Reducing Compounds Equivocally Influence Oxidation during Digestion of a High-Fat Beef Product, which Promotes Cytotoxicity in Colorectal Carcinoma Cell Lines

Dual effects of dietary carnosine during in vitro digestion of a Western meal model with added ascorbic acid

The beneficial role of carnosine during in vitro digestion of meat was previously demonstrated, and it was hypothesized that such benefits could also be obtained in a meal system. The current study, therefore, assessed carnosine effects on markers of lipid and protein oxidation and of advanced glycation end products (AGEs) during gastric and duodenal in vitro digestion of a burger meal model. The model included intrinsic (low) and enhanced (medium and high) carnosine levels in a mix of pork mince and bread, with or without ascorbic acid (AA) and/or fructose as anti- and prooxidants, respectively. In the presence of either AA or fructose, a carnosine prooxidative potential during digestion was observed at the medium carnosine level depending on markers and digestive phases. However, free carnosine found at the high carnosine level exerted a protective effect reducing the formation of 4-hydroxynonenal in the gastric phase and glyoxal in both the gastric and duodenal phases. Dual effects of carnosine are likely concentration related, whereby at the medium level, free radical production increases through carnosine's ferric-reducing capacity, but there is insufficient quantity to reduce the resulting oxidation, while at the higher carnosine level some decreases in oxidation are observed. In order to obtain carnosine benefits during meal digestion, these findings demonstrate that consideration must be given to the amount and nature of other anti- and prooxidants present and any potential interactions. PRACTICAL APPLICATION: Carnosine, a natural compound in meat, is a multifunctional and beneficial molecule for health. However, both pro- and antioxidative effects of carnosine were observed during digestion of a model burger meal when ascorbic acid was included at a supplemental level. Therefore, to obtain benefits of dietary carnosine during digestion of a meal, consideration needs to be given to the amount and nature of all anti- and prooxidants present and any potential interactions.

Effect of fiber-bound polyphenols from highland barley on lipid oxidation products of cooked pork during in vitro gastrointestinal digestion

BACKGROUND

The gastrointestinal (GI) tract is a major site of lipid oxidation, and the lipid oxidation products are related to an increased risk of various chronic diseases. In this study, the inhibition capacity of bound-polyphenol rich insoluble dietary fiber (BP-IDF) from highland barley (HB) to lipid oxidation was evaluated during simulated GI digestion.

RESULTS

We found that the level of lipid hydroperoxides (LOOH) and aldehydes were significantly inhibited when highland barley bound-polyphenol rich insoluble dietary fiber (HBBP-IDF) co-digestion with cooked pork. The lipid oxidation products were more effectively scavenged during simulated gastric digestion, with inhibition of 77.4% for LOOH, 52.3% for malondialdehyde, 46.5% for 4-hydroxy-2-hexenal and 48.7% for 4-hydroxy-2-nonenel, respectively. The fiber-bound polyphenols are the principal scavengers of lipid oxidation products.

CONCLUSION

These findings suggest that HBBP-IDF could be used as a functional ingredient able to scavenge lipid oxidation products across the GI tract. © 2023 Society of Chemical Industry.

Pro- and Antioxidant Effect of Food Items and Matrices during Simulated In Vitro Digestion

The digestive tract can be considered a bioreactor. High levels of reactive oxygen species (ROS) during digestion may predispose for local and/or systemic oxidative stress and inflammation, e.g., inflammatory bowel diseases. Food items rich in antioxidants may prevent such aggravation. This investigation analyzed pro-and antioxidant patterns of food matrices/items following in vitro digestion. Gastrointestinal digestion reflecting typically consumed quantities was performed on nine food items (orange and tomato juice, soda, coffee, white chocolate, sausage, vitamin C and E, and curcumin) and their combinations (n = 24), using the INFOGEST model. Antioxidant potential was measured by FRAP, DPPH, and ABTS, and pro-oxidant aspects by MDA (malondialdehyde) and peroxide formation. An anti-pro-oxidant score was developed, combining the five assays. Liquid food items showed moderately high antioxidant values, except for coffee and orange juice, which exhibited a high antioxidant potential. Solid matrices, e.g., white chocolate and sausage, showed both high pro-oxidant (up to 22 mg/L MDA) and high antioxidant potential (up to 336 mg/L vitamin C equivalents) at the same time. Individual vitamins (C and E) at physiological levels (achievable from food items) showed a moderate antioxidant potential (<220 mg/L vitamin C equivalents). Overall, both antioxidant and pro-oxidant assays correlated well, with correlation coefficients of up to 0.894. The effects of food combinations were generally additive, i.e., non-synergistic, except for combinations with sausage, where strong quenching effects for MDA were observed, e.g., with orange juice. In conclusion, as especially highlighted by complex matrices demonstrating both pro- and antioxidant potential, only measuring one aspect would result in physiological misinterpretations. Therefore, it is imperative to employ a combination of assays to evaluate both pro- and antioxidant properties of food digesta to ensure physiological relevance.

In vitro digestion of nitrite and nitrate preserved fermented sausages - New understandings of nitroso-compounds' chemical reactivity in the digestive tract

In vitro digestions of dry-cured sausages formulated with four different rates of added sodium nitrite and sodium nitrate (NaNO₂ / NaNO₃, in ppm: 0/0; 80/80; 120/120; 0/200) were performed with a dynamic gastrointestinal digester (DIDGI®). The chemical reactivity of the potentially toxic nitroso-compounds (NOCs), oxidation reactions products and different iron types were evaluated over time. No nitrite nor nitrate dose effect was observed on NOCs' chemical reactivity. Nitrosothiols were scarce, and nitrosylheme was destabilized for every conditions, possibly leading to free iron release in the digestive tract. Total noN-volatile N-nitrosamines concentrations increased in the gastric compartment while residual nitrites and nitrates remained stable. The minimal rate of 80/80 ppm nitrite/nitrate was enough to protect against lipid oxidation in the digestive tract. The present results provide new insights into the digestive chemistry of dry sausages, and into new reasonable arguments to reduce the load of additives in formulations.

Evidence for Anticancer Effects of Chinese Medicine Monomers on Colorectal Cancer

Colorectal cancer is one of the most commonly occurring cancers worldwide. Although clinical reports have indicated the anticancer effects of Chinese herbal medicine, the multiple underlying molecular and biochemical mechanisms of action remain to be fully characterized. Chinese medicine (CM) monomers, which are the active components of CM, serve as the material basis of the functional mechanisms of CM. The aim of this review is to summarize the current experimental evidence from in vitro, in vivo, and clinical studies for the effects of CM monomers in colorectal cancer prevention and treatment, providing some useful references for future research.

Health Effects of Dietary Oxidized Milk Administration in Offspring Mice during Pregnancy and Lactation with Metabolomic Strategies

Milk is an important source of nutrients during pregnancy. Previous studies have consistently shown that oxidation in milk and dairy products can induce oxidative stress, inflammation, and fibrosis in the liver and kidney. However, the mechanism underlying these effects remains largely unexplored. This study aimed to investigate the effects of oxidized milk on fecal metabolism and liver and kidney function of offspring mice. Oxidative modification of milk was performed using H₂O₂-Cu or heating, causing varying degrees of oxidative damage. Kunming female mice were fed with a H₂O₂-Cu, heat, or normal control diet until their offspring were 3 weeks old. Feces were collected for the metabolomics study based on mass spectrometry. Forty-two potentially significant metabolic biomarkers were screened, and each group's relative intensity was compared. The results showed that oxidized milk mainly regulated isoleucine metabolism, proline metabolism, and tricarboxylic acid cycle. In addition, the histopathological analysis showed accumulation of protein and lipid oxidation products in the liver and kidney tissues after intake of oxidized milk, which induced oxidative stress, increased the levels of inflammatory factors, and significantly increased the expression of genes and proteins involved in inflammatory pathways. The above results suggest that intake of oxidized milk during gestation may increase the risk of liver and kidney injury in male offspring by interfering with amino acid and energy metabolism, highlighting the potential health risks of oxidized milk in humans.

Adverse effects of linoleic acid: Influence of lipid oxidation on lymphatic transport of citrus flavonoid and enterocyte morphology

Lipids usually contain a large ratio of polyunsaturated fatty acids (PUFAs), which are highly susceptible to oxidation. Presence of oxidized lipids in foods may affect the bioavailability of lipophilic bioactive components after ingestion. In this study, the effect of oxidized and unoxidized linoleic acid (LA) on the transport of a highly lipophilic bioactive citrus flavonoid (5-hydroxy - 6, 7, 8, 4' tetramethoxylflavone or 5-DMT) was determined using a Caco-2 cell model. Results demonstrated that compared to free 5-DMT, unoxidized LA improved the trans-enterocyte absorption of 5-DMT by stimulating the production of lipid droplets and chylomicrons. Although the amount of 5-DMT transported across the enterocyte doubled by oxidized LA compared to free 5-DMT, it significantly induced reactive oxygen species (ROS), affected the function of tight junction and caused damages to the morphology of enterocyte monolayer. This study re-emphasized the importance of preventing lipid oxidation in foods.

Different Effects of Vitamin C-Based Supplements on the Advance of Linseed Oil Component Oxidation and Lipolysis during In Vitro Gastrointestinal Digestion

Although widely consumed, dietary supplements based on Vitamin C contain high doses of this compound, whose impact on lipid oxidation during digestion needs to be addressed. Therefore, the effect of seven commercial supplements and of pure l-ascorbic acid and ascorbyl palmitate on linseed oil during in vitro gastrointestinal digestion was tackled. The advance of lipid oxidation was studied through the generation of oxidation compounds, the degradation of polyunsaturated fatty acyl chains and of gamma-tocopherol, by employing Proton Nuclear Magnetic Resonance. Supplements containing exclusively l-ascorbic acid enhanced the advance of linseed oil oxidation during digestion. This was evidenced by increased formation of linolenic-derived conjugated hydroxy-dienes and alkanals and by the generation of conjugated keto-dienes and reactive alpha,beta-unsaturated aldehydes, such as 4,5-epoxy-2-alkenals; moreover, gamma-tocopherol was completely degraded. Conversely, supplements composed of mixtures of ascorbic acid/salt with citric acid and carotenes, and of ascorbyl palmitate, protected linseed oil against oxidation and reduced gamma-tocopherol degradation. The study through Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry of the volatile compounds of the digests corroborated these findings. Furthermore, a decreased lipid bioaccessibility was noticed in the presence of the highest dose of l-ascorbic acid. Both the chemical form of Vitamin C and the presence of other ingredients in dietary supplements have shown to be of great relevance regarding oxidation and hydrolysis reactions occurring during lipid digestion.

Lipid oxidation and aldehyde formation during in vitro gastrointestinal digestion of roasted scallop (Patinopecten yessoensis) - the role of added antioxidant of bamboo leaves

This study investigated lipid oxidation and aldehyde formation in roasted scallop during in vitro gastrointestinal digestion, and the effects of co-digestion of antioxidant of bamboo leaves (AOB) on this process. The results showed that the contents of lipid hydroperoxides (LOOH), conjugated dienes (CD), and Schiff bases (SB) were increased during gastrointestinal digestion. Besides, malondialdehyde (MDA) levels and total aldehyde formation decreased initially at the gastric stage but increased at the intestinal stage. The results of HPLC-ESI-MS/MS analysis showed that the contents of hexanal (HEX), trans, trans-2,4-octadienal (ODE), trans, trans-2,4-decadienal (DDE), 4-hydroxyhexenal (HHE) and 4-hydroxynonenal (HNE) in the digestive juices were all initially decreased and then increased during gastrointestinal digestion. Meanwhile, the content of acrolein, propanal, and trans-2-pentenal at the end of intestinal digestion was lower than that in the initial stage of gastric digestion. Additionally, the digestion of roasted scallop caused significant oxidation of polyunsaturated fatty acids (PUFAs) and release of free fatty acids (FFA) in the intestinal phase, which were positively related to aldehyde production. However, co-digestion of AOB significantly reduced lipid oxidation and formation of lipid oxidation products (LOOH, CD, SB, and aldehyde) during gastrointestinal digestion, indicating that the addition of AOB was effective in reducing gastrointestinal lipid oxidation.

Comprehensive polar metabolomics and lipidomics profiling discriminates the transformed from the non-transformed state in colon tissue and cell lines

Colorectal cancer (CRC) is the fourth most lethal disease worldwide. Despite an urgent need for therapeutic advance, selective target identification in a preclinical phase is hampered by molecular and metabolic variations between cellular models. To foster optimal model selection from a translational perspective, we performed untargeted ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry-based polar metabolomics and lipidomics to non-transformed (CCD841-CON and FHC) and transformed (HCT116, HT29, Caco2, SW480 and SW948) colon cell lines as well as tissue samples from ten colorectal cancer patients. This unveiled metabolic signatures discriminating the transformed from the non-transformed state. Metabolites involved in glutaminolysis, tryptophan catabolism, pyrimidine, lipid and carnitine synthesis were elevated in transformed cells and cancerous tissue, whereas those involved in the glycerol-3-phosphate shuttle, urea cycle and redox reactions were lowered. The degree of glutaminolysis and lipid synthesis was specific to the colon cancer cell line at hand. Thus, our study exposed pathways that are specifically associated with the transformation state and revealed differences between colon cancer cell lines that should be considered when targeting cancer-associated pathways.

In vitro and in vivo digestion of red cured cooked meat: oxidation, intestinal microbiota and fecal metabolites

Mechanisms explaining epidemiological associations between red (processed) meat consumption and chronic disease risk are not yet elucidated, but may involve oxidative reactions, microbial composition alterations, inflammation and/or the formation of toxic bacterial metabolites. First, in vitro gastrointestinal digestion of 23 cooked beef-lard minces, to which varying doses of nitrite salt (range 0-40 g/kg) and sodium ascorbate (range 0-2 g/kg) were added, showed that nitrite salt decreased protein carbonylation up to 3-fold, and inhibited lipid oxidation, demonstrated by up to 4-fold lower levels of 'thiobarbituric acid reactive substances', 32-fold lower 4-hydroxynonenal, and 21-fold lower hexanal values. The use of ascorbate increased the antioxidant effect of low nitrite salt levels, whereas it slightly increased protein carbonylation at higher doses of nitrite salt. The addition of a low dose of ascorbate without nitrite salt slightly promoted oxidation during digestion, whereas higher doses had varying antioxidant effects. Second, 40 rats were fed a diet of cooked chicken- or beef-lard minces, either or not cured, for three weeks. Beef, compared to chicken, consumption increased lipid oxidation (2- to 4-fold) during digestion, and gut protein fermentation (cecal iso-butyrate, (iso-)valerate, and fecal indole, cresol), but oxidative stress and inflammation were generally not affected. Cured, compared to fresh, meat consumption significantly increased stomach protein carbonylation (+16%), colonic Ruminococcaceae (2.1-fold) and cecal propionate (+18%), whereas it decreased cecal butyrate (-25%), fecal phenol (-69%) and dimethyl disulfide (-61%) levels. Fecal acetaldehyde and diacetyl levels were increased in beef-fed rats by 2.8-fold and 5.9-fold respectively, and fecal carbon disulfide was 4-fold higher in rats consuming cured beef vs. fresh chicken. Given their known toxicity, the role of acetaldehyde and carbon disulfide in the relation between meat consumption and health should be investigated in future studies.

Can Meat and Meat-Products Induce Oxidative Stress?

High meat and meat-products consumption has been related to degenerative diseases. In addition to their saturated fatty acids and cholesterol contents, oxidation products generated during their production, storage, digestion, and metabolization have been largely implicated. This review begins by summarizing the concept of meat and meat-products by the main international regulatory agencies while highlighting the nutritional importance of their consumption. The review also dials in the controversy of white/red meat classification and insists in the need of more accurate classification based on adequate scores. Since one of the negative arguments that meat receives comes from the association of its consumption with the increase in oxidative stress, main oxidation compounds (malondialdehyde, thermaloxidized compounds, 4-hydroxy-nonenal, oxysterols, or protein carbonyls) generated during its production, storage, and metabolization, are included as a central aspect of the work. The review includes future remarks addressed to study the effects meat consumption in the frame of diet-gene interactions, stressing the importance of knowing the genetic variables that make individuals more susceptible to a possible oxidative stress imbalance or antioxidant protection. The importance of consumed meat/meat-products in the frame of a personalized nutrition reach in plant-food is finally highlighted considering the importance of iron and plant biophenols on the microbiota abundance and plurality, which in turn affect several aspects of our physiology and metabolism.

A Global Study by 1H NMR Spectroscopy and SPME-GC/MS of the in Vitro Digestion of Virgin Flaxseed Oil Enriched or not with Mono-, Di- or Tri-Phenolic Derivatives. Antioxidant Efficiency of These Compounds

The effect of enriching virgin flaxseed oil with dodecyl gallate, hydroxytyrosol acetate or gamma-tocopherol on its in vitro digestion is studied by means of proton nuclear magnetic resonance and solid phase microextraction followed by gas chromatography/mass spectrometry. The extent and pattern of the lipolysis reached in each sample is analyzed, as is the bioaccessibility of the main oil components. None of the phenolic compounds provokes inhibition of the lipase activity and all of them reduce the lipid oxidation degree caused by the in vitro digestion and the bioaccessibility of oxidation compounds. The antioxidant efficiency of the three tested phenols is in line with the number of phenolic groups in its molecule, and is dose-dependent. The concentration of some minor oil components such as terpenes, sesquiterpenes, cycloartenol and 24-methylenecycloartenol is not modified by in vitro digestion. Contrarily, gamma-tocopherol shows very low in vitro bioaccessibility, probably due to its antioxidant behavior, although this increases with enrichment of the phenolic compounds. Oxidation is produced during in vitro digestion even in the presence of a high concentration of gamma-tocopherol, which remains bioaccessible after digestion in the enriched samples of this compound.

Effect of the Enrichment of Corn Oil with alpha- or gamma-Tocopherol on Its in Vitro Digestion Studied by 1H NMR and SPME-GC/MS; Formation of Hydroperoxy-, Hydroxy-, Keto-Dienes and Keto-E-epoxy-E-Monoenes in the more alpha-Tocopherol Enriched Samples

The aim of this study is the analysis of the in vitro digestion of corn oil, and of the effect of its enrichment with three levels of gamma- and alpha-tocopherol, by using, for the first time, 1H nuclear magnetic resonance (1H NMR) and a solid phase microextraction followed by gas chromatography/mass spectrometry (SPME-GC/MS). The attention is focused on the hydrolysis degree, the degradation of oil's main components, the occurrence of oxidation reactions and main compounds formed, as well as on the bioaccessibility of oil's main components, of compounds formed in the oxidation, and, of gamma- and alpha-tocopherol. The lipolysis levels reached are high and show a similar pattern in all cases. The oxidation of corn oil components during in vitro digestion is proven, as is the action of gamma-tocopherol as an antioxidant and alpha-tocopherol as a prooxidant. In the more alpha-tocopherol enriched samples, hydroperoxy-, hydroxy-, and keto-dienes, as well as keto-epoxy-monoenes and aldehydes, are generated. The bioaccessibility of the oil's main components is high. The compounds formed in the oxidation process during in vitro digestion can also be considered bioaccessible. The bioaccessibility of alpha-tocopherol is smaller than that of gamma-tocopherol. The concentration of this latter compound remains unchanged during the in vitro digestion of the more alpha-tocopherol enriched oil samples.

Effect of rosemary extract on lipid oxidation of cooked pork during simulated gastric digestion

BACKGROUND

Oxidation of food lipids occurs in the gastrointestinal tract, resulting in potential adverse health effects. Rosemary extract (RE), as one of the most popular naturally sourced antioxidants, is widely used in the food industry. However, the effect of RE on lipid oxidation during gastrointestinal digestion has not been well investigated. Therefore, this study aimed to evaluate the effect of RE on lipid oxidation of cooked pork during simulated gastric digestion.

RESULTS

Results showed that RE at 12.5, 25, 50, and 100 mg kg^-1 pork effectively decreased the formation of malondialdehyde during simulated gastric digestion of cooked pork. RE also effectively mitigated the decline of fatty acids during the simulated gastric digestion of pork. The total phenolic content in RE was calculated to be 170.67 mg gallic acid equivalent (GAE) g^-1 . RE dissolved in distilled water (pH 6.5) or potassium hydrogen phthalate-hydrochloric acid buffer solution (0.2 mol L^-1 , pH 3.0) both exhibited strong 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) and 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activities as well as ferric reducing capacity. The inhibitory effects of RE on lipid oxidation of cooked pork during simulated gastric digestion may be attributed to the phenolic compounds with antioxidant properties.

CONCLUSION

The results lend support to the possible application of rosemary or RE as a rich source of natural antioxidants to inhibit the oxidation of food lipids during gastrointestinal digestion. © 2019 Society of Chemical Industry.

Effect of adding alpha-tocopherol on the oxidation advance during in vitro gastrointestinal digestion of sunflower and flaxseed oils

Few in vitro studies have tackled the effect of alpha-tocopherol on lipid oxidation during digestion, and discrepant results have been reported. As a result, the aim of this study was to elucidate whether the addition of alpha-tocopherol enhances or slows down the advance of oxidation that occurs during in vitro gastrointestinal digestion of polyunsaturated lipids. For this purpose, commercial sunflower and flaxseed oils (as models of omega-6 and omega-3 rich lipid systems, respectively) were in vitro digested in the absence or in the presence of this tocol at different concentrations (0.02%, 0.2% and 2%). Proton Nuclear Magnetic Resonance (¹H NMR) and Solid Phase Microextraction followed by Gas Chromatography/Mass Spectrometry (SPME-GC/MS) were used to investigate in detail potential differences among the digests regarding lipolysis and oxidation level. Alpha-tocopherol addition did not affect the advance of lipolysis, whereas lipid oxidation was enhanced in a dose-dependent manner. In this regard, the increased degradation of polyunsaturated lipids and greater generation of primary and secondary oxidation products observed at higher concentrations of alpha-tocopherol confirmed this observation. Among the formed oxidation products, hydroperoxy-, hydroxy- and keto-dienes, as well as oxygenated alpha,beta-unsaturated aldehydes are worth mentioning. The in vitro bioaccessibility of added tocopherol was estimated to be very low, suggesting a notable transformation under the assayed conditions. Further in vivo studies are necessary to confirm this prooxidant activity of alpha-tocopherol during gastrointestinal digestion.

Lipid and Protein Oxidation during in Vitro Gastrointestinal Digestion of Pork under Helicobacter pylori Gastritis Conditions

Helicobacter pylori gastritis affects gastric pH and concentrations of ascorbic acid, hydrogen peroxide, hypochlorite, ammonia and urea, pepsin, and mucin. First, the separate effects of each of these altered factors on oxidation of pork were investigated during in vitro gastrointestinal digestion. Lipid and protein oxidation increased (range 23-48%) in duodenal digests of pork previously exposed to elevated (6.1) versus normal acidic stomach pH (2.3 to 3.5) conditions. Salivary nitrite reduced the formation of lipid and protein oxidation products (range 14-20%) under normal acidic but not elevated stomach pH conditions. Higher amounts of hydrogen peroxide and lower amounts of ascorbic acid decreased concentrations of lipid oxidation products in duodenal pork digests, whereas ammonia slightly stimulated protein oxidation during digestion. Second, two H. pylori gastritis-duodenal digestion models were installed using a set of altered compound concentrations at normal acidic or elevated stomach pH. The elevated pH-gastritis-duodenal digestion model increased pork protein oxidation compared with the normal pH-gastritis and the normal digestion model (14.3 ± 2.1 vs 8.2 ± 1.0 nmol DNPH/mg protein, P < 0.001). Compared with the other models, protein oxidation was also increased when nitrite-cured pork was exposed to the elevated pH-gastritis-duodenal digestion model (10.8 ± 1.4 vs 5.9 ± 0.8 nmol DNPH/mg protein, P < 0.001), but no significant effect of the model was observed when the pork was seasoned with herbs. Lipid oxidation was not or was marginally affected by the installed model.

Oxidation of marine oils during in vitro gastrointestinal digestion with human digestive fluids - Role of oil origin, added tocopherols and lipolytic activity

The formation of malondialdehyde (MDA), 4-hydroxy-2-hexenal (HHE), 4-hydroxy-2-nonenal (HNE), and 4-oxo-2-nonenal (ONE) in cod liver-, anchovy-, krill-, and algae oil during in vitro digestion with human gastrointestinal fluids was investigated. Adding rabbit gastric lipase, lipase inhibitor (orlistat) and tocopherols to cod liver oil, lipolysis and oxidation was also studied. Among the marine oils, the highest aldehyde levels (18 µM MDA, 3 µM HHE and 0.2 µM HNE) were detected after digestion of cod liver oil, while the lowest levels were detected in krill and algae oils. Addition of rabbit gastric lipase significantly increased the release of HNE during the digestion. Orlistat significantly reduced lipolysis and MDA formation. Formation of MDA and HHE was delayed by tocopherols, the tocopherol mix Covi-ox® T 70 EU being more effective than pure α-tocopherol.

Carbonyl-Phenol Adducts: An Alternative Sink for Reactive and Potentially Toxic Lipid Oxidation Products

Different from the well-characterized function of phenolics as antioxidants, their function as lipid-derived carbonyl scavengers is mostly unknown. However, phenolics react with lipid-derived carbonyls as a function of the nucleophilicity of their reactive groups and the electronic effects and steric hindrances present in the reactive carbonyls. Furthermore, the reaction produces a wide variety of carbonyl-phenol adducts, some of which are stable and have been isolated and characterized but others polymerize spontaneously. This perspective updates present knowledge about the lipid-derived carbonyl trapping ability of phenolics, its competition with carbonyl-amine reactions produced in foods, and the presence of carbonyl-phenol adducts in food products.

Association between red meat consumption and colon cancer: A systematic review of experimental results

A role for red and processed meat in the development of colorectal cancer has been proposed based largely on evidence from observational studies in humans, especially in those populations consuming a westernized diet. Determination of causation specifically by red or processed meat is contingent upon identification of plausible mechanisms that lead to colorectal cancer. We conducted a systematic review of the available evidence to determine the availability of plausible mechanistic data linking red and processed meat consumption to colorectal cancer risk. Forty studies using animal models or cell cultures met specified inclusion criteria, most of which were designed to examine the role of heme iron or heterocyclic amines in relation to colon carcinogenesis. Most studies used levels of meat or meat components well in excess of those found in human diets. Although many of the experiments used semi-purified diets designed to mimic the nutrient loads in current westernized diets, most did not include potential biologically active protective compounds present in whole foods. Because of these limitations in the existing literature, there is currently insufficient evidence to confirm a mechanistic link between the intake of red meat as part of a healthy dietary pattern and colorectal cancer risk. Impact statement Current recommendations to reduce colon cancer include the reduction or elimination of red or processed meats. These recommendations are based on data from epidemiological studies conducted among cultures where meat consumption is elevated and consumption of fruits, vegetables, and whole grains are reduced. This review evaluated experimental data exploring the putative mechanisms whereby red or processed meats may contribute to colon cancer. Most studies used levels of meat or meat-derived compounds that were in excess of those in human diets, even in cultures where meat intake is elevated. Experiments where protective dietary compounds were used to mitigate the extreme levels of meat and meat-derived compounds showed protection against colon cancer, with some essentially negating the impact of meat in the diet. It is essential that better-designed studies be conducted that use relevant concentrations of meat or meat-derived compounds in complex diets representative of the foods consumed by humans.

Health Risks of Food Oxidation

The impact of dietary habits on our health is indisputable. Consumer's concern on aging and age-related diseases challenges scientists to underline the potential role of food on the extension and guarantee of lifespan and healthspan. While some dietary components and habits are generally regarded as beneficial for our health, some others are being found to exert potential toxic effects and hence, contribute to the onset of particular health disorders. Among the latter, lipid and protein oxidation products formed during food production, storage, processing, and culinary preparation have been recently identified as potentially harmful to humans. Upon intake, food components are further degraded and oxidized during the subsequent digestion phases and the pool of compounds formed in the lumen is in close contact with the lamina propria of the intestines. Some of these oxidation products have been found to promote inflammatory conditions in the gut (i.e., bowel diseases) and are also reasonably linked to the onset of carcinogenic processes. Upon intestinal uptake, some species are distributed by the bloodstream causing an increase in oxidative stress markers and impairment of certain physiological processes through alteration of specific gene expression pathways. This chapter summarizes the most recent discoveries on this topic with particular stress on challenges that we face in the near future: understanding the molecular basis of disease, the suitability of using living animals vs in vitro model systems and the necessity of using massive genomic techniques and versatile mass spectrometric technology.