AMIF disputes study claiming cured meats cause leukemia


By Tom Johnston on 2/10/2009


Source of Article:



The American Meat Institute Foundation said cured meats are a safe and healthy part of a balanced diet, responding to a recent Harvard School of Public Health Study that concluded cured meats increase the risk of leukemia in children and young adults.

The study, published in the BioMed Central Cancer journal, found an association between eating smoked or cured meat and fish more than once per week and an increased risk of acute leukemia due to exposure to nitrites and nitrosamines. Moreover, it found that people who consumed vegetables and soybean curd regularly with cured meats demonstrated a reduced risk for leukemia.

Conducted in Taiwan, the population-based case-control study investigated the dietary habits of 515 people who ranged in age from 2 to 20 years and were recruited between 1997 and 2005. Dietary data were obtained from a questionnaire.

AMI warned that, "nutrition decisions should be based on the total body of evidence not on single studies that stand in contrast to U.S. Dietary Guidelines and to other studies in published literature."

Lumped together

AMIF President James H. Hodges noted that epidemiological studies do not establish cause and effect; rather, they allow researchers to identify associations that might warrant further study. He took issue with the researchers lumping cured meats with smoked fish, noting that fish consumed by the subjects in the study Chinese salted fish is classified by the International Agency for Research on Cancer as a class I carcinogen.

"Taking this approach and combining cured meats and salted fish as a single category is like studying someone who ate arsenic and broccoli and blaming a resulting illness equally on the two," Hodges said in a statement, noting a University of California-Berkely study in June 2004, published in the American Journal of Epidemiology, concluded "consumption of hot dogs/lunch meats was not associated with the risk of childhood leukemia."

Hodges also raises the issue of epidemiological studies estimating the strength of associations by using "odds ratios." An odds ratio of 1.0 means a particular variable was neutral in its effect. An odds ratio below 1.0 suggests a variable may protect against a disease outcome. An odds ratio above 1.0 suggests a factor might need to be studied more closely.

The Harvard study's main claim had an odds ratio of 1.74. "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 by chance," AMIF said. "Epidemiological studies though 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."

'Recall bias'

Another possible flaw was the study's "case-control" approach. People were asked to recall what they had eaten, how much they had exercised and other lifestyle choices years later. AMIF said this "approach is plagued by 'recall bias' in which people recall past events inaccurately."

To view the study in its entirety, click here.



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