Heterocyclic amine content in fast-food meat products

Understanding the Development of Heterocyclic Aromatic Amines in Fried Bacon and in the Remaining Oil after Pan-Frying in Five Different Vegetable Oils

The physicochemical properties of five vegetable oils (peanut, corn, rapeseed, sunflower seed, and soybean) and their impact on the development of heterocyclic aromatic amines (HAAs) in pan-fried bacon and in the remaining oil were investigated. Corn oil led to the lowest total free amino acids (FAAs) contents and glucose content of fried bacon (p < 0.05) and rapeseed oil led to the lowest creatine content of fried bacon (p < 0.05). Bacon fried in corn oil had the highest HAA contents (p < 0.05). The total HAA contents of the oils after frying were lowest in rapeseed and soybean oils (p < 0.05). The type of vegetable oil used affected the color of the fried bacon but not the flavor and taste (p < 0.05). To reduce the HAA concentrations of fried bacon, the type of vegetable oil should be considered.

Total Meat Intake is Associated with Life Expectancy: A Cross-Sectional Data Analysis of 175 Contemporary Populations

Background

The association between a plant-based diet (vegetarianism) and extended life span is increasingly criticised since it may be based on the lack of representative data and insufficient removal of confounders such as lifestyles.

Aim

We examined the association between meat intake and life expectancy at a population level based on ecological data published by the United Nations agencies.

Methods

Population-specific data were obtained from 175 countries/territories. Scatter plots, bivariate, partial correlation and linear regression models were used with SPSS 25 to explore and compare the correlations between newborn life expectancy (e₍₀₎), life expectancy at 5 years of life (e₍₅₎) and intakes of meat, and carbohydrate crops, respectively. The established risk factors to life expectancy – caloric intake, urbanization, obesity and education levels – were included as the potential confounders.

Results

Worldwide, bivariate correlation analyses revealed that meat intake is positively correlated with life expectancies. This relationship remained significant when influences of caloric intake, urbanization, obesity, education and carbohydrate crops were statistically controlled. Stepwise linear regression selected meat intake, not carbohydrate crops, as one of the significant predictors of life expectancy. In contrast, carbohydrate crops showed weak and negative correlation with life expectancy.

Conclusion

If meat intake is not incorporated into nutrition science for predicting human life expectancy, results could prove inaccurate.

The Inhibitory Effects of Heterotrigona Itama Honey Marinades on the Formation of Carcinogenic Heterocyclic Amines in Grilled Beef Satay

Heterocyclic amines (HCAs) are carcinogenic food toxicants formed in cooked meats, which may increase the risk of cancer development in humans. Therefore, in this study, the effect of stingless bee honey from different botanical origins on the formation of HCAs in grilled beef satay was investigated. HCAs concentration in grilled beef satay was determined by using high performance liquid chromatography (HPLC). In total, six of the most toxigenic HCAs representing aminoimidazo-azaarenes (AIAs) (MeIQx, 4,8-DiMeIQx, and PhIP) and amino carbolines (norharman, harman, and AαC) groups were identified in all the beef samples investigated. A significant reduction in HCAs was observed in grilled beef marinated in honey as compared to beef samples marinated in table sugar (control), in which the reduction of 95.14%, 88.45%, 85.65%, and 57.22% was observed in gelam, starfruit, acacia, and Apis honey marinades, respectively. According to the partial least squares regression (PLS) model, the inhibition of HCAs in grilled beef was shown to be significantly correlated to the antioxidant activity (IC50) of the honey samples. Therefore, the results of this study revealed that the addition of stingless bee honey could play an important role in reducing HCAs in grilled beef.

Meat intake and risk of hepatocellular carcinoma in two large US prospective cohorts of women and men

BACKGROUND

Epidemiological evidence on the associations between meat intake and risk of hepatocellular carcinoma (HCC) was limited and inconsistent.

METHODS

We prospectively examined the association between consumption of meats and meat mutagens with HCC risk using data from the Nurses' Health Study and the Health Professionals Follow-up Study. Cox proportional-hazards regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) after adjusting for known liver-cancer risk factors.

RESULTS

During up to 32 years of follow-up, we documented 163 incident HCC cases. The HRs of HCC for the highest vs the lowest tertile intake levels were 1.84 (95% CI: 1.16-2.92, Ptrend = 0.04) for processed red meats and 0.61 (95% CI: 0.40-0.91, Ptrend = 0.02) for total white meats. There was a null association between unprocessed red meats and HCC risk (HR = 1.06, 95% CI: 0.68-1.63, Ptrend = 0.85). We found both poultry (HR = 0.60, 95% CI: 0.40-0.90, Ptrend = 0.01) and fish (HR = 0.70, 95% CI: 0.47-1.05, Ptrend = 0.10) were inversely associated with HCC risk. The HR for HCC risk was 0.79 (95% CI: 0.61-1.02) when 1 standard deviation of processed red meats was substituted with an equivalent amount of poultry or fish intake. We also found a suggestive positive association of intake of meat-derived mutagenicity or heterocyclic amines with risk of HCC.

CONCLUSIONS

Processed red meat intake might be associated with higher, whereas poultry or possibly fish intake might be associated with lower, risk of HCC. Replacing processed red meat with poultry or fish might be associated with reduced HCC risk.

The effects of different frying oils on the formation of heterocyclic aromatic amines in meatballs and the changes in fatty acid compositions of meatballs and frying oils

BACKGROUND

The effects of different frying oils (sunflower, hazelnut, canola, commercially mixed, corn, riviera olive, and natural extra virgin olive) on the formation of heterocyclic aromatic amines (HCAs) in meatballs, and the changes in fatty acid composition of meatballs and frying oils before and after deep-fat frying, were determined.

RESULTS

Frying oils had a very significant effect (P < 0.01) on fatty acid composition and the total HCA content of meatballs. It was determined, in meat, intermuscular fat, meatballs, and all of the different frying oils, that the most common saturated fatty acids (SFAs) were palmitic acid and stearic acid, the most common monounsaturated fatty acid (MUFA) was oleic acid, and the most common polyunsaturated fatty acid (PUFA) was linoleic acid. Only 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) was detected in deep-fat fried meatballs, whereas other HCAs (2-amino-3-methylimidazo[4,5-f]quinoxaline (IQx), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (7,8-DiMeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-9H-pyrido[2,3-b]indole (AαC) and 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAαC)) could not be detected. The total amount of HCAs in the meatballs ranged between 30.43 and 43.71 ng g^-1 .

CONCLUSION

The results of the present study showed that MeIQx could be formed in deep-fat fried meatballs with different frying oils. The lowest MeIQx content was found in meatballs fried in hazelnut oil and the highest MeIQx content was found in meatballs fried in commercially mixed oil. © 2018 Society of Chemical Industry.

Prostate Cancer Incidence is Correlated to Total Meat Intake– a Cross-National Ecologic Analysis of 172 Countries

Objective: To examine the association of total meat (animal flesh) consumption to prostate cancer incidence (PC61) at population level. Subjects and Methods: Data from 172 countries were extracted for analysis. Associations between country specific per capita total meat intake and PC61 incidence at country level were examined using Pearson’s r and Spearman rho, partial correlation, stepwise multiple linear regression analyses with ageing, GDP, Is (index of magnitude of prostate cancer gene accumulation at population level), obesity prevalence and urbanization included as the confounding factors. Countries were also grouped for regional association analysis. The data were log-transformed for analysis in SPSS. Microsoft Excel, and ANOVA Post hoc Scheffe tests were applied to calculate and compare mean differences between country groupings. Results: Worldwide, total meat intake was strongly and positively associated with PC61 incidence in Pearson’s r (r= 0.595, p<0.001) and Spearman rho (r= 0.637, p<0.001) analyses. This relationship remained significant in partial correlation (r= 0.295, p<0.001) when ageing, GDP, Is, obesity prevalence and urbanization were kept statistically constant. GDP was weakly and insignificantly associated with PC61 when total meat intake was kept statistically constant. Stepwise multiple linear regression identified that total meat was a significant predictor of PC61 with total meat intake and all the five confounders included as the independent variables (R2=0.417). Post hoc Scheffe tests revealed nine significant mean differences of PC61 between the six WHO regions, but all disappeared when the contributing effect of total meat on PC61 incidence rate was removed. GDP was not identified as the statistically significant predictor of PC61 in either of the models including or excluding total meat as the independent variable. Conclusions: Total meat intake is an independent predictor of PC61 worldwide, and the determinant of regional variation of PC61. The longitudinal cohort studies are proposed to explore the association further.

Presence of heterocyclic amine carcinogens in home-cooked and fast-food camel meat burgers commonly consumed in Saudi Arabia

Heterocyclic amines (HCAs) are formed by cooking protein-rich foods, for instance, meat and fish, and are listed as possible human carcinogens. In the present study, the presence of five potential HCAs (IQ, MeIQ, MeIQx, 4,8-DiMeIQx, and PhIP) in cooked camel meat burgers was analyzed for the first time. The analysis was performed in home-cooked and fast-food burger samples containing food additives. The applied cooking technique for the home-cooked samples was pan frying for a controlled cooking time and temperature. In the control cooked meat samples (samples that contained no food additives), the concentrations of MeIQx, 4,8-DiMeIQx, and PhIP ranged from 2.47 ng/g to 4.89 ng/g, whereas IQ and MeIQ were found to be below the limit of quantification. The concentrations contents of MeIQx, 4,8-DiMeIQx, and PhIP in the home-cooked and fast-food samples ranged from 1.52 ng/g to 2.13 ng/g and 1.85 ng/g to 3.46 ng/g, respectively. IQ and MeIQ were not detected in either type of sample. In comparison to the control samples, the home-cooked and fast-food samples produced lower levels of HCAs. Such observations could result from the existence of antioxidants in incorporated food additives, which induce pro-oxidative effects with the successive formation and/or scavenging of free radicals.

Effect of thermal treatment on meat proteins with special reference to heterocyclic aromatic amines (HAAs)

Meat is one of the most imperative protein sources available with respect to its production and consumption. It is the richest source of some valuable nutrients like proteins, essential amino acids, polyunsaturated fatty acids, vitamins, and minerals like iron, zinc, and selenium. Thermal treatment produces conformational changes in protein structure as well as flavor, texture, and appearance, and chemical properties of the ingredients are also changed. Heterocyclic aromatic amines (HAAs), potent mutagens/carcinogens, are formed during the cooking of meat at high temperature. The review paper highlights the effects of various cooking methods, i.e., pan-frying, deep-frying, charcoal grilling, and roasting, on the formation of HAAs. The levels of HAAs produced in cooked meats vary depending upon the cooking method, time of cooking, and the type of meat being cooked. Metabolic behavior of HAAs is very unique, they interfere in the activity of many enzymes, modify the metabolic pathways, and lead to the adduct formation of DNA. The application of black pepper and several other spices during processing may reduce the formation of these (HAAs) mutagenic compounds.

Intronic and promoter polymorphisms of hMLH1/hMSH2 and colorectal cancer risk in Heilongjiang Province of China

PURPOSE

Given that mismatch repair (MMR) system plays an important role in recognizing and removing insertion/deletion mutations which occur during DNA replication, common variants associated with impaired MMR system may thus increase risk of colorectal cancer (CRC). Therefore, we aimed to demonstrate the associations between common variants in two MMR genes (hMLH1 and hMSH2) and CRC risk.

METHODS

We genotyped 10 intronic/promoter single-nucleotide polymorphisms (SNPs) of hMLH1 and hMSH2 in 451 CRC patients and 630 controls. Associations between genotypes and CRC risk were estimated using odds ratios and 95 % confidence intervals. Gene-gene interactions, as well as gene-environment interactions on CRC risk were also investigated.

RESULTS

We found that IVS15-214T>C and IVS11 + 107A>G of hMSH2 were significantly associated with CRC risk. In dominant model, variant carriers of the two SNPs could decrease risk of CRC by 31 % (ORadj = 0.69, 95 % CI 0.53-0.91, p < 0.01) and 33 % (ORadj = 0.67, 95 % CI 0.47-0.95, p = 0.02), respectively. In addition, IVS7-212T>A, IVS11+183A>G and IVS8+719T>C of hMSH2 were associated with the susceptibility to colon cancer rather than rectal cancer. ATTTGGGT and TCTTAGAC haplotypes were associated with 44 and 45 % decreased risk of CRC, respectively, while ATTTGAGT and TTTCAGAC haplotypes were associated with 1.37-fold and 2.49-fold increased risk of CRC, respectively. There was a significant three-way gene-gene interaction among hMSH2 IVS11+107A>G, IVS11+183A>G and IVS8+719T>C (p < 0.01). Significant gene-environment interactions were observed between hMSH2 IVS15-214T>C and IVS11+107A>G and cereals consumption (both with p < 0.01).

CONCLUSIONS

Our findings suggested that intronic SNPs, gene-gene and gene-environment interactions in hMSH2 might be associated with susceptibility to CRC.

Polymorphisms in xenobiotic metabolizing genes, intakes of heterocyclic amines and red meat, and postmenopausal breast cancer

Heterocyclic amines (HCAs) are mutagenic compounds generated when meats are cooked at high temperature and for long duration. The findings from previous studies on the relation between HCAs and breast cancer are inconsistent, possibly because of genetic variations in the enzymes metabolizing HCAs. To evaluate whether the associations of intakes of estimated HCAs, meat-derived mutagenicity (MDM), and red meat with risk of postmenopausal breast cancer were modified by N-acetyltransferase 2 (NAT2) acetylator genotype or cytochrome P450 1A2-164 A/C (CYP1A2) polymorphism, we conducted a nested case-control study with 579 cases and 981 controls within a prospective cohort, the Nurses' Health Study. HCAs and MDM intakes were derived using a cooking method questionnaire administered in 1996. NAT2acetylator genotype, the CYP1A2 polymorphism, and intakes of HCAs, MDM, and red meat were not associated with risk of postmenopausal breast cancer. There was also no interaction between NAT2 acetylator genotype or CYP1A2 polymorphism and HCAs and MDM and red meat intake in relation to breast cancer. These results do not support the hypothesis that genetic polymorphisms of xenobiotic enzymes involved in the metabolism of HCAs may modify the associations between intakes of red meat or meat-related mutagens and breast cancer risk.

Screening of non-polar heterocyclic amines in urine by microextraction in packed sorbent-fluorimetric detection and confirmation by capillary liquid chromatography

A rapid and simple procedure for the direct screening of urine samples is described. The method involves microextraction in a packed sorbent (MEPS) that is on-line coupled to a capillary liquid chromatograph with fluorimetric detection. The overall arrangement works as a screening/confirmatory system for monitoring non-polar heterocyclic aromatic amines (HAAs) in urine samples. This configuration allows the selective retention of HAAs from urine on a C(18) MEPS cartridge integrated in the needle of a micro-well plate autosampler. Retained HAAs were eluted with methanol/water (90:10, v/v) and directly injected into the fluorimetric detector. This screening method provides a yes/no binary response that may require confirmation. The samples for which the concentration of HAAs was close to or above the established threshold limit (30 ng mL(-1)) were subjected to capillary liquid chromatography (CLC) for confirmation purposes. A mobile phase of acetonitrile and triethylamine (25 mM) at pH 2.5, through a gradient of composition at a flow rate of 20 μL min(-1), resulted in good separations between the analytes in less than 11 min. This confirmation method allowed the determination of the analytes in the 10-100 ng mL(-1) range for harmane and norharmane and from 20 to 200 ng mL(-1) for 3-amino-1,4-dimethyl-5H-pyrido-[4,3-b] indole (Trp-P-1), 3-amino-1-methyl-5H-pyrido-[4,3-b] indole (Trp-P-2), 2-amino-9H-pyrido-[2,3-b] indole (AαC) and 2-amino-3-methyl-9H-pyrido-[2,3-b] indole (MeAαC), with relative standard deviation (RSD) values between 2.12% and 3.73%, and limits of detection between 1.6 and 5.6 ng mL(-1) for all the HAAs.

Meat mutagens and breast cancer in postmenopausal women--a cohort analysis

BACKGROUND

Mutagenic compounds produced when meats are cooked at high temperatures have been hypothesized to increase risk of breast cancer.

METHODS

We examined the association between intakes of the heterocyclic amines (HCA) MeIQx (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline), PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine), DiMeIQx (2-amino-3,4,8-trimethylimidazo[4,5-f]), and meat-derived mutagenic (MDM) activity and risk of breast cancer using a cooking method questionnaire administered in 1996 in the Nurses' Health Study. Between 1996 and 2006, 2,317 breast cancer cases were diagnosed during 533,618 person-years.

RESULTS

Higher intake of HCAs or MDM was not associated with elevated risk of breast cancer [multivariate relative risk and 95% confidence interval for the highest versus lowest quintile: MeIQx: 0.90 (0.79-1.03); PhIP: 0.92 (0.80-1.05); DiMeIQx: 0.92 (0.80-1.05); and MDM: 0.98 (0.85-1.12)]. HCA or MDM was not associated with estrogen receptor-positive/progesterone receptor-positive breast cancer risk either. There was some suggestion of a decreased risk of estrogen receptor-negative/progesterone receptor-negative breast cancer with higher intakes of MeIQx, DiMeIQx, and PhIP, but none of the associations were statistically significant. There was little evidence for an interaction between intake of cruciferous vegetables and HCA or MDM intake and risk of breast cancer.

CONCLUSION

Higher consumption of mutagens from meats cooked at higher temperature and longer duration was not associated with increased risk of postmenopausal breast cancer.

IMPACT

Overall prospective data including results from our study do not provide support for a substantial increase in risk of breast cancer with higher intake of HCAs.

Dietary consumption practices and cancer risk in African Americans in the rural South

This study describes the dietary consumption practices of a sample of African Americans in the rural South. A qualitative research design involving a cross-sectional food diary was utilized. Complete datasets were collected from 114 participants, 66% female, between the ages of 19 and 79 years. The consumption of a variety of fruits, non-starchy vegetables and unprocessed cereals in daily meals was low in this sample. Frequent consumption of fried foods; fast foods; sugary, carbonated beverages; processed, high-fat and high-sodium foods; and low fruit and non-starchy vegetable intake were evident. The findings are crucial to the development for culturally-specific nutrition education intervention programs for African Americans in the rural South targeted at the modification of not only diet, but food preparation methods to reduce cancer risk.

Meat and meat-related compounds and risk of prostate cancer in a large prospective cohort study in the United States

The authors examined associations between meat consumption (type, cooking method, and related mutagens), heme iron, nitrite/nitrate, and prostate cancer in a cohort of 175,343 US men aged 50-71 years. During 9 years of follow-up (1995-2003), they ascertained 10,313 prostate cancer cases (1,102 advanced) and 419 fatal cases. Hazard ratios comparing the fifth intake quintile with the first revealed elevated risks associated with red and processed meat for total (red meat: hazard ratio (HR) = 1.12, 95% confidence interval (CI): 1.04, 1.21; processed meat: HR = 1.07, 95% CI: 1.00, 1.14) and advanced (red meat: HR = 1.31, 95% CI: 1.05, 1.65; processed meat: HR = 1.32, 95% CI: 1.08, 1.61) prostate cancer. Heme iron, barbecued/grilled meat, and benzo[a]pyrene were all positively associated with total (HR = 1.09 (95% CI: 1.02, 1.17), HR = 1.11 (95% CI: 1.03, 1.19), and HR = 1.09 (95% CI: 1.00, 1.18), respectively) and advanced (HR = 1.28 (95% CI: 1.03, 1.58), HR = 1.36 (95% CI: 1.10, 1.69), and HR = 1.28 (95% CI: 1.00, 1.65), respectively) disease. Nitrite (HR = 1.24, 95% CI: 1.02, 1.51) and nitrate (HR = 1.31, 95% CI: 1.07, 1.61) intakes were associated with advanced prostate cancer. There were no clear associations for fatal prostate cancer. Red and processed meat may be positively associated with prostate cancer via mechanisms involving heme iron, nitrite/nitrate, grilling/barbecuing, and benzo[a]pyrene.

Detection of PhIP in grilled chicken entrées at popular chain restaurants throughout California

Heterocyclic amines (HCAs), compounds formed when meat is cooked at high temperatures particularly through pan frying, grilling, or barbequing, pose a potential carcinogenic risk to the public. It is unclear whether there is any level at which consumption of HCAs can be considered safe. Efforts to measure these compounds mainly include cooking studies under laboratory conditions and some measurement of home-cooked foods, but analysis of commercially cooked foods has been minimal. Attempts to estimate exposure of the public to these compounds must take into consideration dining outside the home, which could result in significant exposure for some individuals. We surveyed at least 9 locations each of 7 popular chain restaurants (McDonald's, Burger King, Chick-fil-A, Chili's, TGI Friday's, Outback Steakhouse, and Applebee's) in California, collecting one or two entrees from each location. Entrees were analyzed for 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) using high-performance liquid chromatography tandem mass spectrometry. All 100 samples contained PhIP. Concentrations were variable within and between entrees and ranged from 0.08 to 43.2 ng/g. When factoring in the weight of the entrees, absolute levels of PhIP reached over 1,000 ng for some entrees. Potential strategies for reducing exposure include the avoidance of meats cooked using methods that are known to form PhIP.

Intakes of red meat, processed meat, and meat mutagens increase lung cancer risk

Red and processed meat intake may increase lung cancer risk. However, the epidemiologic evidence is inconsistent and few studies have evaluated the role of meat mutagens formed during high cooking temperatures. We investigated the association of red meat, processed meat, and meat mutagen intake with lung cancer risk in Environment And Genetics in Lung cancer Etiology, a population-based case-control study. Primary lung cancer cases (n = 2,101) were recruited from 13 hospitals within the Lombardy region of Italy examining approximately 80% of the cases from the area. Noncancer population controls (n = 2,120), matched to cases on gender, residence, and age, were randomly selected from the same catchment area. Diet was assessed in 1,903 cases and 2,073 controls and used in conjunction with a meat mutagen database to estimate intake of heterocyclic amines (HCA) and benzo(a)pyrene (BaP). Multivariable odds ratios (OR) and 95% confidence intervals (95% CI) for sex-specific tertiles of intake were calculated using unconditional logistic regression. Red and processed meat were positively associated with lung cancer risk (highest-versus-lowest tertile: OR, 1.8; 95% CI, 1.5-2.2; P trend < 0.001 and OR, 1.7; 95% CI, 1.4-2.1; P trend < 0.001, respectively); the risks were strongest among never smokers (OR, 2.4; 95% CI, 1.4-4.0; P trend = 0.001 and OR, 2.5; 95% CI, 1.5-4.2; P trend = 0.001, respectively). HCAs and BaP were significantly associated with increased risk of lung cancer. When separated by histology, significant positive associations for both meat groups were restricted to adenocarcinoma and squamous cell carcinoma but not small cell carcinoma of the lung. In summary, red meat, processed meat, and meat mutagens were independently associated with increased risk of lung cancer.

Quantification of heterocyclic aromatic amines in fried meat by HPTLC/UV-FLD and HPLC/UV-FLD: a comparison of two methods

A recently developed HPTLC/UV-FLD method was compared to the routinely used HPLC/UV-FLD method for the quantification of heterocyclic aromatic amines (HAA) formed at trace levels during the heating process of meat. For formation of these process contaminants under normal cooking conditions, beef patties were fried in a double-contact grill at 230 degrees C for five different frying times and extracted by solid-phase extraction. The HAAs most frequently found, that is, 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5- f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5- f]quinoxaline (4,8-DiMeIQx), 9 H-pyrido[3,4- b]indole (norharman), and 1-methyl-9 H-pyrido[3,4- b]indole (harman), were quantified by two chromatographic methods, which were orthogonal to each other (normal versus reversed phase system). Both methods showed a similar performance and good correlation of the results ( R (2) between 0.8875 and 0.9751). The comparison of running costs and run time in routine analysis proved HPTLC/UV-FLD to be more economical (factor of 3) and faster (factor of 4) due to its capability of parallel chromatography. The HAA findings calculated by standard addition increased with the heating time from <1 to 33 microg/kg related to 3-6 min of frying time. The precision (RSD) was between 7 and 49% (HPTLC) and between 5 and 38% (HPLC) at these very low HAA levels formed.

Meat and meat mutagens and risk of prostate cancer in the Agricultural Health Study

Meats cooked at high temperatures, such as pan-frying or grilling, are a source of carcinogenic heterocyclic amines and polycyclic aromatic hydrocarbons. We prospectively examined the association between meat types, meat cooking methods, meat doneness, and meat mutagens and the risk for prostate cancer in the Agricultural Health Study. We estimated relative risks and 95% confidence intervals (95% CI) for prostate cancer using Cox proportional hazards regression using age as the underlying time metric and adjusting for state of residence, race, smoking status, and family history of prostate cancer. During 197,017 person-years of follow-up, we observed 668 incident prostate cancer cases (613 of these were diagnosed after the first year of follow-up and 140 were advanced cases) among 23,080 men with complete dietary data. We found no association between meat type or specific cooking method and prostate cancer risk. However, intake of well or very well done total meat was associated with a 1.26-fold increased risk of incident prostate cancer (95% CI, 1.02-1.54) and a 1.97-fold increased risk of advanced disease (95% CI, 1.26-3.08) when the highest tertile was compared with the lowest. Risks for the two heterocyclic amines 2-amino-3,4,8-trimethylimidazo-[4,5-f]quinoxaline and 2-amino-3,8-dimethylimidazo-[4,5-b]quinoxaline were of borderline significance for incident disease [1.24 (95% CI, 0.96-1.59) and 1.20 (95% CI, 0.93-1.55), respectively] when the highest quintile was compared with the lowest. In conclusion, well and very well done meat was associated with an increased risk for prostate cancer in this cohort.

Intestinal bacteria metabolize the dietary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine following consumption of a single cooked chicken meal in humans

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a carcinogenic heterocyclic amine formed in meats during cooking. Although the formation of PhIP metabolites by mammalian enzymes has been extensively reported, the involvement of the intestinal bacteria remains unclear. This study examined the urinary and fecal excretion of a newly identified microbial PhIP metabolite 7-hydroxy-5-methyl-3-phenyl-6,7,8,9-tetrahydropyrido[3',2':4,5]imidazo[1,2-a]pyrimidin-5-ium chloride (PhIP-M1) in humans. The subjects were fed 150 g of cooked chicken containing 0.88-4.7 microg PhIP, and urine and feces collections were obtained during 72 h after the meal. PhIP-M1 and its trideuterated derivate were synthesized and a LC/MS/MS method was developed for their quantification. The mutagenic activity of PhIP-M1, as analyzed using the Salmonella strains TA98, TA100 and TA102, yielded no significant response. Of the ingested PhIP dose, volunteers excreted 12-21% as PhIP and 1.2-15% as PhIP-M1 in urine, and 26-42% as PhIP and 0.9-11% as PhIP-M1 in feces. The rate of PhIP-M1 excretion varied among the subjects. Yet, an increase in urinary excretion was observed for successive time increments, whereas for PhIP the majority was excreted in the first 24h. These findings suggest that besides differences in digestion, metabolism and diet, the microbial composition of the gastrointestinal tract also strongly influences individual disposition and carcinogenic risk from PhIP.