Supports Chapter 8: Why 'Five Portions'?
You may have heard on the news today about this latest study, which didn't find much benefit from forcing five portions of fruit and veges down. I was not surprised as all the ones before it are detailed in Chapter 8 of Trick and Treat. But it was good of the media to report it. 'Bad news' like this is generally missed.
There have been several studies since the '5-a-day' message was first trumpeted. None so far has found much, if any benefit from eating so much vegetation. This latest one is by far the biggest - but its findings are much in line with the earlier studies.
Wouldn't it have been better if the diet dictocrats had thought to do a study before they told us all to eat so much!
The abstract to the latest study is below.
I have written a full article explaining why it's NOT a good idea to eat 5-a-day.
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Paolo Boffetta, et al. Fruit and Vegetable Intake and Overall Cancer Risk in the European Prospective Investigation Into Cancer and Nutrition (EPIC) JNCI 2010 [e-pub ahead of print]
Background: It is widely believed that cancer can be prevented by high intake of fruits and vegetables. However, inconsistent results from many studies have not been able to conclusively establish an inverse association between fruit and vegetable intake and overall cancer risk.
Methods: We conducted a prospective analysis of the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort to assess relationships between intake of total fruits, total vegetables, and total fruits and vegetables combined and cancer risk during 1992–2000. Detailed information on the dietary habit and lifestyle variables of the cohort was obtained. Cancer incidence and mortality data were ascertained, and hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using multivariable Cox regression models. Analyses were also conducted for cancers associated with tobacco and alcohol after stratification for tobacco smoking and alcohol drinking.
Results: Of the initial 142 605 men and 335 873 women included in the study, 9604 men and 21 000 women were identified with cancer after a median follow-up of 8.7 years. The crude cancer incidence rates were 7.9 per 1000 person-years in men and 7.1 per 1000 person-years in women. Associations between reduced cancer risk and increased intake of total fruits and vegetables combined and total vegetables for the entire cohort were similar (200 g/d increased intake of fruits and vegetables combined, HR = 0.97, 95% CI = 0.96 to 0.99; 100 g/d increased intake of total vegetables, HR = 0.98, 95% CI = 0.97 to 0.99); intake of fruits showed a weaker inverse association (100 g/d increased intake of total fruits, HR = 0.99, 95% CI = 0.98 to 1.00). The reduced risk of cancer associated with high vegetable intake was restricted to women (HR = 0.98, 95% CI = 0.97 to 0.99). Stratification by alcohol intake suggested a stronger reduction in risk in heavy drinkers and was confined to cancers caused by smoking and alcohol.
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
The association between high intake of fruits and vegetables and reduction in overall cancer risk is not conclusively established.
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.
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.
This study reveals a very modest association between high intake of fruits and vegetables and reduced risk of cancer.
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.