The epidemiology of chronic gastritis was studied before recognition of Helicobacter pylori as its major cause. This case-control study was conducted in an attempt to elucidate causal associations for H. pylori infection and chronic gastritis. A questionnaire emphasizing diet and lifestyle was administered before gastroscopy to patients attending the gastroenterology clinic of Charity Hospital of New Orleans. H. pylori status and histopathology were evaluated independently to classify patients as cases or controls. A positive association was found between H. pylori infection and African American ethnicity as well as smoking. A strong interaction between race and smoking was found. Adequate intake of antioxidant micronutrients, especially vitamin C, was negatively associated with infection prevalence. H. pylori infection was strongly associated with an increased risk of atrophy (odds ratio (O.R.) = 6.4) and intestinal metaplasia of the gastric mucosa (O.R. = 4.7). Both gastric conditions increased in prevalence with age. Intake of antioxidant micronutrients was negatively associated with the risk of atrophy after adjustment for H. pylori infection.