Diet plays a major role in gastric carcinogenesis. Globally, literature suggests that none or low-starch vegetable including green yellow vegetables, cruciferous and allium vegetables (garlic and onion) and fruits are considered to be probable protective factors. Limited evidence suggests that pulses (including soy) and selenium are also protective in nature.[21
] Recent decline in the incident of stomach cancer in many countries may be in part explained not only by higher consumption of fruit but also due to highly reduced intake of salt, preserved foods as well as the availability of refrigeration.
Five case-control studies and no cohort studies have been published from India in the last 10 years to establish specific dietary and lifestyle habits in relation to gastric cancer. The limited number of studies may be due to the difficulties in measuring the exposure by developing food frequency questionnaire and in preparing nutritional data base.
] high rice intake, spicy food, excess chilly consumption, consumption of high-temperature foods[24
] smoked dried salted meat, use of soda[25
] and consumption of dried salted fish[25
] have emerged as significant dietary risk factors in various parts of India. These practices are prevalent in southern and eastern states of India where a higher frequency of gastric cases are also observed.
One study analyzed its dietary data based on food groups like total pulses, total meat, total fruits, total vegetables and total cereals. The results were found to be insignificant.[24
] Increased association between consumption of milk and beverages containing milk showed higher risk as compared to reduced consumption but results were not statistically significant .
Role of dietary factors in the development of gastric cancer in India
Salt intake is a risk factor for gastric carcinoma as it damages the gastric mucosa, which results in gastritis and increased cell proliferation.[26
] Salted tea, a peculiar beverage, is commonly consumed by a majority of population in Kashmir valley was observed to be a risk factor.[27
] Indian studies have not observed salt intake as a separate factor but salted and processed products were taken into consideration. Soda, which is an additive commonly added in the foods, was found to be associated with increased risk (OR=2.9). A protective effect of leafy vegetables and fruits was observed in these studies. Tea consumption was shown to have protective effects in one study. Reheated foods, reheated oils and refrigeration were not observed to be associated with risk of gastric cancer.[24
The studies on diet and stomach cancer could provide breakthrough in understanding role of diet because of heterogeneous food consumption throughout India. Although the inter-individual variation might be high, the intra-individual variation is usually low. Unlike western countries where animal foods are the major part of diet and being a vegetarian is voluntary, in India the effect of lifelong vegetarianism on risk of gastric cancer could be explored.