Estrogenic Cooked-Meat Carcinogens

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In the 1990s, two international studies found an association between breast cancer, and intake of fried meat and broiled meat, in Finland and Uruguay. In 2000, researchers in Iowa identified the probable culprit: a heterocyclic amine abbreviated PhIP.

Heterocyclic amines are a “class of ubiquitous mutagens found in cooked meats, poultry, fish, and [cigarette] smoke.” The effect was confirmed on Long Island, and extended to grilled barbecued and smoked meats. But, why more breast cancer risk? Well, these cooked meat carcinogens are mutagenic—meaning they damage DNA. In fact, you can directly correlate the number of DNA mutations in human breast tissue with estimates of dietary intake. 

They asked women undergoing breast reduction surgery about their meat-cooking methods, and found that the intake of processed, fried, and stir-fried meat were correlated with the number of DNA mutations they found subsequently in their breast tissue. But, we already knew these chemicals damaged DNA. What surprised everyone was that not only may these meat chemicals trigger the original cancer-causing mutation, they may then promote the growth of the ensuing tumor, as PhIP was discovered to be “a potent estrogen.”  

They dripped the kinds of levels of PhIP you’d expect in your body after eating cooked meat, and found that it activated estrogen receptors almost as powerfully as straight estrogen. And, that’s what they found when they tried it on breast cancer cells. They found its proliferative potency on human breast cancer cells approaching that of pure estrogen.

They concluded that “PhIP possesses oestrogenic activity at low concentrations… supporting the idea that exposure to PhIP, even at low doses, could result in oestrogenic effects. We suggest that the well-established and unequivocable genetic toxicology of PhIP coupled with its oestrogenic activity could drive clonal expansion and promote growth of the initiated [initial cancer cell].”

These were breast cells in a petri dish, though. I mean, how do we know these carcinogens make it from cooked meat, not only into the breast, after you eat it, but into the breast ducts, where most breast cancers arise—so-called ductal carcinoma? We didn’t know for sure, until this study, which measured the levels of PhIP in the breast milk formed in those ducts of nonsmoking women.

And, the average concentration they found in the breast milk of meat-eating women corresponds to about right here on this graph—significant breast cancer cell growth potential. One of the women was vegetarian, though, and of course, none was detected in her breast milk.

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• R. D. Holland, T. Gehring, J. Taylor, B. G. Lake, N. J. Gooderham, R. J. Turesky. Formation of a mutagenic heterocyclic aromatic amine from creatinine in urine of meat eaters and vegetarians. Chem. Res. Toxicol. 2005 18(3):579 - 590
• S. E. Steck, M. M. Gaudet, S. M. Eng, J. A. Britton, S. L. Teitelbaum, A. I. Neugut, R. M. Santella, M. D. Gammon. Cooked meat and risk of breast cancer--lifetime versus recent dietary intake. Epidemiology 2007 18(3):373 - 382
• S. Rohrmann, S.-U. L. Jung, J. Linseisen, W. Pfau. Dietary intake of meat and meat-derived heterocyclic aromatic amines and their correlation with DNA adducts in female breast tissue. Mutagenesis 2009 24(2):127 - 132
• S. N. Lauber, S. Ali, N. J. Gooderham. The cooked food derived carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine is a potent oestrogen: A mechanistic basis for its tissue-specific carcinogenicity. Carcinogenesis 2004 25(12):2509 - 2517
• S. N. Lauber, N. J. Gooderham. The cooked meat-derived mammary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine promotes invasive behaviour of breast cancer cells. Toxicology 2011 279(1 - 3):139 - 145
• L. S. DeBruin, P. A. Martos, P. D. Josephy. Detection of PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) in the milk of healthy women. Chem. Res. Toxicol. 2001 14(11):1523 - 1528
• Rashmi Sinha, Deborah R. Gustafson, Martin Kulldorff, Wan-Qing Wen, James R. Cerhan, Wei Zheng. 2-Amino-1-methyl-6-phenylim-idazo[4,5-b]pyridine, a Carcinogen in High-Temperature-Cooked Meat, and Breast Cancer Risk. Journal of the National Cancer Institute 2000 92(16):1352 - 1354
• P. Knekt, G. Steineck, R. Järvinen, T. Hakulinen, A. Aromaa. Intake of fried meat and risk of cancer: A follow-up study in Finland. Int. J. Cancer 1994 59(6):756 - 760
• A. Ronco, E. De Stefani, M. Mendilaharsu, H. Deneo-Pellegrini. Meat, fat and risk of breast cancer: A case-control study from Uruguay. Int. J. Cancer 1996 65(3):328 - 331

Images thanks to euthman via flickr

• animal products
• animal protein
• beef
• breast cancer
• breast health
• breast milk
• breastfeeding
• cancer
• carcinogens
• chicken
• cooking methods
• DNA damage
• estrogen
• Finland
• fish
• heterocyclic amines
• hormones
• infants
• meat
• oxidative stress
• PhIP
• Plant-Based Diets
• pork
• poultry
• processed foods
• processed meat
• smoking
• turkey
• vegans
• vegetarians
• women's health