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Red meat intake and cancer risk: a study in Italy.

Meat intake has been positively associated with risk of digestive tract cancers in several epidemiological studies, while data on the relation of meat intake with cancer risk at most other sites are inconsistent. The overall data set, derived from an integrated series of case-control studies conducted in northern Italy between 1983 and 1996, included the following incident, histologically confirmed neoplasms: oral cavity, pharynx and esophagus (n = 497), stomach (n = 745), colon (n = 828), rectum (n = 498), liver (n = 428), gallbladder (n = 60), pancreas (n = 362), larynx (n = 242), breast (n = 3,412), endometrium (n = 750), ovary (n = 971), prostate (n = 127), bladder (n = 431), kidney (n = 190), thyroid (n = 208), Hodgkin's disease (n = 80), non-Hodgkin's lymphomas (n = 200) and multiple myelomas (n = 120). Controls were 7,990 patients admitted to hospital for acute, non-neoplastic conditions unrelated to long-term modifications in diet. The multivariate odds ratios (ORs) for the highest tertile of red meat intake (>/=7 times/week) compared with the lowest (</=3 times/week) were 1.6 for stomach, 1.9 for colon, 1.7 for rectal, 1.6 for pancreatic, 1.6 for bladder, 1.2 for breast, 1.5 for endometrial and 1.3 for ovarian cancer. ORs showed no significant heterogeneity across strata of age at diagnosis and sex. No convincing relation with red meat intake emerged for cancers of the oral cavity, pharynx and esophagus, liver, gallbladder, larynx, kidney, thyroid, prostate, Hodgkin's disease, non-Hodgkin's lymphomas and multiple myeloma. For none of the neoplasms considered was there a significant inverse relationship with red meat intake. Thus, reducing red meat intake might lower the risk for several common neoplasms.

Adult↗

Polymorphism of the N-acetyltransferase 2 gene, red meat intake, and the susceptibility of hepatocellular carcinoma.

OBJECTIVE: Carcinogenic aromatic amines, derived from cooked meat, are activated or inactivated by hepatic N-acetyltransferase (NAT). The aim of this study was to evaluate the relationship of NAT2 genetic polymorphisms with hepatocellular carcinoma (HCC), with special reference to the interaction of dietary habits. METHODS: Peripheral white blood cell DNA from 185 HCC patients and 185 matched controls were genotyped for NAT2 by a polymerase chain reaction-restriction fragment length polymorphism method. All the subjects studied were chronic viral hepatitis B or C carriers with liver cirrhosis. Dietary habits of the subjects were assessed using a semiquantitative food frequency questionnaire. RESULTS: There was no association between the susceptibility of HCC and the overall NAT2 genotypes. However, in rapid acetylators (with two wild type NAT2*4 alleles), there was a trend of increased HCC risk from low to intermediate and high red meat intake (OR = 1, 2.66, 3.89; p(trend) = 0.016), even when adjusted for family history of HCC and habitual alcohol drinking. The interaction between red meat intake and the NAT2*4 acetylator status for an increased risk of HCC was significant (p = 0.007). CONCLUSIONS: Polymorphisms of the NAT2 gene may confer different susceptibilities to the effect of red meat intake on HCC. In rapid acetylators with chronic viral hepatitis-related cirrhosis, red meat intake may play a role in hepatocarcinogenesis.

Aged↗

A low-protein diet exacerbates postprandial chylomicron concentration in moderately dyslipidaemic subjects in comparison to a lean red meat protein-enriched diet.

OBJECTIVE: To investigate whether altering energy intake as red meat protein or carbohydrate modifies chylomicron homeostasis and postprandial lipaemia. DESIGN: Randomized single-blind dietary intervention trial. SETTING: School of Public Health, Division of Health Science, Curtin University, Perth, Western Australia. SUBJECTS: A total of 20 moderately hypertriglyceridaemic but otherwise healthy subjects were recruited and completed the study. INTERVENTION: Participants consumed an isocaloric weight maintenance diet low in protein (14, 53 and 30% of energy as protein, carbohydrate and fat, respectively) or high in protein (25, 35 and 30% energy as protein, carbohydrate and fat) for a period of 6 weeks. Fasting plasma lipids and postprandial lipoprotein studies (triglyceride and apolipoprotein B48) following an oral fat challenge were carried out at the start and conclusion of the dietary intervention period. RESULTS: Consumption of the low- or high-protein diet had no significant effect on fasting plasma or postprandial lipaemia, the latter determined as the incremental area under the triglyceride curve following a fat challenge. However, subjects who consumed a low-protein diet for 6 weeks had a substantially exaggerated postprandial chylomicron response, indicated as the area under the apo B48 curve following a fat challenge. The change in postprandial chylomicron kinetics could not be explained by changes in insulin sensitivity, which appeared to be similar before and after intervention with either diet. CONCLUSIONS: Daily moderate consumption of a lean red meat protein-enriched diet attenuates postprandial chylomicronaemia in response to ingestion of a fatty meal.

Adult↗

Comparison of the effects of lean red meat vs lean white meat on serum lipid levels among free-living persons with hypercholesterolemia: a long-term, randomized clinical trial.

BACKGROUND: Patients with hypercholesterolemia are often counseled to limit or eliminate intake of red meats, despite evidence that lean red meats (LRMs) are not hypercholesterolemic in comparison with lean white meats (LWMs). The objective of this study was to evaluate the long-term effects on serum lipids of incorporating LRM (beef, veal, and pork) vs LWM (poultry and fish) into a National Cholesterol Education Program (NCEP) Step I diet in free-living individuals with hypercholesterolemia. METHODS: Subjects included 191 men and women with a serum low-density lipoprotein cholesterol level of 3.37 to 4.92 mmol/L (130-190 mg/dL) and triglyceride level less than 3.96 mmol/L (350 mg/dL). After a 4-week baseline phase, subjects were counseled to follow an NCEP Step I diet including 170 g (6 oz) of lean meat per day, 5 to 7 days per week. Based on random assignment, subjects were instructed to consume at least 80% of their meat in the form of LRM or LWM. Fasting serum lipid levels were assessed 4, 12, 20, 28, and 36 weeks after randomization. RESULTS: After randomization, mean concentrations of total cholesterol (6.09 mmol/L [235.7 mg/dL] vs 6.08 mmol/L [235.2 mg/dL]) and low-density lipoprotein cholesterol (3.99 mmol/L [154.1 mg/dL] vs4.01 mmol/L [154.7 mg/dL]) were nearly identical in the LRM and LWM groups (1%-3% below baseline) during treatment. Mean triglyceride levels remained similar to baseline values and high-density lipoprotein cholesterol concentrations increased by approximately 2% in both groups. CONCLUSIONS: The NCEP Step I diets containing primarily LRM or LWM produced similar reductions in low-density lipoprotein cholesterol and elevations in high-density lipoprotein cholesterol levels, which were maintained throughout 36 weeks of treatment.

Animals↗

Presence of Salmonella in the red meat abattoir lairage after routine cleansing and disinfection and on carcasses.

Foodborne pathogens, such as Salmonella, may remain in abattoir lairages after cleansing and pose a risk of transfer and contamination from one processing day to the next. These organisms may be transferred to the outer surface of animals held in lairage facilities, and the skin or hide may be a significant source of microbial contamination on the red meat carcasses subsequently produced. Sponge samples were taken from various sites in the lairage (n = 556), and single-pass sponge samples were taken from one side of red meat carcasses (n = 1,050) at five commercial abattoirs in Southwest England and tested for the presence of Salmonella. Of these, 6.5% of lairage samples were positive, containing estimated numbers of up to 10(4) Salmonella organisms per sampled area (50 by 50 cm). Salmonella was found on 9.6% of 240 lamb carcasses, 12.7% of 330 beef carcasses, 31% of 70 pig carcasses, 20% of 80 calf carcasses younger than 14 days of age, and none of 330 cull cow and bull carcasses. Subtyping divided the 137 isolates into seven serogroups and three pulsed-field gel electrophoresis clusters, and sensitivity testing against a bank of 16 antimicrobials indicated that 47 isolates had resistance to one or more antimicrobial agents. These results indicate that Salmonella contamination can persist in the lairage environment from one processing day to the next and that Salmonella is present on red meat carcasses, although the implications of residual lairage contamination on carcass meat microbiology are not clear from this study. Abattoir owners should take steps to reduce the level of contamination in their premises to prevent contamination from being carried over from one processing day to the next.

Abattoirs↗

The distribution of Staphylococci in bioaerosols from red-meat abattoirs.

The quality and shelf-life of perishable foodstuffs can be reduced by high concentrations in the processing environment of bioaerosols consisting of spoilage microbiota. A lack of documented literature on the distribution of such bioaerosols has, however, led to the underestimation of their impact. In the study reported here, the deboning rooms of selected South African red-meat abattoirs were investigated for airborne concentrations of staphylococci; the authors studied the distribution of Staphylococcus species in general, as well as the coagulase types of Staphylococcus aureus in particular. Average staphylococci bioaerosol concentrations varied considerably among the abattoirs investigated, with Abattoir B having the highest counts (3 x 10(2) CFUs/m3) and Abattoir A having the lowest (7.6 CFUs/m3). There was a significant link between bioaerosols and microbial loads from red meat in the same environment. The recorded levels were, however, well below the recommended maximum limits for bioaerosols suggested by various international and governmental authorities. Staphylococcus xylosus and S. saprophyticus were found to be the most abundant species in the air of the deboning rooms, while among S. aureus coagulase types, Type III and Type VIII were predominant. On the basis of the ecology of the bacterial groups, the authors suggest probable sources of staphylococcal bioaerosols and propose strategies that could be developed for red-meat abattoirs to reduce the levels of airborne pathogens.

Abattoirs↗

Well-done red meat, metabolic phenotypes and colorectal cancer in Hawaii.

Heterocyclic amines (HAAs) and polycyclic hydrocarbons are suspected colorectal cancer (CRC) carcinogens that are found in well-done meat. They require metabolic activation by phase I enzymes, such as the smoking-inducible CYP1A isoenzymes. N-acetyltransferase 2 (NAT2) also play a role in the further activation of HAAs. We conducted a population-based case-control study in Hawaii to test the associations of preference for well-done red meat and HAA intake with colon and rectal cancers, as well as the modifying effects of NAT2 and CYP1A2. We interviewed 727 Japanese, Caucasian or Native Hawaiian cases and 727 controls matched on sex, age, and ethnicity. HAA intake was estimated based on consumption of meat and fish for each of several cooking methods and doneness levels. A subgroup of 349 cases and 467 controls was phenotyped for CYP1A2 by a caffeine test. We found that preference for well-done red meat was associated with a 8.8-fold increased risk of CRC (95% CI: 1.7-44.9) among ever-smokers with the NAT2 and CYP1A2 rapid phenotypes, compared to ever-smokers with low NAT2 and CYP1A2 activities and who preferred their red meat rare or medium. A dose-dependent association was also found between the HAA intake estimates and male rectal cancer, with a two- to three-fold increase in risk from the low (T(1)) to high (T(3)) tertile of intake for each HAA. This association was strongest for MeIQx. HAA intake was not associated with male colon cancer or colon or rectal cancer in women. These data provide support to the hypothesis that exposure to pyrolysis products through consumption of well-done meat increases the risk of CRC, particularly in individuals who smoke and are genetically susceptible (as determined by a rapid phenotype for both NAT2 and CYP1A2). An attempt to examine the risk associated with specific HAAs suggested that the main HAAs increase risk of rectal cancer in men and that they do not appreciably affect risk of rectal cancer in women or of colon cancer in either sex.

Adolescent↗

Green vegetables, red meat and colon cancer: chlorophyll prevents the cytotoxic and hyperproliferative effects of haem in rat colon.

Diets high in red meat and low in green vegetables are associated with increased colon cancer risk. This association might be partly due to the haem content of red meat. In rats, dietary haem is metabolized in the gut to a cytotoxic factor that increases colonic cytotoxicity and epithelial proliferation. Green vegetables contain chlorophyll, a magnesium porphyrin structurally analogous to haem. We studied whether green vegetables inhibit the unfavourable colonic effects of haem. First, rats were fed a purified control diet or purified diets supplemented with 0.5 mmol haem/kg, spinach (chlorophyll concentration 1.2 mmol/kg) or haem plus spinach (n = 8/group) for 14 days. In a second experiment we also studied a group that received haem plus purified chlorophyll (1.2 mmol/kg). Cytotoxicity of faecal water was determined with a bioassay and colonic epithelial cell proliferation was quantified in vivo by [methyl-(3)H]thymidine incorporation into newly synthesized DNA. Exfoliation of colonocytes was measured as the amount of rat DNA in faeces. In both studies haem increased cytotoxicity of the colonic contents approximately 8-fold and proliferation of the colonocytes almost 2-fold. Spinach or an equimolar amount of chlorophyll supplement in the haem diet inhibited these haem effects completely. Haem clearly inhibited exfoliation of colonocytes, an effect counteracted by spinach and chlorophyll. Finally, size exclusion chromatography showed that chlorophyll prevented formation of the cytotoxic haem metabolite. We conclude that green vegetables may decrease colon cancer risk because chlorophyll prevents the detrimental, cytotoxic and hyperproliferative colonic effects of dietary haem.

Animals↗

Red meat and colon cancer: dietary haem-induced colonic cytotoxicity and epithelial hyperproliferation are inhibited by calcium.

High intake of red meat is associated with increased colon cancer risk. We have shown earlier that this may be due to the high haem content of red meat, because dietary haem increased cytolytic activity of faecal water and colonic epithelial proliferation. Dietary calcium inhibits diet-induced epithelial hyperproliferation. Furthermore, it has been shown that supplemental calcium inhibited the recurrence of colorectal adenomas. Therefore, we studied whether dietary calcium phosphate can exert its protective effects by inhibiting the deleterious effects of haem. In vitro, calcium phosphate precipitated haem and inhibited the haem-induced cytotoxicity. Subsequently, rats were fed diets, differing in haem (0 or 1.3 micromol/g) and calcium phosphate content only (20 or 180 micromol/g). Faeces were collected for biochemical analyses. Cytolytic activity of faecal water was determined from the degree of lysis of erythrocytes by faecal water. Colonic epithelial proliferation was measured in vivo using [(3)H]thymidine incorporation. In rats fed low calcium diets, dietary haem increased cytolytic activity of faecal water (98 +/- 1 versus 1 +/- 1%, P < 0.001) and the concentration of cations in faeces (964 +/- 31 versus 254 +/- 20 micromol/g), when compared with controls. This indicates that dietary haem increased colonic mucosal exposure to luminal irritants. Colonic epithelial proliferation was increased compared with controls (70 +/- 4 versus 48 +/- 8 d.p.m./microg DNA, P < 0.001). This was accompanied by metabolism of the ingested haem and solubilization of haem compounds in the faecal water. A high calcium diet largely prevented this metabolism and solubilization. It also inhibited the haem-induced cytolytic activity of faecal water and increase in faecal cation concentration. In accordance, the haem-induced colonic epithelial hyperproliferation was prevented. We therefore suggest that dietary calcium phosphate acts as a chemopreventive agent in colon carcinogenesis by inhibiting the cytolytic and hyperproliferative effects of dietary haem.

Animals↗

The influence of consuming fatty fish instead of red meat on plasma levels of vitamins A, C and E.

The effect of fatty fish consumption on the plasma levels of vitamins A, C and E and the intake of these vitamins were studied in 12 males and 16 females with a mean age of 32.4 years. This cross-over study had a 3 week baseline, 6 week experimental and 6 week post-experimental period with a washout period of approximately 3 months in between. Four 7 day dietary records were used to collect dietary information. Blood samples were drawn after an overnight fast at baseline and every third week thereafter. Plasma total cholesterol, high density lipoprotein cholesterol, triacylglycerol, vitamin A, C and E levels were determined. During the experimental periods red meat was consumed by half of the volunteers while fatty fish was consumed by the other half. Diets were crossed-over after the washout period. Plasma levels of vitamins A, C and E remained within normal limits in the experimental periods. The intake of polyunsaturated fatty acids (PUFA) was significantly higher in the experimental fatty fish period than in the experimental red meat period. The dietary ratio of vitamin E: PUFA and the plasma vitamin E level were lower (P < 0.01) in the experimental fatty fish period than in the experimental red meat period but the ratio of plasma vitamin E: total cholesterol plus triacylglycerol did not differ between the experimental periods. In this study none of the experimental groups were at risk in terms of their intake of the antioxidant vitamins.

Adult↗

Red meat, family history, and increased risk of gastric cancer with microsatellite instability.

Microsatellite instability (MSI) occurs frequently in sporadic gastric cancer (GC) and may define a distinctive molecular pathway of carcinogenesis. We evaluated the role of dietary risk factors in GC according to MSI status. A large series of 382 GC cases and 561 controls were originally identified in a population-based case-control study carried out in the high-risk area around Florence, Italy; 126 GC patients were typed for MSI status. A MSI+ phenotype was detected in 43 of 126 cases (34.1%), whereas 83 cases were classified as MSI-. A multinomial logistic regression model was used to compare the two subgroups of GC classified according to MSI status in the same analysis, with all of the available population controls. A case-case approach was also used. The risk of MSI+ tumors was positively associated with high consumption of red meat and meat sauce and negatively associated with consumption of white meat. A positive association was also seen with total protein and nitrite intake, whereas no relation was found with micronutrient intake. Risk was especially high among subjects reporting both a positive GC family history and a high consumption of red meat (odds ratio, 25.7; 95% confidence interval, 6.4-102.8). For MSI- tumors, a significant protective effect was associated with frequent consumption of citrus and other fresh fruit, garlic, legumes, vegetables, and olive oil and with high intake of beta-carotene and other antioxidants and sugar, whereas positive associations were seen with protein and sodium intake. In summary, a specific dietary pattern emerged for MSI+ gastric tumors, suggesting that factors related to red meat consumption are involved in this pathway, particularly among individuals with a positive family history. In contrast, the risk of MSI- tumors was strongly reduced by the frequent consumption of fresh fruit and vegetables.

Aged↗

International red meat trade.

The maturation of the US beef and pork markets and increasing consumer demands for convenience, safety, and nutrition suggests that the beef and pork industries must focus on product development and promotion. New marketing arrangements are developing that help coordinate production with consumer demands. The relative high levels of incomes in the United States are likely to increase the demands for branded products rather than increase total per capita consumption. Foreign markets represent the greatest opportunity for increased demand for commodity beef and pork products. Increasing incomes in developing countries will likely allow consumers to increase consumption of animal-source proteins. Real prices of beef and pork have declined substantially because of sagging domestic demand and increasing farm-level production technologies. Increasing US beef and pork exports have obviated some of the price declines. Pork attained a net export position from a quantity perspective in 1995. The United States continues to be a net importer of beef on a quantity basis but is close to becoming a net exporter in terms of value. By-products continue to play a critical role in determining the red meat trade balance and producer prices. The United States, however, must continue to become cost, price, and quality competitive with other suppliers and must secure additional market access if it is to sustain recent trade trends. Several trade tensions remain in the red meat industry. For example, mandated COOL will undoubtedly have domestic and international effects on the beef and pork sectors. Domestically, uncertainty regarding consumer demand responses or quality perceptions regarding product origin, as well as added processor-retailer costs will be nontrivial. How these factors balance out in terms of benefits versus costs to the industry is uncertain. From an international perspective, some beef and pork export suppliers to the United States could view required labeling as a trade restriction, which could ultimately impact future US red meat exports. Conversely, some countries may view such labeling requirements as an opportunity to brand high-quality products. The US lamb meat industry has experienced declining real prices, domestic production, and demand. The cessation of wool incentive payments, increased environmental regulations, and competition by imports have significantly affected the industry. Import suppliers have capitalized on product quality in this niche market. Trade restrictions initially imposed in 1999 by the US Government were ruled illegal by the WTO. The US Government responded by providing financial assistance to lamb producers. Product quality improvements and promotion aimed at the domestic market, however, will be critical factors in shaping the economic viability of the US lamb meat industry.

Animals↗

Red meat and colon cancer: the cytotoxic and hyperproliferative effects of dietary heme.

The intake of a Western diet with a high amount of red meat is associated with a high risk for colon cancer. We hypothesize that heme, the iron carrier of red meat, is involved in diet-induced colonic epithelial damage, resulting in increased epithelial proliferation. Rats were fed purified control diets, or purified diets supplemented with 1.3 micromol/g of hemin (ferriheme), protoporphyrin IX, ferric citrate, or bilirubin (n = 8/group) for 14 days. Feces were collected for biochemical analyses. Fecal cytotoxicity was determined from the degree of lysis of erythrocytes by fecal water. Colonic epithelial proliferation was measured in vivo using [3H]thymidine incorporation into colonic mucosa. The colonic epithelial proliferation in heme-fed rats was significantly increased compared to control rats [55.2 +/- 5.8 versus 32.6 +/- 6.3 dpm/microg DNA (mean +/- SE); P < 0.05]. The fecal water of the heme group was highly cytotoxic compared to the controls (90 +/- 2% versus 2 +/- 1%; P < 0.001), although the concentrations of cytotoxic bile acids and fatty acids were significantly lower. Organic iron was significantly increased compared to the controls (257 +/- 26 versus 80 +/- 21, microM; P < 0.001). Spectrophotometric analyses suggest that this organic iron is heme-associated. Thiobarbituric acid-reactive substances were greatly increased in the fecal water of heme-fed rats compared to the controls (177 +/- 12 versus 59 +/- 7 microM; P < 0.05). Heme itself could not account for the increased cytotoxicity because the addition of heme to the fecal water of the control group, which was equimolar to the organic iron content of the fecal water of the heme group, did not influence the cytotoxicity. Hence, an additional heme-induced cytotoxic factor is involved, which may be modulated by the generation of luminal-reactive oxygen species. Protoporphyrin IX, ferric citrate, and bilirubin did not increase proliferation and cytotoxicity. In conclusion, dietary heme leads to the formation of an unknown, highly cytotoxic factor in the colonic lumen. This suggests that, in heme-fed rats, colonic mucosa is damaged by the intestinal contents. This results in a compensatory hyperproliferation of the epithelium, which supposedly increases the risk for colon cancer.

Animals↗

Urinary mutagenesis and fried red meat intake: influence of cooking temperature, phenotype, and genotype of metabolizing enzymes in a controlled feeding study.

Meat cooked at high temperatures contains potential carcinogenic compounds, such as heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). Samples from a 2-week controlled feeding study were used to examine the relationship between the intake of mutagenicity from meat fried at different temperatures and the levels of mutagenicity subsequently detected in urine, as well as the influence of the genotype of drug metabolizing enzymes on urinary mutagenicity. Sixty subjects consumed ground beef patties fried at low temperature (100 degrees C) for 1 week, followed by ground beef patties fried at high temperature (250 degrees C) the second week. Mutagenicity in the meat was assayed in Salmonella typhimurium TA98 (+S9), and urinary mutagenicity was determined using Salmonella YG1024 (+S9). Genotypes for NAT1, NAT2, GSTM1, and UGT1A1 were analyzed using blood samples from the subjects. Meat fried at 100 degrees C was not mutagenic, whereas meat fried at 250 degrees C was mutagenic (1023 rev/g). Unhydrolyzed and hydrolyzed urine samples were 22x and 131x more mutagenic, respectively, when subjects consumed red meat fried at 250 degrees C compared with red meat fried at 100 degrees C. We found that hydrolyzed urine was approximately 8x more mutagenic than unhydrolyzed urine, likely due to the deconjugation of mutagens from glucuronide. The intake of meat cooked at high temperature correlated with the mutagenicity of unhydrolyzed urine (r = 0.32, P = 0.01) and hydrolyzed urine (r = 0.34, P = 0.008). Mutagenicity in unhydrolyzed urine was not influenced by NAT1, NAT2, or GSTM1 genotypes. However, a UGT1A1*28 polymorphism that reduced UGT1A1 expression and conjugation modified the effect of intake of meat cooked at high temperature on mutagenicity of unhydrolyzed urine (P for interaction = 0.04). These mutagenicity data were also compared with previously determined levels of HCAs (measured as MeIQx, DiMeIQx, and PhIP) and polycyclic aromatic hydrocarbons (PAHs) in the meat, levels of HCAs in the urine, and CYP1A2 and NAT2 phenotypes. The levels of mutagenicity in the meat fried at low and high temperatures correlated with levels of HCAs, but not levels of PAHs, in the meat. Also, levels of mutagenicity in unhydrolyzed urine correlated with levels of MeIQx in unhydrolyzed urine (r = 0.36; P = 0.01), and the levels of mutagenicity of hydrolyzed urine correlated with levels of MeIQx (r = 0.34; P = 0.01) and PhIP (r = 0.43; P = 0.001) of hydrolyzed urine. Mutagenicity in unhydrolyzed urine was not influenced by either the CYP1A2 or NAT2 phenotype. The data from this study indicate that urinary mutagenicity correlates with mutagenic exposure from cooked meat and can potentially be used as a marker in etiological studies on cancer.

Animals↗

Haem, not protein or inorganic iron, is responsible for endogenous intestinal N-nitrosation arising from red meat.

Many N-nitroso compounds (NOC) are carcinogens. In this controlled study of 21 healthy male volunteers, levels of NOC on a high (420 grams) red meat diet were significantly greater (P = 0.001) than on a low (60 grams) meat diet but not significantly greater when an equivalent amount of vegetable protein was fed. An 8-mg supplement of haem iron also increased fecal NOC (P = 0.006) compared with the low meat diet, but 35-mg ferrous iron had no effect. Endogenous N-nitrosation, arising from ingestion of haem but not inorganic iron or protein, may account for the increased risk associated with red meat consumption in colorectal cancer.

Adult↗

Red meat production and meat losses in Burkina Faso (1987-1997).

Based on monthly recorded data collected from 1987 to1997 in all official slaughter houses across the country, this study analyzes the trends of ruminant meat production and importance of meat condemnations by veterinary inspection in Burkina Faso. The average beef production per year is estimated at 6.717.5 + or - 2.969.1 tons, nd for small ruminant meat it is 8,715.5 + or - 4,161.3 tons. During the ten-year period (1987-1997) it appears that a large drop in production (up to 18%) occurred in 1994-1995 consistent with monetary devaluation. The average amount of red meat theoretiacally available for each inhabitant is estimated at 2.14 + or - 0.27 kg per year. Approximately 10 to 16 tons of diseased red meat is condemned every year by veterinary inspection. This is very important for a country where malnutrition and undernutrition is quasi endemic.

Abattoirs↗

Partial substitution of carbohydrate intake with protein intake from lean red meat lowers blood pressure in hypertensive persons.

BACKGROUND: Compared with carbohydrate intake, dietary intake of plant protein can lower blood pressure in humans, but the effects of animal protein intake on blood pressure have yet to be investigated. OBJECTIVE: We aimed to determine whether partial substitution of carbohydrate intake with animal protein intake from lean red meat changes blood pressure and other markers of cardiovascular disease risk in hypertensive persons. DESIGN: Hypertensive persons (n = 60) were recruited to an 8-wk parallel-design study. The participants were randomly assigned either to maintain their usual diet (control group) or to partially replace energy intake from carbohydrate-rich foods with protein from lean red meat (protein group). Measurements were performed at baseline and at the end of the intervention. RESULTS: Compared with the control group, the protein group had a significantly higher protein intake [x (95% CI) percent of energy: 5.3% (3.7%, 6.9%), P < 0.001] and a corresponding lower carbohydrate intake [-5.3% of energy (-7.9%, -2.7%), P < 0.001]. Body weight and intakes of fat, alcohol, and fiber were not significantly different between the groups. Compared with the control group, the clinic, 24-h, awake, and asleep systolic blood pressures were lower [-5.2 (-10.3, -0.1), -4.0 (-7.4, -0.6), -4.7 (-8.9, -0.5), and -4.7 (-10.3, -0.1) mm Hg, respectively, P < 0.05] and fasting plasma glucose concentrations were higher [0.33 mmol/L (0.09, 0.58 mmol/L), P = 0.008] in the protein group. These differences were independent of age, sex, and changes in weight, alcohol intake, or urinary sodium and potassium excretion. Diastolic blood pressure and heart rate, arterial compliance, blood lipids, and serum insulin were not significantly different between the groups. CONCLUSION: Within the context of other studies, these results suggest that modest substitution of carbohydrate-rich foods with protein-rich foods may lower blood pressure in hypertensive persons.

Blood Glucose↗

A high-whey-protein diet reduces body weight gain and alters insulin sensitivity relative to red meat in wistar rats.

A high-protein diet can reduce body weight and increase insulin sensitivity, but whether the type of dietary protein affects these outcomes is unknown. We hypothesized that feeding insulin-resistant rats a high-protein diet (32%) containing whey protein concentrate (WPC) would reduce body weight and tissue lipid levels and increase insulin sensitivity more than a diet containing red meat (RM). Rats were fed a high-fat diet (300 g fat/kg diet) for 9 wk, then switched to a diet containing either 80 or 320 g protein/kg diet, provided by either WPC or RM, for 6 wk (n = 8). The rats were then killed after overnight food deprivation. High dietary protein reduced energy intake (P < 0.001) and visceral (P < 0.001), subcutaneous (P < 0.001), and carcass fat (P < 0.05). Increasing the dietary density of WPC, but not of RM, reduced body weight gain by 4% (P < 0.001). Dietary WPC also reduced plasma insulin concentration by 40% (P < 0.05) and increased insulin sensitivity, compared to RM (P < 0.05). These findings support the conclusions that a high-protein diet reduces energy intake and adiposity and that whey protein is more effective than red meat in reducing body weight gain and increasing insulin sensitivity.

Animals↗