Association of fiber and colorectal cancer risk differs depending on dietary assessment method

April 20, 2010

High dietary fiber intake was associated with a lower risk of colorectal cancer when researchers used data from food diaries but not when they used data obtained from food frequency questionnaires, according to a study published online April 20 in the Journal of the National Cancer Institute.

Previous studies have examined the issue of dietary fiber and risk of colorectal cancer, but the results have been inconsistent, particularly in studies that used food-frequency questionnaires (FFQs).

In this study, Christina Dahm Ph.D., and Kay-Tee Khaw, MBBChir., of the University of Cambridge in the UK, and colleagues used data obtained from both food diaries and food frequency questionnaires to estimate fiber intake. Their prospective, case-control study was nested within seven UK cohort studies and included 579 patients who developed colorectal cancer more than 1 year after they began keeping the food diaries. These case patients' fiber intake was compared with that of 1,996 control subjects who did not develop colorectal cancer. Case and control subjects were matched for sex, age, and date of diary completion.

The researchers found that participants who had higher intakes of fiber, ascertained by food diaries, were less likely to develop colorectal cancer than those with lower intakes. For individuals who consumed an average of 24 grams per day of dietary fiber, the odds of developing colorectal cancer were 30% lower than for those who consumed an average 10 grams per day. The difference was statistically significant and consistent even after the researchers took into account other risk factors for colorectal cancer, such as age, physical activity, and intakes of alcohol and red meats.

However, when the researchers performed the same analysis using data obtained from the food frequency questionnaires, they found no statistically significant association between fiber intake and the risk of colorectal cancer.

"These findings strengthen existing evidence that supports recommendations to increase dietary fiber intake in populations to reduce colorectal cancer incidence," the authors write. They suggest that "the fact that we found no association using...the FFQ may explain the lack of convincing evidence relating fiber intake to a substantial reduction in colorectal cancer risk in some previous studies that relied on FFQs."

In an accompanying editorial, Ross Prentice, Ph.D., of the Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, notes that accurate measurement of dietary components remains a major challenge in studies of diet and cancer risk. He calls for the development of biological markers to measure intake more accurately. "The explicit use of biomarkers to correct nutritional epidemiology associations for systematic and random measurement error in dietary assessment seems a logical next step in the nutritional epidemiology research agenda," he writes.
-end-
Contacts:
Article: Kay-Tee Khaw, +44 1223 217292; kk101@medschl.cam.ac.uk
Editorial: Ross Prentice, (206) 667-4264, rprentic@fhcrc.org

Note to Reporters:

The Journal of the National Cancer Institute is published by Oxford University Press and is not affiliated with the National Cancer Institute. Attribution to the Journal of the National Cancer Institute is requested in all news coverage.

Visit JNCI online at http://jnci.oxfordjournals.org and the JNCI press room at http://www.oxfordjournals.org/our_journals/jnci/press_room.html

For the latest cancer news and studies, follow us on Twitter @JNCI_Now

Journal of the National Cancer Institute

Related Colorectal Cancer Articles from Brightsurf:

Colorectal cancer treatment: the winning combinations
Chemotherapy has distressing side effects for patients and increases the risk of developing resistance to the treatment.

A new model to predict survival in colorectal cancer
This signature could be useful in clinical practice, especially for colorectal cancer diagnosis and therapy.

Roadmap to reducing colorectal cancer deaths
The American Gastroenterological Association has outlined a strategy to increase the number of people screened via tests that are more convenient, accurate and less expensive and tailored to people's individual cancer risks.

Study provides new insight on colorectal cancer growth
A new study by researchers at the University of Kentucky identifies a novel function of the enzyme spermine synthase to facilitate colorectal cancer growth.

Researchers ID target for colorectal cancer immunotherapy
Researchers at the Indiana University Melvin and Bren Simon Comprehensive Cancer Center have identified a target for colorectal cancer immunotherapy.

Colorectal cancer partner-in-crime identified
A protein that helps colorectal cancer cells spread to other parts of the body could be an effective treatment target.

Cancer cell reversion may offer a new approach to colorectal cancer treatment
A novel approach to reverse the progression of healthy cells to malignant ones may offer a more effective way to eradicate colorectal cancer cells with far fewer side effects, according to a KAIST research team based in South Korea.

A novel pathway to target colorectal cancer
Survival rates for patients with late-stage colorectal cancer are dismal, and new therapeutic strategies are needed to improve outcomes.

Colorectal cancer rates in Canada
The incidence of colorectal cancer among younger adults increased in recent years in this analysis of data from Canadian national cancer registries that included about 688,000 new colorectal cancers diagnosed over more than 40 years.

Cancer drugs promote stem cell properties of colorectal cancer
Scientists from the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) and the Mannheim University Medical Center have now discovered that a certain group of cancer drugs (MEK Inhibitors) activates the cancer-promoting Wnt signalling pathway in colorectal cancer cells.

Read More: Colorectal Cancer News and Colorectal Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.