PROTECTIVE EFFECT OF FRUITS AND VEGETABLES ON STOMACH-CANCER IN A COHORT OF SWEDISH TWINS

Observational studies, primarily of a case-control design, have shown an inverse association of fruit and vegetable consumption with the ris k of stomach cancer, a finding tentatively attributed to anti-oxidant vitamins. Ensuing randomized-intervention trials of these vitamins, ho wever, have been mostly negative, Therefore, the seemingly protective effect of fruit and vegetables in case-control studies is suspected to be influenced by the information bias inherent in the retrospective a ssessment of exposure, particularly since pre-conceptions about the wh olesome effects of these foods are common among the public, Our aim wa s to examine the association of fruit and vegetable intake with the ri sk of stomach cancer in a prospective cohort study. Fruit and vegetabl e consumption was assessed in 1967 in 11,546 individuals in the Swedis h Twin Registry, along with a wide range of potentially confounding fa ctors. Complete follow-up through 1992 was attained through record lin kage to the National Cancer and Death Registers. The relative risk of stomach cancer was estimated in proportional hazards models, with conf idence intervals (CIs) adjusted for correlated outcomes. The risk of s tomach cancer was inversely related to fruit and vegetable consumption , Controlling for potentially confounding factors, the relative risk a mong subjects with the lowest compared to those with the highest intak e was 5.5 (95% CI 1.7-18.3) with a statistically significant dose-risk trend (p < 0.05), Our results indicate that information bias is not l ikely to explain the discrepancy between the results of observational studies and of randomized-intervention trials. (C) 1998 Wiley-Liss, In c.