Meta-analysis of studies on breast cancer risk and diet: the role of fruitand vegetable consumption and the intake of associated micronutrients

A meta-analysis was carried out, in order to summarise published data on th e relationship between breast cancer, fruit and vegetable consumption and/o r the intake of beta-carotene and vitamin C. Relative risks were extracted from 26 published studies from 1982 to 1997. Random and fixed effects model s were used. Between studies, heterogeneity was found for vegetables, fruit , vitamin C but not for beta-carotene. Summary relative risk (RR) estimates based upon a random effects model, except for betacarotene, for 'high cons umption' compared with 'low consumption', derived from the studies satisfyi ng the inclusion criteria were as follows: vegetable consumption: RR = 0.75 (95% CI (confidence interval) 0.66-0.85) from 17 studies; fruit consumptio n: RR = 0.94 (95% CI 0.79-1.11) from 12 studies; vitamin C: RR = 0.80 (95% CI 0.68-0.95) from 9 studies; beta-carotene: RR= 0.82 (95% CI 0.76-0.91) fr om Il studies. This analysis confirms the association between intake of veg etables and, to a lesser extent, fruits and breast cancer risk from publish ed sources. Increasing vegetable consumption might reduce the risk of breas t cancer. (C) 2000 Elsevier Science Ltd. All rights reserved.