Intake of Fruits and Vegetables and Risk of Breast Cancer

Abstract

HE ASSOCIATION BETWEEN FRUITand vegetable consumption and breast cancer risk has been examined in more than 25 case-control studies, but relatively few cohort studies.1 A recent summary of 19 case-control and 3 cohort studies concluded that elevated fruit and vegetable consumption probably reduces breast cancer risk. Approximately half of the reported associations for all types of fruit and vegetable groups combined showed at least a 25% reduction in breast cancer risk, whereas few associations showed more than a 50% elevation in risk.2 A meta-analysis of 14 case-control and 3 cohort studies reported that breast cancer risk was reduced by 25% for vegetables (relative risk [RR], 0.75; 95% confidence interval [CI], 0.66-0.85) and by 6% for fruits (RR, 0.94; 95% CI, 0.79-1.11) for comparisons of high vs low consumption. 3Besides the 2 main groups, total fruits and total vegetables, associations for specific food groups or individual foods have been reported sporadically and the associations that have been reported may be subject to publication bias. To gain a better understanding of how total and specific fruit and vegetable Context Some epidemiologic studies suggest that elevated fruit and vegetable consumption is associated with a reduced risk of breast cancer. However, most have been case-control studies in which recall and selection bias may influence the results. Additionally, publication bias may have influenced the literature on associations for specific fruit and vegetable subgroups.Objective To examine the association between breast cancer and total and specific fruit and vegetable group intakes using standardized exposure definitions.Data Sources/Study Selection Eight prospective studies that had at least 200 incident breast cancer cases, assessed usual dietary intake, and completed a validation study of the diet assessment method or a closely related instrument were included in these analyses. Data ExtractionUsing the primary data from each of the studies, we calculated study-specific relative risks (RRs) that were combined using a random-effects model. Data SynthesisThe studies included 7377 incident invasive breast cancer cases occurring among 351 825 women whose diet was analyzed at baseline. For comparisons of the highest vs lowest quartiles of intake, weak, nonsignificant associations were observed for total fruits (pooled multivariate RR, 0.93; 95% confidence interval [CI], 0.86-1.00; P for trend = .08), total vegetables (RR, 0.96; 95% CI, 0.89-1.04; P for trend = .54), and total fruits and vegetables (RR, 0.93; 95% CI, 0.86-1.00; P for trend=.12). No additional benefit was apparent in comparisons of the highest and lowest deciles of intake. No associations were observed for green leafy vegetables, 8 botanical groups, and 17 specific fruits and vegetables. ConclusionThese results suggest that fruit and vegetable consumption during adulthood is not significantly associated with reduced breast cancer risk.

Fruit, vegetables, and antioxidants in childhood and risk of adult cancer: the Boyd Orr cohort

“…29 The lack of association between fruit and vegetable intake in childhood and breast cancer risk supports the result of a recent meta-analysis of cohort studies of adult diet and breast cancer risk. 30 Epidemiological evidence of a protective role of vitamin E intake against breast cancer in adult studies is weak, 2 31 although lower prostate cancer risk associated with vitamin E supplementation has been reported from a large randomised controlled trial. 32 The higher risk of breast cancer associated with increasing intake of retinol is surprising and in contrast with the weak but consistent observational evidence that higher intake of vitamin A, including preformed retinol, is associated with lower risk of breast cancer.…”

Diet and cancer prevention

“…However, most of these studies used casecontrol designs, which are subject to recall bias. Findings from prospective cohort studies of fruits and vegetables in stomach, breast, and colorectal cancer have generated weaker results (World Cancer Research Fund & American Institute for Cancer Research, 1997;Smith-Warner et al, 2001b;Terry et al, 2001c;IARC, 2003). In addition, an intervention study of fruits and vegetables on recurrence of colorectal adenomas did not find a reduction in risk .…”

Dietary attitudes and changes as well as use of supplements and complementary therapies by Australian and Finnish women following the diagnosis of breast cancer

“…Although multiple factors appear to increase the risk of breast cancer, diet is one of the most important lifestyle factors associated with it (Doll & Peto, 1981;Willett, 1995;Rock et al, 1997). The evidence from epidemiological studies is based mainly on observations and case-control studies, in which recall and selection bias may influence the results (Smith-Warner et al, 2001). Pooled analysis of cohort studies has not shown clear evidence for effects of dietary modification in the adulthood to associate with reduced breast cancer risk (Smith-Warner et al, 2001).…”

“…The evidence from epidemiological studies is based mainly on observations and case-control studies, in which recall and selection bias may influence the results (Smith-Warner et al, 2001). Pooled analysis of cohort studies has not shown clear evidence for effects of dietary modification in the adulthood to associate with reduced breast cancer risk (Smith-Warner et al, 2001).…”