The Evidence Becomes Even Stronger:
Meat, Fiber-rich Foods, and Colon Cancer
By Dr. Joel Fuhrman MD
In 2007, the World
Cancer Research Fund (WCRF) released their Expert Report on Food,
Nutrition, Physical Activity, and the Prevention
of Cancer. This year as a part of their Continuous
Update Project, they have released an addendum outlining some of
the new developments in research on the connection between diet and
colorectal cancers.1
Colon cancer is the second most common cancer type. These cancers
are the ones most closely linked to lifestyle – colon and
rectal cancer rates increase with industrialization, and are far more
common in high income countries – this means that colon and
rectal cancers are also the most preventable cancers. As a result of
this 2011 update, the evidence that red and processed meats cause
colorectal cancers and that fiber-rich foods prevent colorectal
cancers has been upgraded from “probable” to “convincing”
by the WCRF.
Red
and processed meats contain a number of potentially carcinogenic
substances, including N-nitroso compounds, which are especially high
in processed meats due to added preservatives. Cooking red meats at
high temperatures forms additional carcinogens called heterocyclic
amines, polycyclic aromatic hydrocarbons, and dioxins.1, 2.
This update took into account six new studies on the combined intake
of red and processed meat, six studies on red meat alone, and eleven
on processed meat alone. The scientists reviewing all of this
information concluded that each 100 grams per day (3.5 ounces) of red
and processed meat consumed increases colon cancer risk by 21%.
For red meat alone, each 3.5 ounce serving per day produced a 17%
increase in risk of colon and rectal cancers. For processed meat
alone, each 1.75 ounce serving per day produced a 24% increase in
colon cancer. Red and processed meats were determined to be a
convincing cause of colon and rectal cancers.1
Fiber-rich foods, such as fruits, vegetables, beans, and whole
grains have been associated in countless studies with lower cancer
rates. In the WCRF’s update, 12 new studies on dietary fiber
and fiber-rich foods were analyzed, and every 10 grams/day of fiber
consumed produced an 11% decrease in colon cancer risk. Ten grams of
fiber is not very much – it is about the amount in one cup of
cooked broccoli plus one medium-sized apple.
A significant risk reduction can be achieved by basing the diet primarily on whole plant foods, which are rich in fiber. It is important to note that these studies were based on food sources of fiber, not supplements – so this decrease in risk is attributed to fiber-rich foods, not fiber itself. This makes sense, since the foods highest in fiber are also the ones highest in protective nutrients – minerals, antioxidants, and other phytochemicals.
In addition, fiber itself increases stool bulk, which shortens transit time in the colon. Also, the fermentation of certain
fibers and resistant starch (abundant in fiber-rich foods) produces
protective substances like butyrate, which has numerous anti-cancer effects.
The release of this report by the WCRF has the goal of helping
people make choices that reduce their chances of developing cancer,
and my goal is the same: to bring this important information to the
public, letting everyone know that our lifestyle choices can have a
huge impact on our risk of cancer.
Dr. Fuhrman is a best-selling author and board certified
family physician specializing in lifestyle and nutritional medicine.
Visit his informative website at DrFuhrman.com.
References:
Continuous Update Project
Interim Report Summary. Food, Nutrition, Physical Activity, and the
Prevention of Colorectal Cancer.. World Cancer Research
Fund / American Institute for Cancer Research.; 2011.
Wu J, Dong S, Liu G, et al: Cooking process: a new
source of unintentionally produced dioxins?Journal of
Agricultural and Food Chemisry 2011;59:5444-5449.
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