No association between red or processed meat consumption and cancer has been found according to a new, comprehensive assessment of the scientific evidence.
The report, funded by the Beef and Pork Checkoff program, examines the hypothesis that meat consumption may contribute to human carcinogenesis.
The hypothesis arose in the 1960s, when certain studies correlated per capita intake levels of animal fat with cancer rates, particularly colorectal cancer and breast cancer. Last year, the Archives of Internal Medicine published a study whose researchers concluded “red and processed meat intakes were associated with modest increases in total mortality, cancer mortality, and cardiovascular disease mortality.” (The study population included the National Institutes of Health–AARP Diet and Health Study cohort of half a million people aged 50 to 71 years. Their meat intake was estimated from a food frequency questionnaire.)
However, this new industry report states that, “despite significant improvements in research methodology, technological advances in statistical computing, an increased understanding of the biological aspects of carcinogenesis, and an abundance of data from hundreds of published studies, a lack of a clear scientific consensus regarding meat consumption and cancer remains today.”
Randomized double-blind controlled clinical trials, the “gold standard” in testing, are not typically conducted on the relationship of meat and cancer and certain other studies can be subject to bias. Published epidemiological studies have often found associations between red meat and processed meat and certain cancers, such as colorectal, esophageal, lung and stomach. However the report points out the following:
- Most associations are weak in magnitude
- Many associations are null or inverse
- Most associations are not statistically significant
- Patterns of associations vary by gender and anatomic location of the tumor
- Red and processed meat definitions vary across studies
- Measures of meat intake and the analytical comparisons are variable
Because researchers believe cancer development is related to a number of genetic, lifestyle, infectious and environmental factors, and usually develops over a long period of time, it makes it difficult to identify the underlying factors of carcinogenesis, according to report author and leading epidemiologist, Dr. Dominik Alexander, PhD, MSPH. Still, he says, “…no mechanism for red meat has been established as being responsible for increasing the risk of cancer in human studies and …the totality of available scientific evidence is not supportive of an independent association between red meat and processed meat and cancer.”
Shalene McNeill, PhD, RD, executive director of nutrition research with the National Cattlemen’s Beef Association (NCBA), a beef checkoff contractor says the report “will serve as a comprehensive resource on the epidemiologic associations of red meat and processed meat and cancer for industry stake holders, nutrition scientists, educators and communicators. It concludes the available epidemiologic evidence is not supportive of a causal relationship between red meat and any of the cancers evaluated.”
