Fruit and vegetables consumption and gastric cancer: a systematic review and meta-analysis of cohort studies.

Fruit and vegetable intake is widely recognized as protective for gastric cancer occurrence but prospective research challenged this belief. To evaluate the influence of design options in such results we did a meta-analysis of relevant published cohort studies identified from inception to 2004 in PubMed, EMBASE, and LILACS. Random-effects meta-analysis, stratification, and meta-regression were used to pool effects and to analyze the association with type of outcome event and length of follow-up independent of other study characteristics. An inverse association was observed between fruit intake and gastric cancer incidence (relative risk, RR = 0.82; 95% confidence interval, CI = 0.73-0.93) and stronger for follow-up periods of > or = 10 yr (RR = 0.66; 95% CI = 0.52-0.83) but not when the study outcome was death (RR = 1.08; 95% CI = 0.86-1.35). For vegetables, the RR was 0.88 (95% CI = 0.69-1.13) using all incidence studies and 0.71 (95% CI = 0.53-0.94) when considering only those with the longer follow-up. The association observed between vegetable intake and gastric cancer mortality was 1.05 (95% CI = 0.89-1.25). Other study characteristics assessed added no significant contribution to explain heterogeneity. This meta-analysis showed that design options might play a key role in the observed magnitude or the direction of the association between fruit and vegetable intake and gastric cancer.