Dietary Fiber and Colon and Rectal Cancer Prevention
Posted Jan 02 2012 9:22pm
For many years, it was widely believed that a diet rich in fiber, and rich in fresh fruits and vegetables in particular, significantly reduced the risk of developing colorectal cancer. However, more recent public health studies have called this assumption into question. As I extensively discuss in my bestselling book, A Cancer Prevention Guide for the Human Race, there is ample clinical evidence that a so-called Mediterranean diet, which does include large amounts of fresh fruits and vegetables (as well as foods rich in unprocessed whole grains), dramatically reduces the risk of colorectal cancer and other GI tract cancers. Now, a landmark new meta-analysis research study provides important new evidence that certain high-fiber foods may, indeed, be associated with a significantly reduced risk of colorectal cancer. This comprehensive research study appears in the current issue of the British Medical Journal.
In this huge meta-analysis, 25 prospectively conducted public health studies, including 14,500 study volunteers, were analyzed; and the findings of this large clinical study may explain why recent large public health studies have not been able to confirm that a diet rich in all types of fiber can reduce colorectal cancer risk. In this meta-analysis study, dietary fiber from fruit and vegetable intake did not appear to significantly reduce the risk of developing colorectal cancer. However, whole grain foods, including cereals rich in whole grains, did appear to significantly reduce colorectal cancer risk. In fact, for each 10 grams of whole grain fiber consumed per day, colorectal cancer risk was reduced by a very significant 10 percent. Among research volunteers who consumed at least three servings of whole grains each day, the risk of developing colorectal cancer was reduced by 17 percent.
The health implications of this meta-analysis study are highly significant. First of all, the authors of this study included only prospectively conducted public health studies in their analysis, thus eliminating some of the major limitations associated with the more common retrospective “case control” studies that make up the majority of public health studies on diet and disease prevention. (As I have often mentioned, retrospective case control and case series studies are very often flawed by “recall bias,” wherein the data that is collected is based purely upon the recollections of volunteers recruited into such studies.) Secondly, the findings of this meta-analysis are supported by higher level research studies that have found that highly refined grains and cereals are stripped of important cancer-preventing nutrients and bulk fiber during processing.
While fresh fruits and vegetables (and brightly colored and dark green leafy vegetables in particular) have been shown by other studies to reduce overall cancer risk, this landmark meta-analysis study appears to reconcile the contradictory findings of previous cancer prevention studies regarding the impact of dietary fiber intake on, specifically, colorectal cancer risk. Based upon the findings of this very important study, a diet rich in unprocessed, or minimally, processed, whole grain foods appears to significantly protect against colorectal cancer. (For a much broader and deeper review of evidence-based approaches to cancer prevention, see my book, A Cancer Prevention Guide for the Human Race.)
For a comprehensive guide to living an evidence-based cancer prevention lifestyle, order your copy of my new book, A Cancer Prevention Guide for the Human Race. For the price of a cheeseburger, fries, and a shake, you can purchase this landmark new book, in both paperback and e-book formats, and begin living an evidence-based cancer prevention lifestyle today!
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Disclaimer: As always, my advice to readers is to seek the advice of your physicianbeforemaking any significant changes in medications, diet, or level of physical activity
Dr. Wascher is an oncologic surgeon, professor of surgery, cancer researcher, oncology consultant, and a widely published author