Beef Checkoff-funded Research on the Association of Red Meat Intake and Cancer Risk

Exponent, Inc. Red meat and processed meat consumption and cancer. A technical summary of the epidemiologic evidence. 2010.
This technical report summarizes the currently available epidemiologic evidence surrounding red meat and processed meat consumption and specific types of cancer.

Over 500 epidemiologic studies that evaluated the association between consumption of total meat; red meat and type of red meat; processed meat and type of processed meat; animal fat and animal protein; characteristics related to cooking practices and doneness of meat; mutagenic chemicals produced from cooking meat; overall dietary patterns; genetic traits and risk of cancers of the colon/rectum, stomach, pancreas, kidney, prostate, and breast were critically examined and findings from these studies were summarized and interpreted in this report.
The authors concluded that “Collectively, we found no conclusive evidence of a causal relation between any of the meat consumption measures and the cancers evaluated in this report.”

Technical report available here


Alexander DD, Cushing CA, Lowe KA, Sceurman B, Roberts MA. Meta-analysis of animal fat or animal protein intake and colorectal cancer. Am J Clin Nutr 2009;89(5):1402-9.
Researchers conducted meta-analyses to evaluate the evidence of animal fat intake and the risk of colorectal cancer. Analyses of high compared with low animal fat intakes and categorical dose-response evaluations were conducted. Subgroup analyses, consisting of evaluations by study design, sex, and tumor site were also performed.

Six prospective cohort studies with comprehensive dietary assessments, contributing 1070 cases of colorectal cancer and an estimated 1.5 million person-years of follow-up, were identified. On the basis of high compared with low intakes of animal fat, an independent association between animal fat intake or animal protein intake and colorectal cancer is not apparent.

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Alexander DD, Cushing CA. Quantitative assessment of red meat or processed meat consumption and kidney cancer. Cancer Detect Prev 2009;32(5-6):340-51.
Researchers conducted a meta-analysis of red meat or processed meat consumption and kidney cancer using evidence from available epidemiologic cohort and case–control studies. Data from 12 case–control studies, three cohort studies, and the Pooling Project of Diet and Cancer publication which included 13 international cohorts was analyzed. No consistent patterns or trends of increased risks with increasing levels of red or processed meat intake were reported in the individual studies. The results of this meta-analysis do not support an independent association between consumption of red meat or processed meat and the development of kidney cancer.

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Alexander DD, Morimoto LM, Mink PJ, Lowe KA. Summary and meta-analysis of prospective studies of animal fat intake and breast cancer. Nutr Res Rev 2010;23(1):169-79.
A meta-analysis was conducted to evaluate the available epidemiological cohort studies to examine the potential association between animal fat and breast cancer. On the basis of high compared with low intakes of animal fat, no significant association was observed. Similarly, no significant association between a 5% increment of energy from animal fat intake and breast cancer was observed. The results of this meta-analysis are not supportive of a positive independent association between consumption of animal fat and breast cancer.

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Alexander DD, Miller AJ, Cushing CA, Lowe KA. Processed meat and colorectal cancer: a quantitative review of prospective epidemiologic studies. Eur J Cancer Prev 2010;19(5):328-41.
A meta-analysis of prospective studies was conducted to evaluate the association between processed meat intake and colorectal cancer. Twenty prospective studies of processed meat intake and colorectal cancer were identified, with nonoverlapping study populations. On the basis of high compared with low intakes of processed meat, associations were weak in magnitude. Additionally, processed meat definitions and analytical comparisons were highly variable across studies, and isolating the independent effects of processed meat intake is difficult, given the likely influence of confounding by other dietary and lifestyle factors. In summary, the currently available epidemiologic evidence is not sufficient to support a clear and unequivocal independent positive association between processed meat consumption and colorectal cancer.

Abstract available here


Alexander DD, Morimoto LM, Mink PJ, Cushing CA. A review and meta-analysis of red and processed meat consumption and breast cancer. Nutr Res Rev 2010;23(2):349-65.
A meta-analysis and review of epidemiological cohort studies was conducted to examine the potential association between animal fat intake and breast cancer. Data from eight prospective cohort studies and the Pooling Project of Diet and Cancer publication which included 13 international cohorts was analyzed. No significant association was observed comparing the highest category of animal fat intake with the lowest. Similarly, no significant association between a 5% increment of energy from animal fat intake and breast cancer was observed. In conclusion, the results of the meta-analysis are not supportive of a positive independent association between consumption of animal fat and breast cancer.

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Alexander DD, Mink PJ, Cushing CA, Sceurman B. A review and meta-analysis of prospective studies of red and processed meat intake and prostate cancer. Nutr J 2010;9:50.
A meta-analysis of prospective studies was conducted to estimate potential associations between red or processed meat intake and prostate cancer. Fifteen studies of red meat and 11 studies of processed meat were included in the analyses. No association between high compared to low red meat consumption and total prostate cancer was observed. Additionally, dose-response analyses saw no associations with 100 g increment of red meat and total prostate cancer. A very weak positive association between processed meat intake and total prostate cancer was found, although the association was attenuated when adjusted for multiple potential confounding factors and publication bias. In conclusion, the results of this meta-analysis are not supportive of an independent positive association between red or processed meat intake and prostate cancer.

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Alexander DD, Cushing CA. Red meat and colorectal cancer: a critical summary of prospective epidemiologic studies. Obesity Reviews 2011;12(5):e472-93.
A comprehensive review was conducted on the currently available epidemiologic prospective studies of red meat intake and colorectal cancer to provide a greater understanding of any potential relationships. Thirty-five prospective studies were evaluated. Collectively, associations between red meat consumption and colorectal cancer are generally weak in magnitude, and there is a lack of a clear dose–response trend. Results are variable by anatomic tumor site (i.e. colon vs. rectum) and by gender, as the epidemiologic data are not indicative of a positive association among women while most associations are weakly elevated among men. The inability to isolate the effect red meat intake from other dietary factors (e.g. Western lifestyle, high intake of refined sugars and alcohol, low intake of fruits, vegetables and fiber) and behavioral factors (e.g. low physical activity, high smoking prevalence, high body mass index) limit the ability to identify the independent effects of red meat consumption. In summary, the currently available epidemiologic evidence is not sufficient to support an independent positive association between red meat consumption and colorectal cancer.

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Alexander DD, Weed DL, Cushing CA, Lowe KA. Meta-analysis of prospective studies of red meat consumption and colorectal cancer. Eur J Cancer Prev. 2011;20(4):293-307.
A meta-analysis of prospective studies was conducted to estimate the summary association between red meat intake and colorectal cancer. Twenty-five independent study populations were identified. On the basis of high compared with low intakes of red meat, associations are weak in magnitude, and insufficient to support an independent and unequivocal positive association between red meat intake and colorectal cancer.

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Alexander DD, Weed DL, Miller PE, Mohamed MA. Red meat and colorectal cancer: A quantitative update on the state of the epidemiologic science. J Am Coll Nutr 2015;34:521-43.
An updated meta-analysis was conducted to evaluate potential associations between red meat intake and colorectal cancer. The researchers comprehensively examined associations by creating numerous sub-group stratifications, conducting extensive sensitivity analyses, and evaluating dose-response using several different methods. Overall, all summary associations were weak in magnitude with no clear dose-response patterns. The researchers concluded that the state of the epidemiologic science on red meat consumption and colorectal cancer is best described in terms of weak associations, heterogeneity, an inability to disentangle effects from other dietary and lifestyle factors, lack of a clear dose-response effect, and weakening evidence over time.

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Bylsma LC, Alexander DD. A review and meta-analysis of prospective studies of red and processed meat, meat cooking methods, heme iron, heterocyclic amines and prostate cancer. Nutr J 2015;14:125.
A meta-analysis of prospective cohort studies of red and processed meats and prostate cancer was conducted to evaluate meat cooking methods, heme iron, and heterocyclic amine (HCA) intake exposure data. Nineteen different cohort studies from 26 publications studies were included in the analysis.

Ten prospective cohort studies were included in the meta-analysis of total red meat and total prostate cancer where no association was observed. Red meat was typically either undefined or defined as a combination of processed and unprocessed beef, pork, and lamb. Nine cohort studies evaluated the association between fresh red meat and total prostate cancer and were included in the meta-analysis where no association was observed. Fresh red meat was typically defined as fresh or unprocessed beef, veal, lamb, and pork. Eleven prospective cohort studies were included in the meta-analysis of processed meat and total prostate cancer where a weakly elevated association was observed. Processed meat was generally either defined as cured or salted meats, including ham, hot dogs, cold cuts, sausage, and bacon, or undefined. No significant associations were observed for any of the meat cooking methods, HCA, or heme iron analyses. Dose-response analyses did not reveal significant patterns of associations between red or processed meat and prostate cancer. In conclusion, the results from the meta-analyses do not support an association between red meat or processed consumption and prostate cancer, although a weak positive summary estimate was observed for processed meats was observed.

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Turner ND, Lloyd SK. Association between red meat consumption and colon cancer: A systematic review of experimental results. Exp Biol Med (Maywood) 2017;242(8):813-39.
A systematic review of experimental literature was conducted to determine whether there are any suggested causal links between red meat intake and development of colon cancer. The assumed association between intake of red meat and colon cancer development is largely based on evidence from observational studies that cannot demonstrate cause and effect nor identify mechanisms. In addition, the observational data does not have the ability to isolate red meat’s effect from the overall dietary pattern. The review concludes there is not enough evidence to support a causal link between red meat consumption in a healthy dietary pattern and colon cancer development.

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Kruger C, Zhou Y. Red meat and colon cancer: A review of mechanistic evidence for heme in the context of risk assessment methodology. Food Chem Toxicol 2018;118:131-53.
The IARC Working Group concluded that there is strong mechanistic evidence by which ingestion of red meat can be linked to human colorectal cancer and assigned red meat to Group 2A "probably carcinogenic to humans", citeing mechanistic evidence for multiple meat components, including those formed from meat processing, such as N-nitroso compounds (NOC) and heterocyclic aromatic amines, and the endogenous compound, heme iron. The mechanism of action for each of these components is different and so it is critical to evaluate the evidence for each component separately. Consequently, this review critically examined studies that investigated mechanistic evidence associated with heme iron to assess the weight of the evidence associating exposure to red meat with colorectal cancer. The evidence from in vitro studies utilized conditions that are not necessarily relevant for a normal dietary intake and thus do not provide sufficient evidence that heme exposure from typical red meat consumption would increase the risk of colon cancer. Animal studies utilized models that tested promotion of preneoplastic conditions utilizing diets low in calcium, high in fat combined with exaggerations of heme exposure that in many instances represented intakes that were orders of magnitude above normal dietary consumption of red meat. Finally, clinical evidence suggests that the type of NOC found after ingestion of red meat in humans consists mainly of nitrosyl iron and nitrosothiols, products that have profoundly different chemistries from certain N-nitroso species which have been shown to be tumorigenic through the formation of DNA adducts. In conclusion, the methodologies employed in current studies of heme have not provided sufficient documentation that the mechanisms studied would contribute to an increased risk of promotion of preneoplasia or colon cancer at usual dietary intakes of red meat in the context of a normal diet.

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Pouzou J, Costard S, Zagmutt F. Probabilistic estimates of heterocyclic amines and polycyclic aromatic hydrocarbons concentrations in meats and breads applicable to exposure assessments. Food Chem Toxicol In Press
Random effect meta-regressions were constructed to estimate concentrations of two heterocyclic amines (HCA) and eight polycyclic aromatic hydrocarbons (PAH) in meat and breads. Eighteen HCA studies and nine PAH studies of food concentration were assembled. Concentration was computed for beef, poultry, pork, and seafood, and bread. Fixed effect predictors included cooking time, form of the food, cooking method, interaction between form and cooking method, temperature at which the food was cooked, fuel of the flame source, percentage of fat, and other elements. Meat type was significant to all HCAs but only three of the PAHs. Cooking method or an interaction between cooking method and food form was significant in all the overall models for each compound, and 80% of models created for stratifications of the data based on meat type. Improvement on compilations such as the Computerized Heterocyclic Amines Resource for Research in Epidemiology of Disease (CHARRED) database comes from inclusion of additional studies, PAH compounds, more generalizable food categories, more cooking methods (such as smoking), and addition of seafood. Meta-regression allows parameters to be estimated with separation of between-study heterogeneity, and extrapolation of exposures to more foods. Resulting uncertainty estimates are useful in a probabilistic exposure assessment.

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Pouzou J, Costard S, Zagmutt F. Probabilistic assessment of dietary exposure to heterocyclic amines and polycyclic aromatic hydrocarbons from consumption of meats and breads in the United States. Food Chem Toxicol In Press
This probabilistic analysis estimated daily dietary exposures of the US population to heterocyclic amines and polycyclic aromatic hydrocarbons from meat and some varieties of bread. Mean concentrations for these foods grouped by cooking method and food form were combined with consumption data from the National Health and Nutritional Examination Survey (NHANES). Mean exposure to HCA2 (PhIP + MeIQx), was 565.3 ng/day (95% CrI: 403.73, 726.88), and to PAH8 (sum of BaP, ChY, BaA, BkF, BbF, DahA, IP, and BghiP), was 634.8 ng/day (568.38, 701.15). HCA2 exposures were not significantly different between meat types, but multiple differences were found between cooking types. Exposures to PAH8 in the mean consumers differed significantly between cooking methods, and were higher for beef than poultry (mean difference: 983 ng, 95%CrI: −77.0, 4076.0) and pork (990 ng, 95%CrI: 23.7, 4061.8), but not for any other food comparisons. Tradeoffs between exposures associated with a typical portion size of potential food replacements were also examined. Differences in HCA2 and PAH8 exposure are primarily driven by the preparation method rather than the type of meat. These findings should be considered in future studies linking PAH and HCA compounds with human health impacts.

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