红肉与加工肉制品致癌风险及风险评估研究进展

红肉及加工肉制品的致癌之说成为世界性的热点话题。本文介绍了近年来许多研究者关于红肉及加工肉制品与结/直肠癌、乳腺癌、前列腺癌、胃癌、肝癌等的相关性研究调查结果,发现存在不一致的结论。揭示了用于评价红肉及加工肉制品的健康危险度衡量法的不足之处,总结并介绍红肉及加工肉制品中N-羟乙酰神经氨酸、4-羟基-2-壬烯醛、杂环胺、多环芳烃和血红素铁等需要注意的风险物质,指导人们理性看待国际癌症研究机构关于红肉及加工肉制品发出的致癌警告,平衡膳食,取其利而避其害。     

红肉、加工肉摄入与人类健康关系的研究进展

通过对相关文献的系统分析和归纳总结,深入讨论了红肉、加工肉制品对人类健康的影响,肯定了红肉、加工肉对人体营养供给方面的积极作用。结合流行病学研究结果,讨论了红肉、加工肉摄入与心血管系统疾病,以及结/直肠癌、前列腺癌、乳腺癌等多种癌症的相关性,并科学分析了可能的致病原因;认为红肉、加工肉摄入对人类健康的负面影响并不突出,合理膳食、均衡营养有利健康。     

红肉、加工肉制品及饮食文化与癌症关系浅析

本文整理综述了红肉、加工肉制品与癌症的关系。并从客观的角度对红肉与加工肉制品致癌的危险性、认为红肉与加工肉制品致癌的科学性、国外的饮食文化及红肉、加工肉制品食用习惯、我国红肉和加工肉制品的消费与发达国家的差距、红肉和加工肉制品的消费与癌症几方面分别论述,为读者提供关于这一问题客观辩证的参考。     

红肉及加工肉制品与癌症风险关系的研究进展

世界卫生组织分支部门——国际癌症研究机构(International Agency for Research on Cancer,IARC)近期发表调查报告,将加工肉制品及红肉分别列为1类致癌物和2A类致癌物。此说法的严谨性和科学性受到世界畜产品加工研究者的质疑。红肉本身不会致癌,并且肉中含有许多营养物质(蛋白质、脂肪、维生素和微量营养素等),具有重要的生理作用,为维持人体健康提供了营养和能量来源。本文综述了红肉及加工肉制品与癌症关系的研究结果,肉中可能存在的有害物质及其控制,肉中主要的营养成分及其生理作用以及关于红肉及加工肉制品合理膳食的建议。     

对世界卫生组织将红肉和肉制品列为致癌物报告的质疑

针对近日世界卫生组织将加工肉制品列为1类致癌物,将红肉列为2A类致癌物,本文在对400余篇密切相关的论文进行详细分析的基础上,对加工肉制品和红肉中可能存在的致癌风险因子进行了分析和研判。现有研究表明,加工肉制品中亚硝胺、杂环胺及多环芳烃等有害物的含量极低,在正常摄入量条件下远低于致癌剂量;红肉中富含人体必需的铁、锌、硒、VB_(11)和VB_(12)等营养物质,正常摄入对保持机体健康具有重要意义。但由于经济、饮食文化、生活习惯等因素的影响,长期过量摄入任何食物,包括加工肉制品和红肉,都可能会对健康造成不良影响。世界卫生组织所依据的流行病学研究结果缺乏严谨的人体量效关系研究,且研究结果并不一致;也没有足够动物实验表明红肉和加工肉制品致癌。因此,我们认为世界卫生组织将加工肉制品列为1类致癌物缺乏充分证据、以偏概全,将"红肉"列为2A类致癌物缺乏证据、不负责任,建议撤销。     

庖丁解“肉”:“红”与“白”的困惑

10月26日,WHO发布的报告致使最近一段时间我们对吃肉这个近乎条件反射似的饮食习惯产生了疑虑,吃什么、怎么吃成为了消费者最关心的话题。红肉与白肉到底怎么区分、又孰轻孰重?我们是不是应该完全杜绝食用红肉和加工肉类呢?实际上从现代科学的角度考虑,我们对于红肉和加工肉制品的消费应该以适量为主,但也大可不必因此"谈肉色变"、对红肉和加工肉制品唯恐避之不及。肉类食品对人类维持身体机能有着难以替代的重要作用,只要每天的红肉和加工肉制品摄入量维持在合理范围内,其对人体的影响是微乎其微的。     

过量摄入红肉及加工肉类对人体致癌风险的研究进展

世界癌症研究基金会(International Agency for Research on Cancer,IARC)报告指出,过多摄入红肉会增加患癌症的风险,但是否有足够令人信服的证据证明呢?本文对近年来有关红肉摄入对人类患肺癌、前列腺癌、乳腺癌、结/直肠癌、膀胱癌、食道癌和胃癌的风险等国外文章进行综述。研究表明,没有人体量-效关系实验等证据证明癌症与食用红肉和加工肉有直接关系,但大量摄入红肉、高温及炸制红肉,患某些癌症的风险会相对增加,还伴随着其他致癌因素,如吸烟、酗酒、癌症家族史、遗传变异等。此结果是否适应我国人群,尚有待进一步研究确证。预防癌症的有效途径为降低或控制红肉过量摄入,采用科学的烹饪和加工方法,戒烟及少饮酒,多摄入新鲜蔬菜、水果等平衡膳食。     

低盐低脂功能性肉制品的研究进展

我国是世界上肉制品生产的第一大国,同时也是肉制品消费总量最多的国家。近年来大量研究表明过量食用红肉及加工肉制品会增加罹患慢性疾病的风险,低盐低脂功能性肉制品的开发受到重视。本文主要综述了低盐低脂功能性肉制品的开发研究进展,并指出功能性肉制品发展中存在的局限性,以期为功能性肉制品的研究和开发提供理论参考。     

膳食血红素铁促进结直肠癌变机制初探

流行病学研究揭示红肉摄入过多增加结直肠癌的发生风险,但机制未明。血红素铁是一种广泛存在于动物红肉、肝脏、血液中的有机铁,为探究红肉摄入对结直肠癌肿瘤发生及增殖的影响,并进一步解析作用机制。该文建立原发结直肠癌肿瘤小鼠模型,发现在血红素铁的干预下,能够显著增加氧化应激及结直肠癌肿瘤的发生发展程度;通过蛋白质印迹法分析,在动物模型的结肠组织中,血红素铁刺激结直肠癌肿瘤小鼠,黄嘌呤氧化酶(xanthine oxidase, XOD)、p-H2AX及p-STAT3表达量均会上调,同时肿瘤组织较瘤旁组织表达更为明显,通过细胞实验发现,在一定剂量的蔗糖铁和脂多糖的共同作用下可以上调经佛波酯诱导THP-1细胞分化成的巨噬细胞XOD的表达量;通过免疫组化实验发现,在小鼠结肠部位中XOD的表达位置和巨噬细胞表达位置相重合。结论显示,血红素铁会增加结直肠癌肿瘤小鼠的肿瘤发生及发展程度,且此现象与XOD表达上调有关。     

红肉可以放开吃？

正红肉,包括猪牛羊肉等,自古就是人类最重要的动物蛋白来源。但是近几十年来,随着营养科学的兴起,它受到了越来越多的质疑,比如有较多的饱和脂肪、胆固醇等。2018年,国际癌症研究中心还将红肉和加工肉制品列入致癌物名单。就在大家把"红肉不健康"变为一条常识的时候,另一项研究却给出了相反的结论。最近发表在《内科医学年鉴》的文章认为,没必要减少红肉或加工肉制品的摄入量。     

Controversy on the correlation of red and processed meat consumption with colorectal cancer risk: an Asian perspective

Abstract

This study aimed to investigate the relationship between meat intake and colorectal cancer risk from an Asian, particularly Korean, perspective. A report by the International Agency for Research on Cancer (IARC) published in 2015 concluded that intake of processed and red meat increases the risk of developing colorectal cancer. We conducted an in-depth analysis of prospective, retrospective, case-control and cohort studies, systematic review articles, and IARC monograph reports, which revealed that the IARC/WHO report weighted the results of studies based in Western countries more and that the correlation between intake of processed meat products and colorectal cancer incidence in Asians is not clearly supported. Among 73 epidemiological studies, approximately 76% were conducted in Western countries, whereas only 15% of studies were conducted in Asia. Furthermore, most studies conducted in Asia showed that processed meat consumption is not related to the onset of cancer. Moreover, there have been no reports showing significant correlation between various factors that directly or indirectly affect colorectal cancer incidence, including processed meat products types, raw meat types, or cooking methods. Further epidemiological studies taking each country’s food culture into consideration are required to reliably elucidate the effects of processed meat product intake, especially on cancer incidence.     

Oxidation During Digestion of Meat: Interactions with the Diet and Helicobacter pylori Gastritis,and Implications on Human Health

The last decade has seen epidemiological evidence of a positive association between high consumption of red meat and processed meat and the risk of developing a range of chronic diseases, such as colorectal cancer, cardiovascular disease, and type 2 diabetes. Oxidative stress is potentially involved in this association; however, oxidative stress is likely limited if red meat and processed meat are consumed in moderation, and combined with high intake of fruits and vegetables and low intake of refined sugars. In addition, it appears that some subgroups of the population are more prone to developing oxidative stress‐related diseases as a consequence of high red and processed meat consumption. For example, the gastric juice in the inflamed stomach of individuals infected with Helicobacter pylori may be an excellent site for enhanced oxidation following meat consumption. Similarly, patients with inflammatory bowel disease may be at increased risk. Oxidative stress resulting from red or processed meat consumption may mediate the onset and/or progression of a wide range of diseases through various mechanisms, which are discussed in this review.     

Meat and cancer

An increasing literature associates high intake of meat, especially red meat and processed meat with an increased risk of cancers, especially colorectal cancer. There is evidence that this risk may not be a function of meat per se, but may reflect high-fat intake, and/or carcinogens generated through various cooking and processing methods. The cancer risk may be modulated by certain genotypes. Cancers associated with high meat consumption may be reduced by the addition of anticarcinogens in the diet, especially at the same time as meat preparation or meat consumption, or modification of food preparation methods. Meat contains potential anticarcinogens, including omega-3 polyunsaturated fatty acids, and conjugated linoleic acid (CLA). Red meat, in particular, is an important source of micronutrients with anticancer properties, including selenium, vitamin B6 and B12, and vitamin D. Adjusting the balance between meat and other dietary components may be critical to protecting against potential cancer risks.     

The role of red and processed meat in colorectal cancer development: a perspective

This paper is based on a workshop held in Oslo, Norway in November 2013, in which experts discussed how to reach consensus on the healthiness of red and processed meat. Recent nutritional recommendations include reducing intake of red and processed meat to reduce cancer risk, in particular colorectal cancer (CRC). Epidemiological and mechanistic data on associations between red and processed meat intake and CRC are inconsistent and underlying mechanisms are unclear. There is a need for further studies on differences between white and red meat, between processed and whole red meat and between different types of processed meats, as potential health risks may not be the same for all products. Better biomarkers of meat intake and of cancer occurrence and updated food composition databases are required for future studies. Modifying meat composition via animal feeding and breeding, improving meat processing by alternative methods such as adding phytochemicals and improving our diets in general are strategies that need to be followed up.     

Effect of Dietary Red Meat on Colorectal Cancer Risk—A Review

Heme iron overload has been implicated as the main cause of the increased risk of cancer due to the consumption of red meat. However, fish and shellfish, teas, and spices contain up to five times more iron than red meat. There is insufficient evidence that iron intake in dietary red meat is the primary causal factor for colorectal cancer. In addition, harmful substances produced during the preparation of red meat, including heterocyclic amines (HCAs), polycyclic aromatic hydrocarbons (PAHs), N‐nitroso compounds, and acrylamide, are extrinsic factors that increase carcinogenicity. HCAs are produced during the cooking of red meat, poultry meat, and fish. PAHs may also be produced during the cooking of diverse food groups, such as dairy products, fruits, vegetables, and cereals. The average daily intake of red meat among Korean individuals is 62 g; the amount of PAHs entering the body via red meat is less than the average amount of PAHs the body is exposed to in the air. Therefore, it is difficult to conclude that dietary red meat is the main cause of colorectal cancer. Rather, there may be an intricate influence of multiple factors, including fruit and vegetable intake, alcohol consumption, smoking, overweight, obesity, and stress.     

Red meat,diseases, and healthy alternatives: A critical review

Meat is an important food for human nutrition, by especially providing high-quality protein and also some essential micronutrients, in front iron, zinc, and vitamin B₁₂. However, a high intake of red and processed meat is associated with an increased risk for diseases, especially type 2 diabetes and colorectal cancer, as several epidemiological studies and meta-analyses have shown. This review summarizes meta-analyses of publications studying the association between red and processed meat intake and type 2 diabetes, cardiovascular diseases, colorectal and other cancers, and all-cause mortality. Various potential mechanisms involved in the increased disease risk are discussed. Furthermore, the beneficial effects of healthy alternatives for meat, like fish, nuts, vegetables and fruits, pulses and legumes, whole grains, and dairy products are reviewed by including selected papers and recent meta-analyses.     

The World Cancer Research Fund report 2007: A challenge for the meat processing industry

One of the 10 universal guidelines for healthy nutrition in a report of the World Cancer Research Fund released at the end of 2007 is to "limit intake of red meat and avoid processed meat", as a result of the "convincing evidence" for an association with an increased risk of colorectal cancer development. In the present paper, the scientific evidence for the association between processed meats intake and colorectal cancer development is explored and the most probable hypothesis on the mechanism underlying this relationship formulated. It seems that the present state of knowledge is not well understood but relates to a combination of haem iron, oxidative stress, formation of N-nitroso compounds and related residues in the digestive tract as the causal factors. Although criticisms of the inaccurate definition of processed meats and the insufficient accounting for the large variability in composition of meat products have been expressed, it is clear that the report urges proper action by the meat and nutrition research community and the meat industry. Research items that in our view should be addressed are discussed. They include: (1) evaluating the health risks associated with processed meats intake within the context of the supply of beneficial nutrients and other nutrition associated health risks; (2) definition of the role of nitrites and nitrates in meat processing; (3) investigating the role of red and processed meats on the endogenous formation of N-nitroso compounds in the digestive tract; and (4) developing improved processed meats using new ingredients.     

Consumption of Red/Processed Meat and Colorectal Carcinoma: Possible Mechanisms Underlying the Significant Association

Epidemiology and experimental studies provide an overwhelming support of the notion that diets high in red or processed meat accompany an elevated risk of developing pre-neoplastic colorectal adenoma and frank colorectal carcinoma (CRC). The underlying mechanisms are disputed; thus several hypotheses have been proposed. A large body of reports converges, however, on haem and nitrosyl haem as major contributors to the CRC development, presumably acting through various mechanisms. Apart from a potentially higher intestinal mutagenic load among consumers on a diet rich in red/processed meat, other mechanisms involving subtle interference with colorectal stem/progenitor cell survival or maturation are likewise at play. From an overarching perspective, suggested candidate mechanisms for red/processed meat-induced CRC appear as three partly overlapping tenets: (i) increased N-nitrosation/oxidative load leading to DNA adducts and lipid peroxidation in the intestinal epithelium, (ii) proliferative stimulation of the epithelium through haem or food-derived metabolites that either act directly or subsequent to conversion, and (iii) higher inflammatory response, which may trigger a wide cascade of pro-malignant processes. In this review, we summarize and discuss major findings of the area in the context of potentially pertinent mechanisms underlying the above-mentioned association between consumption of red/processed meat and increased risk of developing CRC.     

加工肉制品中多环芳烃的研究现状

多环芳烃在环境中广泛存在。对于非职业性接触多环芳烃的工人和非吸烟者来说,通过饮食接触是多环芳烃的主要暴露方式。自2015年国际癌症研究机构(IARC)将红肉及其加工肉制品划分为致癌物后,降低加工肉制品中有毒有害物质(如多环芳烃)生成显得尤为重要。本文根据加工肉制品中多环芳烃研究现状,对其“三致”机理、生成机制、加工肉制品中暴露情况及其控制措施进行概述。     

红肉、N-羟乙酰神经氨酸与癌症关系的研究进展

世界癌症研究基金会报告指出,过多摄入红肉会增加患癌症的风险,红肉可能是导致某些癌症的原因之一。有研究得出,摄入红肉后身体内产生的一种唾液酸--N-羟乙酰神经氨酸（N-glycolylneuraminic acid,Neu5Gc）可能与癌症的发生有关。本文从红肉与癌的关系,引出对Neu5Gc的讨论,从它的结构、来源、生理功能到临床应用价值,最后是与癌症可能的机制讨论,并重申它的研究价值。