Meats and dairy
Bacon should be avoided for breast cancer
Diets high in bacon and other processed meats have been linked in population studies to higher risks of leukemia, stomach cancer, colorectal cancer, esophageal cancer, brain cancer, lung cancer, bladder cancer, pancreatic cancer, and prostate cancer. Processed meats include those that are salted, cured, smoked or preserved, including hot dogs, sausage, ham, bologna, other sandwich or luncheon meats, pâtés, salami, pepperoni, and beef jerky, to name a few. Fresh pork is covered in another web page. Sodium nitrite and related compounds are normally added to processed meats to preserve their freshness and coloring. Sodium nitrite has been shown to react with chemicals in the stomach to produce nitrosamines, which are known to be cancer-promoting. The carcinogenic potential of processed meats appears to be related both to their elevated levels of nitrites and the effects of frying or broiling, which have been shown to produce mutagenic compounds such as heterocyclic aromatic amines and polycyclic aromatic hydrocarbons.
Breast cancer-related effects of eating bacon
A large 2007 U.K. study found that both premenopausal and postmenopausal women with the highest processed meat intake had the highest risk of breast cancer. Another study found that higher red meat consumption during adolescence was associated with increased risk of premenopausal breast cancer in adulthood. A study of tissue removed from healthy women undergoing breast reduction surgery found that the levels of DNA adducts (a type of cancer marker) in the breast tissue was correlated with the women's consumption of fried meat, beef and processed meat. Another study found that consumption of well-done meats (including bacon) appeared to increase the risk of breast cancer in a dose-dependent manner. A study that examined the risks of recurrence and death following diagnosis with early-stage breast cancer found that both the risk of recurrence and the risk of death were positively correlated with the consumption of bacon, especially for premenopausal women.
Additional comments
Generally speaking, bacon-like products made from turkey, beef, and combinations of pork and turkey also contain sodium nitrite and form carcinogenic nitrosamines when consumed, however the levels tend to be lower than for traditional bacon.
Beef is not recommended for breast cancer
Breast cancer-related effects of eating beef
Higher red meat consumption during adolescence by women in the Nurses' Health Study II has been found to be associated with increased risk of premenopausal breast cancer in adulthood. A French population study found that increasing meat consumption was associated with increasing breast cancer risk. A UK study found that both pre- and postmenopausal women who consumed the most meat (including red meat) had the highest risk of breast cancer. A German study of women under 51 years of age also found that breast cancer risk was increased with higher consumption of red meat; women with the highest consumption quartile had an 85% elevated breast cancer risk compared to the lowest quartile. For premenopausal women, the association of meat (especially beef) intake with breast cancer risk was found to be even stronger in this study. A study of tissue removed from healthy women undergoing breast reduction surgery found that the levels of DNA adducts (a type of cancer marker) in the breast tissue was correlated with the women's consumption of fried meat, beef and processed meat. Women in the Iowa Women's Health Study who consistently ate their hamburgers, steak, and bacon very well done were found to have a 4.62 times higher risk of breast cancer than women who consumed the meats rare or medium well done. However, a large 2009 study found no association between meat consumption and breast cancer risk in postmenopausal women.
A number of different factors and mechanisms have been proposed to account for the findings of increased breast cancer risk associated with beef consumption:
• The U.S. beef and veal industry uses zeronal (Ralgro), a non-steroidal substance with estrogenic activity, as a growth promoter. Zeronal has been found to stimulate human breast cancer cell growth and proliferation. Other growth promoters (mostly hormones) that are routinely administered to cattle also are suspected to contribute to breast cancer risk.
• Irradiation of beef, which is widespread in the U.S., has been found to result in the formation of alkylcyclobutanones, which have been shown to have mutagenic and tumor promoting activities.
• Bovine leukemia virus (BLV), which estimated to infect at least 14% of U.S. beef herds, is thought by some observers to be capable of contributing to human breast cancer. Many women have antibodies to BLV, indicating exposure to the virus.
• Some of the heterocyclic aromatic amines (HCAs) formed in very well done beef and steak, and in beef gravy, are known human carcinogens. Two of the HCAs, 2-amino-3-methylimidazo[4,5-b]pyridine and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, have also been shown to have potent estrogenic activity, inducing activation of estrogen-regulated genes, proliferation of estrogen-dependent cells and up-regulation of progesterone receptor.
• While iron deficiency anemia obviously is to be avoided, the contribution of significant heme iron in the diet as a result of regularly consuming beef could be detrimental for some women. Iron depletion has been shown to lead to significant inhibition of breast cancer cell growth in the laboratory. Relatively high levels of iron in benign breast tissue was found in one prospective study to be associated with an increase in risk of subsequent breast cancer. Other studies have found high levels of iron in the blood to be associated with increased breast cancer risk.
If beef is to be consumed, it makes sense to buy organic beef to avoid irradiated and growth hormone-treated meat.
Additional comments
Well done and flame-broiled beef are not recommended. This includes all fast-food hamburgers. Although they are traditionally used as a base for gravies and sauces, be aware that fat drippings and grill residue scrapings contain particularly high levels of HCAs and ideally should be discarded.
Although we do not recommend supplementation with CLA (conjugated linoleic acid), we wish to advise those who do to avoid the t10,c12-CLA isomer (referred to on some supplement labels as Trans-10, Cis-12). The t10,c12 CLA isomer was found to dramatically enhance mammary tumor development in one mouse experiment. The time by which 50% of the mice in the group developed a tumor was shortened from 267 days for mice on a control diet to 169 days for mice fed t10,c12-CLA. Choose products with only the c9,t11 isomer (Cis-9, Trans-11).
The beef industry appears to take an active interest in academic studies concerning the health benefits and drawbacks of beef. We found several cancer studies that had been financed by the Cattlemen's Beef Board.
Butter is not recommended for breast cancer
Made from milk, butter is a rich dietary source of vitamin A, calcium, and conjugated linoleic acid, all of which have been shown to have anticarcinogenic properties. However, butter consumption has been found to be associated with increased risks of leukemia, as well as oral, esophageal, thyroid, stomach, pancreatic, endometrial, colorectal, prostate and testicular cancer. In addition, butter consumption has been found to be associated with increased risk of cardiovascular disease and heart attacks in women as well as in men.
Breast cancer-related effects of consuming butter
Although not all studies of the relationship between breast cancer and dairy foods have found a positive association between butter intake and the risk of breast cancer, many have. Women in the Nurses' Health Study who consumed more butter during high school have been found to have a higher risk of breast cancer in adulthood. Another study found that butter consumption was associated with increased risk of recurrence of early stage breast cancer, especially among premenopausal breast cancer cases. Other U.S, Canadian and European studies have found the use of butter in soups or sauces (i.e., boiled butter), butter at the dinner table, and butter used for frying food to be associated with higher risk of breast cancer.
Additional comments
Ghee is a type of clarified butter used in South Asian cuisine. To make ghee, the water and milk solids are removed from butter by heating to eliminate the water and straining. Consumption of ghee has been associated with cardiovascular disease in India; ghee has an even higher saturated fat content than butter.
Cheese is not recommended for breast cancer
While there are cheeses on the market made from various oils and from the milk of goats, sheep, and other animals, the discussion in this webpage refers to cheese made from cow's milk. Also, "cheese" refers to full-fat cheese rather than reduced fat or non-fat cheese. Cheese is a rich dietary source of calcium, conjugated linoleic acid (CLA), and stearate, all of which have been shown to have anticarcinogenic properties. Numerous studies have found that the consumption of cheese and other high-fat dairy foods is related to lower risk of colon cancer. Cheese consumption also appears to reduce the risks of stomach and pancreatic cancer. On the other hand, studies indicate that the consumption of cheese may increase the risks of developing testicular, ovarian, and thyroid cancers, as well as non-Hodgkin lymphoma. Higher intake of cheese has been associated with increases in prostate cancer risk in many, but not all, studies that have examined the association. Cheese consumption also has been found to increase the risk of new skin cancer (squamous cell carcinoma) among people with previous skin cancer.Breast cancer-related effects of eating cheese
Components of cheese, including calcium, vitamin D, stearate, and conjugated linoleic acid have been found to induce apoptosis of breast cancer cells or reduce mammary tumor size and incidence in the laboratory. However, many (but by no means all) population studies have found that cheese consumption is associated with an increased risk of breast cancer. The factors that may contribute to this increased risk include the fact that much of the milk we drink today is produced from pregnant cows (in which estrogen and progesterone levels are markedly elevated), as well as the presence of saturated fat, recombinant bovine growth hormone, and various environmental contaminants in cheese. On the other hand, like fermented milk products, consumption of low-fat or non-fat cheese may be protective against breast cancer.
Conjugated linoleic acid has been found to inhibit breast cancer in the laboratory at concentrations close to human consumption levels. Several population studies have been performed specifically to evaluate the possible association between consumption of CLA in cheese and other dairy products and the risk of breast cancer. The study results have been contradictory. A large prospective Netherlands population study found a weak positive association between CLA intake and the risk breast cancer (i.e., the association was in the opposite direction expected if CLA was protective) and concluded that the apparent anticarcinogenic properties of CLA in animal and tissue culture models had not been confirmed in humans. However, an earlier Finnish study of women who already had breast cancer found that dietary CLA and levels of CLA in the blood were significantly lower in the postmenopausal breast cancer cases than in the postmenopausal controls without cancer.
Recombinant bovine growth hormone (a synthetic version of the bovine growth hormone that occurs naturally in cows), which is administered to cows to increase milk production, has been suggested to increase breast cancer risk. This hormone is thought to be biologically inactive in humans. However, it causes the cow liver to produce insulin-like growth factor 1 (IGF-1), which enters the blood and milk as well. The bovine form of IGF-1 is identical to the human form. IGF-1 is required for mammary development at puberty and has been implicated in increased risk of breast cancer. Several studies have found a modest positive association between circulating IGF-I levels and breast cancer risk among premenopausal women. In fact, substances that inhibit IGF-I action in the mammary gland are being developed in the hope that they can eventually play a role in breast cancer chemoprevention.
Additional comments
Since calcium and vitamin D both have been shown to be very significant in protecting against several cancers, and since cheese is a major source of both in the typical American diet, it is important that those who start to decrease their overall consumption of cheese add new sources of calcium and vitamin D.
While consuming low-fat dairy products may reduce breast cancer risk compared to full-fat dairy products, it also can increase the risk of infertility in women due to lack of ovulation. High intake of low-fat dairy foods has been found to increase the risk of anovulatory infertility whereas intake of high-fat dairy foods has been associated with lower risk.
Milk is not recommended for breast cancer
Numerous studies have found that the consumption of milk is related to lower risk of colon cancer and that this relationship appears to be due in part to the calcium found in milk. Studies also indicate that the consumption of milk may increase the risk of developing prostate, endometrial, testicular and ovarian cancer, although some of the relative risks do not appear to be high.
Breast cancer-related effects of drinking milk
Many studies have been conducted to try to determine the effects of milk consumption on the risk of breast cancer and on breast cancer development, but the results appear contradictory, presumably because milk has both beneficial and harmful components.
Components of milk, including calcium, vitamin D, stearate, lactaptin, conjugated linoleic acid, and bovine lactoferricin, have been found to induce apoptosis of breast cancer cells or reduce mammary tumor size and incidence in the laboratory. In addition, several major population-based studies have found that milk consumption is not associated with risk of breast cancer.
However, the case against consuming milk appears to be more compelling. One study of rats with carcinogen-induced mammary tumors found that while removing the ovaries of rats reduced the number and size of the tumors, feeding milk to similar ovariectomized rats led to increases in mammary tumor incidence, tumor number and tumor volume. Consumption of both nonfat and whole milk also has been found to increase the incidence and volume of tumors in experimental rats with carcinogen-induced mammary tumors. Several major population-based studies have found that milk consumption is positively associated with the risk of breast cancer. A 2007 study found that bovine leukemia virus, which is prevalent in U.S. dairy herds, could contribute to human breast cancer. Some observers have noted that much of the milk we drink today is produced from pregnant cows, in which estrogen and progesterone levels are markedly elevated. Other components of milk that are suspected to be breast cancer promoting include saturated fat, recombinant bovine growth hormone (rBGH), insulin-like growth factor, pesticides, and polychlorinated biphenyls. Since cream concentrates some of the potentially harmful substnaces found in milk, it is also to be avoided.
Additional comments
Since calcium and vitamin D both have been shown to be very significant in protecting against cancer, and since milk is a major source of both in the typical American diet, it is important that those who start to limit their consumption of milk add new sources of calcium and vitamin D.
Although consuming unpasteurized milk is associated with health hazards due to possible contamination with pathogenic bacteria, it does not appear to increase the risk of cancer. Kefir, a fermented milk drink, has been found to be negatively associated with breast cancer risk.
Pork is not recommended for breast cancer
Pork is a dietary source of iron and selenium. Pork fat is high in saturated fatty acid and cholesterol content. Diets high in pork have been linked in population studies to higher risks of esophageal, thyroid, lung, pancreatic, liver, bladder, colorectal, and prostate cancer, as well as non-Hodgkin's lymphoma. Cured pork products are covered under bacon. In this article, we evaluate the potential impact on breast cancer risk of consuming pork products that are not salted, smoked or cured.
Breast cancer-related effects of eating pork
Relatively high levels of heterocyclic aromatic amines (HCAs) have been found in pork dishes such as pork chops and other pan-fried pork, Chinese-style and Western-style roasted pork, pork ribs, and barbecued pork, as well as pork drippings. HCAs have been shown be associated with the development of various cancers, including breast cancer. Two of the HCAs found in pork cooked using high temperature methods, 2-amino-3-methylimidazo[4,5-b]pyridine and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, have also been shown to have potent estrogenic activity, inducing activation of estrogen-regulated genes, proliferation of estrogen-dependent cells and up-regulation of progesterone receptor.
While iron deficiency anemia is a serious condition to be avoided, the contribution of significant iron in the diet as a result of regularly consuming pork could be detrimental for some women. Pork contains approximately 60 percent of the iron in beef. Iron depletion has been shown to lead to significant inhibition of breast cancer cell growth in the laboratory. Relatively high levels of iron in benign breast tissue was found in one prospective study to be associated with an increase in risk of subsequent breast cancer. Other studies have found high levels of iron in the blood to be associated with increased breast cancer risk. High intake of saturated fat from animal sources including pork has also been found to be associated with increased risk of breast cancer.
Breast cancer risk has been found to increase with increasing consumption of pork in several population studies. In addition, a small Brazilian study found that breast cancer risk was sharply higher for women who regularly consumed pig lard (rendered pig fat) and fatty red meat. However, a 2009 Swedish population study found no association between fresh red meat intake and overall breast cancer risk while suggesting that fried red meat intake may increase the risk of estrogen receptor-positive/progesterone receptor-negative ER+/PR- breast cancer.
Based on the available evidence, pork prepared using high temperature methods (roasting, barbecuing, deep frying), pork drippings (and gravy made with pork drippings), charred pork, pork fat, and lard all should be avoided by breast cancer patients, survivors and those at high risk for breast cancer. In addition, consumption of lean pork dishes prepared using lower temperature methods should be limited.
Additional comments
Pork should eaten fully cooked, not rare or raw, to minimize the risk of trichinosis and listeriosis infections.
While most U.S. consumers avoid cooking with lard because of its known negative health profile, it is used in some processed foods such as baked goods, often in hydrogenated form.
Be countinued Oils & fats
