Everything you need to know about the vital organ you can live without

HONG KONG — The human stomach is surprisingly small when it’s empty, “about the size of a person’s palm”, says Dr Paul Ng, a Hong Kong-based specialist in gastroenterology and hepatology.

Yet as everyone with a good appetite knows, the stomach is elastic and can expand to many times that size. “There are two openings in the stomach” Ng explains. “Sometimes when there is a blockage at the lower opening (pylorus), gastric outlet obstruction (GOO) can occur, in which the stomach becomes extremely distended. Even when that happens, people would vomit instead of having their stomach torn apart by the accumulation, so the stomach doesn’t explode”.

A gourd-shaped organ that sits between the oesophagus and the intestines, the stomach has an important role.

People who say they have a large appetite or they are overweight because they have a large stomach are deluding themselves. Once a person is an adult, the stomach doesn’t change in size. “The intrinsic structure of the stomach is the same for both sexes,” says Dr Ng. “But because males tend to have stronger abdominal wall muscles (the effect of testosterone), the male stomach is more securely placed in the belly. The motility (movement) of the stomach tends to be slower in females due to hormonal effects.” Slow gastric motility can give rise to discomfort or nausea.
Dr Paul Ng is a Hong Kong-based specialist in gastroenterology and hepatology.

Stomach size doesn’t govern what we eat — appetite and cravings do; some people feel full sooner, so they eat less. Stomach rumbling — or to identify it properly ‘borborygmus’ — is normal, it is produced by the movement of fluid and gas in the intestines.

Once swallowed, food takes about seven seconds to get to the stomach. A ball of food is called a bolus while in the oesophagus and upper gastrointestinal tract, and chyme when it’s in the stomach. Smooth muscle tissue contracts in sequence to produce a peristaltic wave to help move the food through the digestive process. The stomach is where food is broken down — partly by the stomach’s mechanical action which grinds food to a paste. This grinding is assisted by gastric acid which is produced in large quantities – about three litres a day.

The acid is necessary to break down what we ingest, it’s also helpful in fighting infection as it helps to kill off bugs that might enter the stomach.

The gastric acid includes industrial-strength hydrochloric acid, which could seriously damage human skin. So the stomach produces large quantities of mucous to cover and protect the stomach’s millimetre thick lining, or mucosa.

Food is only in the stomach for two to five or six hours before it’s sufficiently broken down to pass along the line to the intestines.
Despite its incredibly important role in keeping us nourished, a person can live without a stomach. US-based businessman David Fogel of Silver Spring, Maryland, had his stomach removed to prevent the stomach cancer that killed his aunt. With no feelings of hunger, he needs to set a timer on his watch to remind him to eat small amounts regularly.

During what is called a total gastrectomy, surgeons remove the stomach and directly attach the oesophagus to the small intestine. Some animals, including sea horses and platypuses, have no stomach. Ruminants, cows for example, have four stomachs, to help break down the cellulose in their diet.

Many people know the pain and discomfort of stomach — or peptic — ulcers. These are lesions that develop on the lining of the stomach affecting about 50 million Americans each year. Stress, spicy foods and all that stomach acid were believed to be the cause of stomach ulcers and this belief held for over a century.
In 1982, the truth was discovered when two Australian researchers Barry Marshall and Robin Warren, performed experiments on themselves (which left them unwell) and found the real culprit was a bacterium, Helicobacter pylori, which burrows into the stomach’s mucosal lining.

Asians usually present with gastric ulcer symptoms a decade earlier than Caucasians. Researchers believe this may be attributable to an H. pylori infection at a younger age. Because the infection can now be treated, ulcers are far better managed today.

There is thought to be a connection between stomach ulcers and stomach cancer. The sixth leading cause of cancer deaths in Hong Kong, stomach cancer was responsible for 682 deaths in 2017, accounting for 4.8 per cent of all cancer deaths.

While stomach cancer has traditionally been considered a condition that affects older patients, Dr Travis Grotz, a Mayo Clinic surgical oncologist, says that is changing. “The incidence of gastric cancer in the elderly is decreasing,” he explains. “This is likely due to public health efforts to decrease classic risk factors such as smoking, smoked meats and the treatment of H.pylori.”

On the other hand, “we are seeing an increase in the incidence of young patients developing gastric cancer,” he says. “This worrisome trend is occurring across both genders and all races.”

This could be in part because some younger patients have a specific genetic type of cancer that is more aggressive and resistant to treatment, he says. There is also evidence to suggest obesity may be a risk factor for the increased incidence of gastric cancer in the young, he adds.
“Currently, I recommend young people to eat a healthy diet and exercise,” he continues. “Continue to abstain from smoking, maintain a healthy weight and have their reflux symptoms investigated and treated. If people develop unintentional weight loss, abdominal pain, difficulty eating, reflux or iron deficiency anaemia, they need to see their doctor.”

There are positive advances in medical technology that will continue to help doctors diagnose stomach problems, says Dr Paul Ng. These include advanced endoscopy to diagnose (EUS, for endoscopic ultrasound) and cut out tumours (ESD, for endoscopic submucosal dissection), and burn off precancerous cells (RFA, for radiofrequency ablation). There are even diagnostic electronic capsules — which you swallow, of course — to determine stomach motility and acid reflux, he says. SOUTH CHINA MORNING POST