Pickled food and risk of gastric cancer--a systematic review and meta-analysis of English and Chinese literature.

BACKGROUND Ecological and experimental studies have suggested an increased risk of gastric cancer in relation to consumption of pickled vegetables in East Asia. METHODS We conducted a meta-analysis of epidemiologic observational studies to evaluate the existing evidence. Searching PubMed, Vip Chinese Periodical, and China National Knowledge Infrastructure databases, we found a total of 60 studies, 50 case-control, and 10 prospective. We compared gastric cancer risk in pickled vegetable/food users versus nonusers (11 studies) or versus those in the lowest reported category of use (49 studies). Pooled results were computed with random-effects models. RESULTS Among case-control studies, 30 showed significant increased risk and one showed significant decreased risk. Among prospective studies, two showed a significant increased risk but none showed a significant decreased risk. The OR (95% CI) was 1.52 (1.37-1.68) for the overall association, 1.56 (1.39-1.75) for case-control, and 1.32 (1.10-1.59) for cohort studies. The OR (95% CI) was 1.89 (1.29-2.77) in Korean, 1.86 (1.61-2.15) in Chinese, and 1.16 (1.04-1.29) in Japanese studies, and 1.14 (0.96-1.35) in studies from other countries. There was high heterogeneity in overall and subgroup analyses. There was little evidence for publication bias. CONCLUSION Our results suggest a potential 50% higher risk of gastric cancer associated with intake of pickled vegetables/foods and perhaps stronger associations in Korea and China. IMPACT The results of this study may offer ways to reduce the risk of gastric cancer in highly populated areas with high incidence of gastric cancer.