American Meat Institute Foundation Says Red Meat Is a Safe and Healthy Part of a Balanced DietFriday, November 5, 2010
Washington, D.C. – The American Meat Institute Foundation (AMIF) said that meat continues to be a healthy part of a balanced diet and that nutrition decisions should be based on the total body of evidence – not on single studies that include weak and inconsistent evidence and stand in contrast to U.S. Dietary Guidelines and to other studies.
AMIF issued the statement in response to a study in the American Journal of Gastroenterology that is making news today by alleging a link between esophageal cancer and red meat consumption.
The Foundation noted that this study fails to put esophageal cancer research into perspective. A comprehensive review published in 2008 by the World Health Organization’s International Agency for Research on Cancer (IARC) found that, “The main risk factors for squamous cell esophageal cancer in western countries are alcohol and tobacco consumption, which in individual studies have been found to account for 75–90 percent of the disease.” Another 2003 study by Lawrence Engel of the National Cancer Institute concluded that approximately 89 percent of esophageal squamous cell carcinoma may be attributed to smoking, alcohol use and low fruit and vegetable consumption and approximately 79 percent of esophageal adenocarcinoma cases can be attributed to smoking, obesity, reflux disease and low fruit and vegetable consumption.
In addition, AMIF Director of Scientific
“Unfortunately, epidemiological findings often are reported as definitive, as if a researcher has determined the cause of a disease, case closed. But epidemiological studies simply cannot do that. This study, in particular, showed very weak findings that do not meet the evidence threshold that would merit concern,” Booren said. “Consumers should rest assured that red meat continues to be a healthy part of a balanced diet,” she said.
Booren also said that news reports omitted the study’s finding that processed meats, nitrite and nitrate were not associated with these cancers, and she argued that these types of “null” findings should not be overlooked by media.
According to Booren, epidemiological studies use “odds ratios” to estimate the strength of an association between the disease and the risk potential of a measured variable, such as a specific food or lifestyle choice. An odds ratio of “1.0” means that a particular variable was statistically neutral in its effect. When the number falls below “1.0,” the finding suggests that variable may protect against a disease outcome. When the number is above “1.0,” a factor may need to be examined more closely related to its risk profile.
A general rule of thumb within the field of epidemiology holds that an odds ratio below “2.0” is not viewed as a strong relationship and may actually have occurred merely by chance. Epidemiological studies thought to have truly uncovered significant associations and cause for concern – like studies looking at tobacco and lung cancer -- found odds ratios in the 10-25 range.
“This study did not achieve the standard threshold that would generate concern,” Booren said. “At best, this hypothesis merits further study. It is certainly no reason for dietary changes.”
Booren also said that a characteristic of a study with a meaningful finding is that the number of illnesses being observed should increase when exposure to the factor of concern increases. For example, the risk of lung cancer should increase consistently with the number of cigarettes smoked. This study’s findings did not show a consistent increase in risk. Instead, the risk rose and fell as more meat was consumed. This inconsistency in “dose-response,” calls the study’s conclusions into question.
“The body of evidence clearly demonstrates that meat is a healthy part of a balanced diet. Meat contains protein, amino acids and essential nutrients like iron and zinc that are the keys to good health,” Booren added. “Rather than act on a single study, consumers should rely upon the full body of evidence. That evidence is reflected in the U.S. Dietary Guidelines, which affirm the health benefits of meat. A balanced diet and a healthy body weight are what common sense suggests -- and what the total evidence has shown -- are the keys to good health.”
Additional Resource: Key Quotes from the Epidemiological Community About Studies With Hazard Ratios Below “2.0”:
- The World Health Organization and the
International Agency for Research on Cancer in
1980 wrote, “Relative risks of less than 2.0
may readily reflect some unperceived bias or
confounding factor, those over 5.0 are unlikely
to do so.”
- In 1981, esteemed researcher Sir Richard
Doll argued that “when relative risk lies
between 1 and 2 ... problems of interpretation
may become acute, and it may be extremely
difficult to disentangle the various
contributions of biased information,
confounding of two or more factors, and cause
and effect. In 1994, the National Cancer
Institute wrote, “In epidemiologic research,
relative risks of less than 2 are considered
small and usually difficult to interpret. Such
increases may be due to chance, statistical
bias or effects of confounding factors that are
sometimes not evident.”
- Most recently, in 1999, Robert Temple MD, director of drug evaluation, U.S. Food and Drug Administration in a letter to the Journal of the American Medical Association, wrote, “Relative risks of 2 have a history of unreliability….My basic rule is if the relative risk isn’t at least 3 or 4, forget it.”
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