Professor Tian Yantao: How much do you know about the mysterious "stomach acid"

I believe that many people have a small medicine box at home. Let me guess what is in your medicine box! I guess your medicine box must have cold medicine, anti-inflammatory medicine, painkillers, and antipyretics and diarrhea medicine for children at home. Elderly people often prepare some quick-acting heart-saving pills, and take a bottle of iodine, a few packs of cotton swabs and a box of band-aids. In addition to these, friends with poor digestion and frequent stomach pain will also prepare omeprazole, sucralfate, metoclopramide and other medicines. How about it, it's almost what I guessed! What we are going to talk about today is the acid-suppressing medicine for treating stomach problems.

Many of our friends, especially the elderly, often have indigestion after eating, or have symptoms of acid reflux and heartburn, and then they will diagnose themselves with gastric insufficiency, gastric ulcer, reflux esophagitis, etc., and then find some stomach medicine in the medicine box to deal with it. The patient Aunt Zhang, who we recently received, is also the same. She is 67 years old and said that she has had stomach problems for more than ten years. She often has indigestion, belching, and sometimes acid reflux. Whenever this happens, she will take some omeprazole. She only knows that it is a stomach medicine and doesn’t care whether it is taken right or not. She feels very comfortable after taking it, but feels uncomfortable if she doesn’t take it. Sometimes she even takes double the amount! She has been taking it intermittently for more than ten years, and has never had a gastroscopy. What’s more terrible is that she has Helicobacter pylori infection and has no regular treatment. She always felt that she was fine until her symptoms worsened recently. Taking omeprazole didn’t help, so she went for a gastroscopy. As a result, she saw diffuse atrophy of the entire stomach. Unfortunately, after taking the pathology, she was diagnosed with gastric cancer...

Acid reflux, common clinical symptoms

We all know that too much stomach acid, especially when combined with Helicobacter pylori and a high-salt diet, can damage our gastric mucosa, leading to gastric ulcers, which can further worsen and lead to gastric cancer. But in fact, too little stomach acid is not good either. Aunt Zhang's stomach cancer is likely related to the long-term and incorrect use of acid-suppressing drugs. Why is this?

Let's first understand our gastric juice. The normal pH of gastric juice can reach 0.9-1.5, and the normal secretion volume is 1.5-2.5L/d. You may not have much concept about this. We all know sulfuric acid. The pH value of sulfuric acid is about 1, so it is not an exaggeration to compare our stomach to an acid-producing chemical plant. Can our stomach withstand such an acidic environment? In fact, the reason why our gastric mucosa can remain intact is mainly because there are three barriers, with the epithelial cells of the stomach as the boundary. The surface of the epithelial cells is covered with a 0.5mm thick mucus gel layer and a bicarbonate (alkaline) layer, which can protect the strong acid from damaging the epithelial cells. The epithelial cells are tightly connected and regenerate quickly. They can be repaired quickly after damage, and they also play a barrier role. There is a rich capillary network behind the epithelial cells, which can supply the gastric mucosa with sufficient nutrients and take away the metabolites produced.

Helicobacter pylori can be observed in pathological sections under a microscope

So what important role does gastric acid play in our digestion process? Gastric acid plays a very important role, including the following aspects: ① Activating pepsinogen to play a role in decomposing protein, while promoting the denaturation of protein in food to make it easier to digest; ② The high acid environment can kill bacteria that enter the stomach with food and prevent bacterial growth and reproduction; ③ Combining with calcium ions and iron ions to promote their absorption in the small intestine; ④ Promoting the secretion of pancreatic juice, bile and small intestinal juice.

(Written by Shao Xinxin and Tian Yantao, Department of Pancreatic and Gastric Surgery, Cancer Hospital, Chinese Academy of Medical Sciences)