国际的癌症发病率不同和从移民的研究中，表明环境因素如饮食习惯与患癌症的风险相关。摄取的肉类如牛肉，世界各地存在三倍的差异，世界各地的消耗量最高的在发达国家（23公斤/人均），相比欠发达国家的消耗量（ 6公斤/人均）[1] 。基于Richard Doll and Richard Peto在1981年的研究，据估计，大约有35 ％ （范围10％ - 70％）的癌症可以归因于饮食，这和吸烟致癌的幅度类似达30％（范围25％-40％） [2] 。

已经有一百多篇流行病学研究报道肉类消耗和癌症的风险，这包括了世界各国的不同饮食习惯的研究。这些研究从不同方面对肉类摄入量和癌症的风险的联系进行了评估，既包括了总体肉类摄入量之间的比较，又有更精细的分类，尤其是摄取红肉，其中包括牛肉，羊肉，猪肉，小牛肉摄入量之间的比较，还有处理过肉类，包括肉类保存腌制，熏制，或压制之间的比较。

虽然癌症和肉类摄入量的联系可部分归罪于高能量或高脂肪（ "西化" ）的饮食，但我们更感兴趣是直接作用的潜在致癌化合物。肉类中含有包括N -亚硝基化合物，杂环胺，或多环芳烃。 动物实验中发现N -亚硝基化合物和亚硝胺是烈性致癌物质[3]。同样，杂环胺被列为诱变因素和动物致癌物[4-8] 。科学界公认存在于肉类这些化合物（盐，硝酸盐，亚硝酸盐，血红素铁，饱和脂肪，雌二醇）会增加DNA合成和细胞增殖，增加胰岛素样生长因子，影响激素代谢，促进自由基损伤，并产生致癌物质杂环胺[9-16] ，所有这些都可能促进癌症的产生。

肠癌

肉类摄入量和结肠癌的关系被研究得最广泛。地球人生态研究发现，人均肉类摄入量与结肠癌发病率（>0.85）和死亡率（>0.70）率联系非常高[17,18] 。同样在案例和人群研究中发现，大肠癌的风险直接与红肉和加工肉类摄入量相关。 1997年总结这些研究后，由世界癌症研究基金组织和美国癌症研究组织得出的结论是，摄入的红肉可能增加患结直肠癌的几率，而加工肉类可能增加大肠癌的危险[ 19 ] 。据报道，在世界卫生组织的共识会议结肠癌讨论小组[20]和关于饮食与癌症的委员会对医疗方面的食品和营养政策工作组[21] 得出类似的结论。在最近的汇总分析肠癌（其中包括公布到2005年研究）结论表示，红肉摄取量增加肠癌风险28 ％ -35 ％，加工肉类增加肠癌风险的20% - 49% [22-24]。

其他癌症

此外，还有大量的研究探讨了肉类摄入量与胃癌的风险。在最近一次的汇总分析得出结论：加工肉类摄入量增加胃癌的风险[25]。现在有一些研究报道，肉类摄入量与膀胱癌[26,27]、乳腺癌[28,29]、子宫内膜癌[30]、神经胶质瘤[31]、胰脏癌[32-34]、前列腺癌[35]，肾癌[36]风险有关，但需要更多的实验数据支持。同样，肉类摄入量和肺癌[37,38]、食道癌[39]、口腔癌[40,41] ，卵巢[42-44] ，子宫颈[45]，与肝癌[41]的风险有待于更多实验数据支持。这些研究需要进一步考虑能量摄入或身体质量指数两个指标。

最新的多种癌症研究

在这期plos医药杂志上，Amanda Cross和他的同事，分析了一个很有前瞻性的大型的关于红色和加工肉类摄入量与人体数种癌症风险联系的人群研究[46]。这个研究是美国国家卫生研究院（NIH）和美国退休者协会（前身为美国退休人员协会）的饮食习惯和健康研究，它包括了500000美国人，其中超过53000癌症案例。

对于肠癌，红肉摄入量62.5克/1000千卡增加24％的风险，红肉摄入量22.6克/1000千卡增加20%的风险。男性和女性没有区别。这个结论和以前汇总结论相同[22-24]。研究人员还发现，红肉摄入量增加食道癌、肝癌、肺癌风险20％ - 60％。加工肉制品摄入量增加肺癌16％。红肉和加工肉类摄入会增加男人胰腺癌的风险。

References

1  Delgado CL (2003) Rising consumption of meat and milk in developing countries has created a new food revolution. J Nutr 133: 3907S–3910S.
2  Doll R, Peto R (1981) The causes of cancer: quantitative estimates of avoidable risks of cancer in the United States today. J Natl Cancer Inst 66: 1191–1308.
3  Lijinsky W (1999) N-nitroso compounds in the diet. Mutat Res 443: 129–138.
4  Ohgaki H, Hasegawa H, Kato T, Suenaga M, Sato S, et al. (1985) Carcinogenicities in mice and rats of IQ, MeIQ, and MeIQx. Princess Takamatsu Symp 16: 97–105.
5  Ito N, Hasegawa R, Sano M, Tamano S, Esumi H, et al. (1991) A new colon and mammary carcinogen in cooked food, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Carcinogenesis 12: 1503–1506.
6  Ito N, Hasegawa R, Shirai T, Fukushima S, Hakoi K, et al. (1991) Enhancement of GST-P positive liver cell foci development by combined treatment of rats with five heterocyclic amines at low doses. Carcinogenesis 12: 767–772.
7 Ghoshal A, Preisegger KH, Takayama S, Thorgeirsson SS, Snyderwine EG (1994) Induction of mammary tumors in female Sprague-Dawley rats by the food-derived carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and effect of dietary fat. Carcinogenesis 15: 2429–2433.
8  Weisburger JH, Rivenson A, Reinhardt J, Aliaga C, Braley J, et al. (1994) Genotoxicity and carcinogenicity in rats and mice of 2-amino-3,6-dihydro-3-methyl-7H-imidazolo[4,5-f]quinolin-7- one: an intestinal bacterial metabolite of 2-amino-3-methyl-3H-imidazo[4,5-f]quinoline. J Natl Cancer Inst 86: 25–30.
9  Norrish AE, Ferguson LR, Knize MG, Felton JS, Sharpe SJ, et al. (1999) Heterocyclic amine content of cooked meat and risk of prostate cancer. J Natl Cancer Inst 91: 2038–2044.
10 Gann PH, Hennekens CH, Sacks FM, Grodstein F, Giovannucci EL, et al. (1994) Prospective study of plasma fatty acids and risk of prostate cancer. J Natl Cancer Inst 86: 281–286.
11 Allen NE, Appleby PN, Davey GK, Key TJ (2000) Hormones and diet: low insulin-like growth factor-I but normal bioavailable androgens in vegan men. Br J Cancer 83: 95–97.
12 Habito RC, Montalto J, Leslie E, Ball MJ (2000) Effects of replacing meat with soyabean in the diet on sex hormone concentrations in healthy adult males. Br J Nutr 84: 557–563.
13 Ngo TH, Barnard RJ, Cohen P, Freedland S, Tran C, et al. (2003) Effect of isocaloric low-fat diet on human LAPC-4 prostate cancer xenografts in severe combined immunodeficient mice and the insulin-like growth factor axis. Clin Cancer Res 9: 2734–2743.
14 Weinberg ED (1996) The role of iron in cancer. Eur J Cancer Prev 5: 19–36.
15 McCord JM (1998) Iron, free radicals, and oxidative injury. Semin Hematol 35: 5–12.
16 Daxenberger A, Ibarreta D, Meyer HH (2001) Possible health impact of animal oestrogens in food. Hum Reprod Update 7: 340–355.
17 Rose DP, Boyar AP, Wynder EL (1986) International comparisons of mortality rates for cancer of the breast, ovary, prostate, and colon, and per capita food consumption. Cancer 58: 2363–2371.
18 Armstrong B, Doll R (1975) Environmental factors and cancer incidence and mortality in different countries, with special reference to dietary practices. Int J Cancer 15: 617–631.
19 World Cancer Research Fund, American Institute for Cancer Research Expert Panel (1997) Food, nutrition and the prevention of cancer: a global perspective Washington (D. C.): American Institute for Cancer Research.
20 Scheppach W, Bingham S, Boutron-Ruault MC, Gerhardsson de Verdier M, et al. (1999) WHO consensus statement on the role of nutrition in colorectal cancer. Eur J Cancer Prev 8: 57–62.
21 United Kingdom Department of Health (1998) Nutritional aspects of the development of cancer Norwich: Her Majesty's Stationery Office.
22 Larsson SC, Wolk A (2006) Meat consumption and risk of colorectal cancer: a meta-analysis of prospective studies. Int J Cancer 119: 2657–2664.
23 Norat T, Lukanova A, Ferrari P, Riboli E (2002) Meat consumption and colorectal cancer risk: dose-response meta-analysis of epidemiological studies. Int J Cancer 98: 241–256.
24 Sandhu MS, White IR, McPherson K (2001) Systematic review of the prospective cohort studies on meat consumption and colorectal cancer risk: a meta-analytical approach. Cancer Epidemiol Biomarkers Prev 10: 439–446.
25 Larsson SC, Orsini N, Wolk A (2006) Processed meat consumption and stomach cancer risk: a meta-analysis. J Natl Cancer Inst 98: 1078–1087.
26 Steinmaus CM, Nunez S, Smith AH (2000) Diet and bladder cancer: a meta-analysis of six dietary variables. Am J Epidemiol 151: 693–702.
27 Michaud DS, Holick CN, Giovannucci E, Stampfer MJ (2006) Meat intake and bladder cancer risk in 2 prospective cohort studies. Am J Clin Nutr 84: 1177–1183.
28 Missmer SA, Smith-Warner SA, Spiegelman D, Yaun SS, Adami HO, et al. (2002) Meat and dairy food consumption and breast cancer: a pooled analysis of cohort studies. Int J Epidemiol 31: 78–85.
29 Cho E, Chen WY, Hunter DJ, Stampfer MJ, Colditz GA, et al. (2006) Red meat intake and risk of breast cancer among premenopausal women. Arch Intern Med 166: 2253–2259.
30 Bandera EV, Kushi LH, Moore DF, Gifkins DM, McCullough ML (2007) Consumption of animal foods and endometrial cancer risk: a systematic literature review and meta-analysis. Cancer Causes Control 18: 967–988.
31 Huncharek M, Kupelnick B, Wheeler L (2003) Dietary cured meat and the risk of adult glioma: a meta-analysis of nine 31 observational studies. J Environ Pathol Toxicol Oncol 22: 129–137.
32 Larsson SC, Hakanson N, Permert J, Wolk A (2006) Meat, fish, poultry and egg consumption in relation to risk of pancreatic cancer: a prospective study. Int J Cancer 118: 2866–2870.
33 Lin Y, Kikuchi S, Tamakoshi A, Yagyu K, Obata Y, et al. (2006) Dietary habits and pancreatic cancer risk in a cohort of middle-aged and elderly Japanese. Nutr Cancer 56: 40–49.
34 Nothlings U, Wilkens LR, Murphy SP, Hankin JH, Henderson BE, et al. (2005) Meat and fat intake as risk factors for pancreatic cancer: the multiethnic cohort study. J Natl Cancer Inst 97: 1458–1465.
35 Dagnelie PC, Schuurman AG, Goldbohm RA, Van den Brandt PA (2004) Diet, anthropometric measures and prostate cancer risk: a review of prospective cohort and intervention studies. BJU Int 93: 1139–1150.
36 Faramawi MF, Johnson E, Fry MW, Sall M, Zhou Y (2007) Consumption of different types of meat and the risk of renal cancer: meta-analysis of case-control studies. Cancer Causes Control 18: 125–133.
37 Alavanja MC, Field RW, Sinha R, Brus CP, Shavers VL, et al. (2001) Lung cancer risk and red meat consumption among Iowa women. Lung Cancer 34: 37–46.
38 Sinha R, Kulldorff M, Curtin J, Brown CC, Alavanja MC, et al. (1998) Fried, well-done red meat and risk of lung cancer in women (United States). Cancer Causes Control 9: 621–630.
39 Gonzalez CA, Jakszyn P, Pera G, Agudo A, Bingham S, et al. (2006) Meat intake and risk of stomach and esophageal adenocarcinoma within the European Prospective Investigation Into Cancer and Nutrition (EPIC). J Natl Cancer Inst 98: 345–354.
40 Levi F, Pasche C, Lucchini F, Bosetti C, La Vecchia C (2004) Processed meat and the risk of selected digestive tract and laryngeal neoplasms in Switzerland. Ann Oncol 15: 346–349.
41 Tavani A, La Vecchia C, Gallus S, Lagiou P, Trichopoulos D, et al. (2000) Red meat intake and cancer risk: a study in Italy. Int J Cancer 86: 425–428.
42 Kushi LH, Mink PJ, Folsom AR, Anderson KE, Zheng W, et al. (1999) Prospective study of diet and ovarian cancer. American Journal of Epidemiology 149: 21–31.
43 Bertone ER, Rosner BA, Hunter DJ, Stampfer MJ, Speizer FE, et al. (2002) Dietary fat intake and ovarian cancer in a cohort of US women. Am J Epidemiol 156: 22–31.
44 Larsson SC, Wolk A (2005) No association of meat, fish, and egg consumption with ovarian cancer risk. Cancer Epidemiol Biomarkers Prev 14: 1024–1025.
45 Ziegler RG, Brinton LA, Hamman RF, Lehman HF, Levine RS, et al. (1990) Diet and the risk of invasive cervical cancer among white women in the United States. Am J Epidemiol 132: 432–445.
46 Cross AJ, Leitzmann MF, Gail MH, Hollenbeck AR, Schatzkin A, et al. (2007) A prospective study of red and processed meat intake in relation to cancer risk. PLoS Med 4: e325. doi:10.1371/journal.pmed.0040325.
47 Deneo-Pellegrini H, De Stefani E, Ronco A, Mendilaharsu M, Carzoglio JC (1996) Meat consumption and risk of lung cancer; a case-control study from Uruguay. Lung Cancer 14: 195–205.
48 Castellsague X, Munoz N, De Stefani E, Victora CG, Castelletto R, et al. (2000) Influence of mate drinking, hot beverages and diet on esophageal cancer risk in South America. Int J Cancer 88: 658–664.
49 Ward MH, Sinha R, Heineman EF, Rothman N, Markin R, et al. (1997) Risk of adenocarcinoma of the stomach and esophagus with meat cooking method and doneness preference. Int J Cancer 71: 14–19.
50 Takezaki T, Gao CM, Wu JZ, Ding JH, Liu YT, et al. (2001) Dietary protective and risk factors for esophageal and stomach cancers in a low-epidemic area for stomach cancer in Jiangsu Province, China: comparison with those in a high-epidemic area. Jpn J Cancer Res 92: 1157–1165.
51 Bahmanyar S, Ye W (2006) Dietary patterns and risk of squamous-cell carcinoma and adenocarcinoma of the esophagus and adenocarcinoma of the gastric cardia: a population-based case-control study in Sweden. Nutr Cancer 54: 171–178.
52 Anderson KE, Sinha R, Kulldorff M, Gross M, Lang NP, et al. (2002) Meat intake and cooking techniques: associations with pancreatic cancer. Mutat Res 506–507 225–231.
53 De Stefani E, Munoz N, Esteve J, Vasallo A, Victora CG, et al. (1990) Mate drinking, alcohol, tobacco, diet, and esophageal cancer in Uruguay. Cancer Res 50: 426–431.
54 Castelletto R, Castellsague X, Munoz N, Iscovich J, Chopita N, et al. (1994) Alcohol, tobacco, diet, mate drinking, and esophageal cancer in Argentina. Cancer Epidemiol Biomarkers Prev 3: 557–564.
55 Launoy G, Milan C, Day NE, Pienkowski MP, Gignoux M, et al. (1998) Diet and squamous-cell cancer of the oesophagus: a French multicentre case-control study. Int J Cancer 76: 7–12.
56 Levi F, Pasche C, Lucchini F, Bosetti C, Franceschi S, et al. (2000) Food groups and oesophageal cancer risk in Vaud, Switzerland. Eur J Cancer Prev 9: 257–263.
57 Lyon JL, Slattery ML, Mahoney AW, Robison LM (1993) Dietary intake as a risk factor for cancer of the exocrine pancreas. Cancer Epidemiol Biomarkers Prev 2: 513–518.
58 Michaud DS, Giovannucci E, Willett WC, Colditz GA, Fuchs CS (2003) Dietary meat, dairy products, fat, and cholesterol and pancreatic cancer risk in a prospective study. Am J Epidemiol 157: 1115–1125.
59 Thompson FE, Midthune D, Subar AF, Kipnis V, Kahle LL, et al. (2007) Development and evaluation of a short instrument to estimate usual dietary intake of percentage energy from fat. J Am Diet Assoc 107: 760–767.
60 Hu FB (2002) Dietary pattern analysis: a new direction in nutritional epidemiology. Curr Opin Lipidol 13: 3–9.
61 Ledikwe JH, Blanck HM, Kettel Khan L, Serdula MK, Seymour JD, et al. (2006) Dietary energy density is associated with energy intake and weight status in US adults. Am J Clin Nutr 83: 1362–1368.
62 Ledikwe JH, Blanck HM, Khan LK, Serdula MK, Seymour JD, et al. (2006) Low-energy-density diets are associated with high diet quality in adults in the United States. J Am Diet Assoc 106: 1172–1180.
63 Newby PK, Muller D, Hallfrisch J, Qiao N, Andres R, et al. (2003) Dietary patterns and changes in body mass index and waist circumference in adults. Am J Clin Nutr 77: 1417–1425.
64 Matthews KH, Bernstein JJCB, (2003) International trade of meat/poultry products and food safety issues. In Buzby JC, editor International trade and food safety: economic theory and case studies Available: http://www.ers.usda.gov/Publications/AER828/. Accessed 12 November 2007.
65 European Commission Health and Consumer Protection Directorate General (2002) Opinion of the Scientific Committee on Veterinary Measures Relating to Public Health on Review of previous SCVPH opinions of 30 April 1999 and 3 May 2000 on the potential risks to human health from hormones residues in bovine meat and meat products. Available: http://ec.europa.eu/food/fs/sc/scv/outcome_en.html. Accessed 12 November 2007.
66 United States Department of Health and Human Services and the Department of Agriculture (2005) Dietary Guidelines for Americans, 2005. Available: http://www.health.gov/dietaryguidelines/dga2005/document/default.htm. Accessed 12 November 2007.
67 American Cancer Society (2005) Cancer Facts and Figures 2005. Available: http://www.cancer.org/docroot/STT/content/STT_1x_Cancer_Facts__Figures_2005.asp. Accessed 12 November 2007.