High intake of dietary fiber not associated with reduced risk of colorectal cancer

In an analysis combining data from 13 studies, high intake of dietary fiber was not associated with reduced risk of colorectal cancer, according to a study in the December 14 issue of JAMA.


Dietary fiber has been hypothesized to reduce the risk of colorectal cancer, according to background information in the article. However, the results of numerous epidemiological studies have been inconsistent. Ecological correlation studies and many case-control studies have found an inverse association between dietary fiber intake and risk of colorectal cancer. But most prospective cohort studies have found no association between dietary fiber intake and risk of colorectal cancer or adenomas (precursors of colorectal cancer), and randomized clinical trials of dietary fiber supplementation have failed to show reductions in the recurrence of colorectal adenomas.

Yikyung Park, Sc.D., formerly of the Harvard School of Public Health, Boston, and colleagues evaluated the association between dietary fiber intake and risk of colorectal cancer by reanalyzing the primary data from 13 prospective cohort studies (Pooling Project of Prospective Studies of Diet and Cancer). The pooled analysis included 725,628 men and women who were followed-up for 6 to 20 years across studies.

During the follow-up, 8,081 colorectal cancer cases were identified. Among the studies, median (midpoint) energy-adjusted dietary fiber intake ranged from 14 to 28 g/d in men and from 13 to 24 g/d in women. The major source of dietary fiber varied across studies with cereals as a major contributor to dietary fiber intake in the European studies, and fruits and vegetables as the main sources in the North American studies.

In the age-adjusted model, dietary fiber intake was significantly associated with a 16 percent lower risk of colorectal cancer in the highest quintile compared with the lowest. This association was attenuated slightly but still remained statistically significant after adjusting for nondietary risk factors, multivitamin use, and total energy intake. Additional adjustment for dietary folate intake further weakened the association. In the final model, which further adjusted for other dietary factors, such as red meat, total milk, and alcohol intake, only a nonsignificant weak inverse association was found. Fiber intake from cereals, fruits, and vegetables was not associated with risk of colorectal cancer.

“The association between dietary fiber intake and risk of colorectal cancer has been inconsistent among observational studies and several factors may explain the disparity: potential biases in each study, the failure to adjust for covariates in the multivariate models, and the range of dietary fiber intake,” the authors write.

“In conclusion, we did not find support for a linear inverse association between dietary fiber intake and risk of colorectal cancer in a pooled analysis of 13 prospective cohort studies. Although high dietary fiber intake may not have a major effect on the risk of colorectal cancer, a diet high in dietary fiber from whole plant foods can be advised because this has been related to lower risks of other chronic conditions such as heart disease and diabetes,” the researchers write.

Media Contact

Kevin Myron EurekAlert!

More Information:

http://www.jamamedia.org

All latest news from the category: Health and Medicine

This subject area encompasses research and studies in the field of human medicine.

Among the wide-ranging list of topics covered here are anesthesiology, anatomy, surgery, human genetics, hygiene and environmental medicine, internal medicine, neurology, pharmacology, physiology, urology and dental medicine.

Back to home

Comments (0)

Write a comment

Newest articles

Lighting up the future

New multidisciplinary research from the University of St Andrews could lead to more efficient televisions, computer screens and lighting. Researchers at the Organic Semiconductor Centre in the School of Physics and…

Researchers crack sugarcane’s complex genetic code

Sweet success: Scientists created a highly accurate reference genome for one of the most important modern crops and found a rare example of how genes confer disease resistance in plants….

Evolution of the most powerful ocean current on Earth

The Antarctic Circumpolar Current plays an important part in global overturning circulation, the exchange of heat and CO2 between the ocean and atmosphere, and the stability of Antarctica’s ice sheets….

Partners & Sponsors