Showing papers on "Red Meat Consumption published in 2002"

Meat consumption and colorectal cancer risk: Dose‐response meta‐analysis of epidemiological studies

Abstract: The hypothesis that consumption of red and processed meat increases colorectal cancer risk is reassessed in a meta-analysis of articles published during 1973-99. The mean relative risk (RR) for the highest quantile of intake vs. the lowest was calculated and the RR per gram of intake was computed through log-linear models. Attributable fractions and preventable fractions for hypothetical reductions in red meat consumption in different geographical areas were derived using the RR log-linear estimates and prevalence of red meat consumption from FAO data and national dietary surveys. High intake of red meat, and particularly of processed meat, was associated with a moderate but significant increase in colorectal cancer risk. Average RRs and 95% confidence intervals (CI) for the highest quantile of consumption of red meat were 1.35 (CI: 1.21-1.51) and of processed meat, 1.31 (CI: 1.13-1.51). The RRs estimated by log-linear dose-response analysis were 1.24 (CI: 1.08-1.41) for an increase of 120 g/day of red meat and 1.36 (CI: 1.15-1.61) for 30 g/day of processed meat. Total meat consumption was not significantly associated with colorectal cancer risk. The risk fraction attributable to current levels of red meat intake was in the range of 10-25% in regions where red meat intake is high. If average red meat intake is reduced to 70 g/week in these regions, colorectal cancer risk would hypothetically decrease by 7-24%.

Effect of White Versus Red Meat on Endogenous N-Nitrosation in the Human Colon and Further Evidence of a Dose Response

Abstract: N-Nitroso compounds are found in the colon and are formed endogenously because amines and amides are produced by bacterial decarboxylation of amino acids in the large gut. They can be N-nitrosated in the presence of a nitrosating agent. To test the hypothesis that increased nitrogenous residues from red meat would increase endogenous N-nitrosation, thus accounting for the epidemiologic association between red meat consumption and colorectal cancer, we fed increased levels of red meat and measured apparent total N-nitroso compounds (ATNCs) in fecal samples in a series of studies of volunteers maintained under controlled conditions. A result of these studies is that we have shown a consistent dose response to red meat consumption. Fiber, in the form of vegetables, bran or resistant starch, does not reduce the level of ATNCs formed, although transit time is reduced and fecal weight are increased. Here we show that the equivalent amount (420-600 g) of meat as white meat has no effect on fecal ATNCs in 12 volunteers (P = 0.338). At dosages of 0, 60, 120, 240 and 420 g of red meat/d, mean levels of ATNC output are highly correlated with dose of meat: for concentration ATNC versus dose of meat in g/d, r = 0.972, β = 0.252 ng/g (SE 0.035); for total ATNC output versus dose of meat in g/d, r = 0.963, β = 2.605 μg/d (SE 0.419). The effects of nonmeat protein and of heme on increased N-nitrosation and the genotoxic effects of the ATNCs produced are presently being investigated.

Dietary factors in relation to endometrial cancer: a nationwide case-control study in Sweden

Abstract: The incidence of endometrial cancer varies up to 10-fold between high- and low-incidence regions, suggesting the importance of environmental factors, including diet, in the etiology of this disease. However, few studies have examined the role of diet in the etiology of endometrial cancer. Using unconditional logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI), we analyzed data from a large, case-control study of Swedish-born postmenopausal women aged 50-74 yr (709 cases and 2,887 controls) residing in Sweden between 1994 and 1995. We found no clear association between foods or food groups and endometrial cancer risk, although high consumption of certain foods, such as Brassica vegetables, coffee, and legumes, might be associated with small-to-moderate reduced risks of endometrial cancer, while red meat consumption might be associated with a small-to-moderate increased risk. Daily use of calcium supplements appeared to lower endometrial cancer risk (OR = 0.5, 95% CI = 0.3-0.9, P for trend = 0.04), especially among women with low calcium intake from dairy products. On the other hand, the use of iron supplements appeared to increase the risk (OR = 1.7, 95% CI = 0.9-3.3, P for trend = 0.03). The findings are discussed with respect to previous studies and the possible underlying mechanisms.

Meat, smoking, alcohol, and colorectal tumors: the role of genetic susceptibility

Abstract: Colorectal cancer is the second most common cancer in the Western world and is thought to arise mainly from colorectal adenomas. Red meat and alcohol intake and (long-term) cigarette smoking probably increase colorectal tumor risk. Although risk increase was found to be weak, certain subgroups might be more susceptible to these carcinogens because of inherited polymorphisms resulting in increased activation of potential carcinogens. In this thesis, we investigated whether meat consumption, cigarette smoking, and alcohol intake, in combination with such genetic polymorphisms, increase the risk of colorectal adenomas and colorectal cancer. For this purpose, we used two different study populations. One was an adenoma case-control study with 440 adenoma cases and 447 polyp-free controls recruited among those undergoing endoscopy at eight Dutch outpatient clinics between June 1997 and June 2000. The other was a Dutch prospective cohort enrolled between January 1987 and December 1991. Follow-up for 8.5 years resulted in 102 colorectal cancer cases. We compared these cases with a random sample of 537 controls frequency-matched on age, sex and town. Information on dietary and lifestyle habits was collected through self-administered questionnaires. DNA was isolated from whole blood and genetic polymorphisms were subsequently determined by use of standardized methods. We found that colorectal adenoma risk was not increased with high meat consumption (OR 1.2, 95% CI 0.8-1.9) or unfavorable meat preparation methods. These null-associations were not modified by genetic polymorphisms affecting metabolism of heterocyclic amines that may be formed during preparation of meat at high temperatures ( N -acetyltransferases ( NAT ) 1 and 2, sulfotransferase ( SULT ) 1A1 , and glutathione S- transferases ( GST ) M1 and T1 ). Long-term cigarette smoking increased adenoma risk (OR 2.4, 95% CI 1.4-4.1 for smoking for more than 25 years compared to never smokers). Although most pronounced in those with fast SULT1A1 (OR 4.3, 95% CI 1.6-11.8) and slow NAT2 variants (OR 3.5, 95% CI 1.9-6.4), there was no statistically significant effect modification by genetic polymorphisms involved in metabolism of arylamines and polycyclic aromatic hydrocarbons from cigarette smoke ( NAT1 , NAT2 , SULT1A1 , GSTM1 , GSTT1 , and epoxide hydrolase). Alcohol consumption increased colorectal adenoma risk especially among women (OR 1.8, 95% CI 1.0-3.2 for 10 or more drinks weekly versus less than one drink per week). Among men, adenoma risk increased only with consumption of more than 21 drinks per week (OR 1.8, 95% CI 0.9-3.8). Alcohol is metabolized to carcinogenic acetaldehyde by alcohol dehydrogenase (ADH3). The association between alcohol and adenomas was weakly - but not statistically significantly - stronger among those with the fast ADH3 variant compared to those with imputed slow phenotypes. Colorectal cancer risk increased slightly with frequent red meat consumption (OR 1.6, 95% CI 0.9-2.9, highest vs. lowest intake). Genetic polymorphisms in NAT1 , NAT2 , and GSTM1 did not importantly modify this association. Risk of colorectal cancer was increased with smoking duration, but only among former smokers having smoked for more than 15 years (OR 2.7, 95% CI 1.0-7.4) compared to former smokers having smoked for shorter time. NAT1 , NAT2 , and GSTM1 polymorphisms did not influence this association. In summary, the results of our studies do not point toward strong modifying effects of genetic polymorphisms of enzymes involved in carcinogen metabolism, which is in accordance with results of similar studies on colorectal tumors. Such effects may however be present, but possibly, we were not able to demonstrate them. To elucidate the potential role of genetic susceptibility in colorectal carcinogenesis, alternative epidemiologic study designs and statistical methods should be considered. These observational studies should be conducted simoultaneously with experimental studies aiming to generate more biological knowledge on the diverse processes leading to colorectal tumorigenesis in humans.

Estimated absorbable iron intakes in quebec adults.

Abstract: In the last 30 years, the prevalence of low dietary iron intake has increased, partly because North Americans have been encouraged to choose lower fat foods, including leaner meats As a result, there has been a decrease in red meat consumption The objective of this study was to estimate absorbable iron intakes of a representative sample of the Quebec adult population and to compare these results with the new North American recommendations for iron Dietary intakes were obtained by 24-hour recall and absorbable iron intakes were estimated using Monsen & coworker's model While 189 % and 25% of women and men respectively had an iron intake below the estimated average requirement (EAR), 662 % and 256% had an estimated available iron intake below the recommended level for absorbed iron Beef consumption had the strongest association with estimated absorbable iron, followed by vegetables Subjects with a high education level consumed significantly less meat, beef and heme iron than subjects whose educati

Do differences in the food supply explain discrepancies in epidemiology

Abstract: Epidemiological studies often show correlations within a population between specific food types and disease outcomes. However a considerable amount of variability exists between such studies in terms of level of significance (or relevance) of these correlations, particularly between different regional or national settings. These differing outcomes are often a result of three distinct shortcomings of epidemiological investigations involving diet: (i) Poor adjustment for intake (or lack of intake) of other dietary factors, (ii) Lack of adequate description or subgrouping of food types on dietary recall tools such as food frequency questionnaires, (iii) Food compositional differences at a regional or national level. The first limitation requires a case by case evaluation, however the latter two points are best illustrated by reference to a specific case, that of the ongoing debate over red meat consumption and colon cancer. For the situation regarding the recording of food intake, the recall tools are usually ‘blunt’ instruments that collect simplified information from which unsubstantiated conclusions are made. For instance frequency data is collected on ‘meat’ intake (often without quantities) where the term ‘meat’ includes: lean meat, fatty meat cuts and dishes and meat products (with added fat, food additives and other food types). In the case of national food compositional differences, red meat can have a broad range of nutrient, contaminant and fat content and type. The US situation from which many of these studies originate involves dramatic differences in animal feeding regimes, meat composition and preparation to Australia. For instance the average selvedge fat on retail Australian beef and lamb cuts is 2.35 mm and 3.73 mm, respectively, with most cuts completely trimmed of fat (1). In a US study, average selvedge fat on retail beef and lamb cuts was 3.8 mm (1991) (2). Nutrition surveys also suggest that around 80% of Australians eat their meat trimmed of fat (3). In addition high red meat eaters have been shown to consume almost 40% more vegetables than non red meat eaters and 60% more than light red meat eaters (4). The majority of Australian beef and lamb are grass-fed. Due to the extensive practice of grain-feeding (mainly corn), US beef cuts are more marbled and contain almost twice as much fat and saturated fatty acids as comparable Australian beef cuts (5). Grass-fed Australian beef contains significantly more long chain omega 3 polyunsaturated fatty acids (LCPUFA) than grain-fed US beef. Lean Australian beef rump contains approximately 100 mg of LC n-3 PUFA which is comparable to that of many species of white fish in Australia (6). Furthermore, the intramuscular fat of Australian grass-fed steers has higher levels of conjugated linoleic (7) acid and lower levels of trans-fatty acids than grain fed steers (8). Lean red meat is more widely available in Australia than in the US. The data presented suggests that studies investigating the association between red meat consumption and cancer in US populations may not be relevant to Australians due to these differences in the red meat supply.

Congruence of red meat descriptors reported by a group of elderly volunteers and those found in an Australian nutrient database

Abstract: The role of red meat in the Australian diet has been the subject of substantial interest in both academic and industry circles (1)with further research expanding nutrition knowledge and its applications. However, in studies of dietary habits the issue ofaccuracy of assessments warrants attention. Some of the problems relate to discrepancies between consumer accounts offoods consumed and the descriptors used in food databases. The aim of this paper is to describe the categories of red meatreported by elderly subjects in a trial involving red meat consumption, and to identify potential sources of error in using thisdata as the basis for intervention.Thirty four elderly adults (mean age 68.1years, range 61–80yrs) volunteered to participate in an intervention trial with 3 dietitians undertaking a detailed open ended diet history interview where subjects described their eating patterns ineveryday terms (2). A checklist was included at the end of the interview, summarizing meat types, amounts and frequency ofconsumption. Participants reported 5, 4 and 1 main categories of beef, lamb and veal respectively. Within the beef and lambcategories there were a further 15 and 7 sub-categories respectively. The 3 main categories reported were rump steak, mince(with ‘premium’regularly used as a qualifier) and short loin lamb chops. Participants reportedly consumed meat at dinner inthe evening at home, with the exception of one male who ate lunches at clubs twice a week and another who chose meat piefor lunch once a week. Five individuals and 3 couples reported consuming small amounts of cold meats (60g) at the lunchmeal 1–3 times per week and only one subject reported eating meat in a takeaway breakfast twice a week. The AUSNUT(ANZFA, 1999) database in the Foodworks nutrient analysis software program (version 3.00, 2002. Xyris software, Brisbane)indicated 12 options for rump steak: 3 raw and 9 cooked (3 fried, 3 grilled, 3 non-specified, NS), and each with fat descriptorsof fat trimmed, lean & fat, and NS fat trimmed. If barbecued rump steak were itemized a potential difference of 6g fat and300kJ could result from the average serve of the study sample if the fat specification were not accurately determined. Volunteers for our dietary study generally reported meat categories congruent with descriptors in the current database.Three quarters reported consuming mixed dishes and all but 2 gave some description of fat removal. This and the relativestability of their eating patterns appear to reflect the age of the group. Nevertheless, the risk of measurement error still lieswith elucidating recipes for mixed dishes, and in the accurate assessment of the fat content in consumed meats.