Troubling Meaty 'Estrogen'
By Janet Raloff
Women take note. Researchers find that a chemical that forms in overcooked meat, especially charred portions, is a potent mimic of estrogen, the primary female sex hormone. That's anything but appetizing, since studies have linked a higher lifetime cumulative exposure to estrogen in women with an elevated risk of breast cancer.
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HORMONAL HAMBURGER? Depending on the temperature at which this burger was grilled—especially how hot its outer surface got—it may have hosted chemical reactions that created PhIP, a carcinogen that has a potent hormonal alter-ego. It can mimic the biological activity of estrogen, the primary female sex hormone. |
Indeed, the new finding offers a "biologically plausible" explanation for why diets rich in red meats might elevate breast-cancer risk, notes Nigel J. Gooderham of Imperial College London.
At the very high temperatures reached during frying and charbroiling, natural constituents of meats can undergo chemical reactions that generate carcinogens known as heterocyclic amines (see Carcinogens in the Diet). Because these compounds all have very long, unwieldy chemical monikers, most scientists refer to them by their abbreviations, such as IQ, MeIQ, MeIQx, and PhIP.
Of the nearly two dozen different heterocyclic amines that can form, PhIP dominates. It sometimes accumulates in amounts 10 to 50 times higher than that of any other member of this toxic chemical family, Gooderham says. Moreover, he adds, although heterocyclic amines normally cause liver tumors in exposed animals, PhIP is different: "It causes breast cancer in female rats, prostate cancer in male rats, and colon cancer in both." These are the same cancers that in people are associated with eating a lot of cooked meats.
However, the means by which such foods might induce cancer has remained somewhat elusive. So, building on his team's earlier work, Gooderham decided to probe what the heterocyclic amine did in rat pituitary cells. These cells make prolactin—another female sex hormone—but only when triggered by the presence of estrogen. Prolactin, like estrogen, fuels the growth of many breast cancers.
In their new test-tube study, Gooderham and coauthor Saundra N. Lauber show that upon exposure to PhIP, pituitary cells not only make progesterone, but also secrete it. If these cells do the same thing when they're part of the body, those secretions would circulate to other organs—including the breast.
But "what was startling," Gooderham told Science News Online, is that it took just trace quantities of the heterocyclic amine to spur prolactin production. "PhIP was incredibly potent," he says, able to trigger progesterone production at concentrations comparable to what might be found circulating in the blood of people who had eaten a couple of well-done burgers.
The toxicologist cautions that there's a big gap between observing an effect in isolated cells growing in a test-tube and showing that the same holds true in people.
However, even if PhIP does operate similarly in people, he says that's no reason to give up grilled meat. Certain cooking techniques, such as flipping hamburgers frequently, can limit the formation of heterocyclic amines. Moreover, earlier work by the Imperial College team showed that dining on certain members of the mustard family appear to detoxify much of the PhIP that might have inadvertently been consumed as part of a meal.
For more information, see this week's Food for Thought column.
References:
Cho, E., et al. 2006. Red meat intake and risk of breast cancer among premenopausal women. Archives of Internal Medicine 166(Nov. 13):2253-2259. Abstract available at http://archinte.ama-assn.org/cgi/content/short/166/20/2253.
Felton, J.S., et al. 1995. Reduction of heterocyclic aromatic amine mutagens/carcinogens in fried beef patties by microwave pretreatment. Available at http://www.llnl.gov/str/pdfs/UCRL-JC-116450.pdf.
Gooderham, N.J., et al. 2007. Mechanisms of action of the carcinogenic heterocyclic amine PhIP. Toxicology Letters 168(Feb. 5):269-277. Abstract available at http://dx.doi.org/10.1016/j.toxlet.2006.10.022.
Lauber, S.N., and N.J. Gooderham. 2007. The cooked meat–derived genotoxic carcinogen 2-amino-3-methylimidazo[4,5-b]pyridine has potent hormone-like activity: Mechanistic support for a role in breast cancer. Cancer Research 67(Oct. 1):9597-9602. Abstract available at http://cancerres.aacrjournals.org/cgi/content/abstract/67/19/9597.
Murray, S., . . . and N.J. Gooderham. 2001. Effect of cruciferous vegetable consumption on heterocyclic aromatic amine metabolism in man. Carcinogenesis 22(September):1413-1420. Available at http://carcin.oxfordjournals.org/cgi/content/full/22/9/1413.
Steck, S.E., et al. 2007. Cooked meat and risk of breast cancer—Lifetime versus recent dietary intake. Epidemiology 18(May):373-382. Abstract available at http://www.epidem.com/pt/re/epidemiology/
abstract.00001648-200705000-00016.htm.
Taylor, E.F., et al. 2007. Meat consumption and risk of breast cancer in the UK Women's Cohort Study. British Journal of Cancer 96(April 10):1139-1146. Available at http://www.nature.com/bjc/journal/v96/n7/full/6603689a.html.
Walters, D.G. . . . N.J. Gooderham, et al. 2004. Cruciferous vegetable consumption alters the metabolism of the dietary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in humans. Carcinogenesis 25(September):1659-1669. Available at http://carcin.oxfordjournals.org/cgi/content/full/25/9/1659.
Further Readings:
Raloff, J. 2007. Concerns over genistein, part II—Beyond the heart. Science News Online (July 7). Available at http://www.sciencenews.org/articles/20070707/food.asp.
______. 2007. Concerns over genistein, part I—The heart of the issue. Science News Online (June 16). Available at http://www.sciencenews.org/articles/20070616/food.asp.
______. 2006. Pesticides mimic estrogen in shellfish. Science News 170(Dec. 16):397. Available to subscribers at http://www.sciencenews.org/articles/20061216/note12.asp.
______. 2006. No-stick chemicals can mimic estrogen. Science News 170(Dec. 2):366. Available to subscribers at http://www.sciencenews.org/articles/20061202/note16.asp.
______. 2006. Meat poses exaggerated cancer risk for some people. Science News Online (March 25). Available at http://www.sciencenews.org/articles/20060325/food.asp.
______. 2005. Beer's well done benefit. Science News Online (March 5). Available at http://www.sciencenews.org/articles/20050305/food.asp.
______. 2005. Carcinogens in the diet. Science News Online (Feb. 19). Available at http://www.sciencenews.org/articles/20050219/food.asp.
______. 2004. How carbs can make burgers safer. Science News Online (Dec. 4). Available at http://www.sciencenews.org/articles/20041204/food.asp.
______. 2004. Uranium, the newest 'hormone'. Science News 166(Nov. 13):318. Available to subscribers at http://www.sciencenews.org/articles/20041113/note14.asp.
______. 2001. Fire retardant catfish? Science News Online (Dec. 8). Available at http://www.sciencenews.org/articles/20011208/food.asp.
______. 1999. Well-done research. Science News 155(April 24):264-266. Available at http://www.sciencenews.org/pages/sn_arc99/4_24_99/bob1.htm.
______. 1998. Very hot grills may inflame cancer risks. Science News 154(Nov. 28):341. Available at http://www.sciencenews.org/pages/sn_arc98/11_28_98/fob3.htm.
______. 1996. Another meaty link to cancer. Science News 149(June 8):365. Available at http://www.sciencenews.org/pages/pdfs/
data/1996/149-23/14923-13.pdf.
______. 1996. 'Estrogen' pairings can increase potency. Science News 149(June 8):356. Available at http://www.sciencenews.org/pages/
pdfs/data/1996/149-23/14923-03.pdf.
______. 1995. Beyond estrogens: Why unmasking hormone-mimicking pollutants proves so challenging. Science News 148(July 15):44. Available at http://www.sciencenews.org/pages/
pdfs/data/1995/148-03/14803-15.pdf.
______. 1994. Meaty carcinogens: A risk to the cook? Science News 146(Aug. 13):103.
______. 1994. Not so hot hot dogs? Science News 145(April 23):264-269.
______. 1994. How cooked meat may inflame the heart. Science News 145(March 12):165.
______. 1994. The gender benders. Science News 145(Jan. 8):24. Available at http://www.sciencenews.org/pages/sn_edpik/ls_7.htm.
Smith-Roe, S.L., et al. 2006. Induction of aberrant crypt foci in DNA mismatch repair-deficient mice by the food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP). Cancer Letters. 244(Nov. 28):79-85. Abstract available at http://dx.doi.org/10.1016/j.canlet.2005.12.002.
______. 2006. Mlh1-dependent responses to 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP), a food-borne carcinogen. (Abstract # 514). Toxicologist 90(March):105.
______. 2006. Mlh1-dependent suppression of specific mutations induced in vivo by the food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP). Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 594(Feb. 22):101-112. Abstract available at http://dx.doi.org/10.1016/j.mrfmmm.2005.08.011.
Sources:
Janet E. Cade
UK Women's Cohort Study
Centre for Epidemiology and Biostatistics
30/32 Hyde Terrace
The University of Leeds
Leeds LS2 9LN
United Kingdom
Eunyoung Cho
Channing Laboratory
Department of Medicine
Harvard Medical School
181 Longwood Avenue
Boston, MA 02115
Nigel J. Gooderham
Biomolecular Medicine
Imperial College London
Sir Alexander Fleming Building
London SW7 2AZ
United Kingdom
Susan Elizabeth Steck
Department of Epidemiology and Biostatistics
Statewide Cancer Prevention and Control Program
Arnold School of Public Health
University of South Carolina
2221 Devine Street, Room 231
Columbia, SC 29208
Comments
A good friend of ours just went through an ordeal with breast cancer. The incidence of breast cancer has increased to 1 in 8 women, with 4,000 new cases weekly.
You might ask, could there be a preventive measure which is safe, cheap and widely available that has been overlooked?
The answer is YES , and it’s the essential mineral, Iodine, which was added to table salt in 1924 as part of a national program to prevent Goiter. It turns out that this same Iodine in table salt is the key to breast cancer prevention as proposed by the following list of prestigious doctors:
Guy Abraham, MD, Robert Derry MD PHD, David Brownstein MD, George Flechas MD, Donald Miller, M.D.
Dr. B.A. Eskin published 80 papers over 30 years researching iodine and breast cancer, and he reports that iodine deficiency causes breast cancer and thyroid cancer in humans and animals. Iodine deficiency is also known to cause a pre-cancerous condition called fibrocystic breast disease.
W.R. Ghent published a paper in 1993 which showed iodine supplementation works quite well to reverse and resolve fibrocystic changes of the breast, and this is again the subject of a current clinical study.(Can J Surg. 1993 Oct;36(5):453-60.)
Despite its obvious potential, not much has been done with Iodine treatment over the past 40 years in the United States. Since iodine isn't patentable and is therefore unlikely to be profitable to market, there is no money to fund studies for “FDA approval". However, FDA approval is not required since Iodine is already an additive to table salt at the supermarket.
For more information see my newsletter.
Jeffrey Dach MD my web site
Posted by: Jeffrey Dach MD | October 21, 2007 05:13 PM