Inhibitory effect of mixture herbs/spices on formation of heterocyclic amines and mutagenic activity of grilled beef

A comprehensive review of structure-activity relationships and effect mechanisms of polyphenols on heterocyclic aromatic amines formation in thermal-processed food

Heterocyclic aromatic amines (HAAs) are potent carcinogenic substances mainly generated in thermal-processed food. Natural polyphenols have been widely used for inhibiting the formation of HAAs, whereas the effect of natural polyphenols on HAAs formation is complex and the mechanisms are far from being clearly elucidated. In order to clarify the comprehensive effect of polyphenols on HAAs, this review focused on the structure-activity relationships and effect mechanisms of polyphenols on the formation of HAAs. In addition, the effects of polyphenols on HAAs toxicity were also first reviewed from cell, gene, protein, and animal aspects. An overview of the effect of polyphenol structures such as parent ring and exocyclic group on the mitigation of HAAs was emphasized, aiming to provide some valuable information for understanding their effect mechanism. The HAAs formation is inhibited by natural polyphenols in a dose-dependent manner largely through eliminating free radicals and binding precursors and intermediates. The inhibitory effect was probably affected by the quantity and position of hydroxyl groups in the aromatic rings, and polyphenols with m-hydroxyl group in the aromatic ring had the stronger inhibitory effect. However, the presence of other substituents and excessive hydroxyl groups in natural polyphenols might mitigate the inhibitory effect and even promote the formation of HAAs. This review can provide theoretical reference for effectively controlling the formation of HAAs in thermal-processed food by natural polyphenols and reducing their harm to human health.

Using bioactive compounds to mitigate the formation of typical chemical contaminants generated during the thermal processing of different food matrices

With rising consumer awareness of health and wellness, the demand for enhanced food safety is rapidly increasing. The generation of chemical contaminants during the thermal processing of food materials, including polycyclic aromatic hydrocarbons, heterocyclic aromatic amines, and acrylamide happens every day in every kitchen all around the world. Unlike extraneous chemical contaminants (e.g., pesticides, herbicides, and chemical fertilizers), these endogenic chemical contaminants occur during the cooking process and cannot be removed before consumption. Therefore, much effort has been invested in searching for ways to reduce such thermally induced chemical contaminants. Recently, the addition of bioactive compounds has been found to be effective and promising. However, no systematic review of this practical science has been made yet. This review aims to summarize the latest applications of bioactive compounds for the control of chemical contaminants during food thermal processing. The underlying generation mechanisms and the toxic effects of these chemical contaminants are discussed in depth to reveal how and why they are suppressed by the addition of certain bioactive ingredients. Examples of specific bioactive compounds, such as phenolic compounds and organic acids, as well as their application scenarios, are outlined. In the end, outlooks and expectations for future development are provided based on a comprehensive summary and reflection of references.

Effects of Phenols from Olive Vegetation Water on Mutagenicity and Genotoxicity of Stored-Cooked Beef Patties

This explorative study aimed to assess the mutagenicity and genotoxicity of stored-cooked beef patties formulated with and without phenols (7.00 mg of phenols/80-g patty) extracted from olive vegetation water (OVW), as related to the formation of cholesterol oxidation products (COPs) and heterocyclic amines (HCAs). The patties were packaged in a modified atmosphere, sampled during cold storage (4 °C) for 9 days, and grilled at 200 °C. The genotoxicity was evaluated by the Comet assay. The patty extract was found to be genotoxic on primary peripheral blood mononuclear cells (PBMCs), while no mutagenicity was detected. The addition of OVW phenols significantly decreased the genotoxicity of the patty extract and reduced the total COPs content in stored-cooked patties (4.59 times lower than control); however, it did not affect the content of total HCAs (31.51-36.31 ng/patty) and the revertants' number. Therefore, these results demonstrate that the OVW phenols were able to counteract the formation of genotoxic compounds in stored-cooked beef patties.

The impact of natural spices additions on hazards development and quality control in roast beef patties

The current focus in thermally processed meat production is to reduce the presence of hazardous compounds while maintaining product quality. This study utilized UPLC-MS/MS to examine the effects of rosemary, turmeric, and bay leaf on the development of hazards in roast beef patties, which demonstrated simultaneous inhibitory effects on malondialdehyde, glyoxal, methylglyoxal, 12 heterocyclic aromatic amines, acrylamide, and 5-hydroxymethylfurfural. Correlation analysis revealed that the total phenolic content and ferric-reducing antioxidant power of the spices were negatively correlated with polar hazards, non-polar heterocyclic aromatic amines, and aldehyde hazards, respectively. These findings underscore the vital role of hydroxyl groups and aromatic rings of phenols in inhibiting hazards formation. Additionally, the application of spices significantly reduced cooking loss and water loss and positively influenced textural quality and amino acid retention. These findings contribute to the understanding of the inhibitory effects of spices on multiple hazards and the quality control of heat-processed meat products.

Heterocyclic aromatic amines in meat: Formation mechanisms, toxicological implications, occurrence, risk evaluation, and analytical methods

Heterocyclic aromatic amines (HAAs) are detrimental substances can develop during the high-temperature cooking of protein-rich foods, such as meat. They are potent mutagens and carcinogens linked to an increased risk of various cancers. HAAs have complex structures with nitrogen-containing aromatic rings and are formed through chemical reactions between amino acids, creatin(in)e, and sugars during cooking. The formation of HAAs is influenced by various factors, such as food type, cooking temperature, time, cooking method, and technique. HAAs exert their toxicity through mechanisms like DNA adduct formation, oxidative stress, and inflammation. The research on HAAs is important for public health and food safety, leading to risk assessment and management strategies. It has also led to innovative approaches for reducing HAAs formation during cooking and minimizing related health risks. Understanding HAAs' chemistry and formation is crucial for developing effective ways to prevent their occurrence and protect human health. The current review presents an overview about HAAs, their formation pathways, and the factors influencing their formation. Additionally, it reviews their adverse health effects, occurrence, and the analytical methods used for measuring them.

Unveiling heterocyclic aromatic amines (HAAs) in thermally processed meat products: Formation, toxicity, and strategies for reduction - A comprehensive review

This comprehensive review focuses on heterocyclic aromatic amines (HAAs), a class of chemicals that commonly form during the cooking or processing of protein-rich foods. The International Agency for Research on Cancer (IARC) has categorized certain HAAs as probable human carcinogens, highlighting the significance of studying their formation and control in food safety research. The main objective of this review is to address the knowledge gaps regarding HAAs formation and propose approaches to reduce their potential toxicity during thermal processing. By summarizing the mechanisms involved in HAAs formation and inhibition, the review encompasses both conventional and recent detection methods. Furthermore, it explores the distribution of HAAs in thermally processed meats prepared through various cooking techniques and examines their relative toxicity. Additionally, considering that the Maillard reaction, responsible for HAAs formation, also contributes to the unique flavors and aromas of cooked meat products, this review investigates the potential effects of inhibiting HAAs formation on flavor substances. A thorough understanding of these complex interactions provides a foundation for developing targeted interventions to minimize the formation of HAAs and other harmful compounds during food processing.

Marinades Based on Natural Ingredients as a Way to Improve the Quality and Shelf Life of Meat: A Review

Marinating is a traditional method of improving the quality of meat, but it has been modified in response to consumer demand for "clean label" products. The aim of this review is to present scientific literature on the natural ingredients contained in marinades, the parameters of the marinating process, and certain mechanisms that bring about changes in meat. A review was carried out of publications from 2000 to 2023 available in Web of Science on the natural ingredients of meat marinades: fruit and vegetables, seasonings, fermented dairy products, wine, and beer. The review showed that natural marinades improve the sensory quality of meat and its culinary properties; they also extend its shelf life. They affect the safety of meat products by limiting the oxidation of fats and proteins. They also reduce biogenic amines and the formation of heterocyclic aromatic amines (HAAs) and polycyclic aromatic hydrocarbons (PAHs). This is possible due to the presence of biologically active substances and competitive microflora from dairy products. However, some marinades, especially those that are acidic, cause a slightly acidic flavour and an unfavourable colour change. Natural compounds in the ingredients of marinades are accepted by consumers. There are no results in the literature on the impact of natural marinades on the nutritional value and health-promoting potential of meat products, so it can be assumed that this is a future direction for scientific research.

Application of High-Performance Liquid Chromatography with Fluorescence Detection for Non-Polar Heterocyclic Aromatic Amines and Acridine Derivatives Determination in Pork Loin Roasted in a Roasting Bag

Heat treatment of meat can lead to the formation of carcinogenic organic compounds. The influence of dried fruits on the formation of non-polar heterocyclic aromatic amines (carbolines) and nitrogen derivatives of polycyclic aromatic hydrocarbons (azaarenes) in roasted pork loin was elucidated. Two hundred grams of fruit per 1 kg of meat were used as stuffing. Carbolines, derivatives of pyridoimidazole and pyridoindole, and azaarenes (benzoacridines and dibenzoacridines) were determined by means of high-performance liquid chromatography with fluorescence detection. The total concentration of six δ-, γ- and α-carbolines in roasted pork loin was 1.3 ng/g. This content decreased by 64%, 58%, and 54% in pork loin stuffed with prunes, apricots, and cranberries, respectively. Concentrations of β-carbolines (harmane and norharmane) increased under the influence of added fruits. The norharmane content increased the most, from 2.2 ng/g in the control sample to 12.3 ng/g in meat prepared with cranberries. The harmane content increased from 1.0 ng/g to 3.6 ng/g in meat with prunes. The total concentration of azaarenes (two benzoacridines and dibenzo[a,c]acridine), which was close to 0.1 ng/g, decreased in dishes with prunes and apricots by 54% and 12%, respectively. Azaarenes were not found in samples of meat stuffed with cranberries.

Formation and Inhibition of Heterocyclic Amines and Polycyclic Aromatic Hydrocarbons in Ground Pork during Marinating

This study aims to simultaneously extract heterocyclic amines (HAs) and polycyclic aromatic hydrocarbons (PAHs) from ground pork for respective analysis by UPLC-MS/MS and GC-MS/MS, and study the effects of different flavorings and marinating time length on their formation and inhibition. Results showed that both HA and PAH contents followed a time-dependent increase during marinating, with HAs being more susceptible to formation than PAHs. The total HA contents in unmarinated pork and juice was, respectively, 61.58 and 139.26 ng/g, and rose to 2986.46 and 1792.07 ng/g after 24-h marinating, which can be attributed to the elevation of reducing sugar and creatinine contents. The total PAH contents in unmarinated pork and juice were, respectively, 34.56 and 26.84 ng/g, and increased to 55.93 and 44.16 ng/g after 24-h marinating, which can be due to the increment of PAH precursors such as benzaldehyde, 2-cyclohexene-1-one and trans,trans-2,4-decadienal. Incorporation of 0.5% (w/v) cinnamon powder or 0.5% (w/v) green tea powder was effective in inhibiting HA formation with the former showing a more pronounced effect for marinated pork, while the latter was for marinated juice. However, their addition was only effective in inhibiting PAH formation in marinated pork. Principle component analysis revealed the relationship between HA and PAH formation in ground pork and juice during marinating.

Formation of Carcinogens in Processed Meat and Its Measurement with the Usage of Artificial Digestion—A Review

Meat is a rich source of various nutrients. However, it needs processing before consumption, what in turn generates formation of carcinogenic compounds, i.a., polycyclic aromatic hydrocarbons (PAH), nitrosamines (NOCs), and the most mutagenic heterocyclic aromatic amines (HAAs). It was widely found that many factors affect the content of carcinogens in processed meat. However, it has recently been discovered that after digestion free HAAs are released, which are not detectable before enzymatic treatment. It was established that the highest percentage of carcinogens is released in the small intestine and that its amount can be increased up to 6.6-fold. The change in free HAAs content in analyzed samples was dependent on many factors such as meat type, doneness, particle size of meat, and the enzyme concentration used for digestion. In turn, introduction of bacteria naturally occurring in the human digestive tract into the model significantly decreases total amount of HAAs. Contrary, the addition of food ingredients rich in polyphenols, fiber, and water (pepper powder, onions, apples) increases free HAAs’ release up to 56.06%. Results suggests that in vitro digestion should be an integral step of sample preparation. Artificial digestion introduced before chromatographic analysis will allow to estimate accurately the content of carcinogens in processed meat.

Consumption of Thermally Processed Meat Containing Carcinogenic Compounds (Polycyclic Aromatic Hydrocarbons and Heterocyclic Aromatic Amines) versus a Risk of Some Cancers in Humans and the Possibility of Reducing Their Formation by Natural Food Additives-A Literature Review

(1) Background: Thermal treatment of high-protein food may lead to the formation of mutagenic and carcinogenic compounds, e.g., polycyclic aromatic hydrocarbons and heterocyclic aromatic amines. Frequent consumption of processed meat was classified by the International Agency for Research on Cancer as directly carcinogenic for humans. (2) Methods: A literature review was carried out based on a search of online databases for articles on consuming thermally processed meat containing carcinogenic compounds versus a risk of cancers in humans published between 2001 and 2021. (3) Results: A review of the current literature on the participation of PAHs and HAA in the formation of certain neoplasms indicates a positive relationship between diet and the incidences of many cancers, especially colon cancer. A simple way to obtain dishes with reduced contents of harmful compounds is the use of spices and vegetables as meat additives. These seasonings are usually rich in antioxidants that influence the mechanism of HAA and PAH synthesis in food. (4) Conclusions: As there is a growing risk of a cancer tendency because of exposing humans to PAHs and HAAs, it is extremely vital to find a simple way to limit carcinogenic compound synthesis in a processed proteinaceous food. Disseminating the knowledge about the conditions for preparing dishes with a reduced content of carcinogenic compounds could become a vital element of cancer prevention programs.

Inhibitory Effect of Tamarix ramosissima Extract on the Formation of Heterocyclic Amines in Roast Lamb Patties by Retarding the Consumption of Precursors and Preventing Free Radicals

Tamarix ramosissima has been widely used as barbecue skewers for the good taste and unique flavor it gives to the meat, but the effects of T. ramosissima on heterocyclic amine (HA) formation in roast lamb are unknown. The influence of T. ramosissima extract (TRE) on HA formation, precursors’ consumption, and free radicals’ generation in roast lamb patties were elucidated by UPLC-MS, HPLC, and electron spin resonance (ESR) analysis, respectively. Six HAs were identified and compared with the control group; the total and polar HAs decreased by 30.51% and 56.92% with TRE addition at 0.30 g/kg. The highest inhibitory effect was found against 2-amino-1-methyl-6-phenylimidazo[4,5-f]pyridine (PhIP) formation (70.83%) at 0.45 g/kg. The addition of TRE retarded the consumption of HA precursors, resulting in fewer HAs formed. The typical signal intensity of free radicals in roast lamb patties significantly decreased with TRE addition versus the control group (p < 0.05), and the higher the levels of the TRE, the greater the decrease in signal intensity. We propose that the inhibitory effects of TRE on HA formation, especially on polar HAs, were probably achieved by retarding the consumption of precursors and preventing free radicals from being generated in roast lamb patties. These findings provide valuable information concerning TRE’s effectiveness in preventing HA formation through both the precursor consumption and free radical scavenging mechanisms.

The effect of onion and garlic on non-polar heterocyclic aromatic amines (α-, β-, γ- and δ-carbolines) formation in pan-fried meat and gravy

Thermal treatment of protein-rich food can lead to the formation of biologically active heterocyclic aromatic amines (HAAs). One of the methods to learn how to reduce the content as well as the influence of these compounds on heath is the study of factors inhibiting their synthesis. In the current investigation, the effect of onion and garlic on the formation of six possibly carcinogenic non-polar HAAs (α-, γ- and δ-carbolines) and two co-mutagenic β-carbolines (harmane and norharmane) was evaluated by comparing their contents in meat and gravy samples obtained from pan-fried pork dishes prepared in the presence and absence of these vegetables. Carbolines were isolated from food samples by solid phase extraction. The quantitative analysis was performed by high-performance liquid chromatography with fluorescence detection. The concentrations of individual compounds in dishes prepared without added vegetables ranged from 0.02 ng g^-1 (3-amino-1,4-dimethyl-5 H-pyrido(4,3-b)indole; Trp-P-1) to 10.1 ng g^-1 of meat (2-amino-9 H-pyrido[2,3-b]indole; AαC). Onion (30 g/100 g of meat) and garlic (15 g/100 g of meat) lowered the total content (in meat and gravy) of the α-, δ- and γ-carbolines in the range from 52% to 87%. In contrast, onion caused an increase in the norharmane concentration both in meat and gravy. The percentage of carbolines in the gravies (assuming that their total content in meat and gravy is 100%) was higher in dishes prepared with onion and garlic than in dishes without these seasonings.

Recent Applications of Mixture Designs in Beverages, Foods, and Pharmaceutical Health: A Systematic Review and Meta-Analysis

Design of Experiments (DoE) is a statistical tool used to plan and optimize experiments and is seen as a quality technology to achieve products excellence. Among the experimental designs (EDs), the mixture designs (MDs) stand out, being widely applied to improve conditions for processing, developing, or formulating novel products. This review aims to provide useful updated information on the capacity and diversity of MDs applications for the industry and scientific community in the areas of food, beverage, and pharmaceutical health. Recent works were selected following the Preferred Reporting Items for Systematic Review and Meta-Analyses statement (PRISMA) flow diagram. Data analysis was performed by self-organizing map (SOM) to check and understand which fields of application/countries/continents are using MDs. Overall, the SOM indicated that Brazil presented the largest number of works using MDs. Among the continents, America and Asia showed a predominance in applications with the same amount of work. Comparing the MDs application areas, the analysis indicated that works are prevalent in food and beverage science in the American continent, while in Asia, health science prevails. MDs were more used to develop functional/nutraceutical products and the formulation of drugs for several diseases. However, we briefly describe some promising research fields in that MDs can still be employed.

Heterocyclic Aromatic Amines in Meat: Formation, Isolation, Risk Assessment, and Inhibitory Effect of Plant Extracts

Heterocyclic aromatic amines (HAAs) are potent carcinogenic compounds induced by the Maillard reaction in well-done cooked meats. Free amino acids, protein, creatinine, reducing sugars and nucleosides are major precursors involved in the production of polar and non-polar HAAs. The variety and yield of HAAs are linked with various factors such as meat type, heating time and temperature, cooking method and equipment, fresh meat storage time, raw material and additives, precursor’s presence, water activity, and pH level. For the isolation and identification of HAAs, advanced chromatography and spectroscopy techniques have been employed. These potent mutagens are the etiology of several types of human cancers at the ng/g level and are 100- to 2000-fold stronger than that of aflatoxins and benzopyrene, respectively. This review summarizes previous studies on the formation and types of potent mutagenic and/or carcinogenic HAAs in cooked meats. Furthermore, occurrence, risk assessment, and factors affecting HAA formation are discussed in detail. Additionally, sample extraction procedure and quantification techniques to determine these compounds are analyzed and described. Finally, an overview is presented on the promising strategy to mitigate the risk of HAAs by natural compounds and the effect of plant extracts containing antioxidants to reduce or inhibit the formation of these carcinogenic substances in cooked meats.

Effects of seasoning on the formation of heterocyclic amines and polycyclic aromatic hydrocarbons in meats: A meta-analysis

Cooking improves digestibility, palatability, and microbiological profile of meats, but can produce compounds with carcinogenic potential, such as heterocyclic amines (HAs) and polycyclic aromatic hydrocarbons (PAHs). It has been shown that the formation of these compounds in meats can be inhibited by spiced marinades, but there is a complexity to check and compare the results of isolated studies with so many variables involved. Thus, this work aimed to review studies that evaluated the effects of spices on the formation of HAs and PAHs in meats according to cooking techniques and spice type. A meta-analysis with a random effect model was conducted using response ratios (R) to identify and summarize previous results and answer the research question. The use of spices before frying (R* = 0.52), grilling (R* = 0.63), or roasting (R* = 0.74) meat, and spicing with garlic and onion (R* = 0.57), pepper (R* = 0.63), and other spices with phenolic compounds (R* = 0.63), decrease the formation of HAs and PAHs, due to the antioxidant and electron transfer capacity. In this article, we discuss how the improvement of culinary techniques with the dissemination of knowledge about meat preparation conditions is an effective strategy for reducing the formation and ingestion of HAs and PAHs; this is important due to the growing evidence about the association between meat consumption and chronic diseases. This is the first systematic review with meta-analysis about this topic and can guide industry, food services, and population to improve the safety associated with meat consumption.

Inhibitory effects of Portulaca oleracea L. and selected flavonoid ingredients on heterocyclic amines in roast beef patties and Density Function Theory calculation of binding between heterocyclic amines intermediates and flavonoids

The inhibitory effects of Portulaca oleracea L. (PO) and its flavonoid ingredients on the formation of heterocyclic amines (HAs) in roast beef patties were investigated. Ten HAs were found in control patties, and the total content was 212.73 ± 7.13 ng/g. With the addition of PO (1%, 5%, and 10%, w/w), HAs decreased by 62.39%, 68.03%, and 73.75%, respectively. The main flavonoid ingredients (rutin, hesperidin, and flavanone) also present a similar inhibitory effect. The Density Function Theory (DFT) methods were adopted to investigate the inhibitory mechanism. These ingredients bonded with the intermediate to block the formation of norharman. Both experimental and calculated data of the ingredients were analyzed on their HAs inhibitory capacity. Our results provide a novel and valuable strategy to reduce HAs via a low additive level of medicinal and edible plants. And the correlation between experimental and calculated data could be applied to predict the inhibitory ability of inhibitors.

Revealing a key inhibitory mechanism of 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline via trapping of methylglyoxal

The inhibitory effects of vitamins (nicotinic acid, pyridoxamine [PM], and l-ascorbic acid) and phenolic acids (ferulic acid and p-coumaric acid) on the formation of 2-amino-3,8-dimethylimidazo [4,5-f] quinoxaline (MeIQx) were studied in a glycine/glucose/creatinine model system and fried tilapia cakes. The results showed that PM was the most potential inhibitor and the inhibition rates reached 82.72% and 78.54% in model system and fried tilapia cakes, respectively. Detailed formation mechanism of MeIQx was put forward to find the inevitable species in the non-free radical formation mechanism of MeIQx. Dose-dependent analysis of PM on methylglyoxal (MGO ) and MeIQx formation were studied by using model systems and the results showed that MGO and MeIQx were both reduced about 60% in reaction mixtures when the molar ratio of PM to glycine was 1:16, which indicated that MGO is a key intermediate on the pathway of MeIQx formation. Quantum chemistry calculations showed that PM can act as a useful inhibitor to inhibit the formation of MeIQx and react with MGO to form new compounds. A pathway for the inhibitory activity of PM against MeIQx formation was proposed. PRACTICAL APPLICATION: Pyridoxamine was the most effective inhibitor against heterocyclic aromatic amines (HAAs) and could be applied to a variety of food systems. While the inhibitory mechanism is still unclear. Detailed formation mechanism of MeIQx was put forward first and suggested methylglyoxal as an inevitable species in the non-free radical formation mechanism of MeIQx in this study. Pyridoxamine trapping methylglyoxal is likely a key mechanism against the generation of MeIQx was demonstrated by quantum chemistry calculation and experimental demonstration. These findings may provide effective suggestions for reducing HAAs and similar toxicants in daily cuisine.

Preventive potential and mechanism of dietary polyphenols on the formation of heterocyclic aromatic amines

Thermal processing is the most important and popular domestic cooking method. More than 30 heterocyclic aromatic amines have been identified in cooked meat using various methods. This review highlights preventive potential and mechanism of dietary polyphenols on the formation of heterocyclic amines. Tea, coffee, fruits, vegetable, and spice extracts rich in polyphenols exerted significant inhibition against the formation of heterocyclic aromatic amines. Some polyphenols, such as naringenin and epigallocatechin 3‐O‐gallate, can actively participate into food chemistry reaction to trap Strecker aldehyde and lower the formation of heterocyclic aromatic amines. In addition, some polyphenols can lower the mutagenicity of heterocyclic aromatic amines. More specifically, polyphenols possessing two hydroxyl groups at the meta position of aromatic ring are the most efficient one, but the presence of carboxylic or alkyl groups as substituents in the aromatic ring slightly reduced the inhibitory effect.

Xenobiotics Formed during Food Processing: Their Relation with the Intestinal Microbiota and Colorectal Cancer

The colonic epithelium is exposed to a mixture of compounds through diet, among which some are procarcinogens, whereas others have a protective effect. Therefore, the net impact of these compounds on human health depends on the overall balance between all factors involved. Strong scientific evidence has demonstrated the relationship between nitrosamines (NA), heterocyclic amines (HCAs), and polycyclic aromatic hydrocarbons (PAHs), which are the major genotoxins derived from cooking and food processing, and cancer. The mechanisms of the relationship between dietary toxic xenobiotics and cancer risk are not yet well understood, but it has been suggested that differences in dietary habits affect the colonic environment by increasing or decreasing the exposure to mutagens directly and indirectly through changes in the composition and activity of the gut microbiota. Several changes in the proportions of specific microbial groups have been proposed as risk factors for the development of neoplastic lesions and the enrichment of enterotoxigenic microbial strains in stool. In addition, changes in the gut microbiota composition and activity promoted by diet may modify the faecal genotoxicity/cytotoxicity, which can be associated with a higher or lower risk of developing cancer. Therefore, the interaction between dietary components and intestinal bacteria may be a modifiable factor for the development of colorectal cancer in humans and deserves more attention in the near future.