Many studies have confirmed that vitamins C and E may prevent the development of stomach cancer. A study by Dr. Taylor of the National Cancer Institute showed that for men who smoked, vitamin C reduced the risk of stomach cancer by about 40 percent, and eating more fruit regularly reduced the risk by 50 percent. Studies in Shanghai and Qingdao have also confirmed that both onions and garlic can reduce the risk of stomach cancer. Fresh vegetables and fruits, especially green leafy vegetables and citrus, are rich in vitamin C. Yellow green vegetables contain more vitamin E. Vitamin C can reduce nitrite to nitrogen oxide, thus blocking the nitro reaction of amines. Animal experiments have shown that high doses of vitamin C can directly inhibit the nitrosamines gastric cancer process. Vitamin E is an important intracellular antioxidant, and its mechanism of action to inhibit nitrosation is similar to that of vitamin C. From the twentieth century, the widespread and rapid popularity of refrigerators in developed countries has led to fundamental changes in the way food is stored and transported, allowing people to consume vegetables and fruits evenly throughout the year and reducing the preparation of pickled and smoked foods. The process of spontaneous conversion of nitrate to nitrite at 2°C was almost completely inhibited, thus reducing the intake of nitrite. It is thought that the spread of home refrigerators, reduced use of nitrite as a meat additive, decreased salt consumption, and increased intake of fresh vegetables and fruits and dairy products are among the reasons for the significant decline in gastric cancer.