Stomach cancer was the leading carcinoma of the beginning of the 19th Century. It has currently dropped to number seven. This is probably directly due to our change of diet from smoked-and salted foods to refrigeration. One of the highest risk factors in stomach cancer is nitrite. Nitrite is used as a preservative and found in some drinking water. Nitrate is found in many vegetables, and when they spoil or oxidize, it turns to nitrite. Refrigeration has cut down on this oxidation process.
H-pylori bacteria found to cause an increase in the number of ulcers is also a risk factor. Chronic H-pylori infection can lead to atrophic gastritis. This is a condition where the stomach loses the normal folds on the inside layer. H-pylori also causes a loss of the acid secreting cells. This can cause the nitrates from foods to oxidize into nitrites inside the stomach. Vitamin C and E have been shown to be protective against this. Nitrites are also found in smoked fish and meats. Japan has a very high stomach cancer rate. They average around 300 milligrams per day of nitrites compared to 60 to 80 milligrams a day in the United States.
Selenium deficiency has been reported in a number of different cancers including stomach. Beta-carotene, Vitamin C and E have shown benefits of decreasing risk of stomach cancer. This may be associated with the antioxidant effect in the stomach. Fruits and vegetables are rich sources of beta-carotene, Vitamin C and Vitamin E. These have also shown to decrease risk of stomach cancer. Garlic has shown to decrease risk and may be due to the anti-bacterial effect on H-pylori. Rounding it out, whole grain foods showed good evidence to decrease risk while pasta and rice may have a slight increased risk of stomach cancer.