Does Eating More Variety of Fruits and Vegetables Reduce Risk of Cancer? Findings from a Systematic Review and Meta-Analysis

Specific food groups, particularly fruits and vegetables, have been shown to reduce the risk of some cancers. However, cancer reduction from greater variety within these food groups is under-studied. This study aimed to evaluate the evidence on the relationship between greater variety, especially within fruits and vegetables, and incident cancer. A systematic search of recent prospective studies was conducted in PubMed, Scopus, Web of Science, supplemented by hand-searching, and appraised for quality. Summary risk ratios (RRs) and 95% confidence intervals were estimated using fixed- and random-effects models for high vs. low intake categories and for linear associations; Cochrane Q test detected sources of heterogeneity among included studies. Total sample size was 2285,720 with 9420 cases of cancers in 5 included studies. All were assessed as high quality and 4 provided 7 risk estimates for meta-analysis. The risk of all cancers was not associated with high vs. low variety of both fruit and vegetable items, fruits, vegetables, and subtypes of vegetable items. Studies adjusting for BMI showed an inverse association for high variety of vegetable subgroups (RR 0.80, 95% CI: 0.68, 0.95). Risk of stomach cancer or rectal cancer increased with high variety of fruit and vegetable, or fruit variety. However, lung cancer risk reduced with high vegetable subgroup variety and, in men only, colon cancer risk reduced with high variety of all foods across 5 food groups. Although no dose-response was found between fruits and/or vegetables variety and risk of all cancers, the risk of esophageal squamous cancer significantly decreased with two new fruit, or fruit and vegetable, items by 24% and 12%, respectively. We found that only higher variety of vegetables subgroups was linked to lower risk of cancer, particularly lung. Total diet variety lowered men’s risk of colon cancer. None.