Dietary Factors and Helicobacter pylori Infection
Chemoprevention

Note: Separate PDQ summaries on Screening for Gastric Cancer, Gastric Cancer Treatment, and Levels of Evidence for Cancer Screening and Prevention Studies are also available.

Based on good evidence, Helicobacter pylori is associated with an increased risk of gastric cancer.

Description of the Evidence

A. Study Design: Evidence obtained from cohort or case-control studies.

B. Internal Validity: Good.

C. Consistency: Good, multiple studies.

D. Direction and Magnitude of Effect: Increased risk, moderate magnitude.

E. External Validity: Good.

Based on fair evidence, excessive salt intake and deficient dietary consumption of fresh fruits and vegetables are associated with an increased risk of gastric cancer. Vitamin C contained in vegetables, fruits, and other foods of plant origin is associated with a reduced risk of gastric cancer. Diets high in whole-grain cereals, carotenoids, allium compounds, and green tea are also associated with a reduced risk of this cancer.

Description of the Evidence

A. Study Design: Evidence obtained from cohort or case-control studies.

B. Internal Validity: Good.

C. Consistency: Small number of studies.

D. Direction and Magnitude of Effect: Small, difficult to determine.

E. External Validity: Fair (populations vary greatly in their underlying nutritional status).

The evidence is insufficient to determine if dietary or antibiotic interventions will reduce the risk of developing gastric cancer. A chemoprevention trial in China reported a statistically significant reduction of gastric cancer mortality after supplementation with beta-carotene, vitamin E, and selenium.

In a randomized controlled trial, eradication treatment with a regimen of omeprazole, a combination of amoxicillin and clavulanate potassium, and metronidazole twice daily for 2 weeks did not reduce the risk of gastric cancer during a 7.5-year period. In a subset of individuals without precancerous lesions at baseline, eradication of Helicobacter pylori decreased the risk of gastric cancer.

A randomized trial examining regression rates of metaplasia and/or atrophy with antibiotic and/or antioxidant therapy observed increased rates of regression for anti-Helicobacter pylori treatment and ascorbic acid and/or beta-carotene supplements.

A. Study Design: Evidence obtained from randomized controlled trials.

B. Internal Validity: Fair.

C. Consistency: Poor.

D. Direction and Magnitude of Effect: Cannot determine.

E. External Validity: Fair.

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