Nowadays, people’s living standard is getting better and better, but the incidence of tumors is also getting higher and higher, and digestive tract tumors are most common with esophageal cancer and stomach cancer. Onion and garlic are definitely on the table of Shandong people. These two foods are not only locally abundant, but also one of the reasons why Shandong people have a lower incidence of stomach cancer. Because garlic extract can reduce the content of carcinogenic nitrite, while onion is rich in propylene sulfide, which can inhibit the conversion of nitrate to amine nitrite by gastrointestinal bacteria, blocking the carcinogenic process. In a previous survey on the dietary structure, nutrients and eating habits of healthy residents in areas with high and low incidence of gastric cancer, the incidence of gastric cancer was significantly lower among Shandong people who ate more garlic in a study in Shandong Province. Allicin is the real bactericidal effect of garlic, and it is also the source of the unique pungent and stimulating taste of garlic. Also, it is best to slice garlic and leave it for 15 minutes so that it can combine with oxygen to produce allicin before consumption. In Shandong, you will find something called garlic mortar in every house, which is used to crush garlic and eat it together with cold dishes, few people eat cooked garlic. Similarly, people in Shandong eat green onions mainly raw, either cut into pieces and dipped in sauce or served in cold dishes. The main nutrients of green onions are protein, vitamin A, vitamin C and minerals such as phosphorus, iron and magnesium. Modern pharmacology has found that green onions contain pungent volatile oils and spicy elements, which have a strong bactericidal effect and can stimulate the secretion of digestive juices, promote appetite, enhance physical fitness, improve patients’ immunity and naturally reduce the risk of cancer. As for the relationship with stomach cancer, the main reason is that green onions are rich in a kind of organic sulfide called propylene sulfide, which can enhance the activity of enzymes in the body to remove carcinogens and prevent cancer. The polysaccharides contained in onion leaves can agglomerate with cancer cells, thus inhibiting their growth. Therefore, to prevent gastric cancer, you may want to learn from Shandong people and eat onions and garlic, and also eat less pickles, dry salted fish, salted meat, etc. to avoid excessive intake of nitrates and their conversion into carcinogens nitrosamines, which can induce gastric cancer.