We’ve been told by the authorities repetitively that eating plenty of fruits and vegetables will lower our risk of cancer. However, a recent study in the American Journal of Clinical Nutrition says that ain’t so.
Fire up the grill—we’re havin’ steak tonight!
Researchers looked at data from over 450,000 participants (men and women over 50) in the National Institutes of Health—AARP Diet and Health Study. Diet data was collected by self-administered questionnaire. State-level cancer registries identified the cancers that developed during the average follow-up of seven years.
Their conclusions and selected comments:
Intake of fruit and vegetables was generally unrelated to total cancer incidence in this cohort.
However, on the basis of animal studies, human case control and cohort studies, and randomized controlled trials, there is likely no harm associated with the consumption of fruit and vegetables and their consumption may prevent cardiovascular disease.
Indeed, analyses in this cohort and in others that have investigated dietary patterns rich in fruit and vegetables have found reduced risks of colorectal cancer [three references cited] and mortality, including death from cardiovascular disease and all cancers [one reference was cited supporting reduced deaths from CVD and all cancers—a Mediterranean diet study].
As in all good science reports, the researchers compare and contrast their findings with similar published research. They note that theirs is one of only four large cohort studies that have examined this issue. Two of the other three (see references below) also found no association between total cancers and fruit and vegetable consumption. The one that did find a beneficial linkage was the smallest of the four, so not as compelling.
Before this research was published, some experts suggested that adequate fruit and vegetable intake could prevent between 5 and 12% of cancers.
Eat your fruits and vegetables because they taste good, provide myriad nutrients, and may have some other healthful properties. But not to lower overall cancer risk.
References:
George, Stephanie, et al. Fruit and vegetable intake and risk of cancer: a prospective cohort study. American Journal of Clinical Nutrition, 89 (2009): 347-353.
Hung, H.C., et al. Fruit and vegetable intake and risk of major chronic disease. Journal of the National Cancer Institute, 96 (2004): 1,577-1,584.
Takachi, R., et al. Fruit and vegetable intake and risk of total cancer and cardiovascular disease [in Japan]. American Journal of Epidemiology, 167 (2008): 59-70.
Benetou, V., et al. Vegetables and fruit in relation to cancer risk: evidence from the Greek EPIC Cohort Study. Cancer Epidemiology, Biomarkers, and Prevention, 17 (2008): 387-392.
Diabetic Mediterranean Diet 
Ok, that one surprises me big time. I thought it was a foregone conclusion with heart disease but I’ll throw the question out to you, though. Is there any data looking at fruit/veggie consumption and CV disease, or all cause mortality? I thought that had been shown with the Mediterranean diet and that’s high in plant products. But maybe it’s not the fruit and veggies, per se and more about the fats involved.
I know the DASH diet can lower bp and that’s high in fruits, especially those high in potassium, but nothing with hard outcomes has been run yet.
I’m still researching fruit/veggies and effects on cardiovascular disease and all-cause mortality. Will report on it here.
I find a frustrating amount of inconsistency and contradictions in the nutritional literature.
-Steve
See the article by Dr Groves :-http://www.second-opinions.co.uk/why-eat-5-portions-1.html
P Winter, thanks for that link. Dr. Groves cites 21 references in support of his opinions.
[For American readers of Dr. Groves article, be aware that a “solicitor” in the U.K. is an attorney.