The present study was designed to investigate levels of estrogen in beef and chicken. Estrogen in contraceptive pills has been reported to contribute to the incidence of hormone-dependent cancers in women. However, there appears to be very little discussion concerning dietary estrogen from meat in relation to cancer incidence despite the fact that beef and chicken may come from animals fed with supplemental estrogen. Intra-tissue concentrations of estradiol-17β (E2) and estrone (E1) were measured in beef produced in the U.S. (40 samples) and Japan (40 samples), and chicken produced in the U.S., Japan, and Brazil (25 samples each) by liquid chromatography-mass spectrometry. Fat and muscle meat (red meat) were examined separately. For comparison, the authors also analyzed fat tissues of 25 postmenopausal Japanese women. Generally speaking, estrogen levels were higher in fat than in red meat. Median concentrations (picograms per gram (pg/g)) of estrogen in Japanese chicken fat (E2 = 21.1, E1 = 65.7) and in U.S. chicken fat (20.7, 54.6) were the highest of the samples assessed. U.S. beef fat also had a high level (14.0, 7.7). However, Japanese beef red meat (0.0, 0.1) and Brazilian chicken red meat (0.2, 0.4) were found to incorporate nearly zero levels of estrogen, and the estrogen levels in their fat were also low. The high E2 levels in Japanese and U.S. chicken exceeded the levels found in the fat of Japanese women (16.3). On the other hand, levels in meat with low estrogen content were a hundred times lower than in human fat. The authors comment that the high estrogen concentrations in Japanese and U.S. chicken, as well as U.S. beef, have been attributed to the residue of external estrogen in the feed given to the livestock. The nearly zero level found in Japanese beef and Brazilian chicken may be considered the natural endogenous amount without estrogen supplementation. The estrogen levels found in U.S. chicken and beef are much lower than those of contraceptive pills (0.035 mg/tablet). However, estrogen intake from meat consumption cannot be dismissed as a factor governing human health, according to the authors, considering lifetime exposure to such meat. The authors conclude that dietary estrogen intake from meat might promote estrogen accumulation in the human body and could be related to the incidence of hormone-dependent cancers.

The present review was designed to provide an overview of the effect of nutrition on breast cancer risk among breast cancer gene mutation carriers as well as those with sporadic breast cancer (i.e., those without a known family history of the disease). Breast cancer is the second most prevalent cause of cancer-related deaths among women in most industrialized nations. Most breast cancers are sporadic, with only 5% to 10% likely due to inherited susceptibility. Studies published between 1999 and 2007 were reviewed to examine the relationship between nutrition and breast cancer among both sporadic cases and gene mutation carriers. It was found that consumption of fruits, vegetables, low-fat dairy products, fish, monounsaturated and polyunsaturated fatty acids, vitamin D, calcium, and phytoestrogens are associated with lower risk of breast cancer. On the other hand, high levels of consumption of meat, poultry, total calories, total fat, and saturated fatty acids are associated with increased risk of this disease. The authors conclude that diet is a modifiable risk factor on which to focus prevention efforts.

The current case-control study was designed to compare the diets of a group of Korean breast cancer patients with a healthy control group. The cases included 97 women with newly confirmed diagnoses of breast cancer at the inpatient or outpatient clinic of Yeouido St. Mary’s Hospital in Seoul, and excluded women with any history of liver diseases, diabetes mellitus, respiratory disorders and cardiovascular diseases. The 97-person control group also excluded women with known malignant, hormonal, gynecological or endocrine diseases. Intake of nutrients in 117 food items were estimated in the breast cancer patients and age-matched healthy controls using a quantitative food frequency questionnaire administered by a trained dietitian. The questionnaire also included general information (age, sex and marital status), age at menarche, and pregnancy history. It was found that the average caloric intake of the breast cancer patients and the healthy controls did not differ significantly. However, the breast cancer patients consumed significantly less fat and antioxidant nutrients such as vitamin A, retinol, beta-carotene, vitamin C and vitamin E than did the controls. Consumption of eggs (p<0.01), legumes (p<0.05), vegetables (p<0.05), seasonings (p<0.001), and oils and fats (p<0.01) was significantly lower in the breast cancer patients. However, the level of energy from fat is relatively low in Korean patients compared to their Western counterparts, and fat consumption may not be an independent risk factor at this level of intake. With respect to particular foods, in addition to eggs, the breast cancer patients consumed a significantly lower quantity of bean curd (tofu), onion, garlic, green pepper, sweet pepper, kale, cucumber, seasoned bean sprouts, sesame leaf, zucchini, radish, mushroom, crown daisy, red pepper paste, bean paste, spicy bean paste, orange juice, grape juice, and tomato juice than the controls. On the other hand, the breast cancer patients consumed significantly greater quantities of cooked rice, noodles, deep fried chicken, satsuma mandarin, Korean melon, kimchi and coffee than the controls. The authors conclude that since the breast cancer patients consumed less soy and vegetables, they had a lower intake than the controls of rich sources of antioxidant nutrients, phytosterols, fiber and non-nutritional components that may reduce the risk of cancer. In addition, the breast cancer patients in this study consumed lower quantities of red pepper paste, bean paste and spicy bean paste, causing their intake of pepper flavonols (which may have a protective effect on breast cancer risk) to be lower than that of the controls.

The current study was designed to estimate heterocyclic aromatic amine (HAA) levels in the diet of ethnic Chinese in Singapore (a country with 77% ethnic Chinese). HAAs formed in meat during high-temperature cooking have found to be associated with risk of colorectal and breast cancer. In the study, 25 samples of meat and fish cooked as commonly consumed were analyzed by high-performance liquid chromatography for concentrations of seven different HAAs. The study included the diets of 497 randomly sampled Chinese men and women aged 20 to 59 years old. Meat consumption (g/day), including meat type and cooking method, was assessed using a food-frequency questionnaire. 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, 2-amino-3,8- dimethylimidazo[4,5-f]quinoxaline, and 2-amino-3, 4,8-trimethylimidazo[4,5-f]quinoxaline were the most abundant HAAs detected. Total HAAs concentrations varied from <0.10 to 6.77 ng/g, of which Chinese-style roasted pork had the highest levels. The estimated average daily exposure to HAAs was 49.95 ng/day; this was 50% higher among younger compared to those at least 40 years old. Seven specific meat-cooking method combinations contributed 90.1% of the HAAs intake: pan-fried fish, pork, and chicken; deep-fried chicken and fish; roasted/barbecued pork; and grilled minced beef.

This large population-based, case-control study was designed to investigate the association between calcium intake and breast cancer risk. Epidemiological evidence suggests that dietary calcium may be inversely related to risk of breast cancer. The study included 1,459 cases and 1,556 controls and was conducted in Shanghai between 1996 and 1998. A quantitative food-frequency questionnaire was used to assess diet. The multivariate-adjusted odds ratio (OR) comparing the highest to the lowest tenths of total calcium intake was found to be 0.74 (95% confidence interval (CI) = 0.46-1.20, i.e., not statistically significant). However, calcium primarily derived from poultry consumption was found to be inversely associated with risk for breast cancer (comparing the highest to lowest quintile OR = 0.71, 95% CI = 0.55-0.93) with a statistically significant test for trend. Calcium derived from milk, seafood, fruit, and vegetables was not found to be associated with breast cancer risk. The authors conclude that even a moderate inverse association between calcium and breast cancer risk, if confirmed, could have important public health implications in breast cancer prevention.

The current case-control study was designed to investigate the associations between white meat intake and the risk of breast cancer among Uruguayan women. The study, which was conducted during 1999 to 2001, included 111 cases and 222 healthy women (with normal mammography results) as controls. The women were interviewed with a questionnaire, which elicited information concerning 120 food items, as well as sociodemographic, familial, reproductive, medical and lifestyle variables. After controlling for potential confounders, multivariate analysis was performed. Increased risks of breast cancer were found for high intakes of fried fish and chicken with skin. On the other hand, skinless chicken, fish other than fried fish, and total white meat consumption were inversely associated with breast cancer risk. The authors conclude that cooking method influences the associations of white meat types with risk of breast cancer.

Animal studies have shown that intake of the carcinogen benzo[a]pyrene, a polycyclic aromatic hydrocarbon, causes increases in tumor levels, particularly in the upper gastrointestinal tract. However, the role of benzo[a]pyrene in food and cancer in humans is unclear. The authors created a benzo[a]pyrene database of selected foods that could be used in combination with a food frequency questionnaire to estimate benzo[a]pyrene intake. Meat samples were prepared by different cooking techniques in controlled conditions, and by several restaurants and fast-food chains. Other foods were purchased from major national supermarket chains. Benzo[a]pyrene levels were measured for each food. The database was linked to the results from the food frequency questionnaire to estimate the daily benzo[a]pyrene intake through food in 228 subjects in Washington, DC. The highest concentrations of benzo[a]pyrene (up to approximately 4 ng benzo[a]pyrene/g of cooked meat) were found in grilled or barbecued very well done steaks and hamburgers and in grilled or barbecued well done chicken with skin. Benzo[a]pyrene levels were found to be lower in meats that were grilled or barbecued to medium done and in all broiled or pan-fried meat samples independent of doneness level. The benzo[a]pyrene levels in non-meat items generally were low. However, some cereals and greens (e.g. kale, collard greens) had levels of benzo[a]pyrene up to 0.5 ng/g. In the study population, the bread/cereal/grain and grilled/barbecued meat, respectively, contributed 29 and 21 percent to the average daily intake of benzo[a]pyrene.

The present prospective population study was designed to compare two methods of assessing dietary fat and breast cancer risk. Study participants were part of the National Health Epidemiologic Follow-up Study (NHEFS) cohort. Between 1982 and 1984, 6,156 women aged 32 to 86 years old completed the NHEFS survey, which included a 93-item food frequency questionnaire. The participants also answered questions concerning food habits, such as choice of salad dressing, trimming fat from meat, and eating the skin on poultry. During the four-year follow-up period, 53 women reported a breast cancer diagnosis. The rate ratios (RR) and 95% confidence intervals (CI) for each quartile of percentage of calories from fat were found to be 1.0, 0.96 (CI: 0.5–2.1), 1.0 (CI: 0.5–2.2) and 0.98 (CI: 0.5–2.1). In other words, the breast cancer rates for women in the upper three quartiles (who reported diets with higher energy from fat) were not significantly different from those of women in the lowest quartile of intake. However, the answers to three of the four food habit questions were found to be associated with risk of developing breast cancer. For study participants who used regular instead of lean or extra lean ground beef, RR = 2.2 (95% CI = 1.2 - 4.0); for participants who reported eating the skin on poultry, RR = 1.7 (95% CI = 0.9 - 2.9); for participants who used full-fat salad dressings rather than low fat, RR = 1.3 (95% CI = 0.7 - 2.3). The authors concluded that the food habit questions may be less subject to misclassification than dietary information of fat intake derived from the food frequency questionnaire.

The current Italian population study was designed to elucidate the role of dietary habits on breast cancer risk. Study participants included 2,569 women with incident breast cancer (median age 55 years) and 2,588 controls (median age 56 years) hospitalized with acute non-cancer conditions in six different Italian areas. The women were interviewed between 1991 and 1994 using a validated food frequency questionnaire which included 79 food items and recipes, which were grouped into 18 food groups. After allowance for non-dietary confounding factors and total calorie intake, significant trends of increasing breast cancer risk with increasing intake were found for the following food groups: (1) bread and cereal dishes; (2) pork and processed meats; and (3) sugar and candies. On the other hand, high intake of milk, poultry, fish, raw vegetables, potatoes, coffee and tea appeared to exert a protective effect against breast cancer risk. Consumption of soups, eggs, other meats, cheese, cooked vegetables, citrus fruits, other fruits, and cake and desserts were found not to be significantly related to breast cancer risk. A high degree of variety of vegetables consumed weekly appeared to have a beneficial effect beyond the advantage of high vegetable intake per se.