The role of diet in the development of tumors has been confirmed by studies at different levels of evidence, and a number of scholars, led by Abnet of the U.S. National Cancer Institute, have reviewed the relationship between diet and upper gastrointestinal (GI) tract tumors in a paper recently published in the journal Gastroenterology. Fruits and Vegetables The risk of esophageal and gastric cancers and certain precancerous lesions is associated with the intake of fruits and vegetables, which may vary depending on the site and type of pathology. Systematic evaluations have shown that those with a high intake of fruits and vegetables have a reduced risk of esophageal and gastric cancers, and some scholars even recommend a total daily intake of fruits and vegetables of not less than 400 g. The effect of fruits and vegetables on gastric cancer may be related to tumor type, site, and individual factors. A large European prospective study showed that the risk of gastric cancer was reduced in people with a high intake of fruits and vegetables, and was only statistically significant in fresh fruits and gastric cancer, citrus and pancreatic cancer, smoking, and northern European populations. Similarly, high fruit and vegetable intake reduced the risk of squamous esophageal cancer and adenocarcinoma, and diversity of intake, in addition to total intake, was an important factor. In a European study, the variety of fruits and vegetables consumed was negatively associated with the development of squamous esophageal cancer. The mechanism by which fruits and vegetables reduce the risk of tumorigenesis may lie in preventing the further development of precancerous lesions. A study in the Netherlands showed that the risk of Barrett’s esophagus was lower in men with a high intake of vegetables, while the risk of Barrett’s esophagus was not significantly altered in fruit eaters or in women. Meat Red meat and processed meats increase the risk of gastrointestinal tumors, an observation that is generally confirmed in colorectal cancer. Heterocyclic amines, nitroso-complexes, polycyclic aromatic hydrocarbons, and high ferrous hemoglobin in red meat produced by certain cooking methods have been associated with tumorigenesis. Dietary intake databases such as CHARRED can provide information on possible carcinogens in meat. Case-control studies have shown that red meat is strongly associated with the risk of esophageal cancer, and cohort studies provide similar but weaker evidence. Studies have also shown that ferrous hemoglobin may be the most direct potential factor in the development of esophageal cancer. Similarly, case-control studies have shown that red meat is associated with the development of gastric cancer, but cohort studies do not support this at this time. Studies suggest that the interaction of different foods with gastrointestinal flora may influence tumorigenesis. Gut bacteria reduce levels of nitrosamines, which are carcinogens in some tumors. In addition, diet can rapidly and significantly alter the colonic flora to affect the whole organism, e.g. metabolites formed by gut bacteria after breaking down cholesterol in red meat are associated with atherosclerosis formation. Hot drinks As early as 1939, WL Waston et al. reviewed the clinical data of 771 cases of esophageal cancer patients and concluded that esophageal cancer may be related to the effect of prolonged thermal stimulation. Since then, scholars have conducted a large number of clinical and epidemiological studies. What has gained public publication is that mate tea is associated with the development of esophageal squamous carcinoma, while the relationship between hot tea and esophageal squamous carcinoma is not clear. Few studies have shown that coffee increases the risk of esophageal cancer; on the contrary, newer studies suggest a protective effect. Although several studies have shown that hot tea increases esophageal cancer risk, other studies have shown no association or a protective effect of hot tea, and perhaps only large amounts of particularly hot tea increase esophageal cancer risk. The reason for the mixed results in related studies may be related to the heterogeneity of the specific components of tea and coffee. Matei tea contains high levels of polycyclic aromatic hydrocarbons and may therefore be carcinogenic. On the contrary, tea polyphenols contained in green tea have been shown to inhibit proliferation, anti-angiogenesis, promote apoptosis, enhance immunity, etc., however, only in cell lines or animal models. Some scholars have also studied the relationship between tea, coffee and maté tea and other digestive tract tumors, but the results are difficult to unify, among which the interesting and highly popularized hypothesis is that coffee helps prevent liver cancer.