The most recent estimates of global cancer incidence indicate that in 1990 stomach cancer was the second most frequent cancer in the world (after lung cancer), with about 800,000 new cases diagnosed every year (Parkin et al., 1999). Steady declines in incidence rates of gastric cancer have been observed worldwide in the last few decades. The exact causes of the decline are not well understood, but may include improvements in diet and food storage and a decline in the prevalence of Helicobacter pylori infection. Dietary modifications remain potentially one of the most important tools for the prevention of gastric cancer. Control of H. pylori infection, by indirect means such as improving the general sanitary conditions or by direct intervention such as eradication or immunization, is also likely to offer great potential for prevention.