We conducted an epidemiological study to investigate the relation of food intake to Helicobacter pylori (H.pylori) infection in an area endemic for H.pylori. In this study, 365 subjects, 104 men and 261 women, were randomly selected from 7,389 adult (over age 20) inhabitants of town A, Japan. The prevalence of immunoglobulin G (IgG) class antibody to H.pylori (anti-H.pylori) was 83.7% and the prevalence of anti-H.pylori increased with age significantly (P<0.05). Subjects with anamnesis of gastritis, gastroduodenal ulcer and gastric cancer tended to have a higher anti-H.pylori positive ratio (93.5%) than those without (81.0%). But there was no relationship between anti-H.pylori prevalence and sex, blood type, smoking or drinking habits. Daily intake of foods by food groups, nutrients and the concentrations of serum ingredients were compared between 37 anti-H.pylori-positive and 40 negative subjects selected from 365 inhabitants by matching up according to sex and age. The daily intake of cereals, potatoes and starches, and milks tended to be higher in positive than negative subjects, while the daily intake of algae and tea appeared to be a little higher in negative than in positive subjects. The daily zinc intake of antibody-positive subjects was significantly higher (P<0.05) than in antibody negative subjects. On the other hand, the daily iron intake in negative subjects was significantly higher (P<0.05) than in positive subjects. The serum concentrations of copper, zinc, and vitamin E tended to be higher in positive than negative subjects. But there were no significant differences in serum ingredients concentrations between antibody negative and positive subjects. Our findings suggest that iron and zinc intakes may effect on H.pylori infection.

The presence of Helicobacter pylori (H. pylori) in the natural environment has been demonstrated in a number of studies. However, its route of infection into humans is unknown. To study this further, we attempted to detect H. pylori in the natural environment in a region of Japan with a high infection rate. Tap and well water and field soil samples were collected from around the residences of subjects who had participated in an epidemiological survey in 1996. Samples of water from rivers and ponds, and specimens of flies and cow faeces were collected in the region. DNA was extracted from the water, field soil and faecal samples after selective collection of H. pylori by the immunomagnetic-bead separation technique. H. pylori-specific DNA was detected in water, field soil, flies and cow faeces by nested polymerase chain reaction (PCR), and the ureA partial sequences of the PCR products were aligned. The nucleotide sequences of the samples amplified by PCR were highly homologous (96-100%) with the H. pylori sequence in the GenBank database and the H. pylori-specific DNA sequences were highly homologous with each other. These findings suggest the existence of H. pylori in the natural environment and a possible transmission route.

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