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Just-Released European Colon Cancer Study Is No Cause for Diet Changes

Tuesday, June 14, 2005

Consumers should maintain their focus on the U.S. Dietary Guidelines, which recommend a balanced diet that includes red meat and poultry, according to the American Meat Institute Foundation. AMIF made its statement in the wake of a European study published in the Journal of the National Cancer Institute that suggested a weak association between meat consumption and colon cancer.

“It’s imperative that consumers not ride the bumpy and contradictory roller coaster of dietary epidemiology research,” said AMI Foundation Vice President of Scientific Affairs Dr. Randy Huffman. “Instead, consumers should focus on the U.S. Dietary Guidelines, which are based upon the full body of nutrition research – not just a single questionnaire-based study. The U.S. Dietary Guidelines clearly affirm the role that meat and poultry play in a healthy, balanced diet.”

In commenting upon the study, Dr. Huffman pointed out a number of issues with its methodology and conclusions:

* The study is epidemiological by design, which means it does not prove cause and effect. In most locations where study data was collected, participants were asked to keep records of what they ate – a practice that the authors themselves wrote is “known to provide imprecise estimates of food intake. Random measurement errors of food intake lead to the attenuation of disease risk estimates.” This “imprecise” technique done in a study that involved as many people at this one did could lead to measurement errors that significantly impact the interpretation of results.

* According to epidemiological experts, guided by the Bradford Hill Criteria for epidemiological research, the study’s relative risk finding of 1.71 should be viewed with skepticism. In the American Journal of Epidemiology, the esteemed epidemiologist Ernst Wynder in 1986 went even further and said that relative risks under 3.0 are suspect: “We should not rush to judgment about a causative implication when in fact the word ‘association’ ought to be used,” Wynder said.

* In layman’s terms, the researchers concluded that in a population of a hundred people, in ten years, 1.7 people vs. 1.3 people may develop colon cancer if they eat large quantities versus small quantities of red meat. It is very possible that this small increase is due to statistical chance. Strong and proven associations between a food or lifestyle factors and cancer would be expected to show risk factors that are 20 to 30 times that number.

* Other recent studies done in the U.S. in 2003 and 2005 and referenced in today’s paper have shown no evidence of a relationship between red meat and colorectal cancer.

Dr. Huffman referenced a number of comments made by the New England Journal of Medicine in April 1998, where they wrote about attempts to isolate foods and lifestyle to factors and prove cause and effect. The editors said, “Calculations of attributable risk are fraught with problems. They provide only an upper bound for the effect of a single variable because many other factors, both recognized and unrecognized, may also be contributing to the outcome. When several known factors are taken into account, it is even possible to find that they account for more than 100 percent of deaths – a nonsensical result.”

“It’s imperative that U.S. consumers value Dietary Guidelines over headlines,” Dr. Huffman said. “Although our mothers’ urgings to eat a balanced diet may not be as exciting as new research and splashy headlines, it has been proven time and again to be the most prudent.

For more information contact:
David Ray
Vice President, Public Affairs
Janet Riley
Sr. Vice President, Public Affairs

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