open access: Fruit and vegetables and cancer risk - UKPMC Article - UK PubMed Central

Blogger's note: the article/reference(s) does not include ovarian cancer research on this issue

The possibility that fruit and vegetables may help to reduce the risk of cancer has been studied for over 30 years, but no protective effects have been firmly established..........

JNCI podcast: re: recent frutis/vegetable/cancer risk study

Note: scroll down the page - the link as below will automatically start

"JNCI Interview: Dr. Regina Ziegler discusses a large study suggesting that fruits and vegetables are associated with only a modest reduction in cancer risk."

An apple (and four other fruit and vegetables) a day… : The Lancet

JNCI Editorial: Fruits, Vegetables, and Cancer Prevention: Turmoil in the Produce Section

Some key excerpts - full text of Editorial available without cost:

•  In this issue of the Journal, Boffetta et al. (6) report findings from a European cohort of nearly 400 000 men and women who developed approximately 30 000 cancers at all sites combined over nearly 9 years of follow-up. After accounting for measurement error, a very weak but statistically significant inverse association was seen—a 4% lower incidence of all cancers combined for an increment of 200 g of total fruits and vegetables per day, which corresponds to about two extra servings per day.

• Most fundamentally, this study strongly confirms the findings from other prospective studies that the results of case–control studies were overly optimistic and that any association of intake of fruits and vegetables with risk of cancer is weak at best.

• Their more detailed analyses suggesting a stronge rbenefit among heavier consumers of alcohol lend some weight to a causal interpretation because other studies (7,8) have suggested that folate, primarily from fruits and vegetables,may be more beneficial in the context of regular alcohol consumption.

• A very weak or undetectable association between fruits and vegetables and risk of cancer does not exclude the possibility that oneor a small group of fruits or vegetables, or a specific substance in some of these foods, has an important protective effect.

• Even if we assume that the weak association seen in the EPIC cohort represents a true protective effect of fruits and vegetables,the question would still remain whether an effect of this magnitude should lead to clinical interventions or public health actions.Conveniently, although the evidence for benefits of fruits and vegetables against cancer was waning, data supporting benefits for cardiovascular disease were accumulating.

•  In summary, the findings from the EPIC cohort add further evidence that a broad effort to increase consumption of fruits and vegetables will not have a major effect on cancer incidence.

Fruit and Vegetable Intake and Overall Cancer Risk in the European Prospective Investigation Into Cancer and Nutrition (EPIC) - JNCI abstract

Abstract:
Conclusions: A very small inverse association between intake of total fruits and vegetables and cancer risk was observed in this study. Given the small magnitude of the observed associations, caution should be applied in their interpretation.

CONTEXT AND CAVEATS
Prior knowledge
The association between high intake of fruits and vegetables and reduction in overall cancer risk is not conclusively established.
Study design
European Prospective Investigation into Cancer and Nutrition (EPIC) cohort study was conducted between 1992 and 2000. Diet and lifestyle data were self-reported by the participants. Cancer incidence and mortality data were obtained from country-specific national and regional registries. Association between overall cancer risk and high intake of total fruits, total vegetables, and total fruits and vegetables combined was assessed. Estimated cancer risks were adjusted for smoking, alcohol consumption, and many other variables.
Contribution
High intake of vegetables, and fruits and vegetables combined, was associated with a small reduction in overall cancer risk. The association was stronger in heavy alcohol drinkers but was restricted to cancers caused by smoking and drinking.
Implications
This study reveals a very modest association between high intake of fruits and vegetables and reduced risk of cancer.
Limitations
The inverse association between overall cancer risk and high intake of fruits and vegetables was weak. Errors inherent to self-reported dietary habits may have resulted in bias.
From the Editors