Different Fruits And Vegetables Affect Cancer Risk In Different Parts Of Bowel

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Academic Journal
Main Category: Colorectal Cancer
Also Included In: Nutrition / Diet
Article Date: 26 Sep 2011 - 2:00 PDT

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Eating more apples is linked to lower risk of distal colon cancer, brassicas like cabbage, cauliflower, broccoli and Brussels sprouts are linked to lower risk of cancer in both the proximal and the distal colon, while on the other hand, drinking more fruit juice appears to raise the risk of rectal cancer, according to new research from Australia published in the October issue of the Journal of the American Dietetic Association.

The large bowel comprises the rectum (the part that terminates in the anus), the distal colon (next to the rectum, includes the descending colon, sigmoid colon, and large intestine), and the proximal colon (on the other side of the distal colon to the rectum, includes the cecum, appendix, ascending colon, hepatic flexure, transverse colon and splenic flexure).

Previous studies on colorectal cancer have often failed to differentiate among sites of tumor origin in the large bowel, even though we now know that colorectal cancer (CRC) risk varies by site in the bowel, and that tumors in the proximal colon develop in a different way to tumors in the distal colon and rectum.

The reason for doing this study is because we know little about how different foods may affect different sites of the large bowel.

Lead author Professor Lin Fritschi, head of the Epidemiology Group at the Western Australian Institute for Medical Research, Perth, Western Australia, told the press:

"Fruits and vegetables have been examined extensively in nutritional research in relation to CRC, however, their protective effect has been subject to debate, possibly because of different effects on different subsites of the large bowel."

She suggested perhaps some of the confusion about the links between diet and CRC risk is because previous research did not take into account the site of the CRC.

Fritschi and colleagues from the Western Australian Institute for Medical Research, University of Western Australia and Deakin University, looked at links between fruit and vegetables and cancers and three parts of the large bowel: the proximal colon, the distal colon and the rectum.

They recruited 918 participants with CRC and 1,021 control participants with no history of the disease to take part in a case-control study. All participants filled in detailed questionnaires about their medical status and their diet and demographic information to help the researchers account for potential confounders such as socioeconomic status.

When the researchers analysed the results they found that:

• A reduced rate of proximal colon cancer was linked to eating brassicas like broccoli, cabbage, cauliflower, Brussels sprouts.


• Both total vegetable intake and total vegetable and fruit intake were linked to a lower risk of distal colon cancer.


• A significant reduction in distal colon cancer risk was linked to dark yellow vegetables and apples.


• But, fruit juice, on the other hand, appeared to raise the risk for rectal cancer.


• Neither total fruit and vegetable nor total fruit nor total vegetable showed any links with risk of proximal colon cancer and rectal cancer.

"... from a public health point of view it is easier to translate food-based analyses into dietary recommendations, rather than using the intake of single nutrients," conclude the authors.

Fritschi said we now need to confirm these results:

"The replication of these findings in large prospective studies may help determine whether a higher intake of vegetables is a means for reducing the risk of distal CRC."

According to Cancer Council Australia, excluding non-melanoma skin cancer, colorectal cancer is the second most common cancer in both men and women in Australia, where there are more than 14,000 new cases every year and 4,047 people died from the disease in 2007.

Written by Catharine Paddock PhD
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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