Department of Food Science, Volcani Center, ARO, Israel. email@example.com
Lipid oxidation in foods is one of the major degradative processes responsible for losses in food quality. The oxidation of unsaturated fatty acids results in significant generation of dietary advanced lipid oxidation endproducts (ALEs) which are in part cytotoxic and genotoxic compounds. The gastrointestinal tract is constantly exposed to dietary oxidized food compounds, after digestion a part of them are absorbed into the lymph or directly into the blood stream. After ingestion of oxidized fats animals and human have been shown to excrete in urine increase amounts of malondialdehyde but also lipophilic carbonyl compounds. Oxidized cholesterol in the diet was found to be a source of oxidized lipoproteins in human serum. Some of the dietary ALEs, which are absorbed from the gut to the circulatory system, seems to act as injurious chemicals that activate an inflammatory response which affects not only circulatory system but also organs such as liver, kidney, lung, and the gut itself. We believe that repeated consumption of oxidized fat in the diet poses a chronic threat to human health. High concentration of dietary antioxidants could prevent lipid oxidation and ALEs generation not only in foods but also in stomach condition and thereby potentially decrease absorption of ALEs from the gut. This could explains the health benefit of diets containing large amounts of dietary antioxidants such those present in fruits and vegetables, or products such as red-wine or tea consuming during the meal.
Department of Life Sciences, Roehampton University, Holybourne Avenue, London SW15 4JD, UK. Simon.Dyall@roehampton.ac.uk
There is growing interest into researching omega-3 fatty acids; however, there are considerable variations in the methodologies employed. Many studies add oils to animal feed and under ambient conditions omega-3 fatty acids are particularly unstable and prone to autoxidation and peroxidative damage. It is therefore important to take specific precautions with the stock preparations and when preparing the experimental diets. There is a need for clarity in the reporting of methodologies employed, such as how oil preparations are stored and handled, how experimental diets are prepared, the potential effects of adding additional antioxidants, whether there is a clear rationale for the selection of control/placebo diets, which may be situation dependent, and consistency in expressing the experimental doses. The purpose of this article is to highlight some of these issues in the hope of promoting discussion, and potentially developing guidelines as to what represents best practice.
Food Nutr Res. 2011 ;55 : 21691461
Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
There is convincing evidence that replacing dietary saturated fats with polyunsaturated fats (PUFA) decreases risk of cardiovascular diseases. Therefore, PUFA rich foods such as vegetable oils, fatty fish, and marine omega-3 supplements are recommended. However, PUFA are easily oxidizable and there is concern about possible negative health effects from intake of oxidized lipids. Little is known about the degree of lipid oxidation in such products. To assess the content of lipid oxidation products in a large selection of vegetable oils and marine omega-3 supplements available in Norway. Both fresh and heated vegetable oils were studied. A large selection of commercially available vegetable oils and marine omega-3 supplements was purchased from grocery stores, pharmacies, and health food stores in Norway. The content of lipid oxidation products were measured as peroxide value and alkenal concentration. Twelve different vegetable oils were heated for a temperature (225°C) and time (25 minutes) resembling conditions typically used during cooking. The peroxide values were in the range 1.04-10.38 meq/kg for omega-3 supplements and in the range 0.60-5.33 meq/kg for fresh vegetable oils. The concentration range of alkenals was 158.23-932.19 nmol/mL for omega-3 supplements and 33.24-119.04 nmol/mL for vegetable oils. After heating, a 2.9-11.2 fold increase in alkenal concentration was observed for vegetable oils. The contents of hydroperoxides and alkenals in omega-3 supplements are higher than in vegetable oils. After heating vegetable oils, a large increase in alkenal concentration was observed.
Georgia-Persephoni Voulgaridou, Ioannis Anestopoulos, Rodrigo Franco, Mihalis I Panayiotidis, Aglaia Pappa
Department of Molecular Biology and Genetics, Democritus University of Thrace, Alexandroupolis, 68100, Greece.
DNA damage plays a major role in various pathophysiological conditions including carcinogenesis, aging, inflammation, diabetes and neurodegenerative diseases. Oxidative stress and cell processes such as lipid peroxidation and glycation induce the formation of highly reactive endogenous aldehydes that react directly with DNA, form aldehyde-derived DNA adducts and lead to DNA damage. In occasion of persistent conditions that influence the formation and accumulation of aldehyde-derived DNA adducts the resulting unrepaired DNA damage causes deregulation of cell homeostasis and thus significantly contributes to disease phenotype. Some of the most highly reactive aldehydes produced endogenously are 4-hydroxy-2-nonenal, malondialdehyde, acrolein, crotonaldehyde and methylglyoxal. The mutagenic and carcinogenic effects associated with the elevated levels of these reactive aldehydes, especially, under conditions of stress, are attributed to their capability of causing directly modification of DNA bases or yielding promutagenic exocyclic adducts. In this review, we discuss the current knowledge on DNA damage induced by endogenously produced reactive aldehydes in relation to the pathophysiology of human diseases.
Effect of aqueous and lipophilic mullet (Mugil cephalus) Bottarga extracts on the growth and lipid profile of intestinal Caco-2 cells.
Antonella Rosa, Angela Atzeri, Monica Deiana, M Paola Melis, Debora Loru, Alessandra Incani, Barbara Cabboi, M Assunta Dessì
Dipartimento di Biologia Sperimentale, Sezione di Patologia Sperimentale, Università degli Studi di Cagliari , Cittadella Universitaria, SS 554, Km 4.5, 09042 Monserrato, Cagliari, Italy. firstname.lastname@example.org
The importance of n-3 polyunsaturated fatty acid (n-3 PUFA) intake has long been recognized in human nutrition. Although health benefits, n-3 PUFA are subject to rapid and/or extensive oxidation during processing and storage, resulting in potential alteration in nutritional composition and quality of food. Bottarga, a salted and semi-dried mullet ( Mugil cephalus ) ovary product, is proposed as an important source of n-3 PUFA, having high levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In this work, we investigated the extent of lipid oxidation of grated bottarga samples during 7 months of storage at -20 °C and room temperature under light exposure. Cell viability, lipid composition, and lipid peroxidation were measured in intestinal differentiated Caco-2 cell monolayers after 6-48 h of incubation with lipid and hydrophilic extracts obtained from bottarga samples at different storage conditions. The storage of bottarga did not affect the n-3 PUFA level, but differences were observed in hydroperoxide levels in samples from different storage conditions. All tested bottarga extracts did not show a toxic effect on cell viability of differentiated Caco-2 cells. Epithelial cells incubated with bottarga oil had significant changes in fatty acid composition but not in cholesterol levels with an accumulation of EPA, DHA, and 22:5. Cell hydroperoxides were higher in treated cells, in relation to the oxidative status of bottarga oil. Moreover, the bottarga lipid extract showed an in vitro inhibitory effect on the growth of a colon cancer cell line (undifferentiated Caco-2 cells).
Heme iron from meat and risk of colorectal cancer: a meta-analysis and a review of the mechanisms involved.
INRA TOXALIM (Research Centre in Food Toxicology), Université de Toulouse; INP ENVT, Toulouse, France.
Red meat and processed meat intake is associated with a risk of colorectal cancer, a major cause of death in affluent countries. Epidemiological and experimental evidence supports the hypothesis that heme iron present in meat promotes colorectal cancer. This meta-analysis of prospective cohort studies of colon cancer reporting heme intake included 566,607 individuals and 4,734 cases of colon cancer. The relative risk of colon cancer was 1.18 (95% CI: 1.06-1.32) for subjects in the highest category of heme iron intake compared with those in the lowest category. Epidemiological data thus show a suggestive association between dietary heme and risk of colon cancer. The analysis of experimental studies in rats with chemically-induced colon cancer showed that dietary hemoglobin and red meat consistently promote aberrant crypt foci, a putative precancer lesion. The mechanism is not known, but heme iron has a catalytic effect on (i) the endogenous formation of carcinogenic N-nitroso compounds and (ii) the formation of cytotoxic and genotoxic aldehydes by lipoperoxidation. A review of evidence supporting these hypotheses suggests that both pathways are involved in heme iron toxicity.
Department of Cardiology, Sree Chitra Tirunal Institute for Medical Sciences & Technology, Thiruvananthapuram, Kerala, India. email@example.com
Globalization has made calorie rich, cheap, convenient marketed foods the main menu for the common man. Indians are particularly susceptible to the adverse outcomes of this dietary change because of ethnic, epigenetic reasons and sarcopenic adiposity (less muscle more fat for the same body weight). Children have smaller body frame making them more susceptible to adverse effects of hyperglycaemia leading to stress on beta cells and their damage. This has resulted in escalation of lifestyle diseases by three-fold, that too at our younger age group at lower body mass indices. Preventive measures are necessary in early life to protect the beta cells, to achieve a metabolically healthy society. This will help in sustaining optimal beta cell function throughout a person's life. Modification in dietary habits by educating the society, proper food labelling and legal regulation, restricting calorie, sugar, saturated fat, trans-fat and salt intake has proved its benefits in the developed world. Changes in the quality of food is as important as restricting calorie intake. This includes facilitation of increased consumption of dietary fiber, complex carbohydrates, nuts, fruits and vegetables. Restrictions are needed to reduce trans-fats, saturated fats and cooking habits such as deep frying which oxidizes cholesterol and lipids. Foods with long shelf-life shorten the life line because of their salt, sugar or trans-fat content. Individual meals need to be targeted in the general dietary guidelines, to minimize the post-prandial metabolic insult. In general, we need healthy start to early life particularly the first twenty years of life so that the habits cultured during childhood are sustained for the rest of productive years.
J Agric Food Chem. 2010 Feb 16;: 20158199
Role of Continuous Phase Anionic Polysaccharides on the Oxidative Stability of Menhaden Oil-in-Water Emulsions.
Department of Food Science, University of Massachusetts, Amherst, Massachusetts 01003.
The antioxidant role of selected polysaccharides was studied in the continuous phase of a Menhaden oil-in-water emulsion coated by polyoxyethylene(23) lauryl ether (Brij 35) at neutral pH. The addition of low-methoxyl (LM) and high-methoxyl (HM) pectin (0.02-0.1 wt %) reduced the formation of lipid hydroperoxides and thiobarbituric acid reactive substances with an inhibition that increased with increasing polysaccharide concentration in the continuous phase. alpha-Carrageenan and sodium alginate were less effective antioxidants than pectin and were prooxidative under certain conditions. None of the polysaccharides impacted the physical properties of the emulsions as determined by droplet particle size (d(43) approximately 0.32 mum) and creaming index. LM and HM pectins had higher iron-binding capacities as compared to alpha-carrageenan and sodium alginate, which may relate to their higher antioxidant activities. These results suggest that the addition of anionic polysaccharides to the continuous phase of oil-in-water emulsions could be used to increase the oxidative stability of oil-in-water emulsions and thus prolong shelf life.
Chemical Modeling of Heme-Induced Lipid Oxidation in Gastric Conditions and Inhibition by Dietary Polyphenols.
UMR408 Safety and Quality of Plant Products, INRA, University of Avignon, Avignon, France.
The gastric tract may be the first site exposed to diet-related oxidative stress. After food intake, dietary iron such as (met)myoglobin, the pigment of meat, oxygen, and polyunsaturated lipids come into close contact. The main goal of this work is the in vitro investigation of lipid oxidation taking place in the gastric compartment and its inhibition by dietary polyphenols. Oil-in-water emulsions stabilized either by bovine serum albumin (BSA) or egg yolk phospholipids (PL) were designed to model the gastric content. The metmyoglobin-initiated lipid oxidation led to the accumulation of lipid-derived conjugated dienes and volatile aldehydes. These reactions were faster in the BSA model than in the PL model, highlighting the influence of the interfacial composition. Quercetin, rutin,(+)-catechin, caffeic acid, and chlorogenic acid proved to be better inhibitors than alpha-tocopherol and ascorbic acid. Emulsions as models of the gastric environment are valuable tools to study the stability of macro- and micronutrients.
Pro-oxidant and proapoptotic effects of cholesterol oxidation products on human colonic epithelial cells: a potential mechanism of inflammatory bowel disease progression.
Fiorella Biasi, Cinzia Mascia, Marco Astegiano, Elena Chiarpotto, Mario Nano, Barbara Vizio, Gabriella Leonarduzzi, Giuseppe Poli
Department of Clinical and Biological Sciences, University of Turin at San Luigi Gonzaga Hospital, 10043 Orbassano (Turin), Italy.
With the aim of investigating whether cholesterol oxidation products could contribute to the pathogenesis of the intestinal epithelial barrier dysfunction that occurs in human inflammatory bowel disease (IBD), differentiated versus undifferentiated CaCo-2 cells, an accepted model for human intestinal epithelial cells, were challenged with a dietary-representative mixture of oxysterols. Only differentiated colonic cells were susceptible to the proapoptotic action of the oxysterol mixture, checked both by enzymatic and by morphological methods, mainly because of a very low AKT phosphorylation pathway compared to the undifferentiated counterparts. Enhanced production of reactive oxygen species by a colonic NADPH oxidase hyperactivation seemed to represent the key event in oxysterol-induced up-regulation of the mitochondrial pathway of programmed death of differentiated CaCo-2 cells. These in vitro findings point to the pro-oxidant and cytotoxic potential of cholesterol oxidation products, of both dietary and endogenous origin, as an important mechanism of induction and/or worsening of the functional impairment of enteric mucosa that characterizes IBD.
In vitro digestion of betalainic foods. Stability and bioaccessibility of betaxanthins and betacyanins and antioxidative potential of food digesta.
Dipartimento Farmacochimico Tossicologico e Biologico, Universita di Palermo, Palermo, Italy.
Betalains are considered to be bioactive dietary phytochemicals. The stability of betacyanins and betaxanthins from either fresh foods or manufactured products of cactus pear fruit ( Opuntia ficus indica L. Mill. cv. Gialla and Rossa) and red beet ( Beta vulgaris L. ssp. vulgaris) was assessed in a simulated oral, gastric, and small intestinal digestion and compared with the digestive stability of purified pigments. A minor loss of indicaxanthin, at the gastric-like environment only, and a decrease of vulgaxanthin I through all digestion steps were observed, which was not affected by food matrix. In contrast, food matrix prevented decay of betanin and isobetanin at the gastric-like environment. Loss of betacyanins, either purified or food-derived, was observed during the small intestinal phase of digestion. Betalamic acid accumulated after digestive degradation of purified pigments, but not of food betalains. Betaxanthins were wholly soluble in the aqueous (bioaccessible) fraction after ultracentrifugation of the postintestinal (PI) digesta, whereas release of betacyanins from the matrix was incomplete. PI digesta inhibited dose-dependently the oxidation of methyl linoleate in methanol, an effect not correlated with the betalain content. The data suggest that digestive stability controls bioaccessibility of dietary betaxanthins, whereas additional factors, relevant to the food matrix and style of processing, affect betacyanin bioaccessibility.
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Arch Oral Biol. 2012 May 28;: 22647426
Saliva increases the availability of lipophilic polyphenols as antioxidants and enhances their retention in the oral cavity.
The Faculty of Dental Medicine, Institute for Dental Sciences, Hebrew University, Hadassah Medical Center, P.O. Box 12065, Jerusalem 91120, Israel.
OBJECTIVE: Lipophilic polyphenols in fruit beverages can avidly bind to surfaces of microorganisms and to blood cells and to impart upon them enhanced oxidant scavenging abilities (OSA). However, since many of the polyphenols are actually not fully soluble in water, they are therefore not available to act as effective antioxidant agents. We hypothesized that whole saliva, proteins such as albumin and mucin, human red blood cells and platelets, may all increase the "solubility" and availability of lipophilic antioxidant polyphenols thus increasing the OSA of whole saliva. DESIGN: The OSA of whole un-stimulated human saliva, obtained from healthy donors and of combinations among saliva, mucin, blood cells, fruit beverages and reagent polyphenols were quantified by chemiluminescence, DPPH radical and tetrazolium reduction assays. Kinetics of the clearance of polyphenols from saliva after holding in the mouth for 30s of an extract from beverages cinnamon was assayed by the Folin Ciocalteu's and the luminescence assays. RESULTS: OSA of fruit beverages and of reagent polyphenols were markedly increased by whole saliva, mucin and by red blood cells. Polyphenols associated with a cinnamon extract were retained in the oral cavity for several hours as measured by luminescence and Folin reagent techniques. CONCLUSIONS: A new approach to explain the additional role of saliva and salivary proteins and of blood cells as enhancers of OSA of lipophilic polyphenols is presented. This might have a significant importance to assess complex interactions among polyphenols from nutrients, salivary antioxidants, salivary proteins and blood cells extravasated from injure capillaries during infection and inflammation.
J Agric Food Chem. 2012 May 3;: 22530973
Protection by Polyphenols of Postprandial Human Plasma and Low-Density Lipoprotein Modification: The Stomach as a Bioreactor.
Department of Food Science, ARO , Volcani Center, Bet Dagan, Israel.
Recent studies dramatically showed that the removal of circulating modified low-density lipoprotein (LDL) results in complete prevention of atherosclerosis. The gastrointestinal tract is constantly exposed to food, some of it containing oxidized compounds. Lipid oxidation in the stomach was demonstrated by ingesting heated red meat in rats. Red wine polyphenols added to the rats' meat diet prevented lipid peroxidation in the stomach and absorption of malondialdehyde (MDA) in rat plasma. In humans, postprandial plasma MDA levels rose by 3-fold after a meal of red meat cutlets. MDA derived from meat consumption caused postprandial plasma LDL modification in human. The levels of plasma MDA showed a 75% reduction by consumption of red wine polyphenols during the meat meal. Locating the main biological site of action of polyphenols in the stomach led to a revision in the understanding of how antioxidants work in vivo and may help to elucidate the mechanism involved in the protective effects of polyphenols in human health.
Department of Food Science, ARO, Volcani Center, Bet-Dagan 50250, Israel.
Polyphenols, which occur both in edible plants and in foodstuff, have been reported to exert a wide range of health effects; however, the mechanism of action of these molecules is not fully understood. One important cellular pathway affected by polyphenols is the activation of the transcription factor Nrf2 via the electrophile response element, which mediates generation of phase 2 detoxifying enzymes. Our study found that Nrf2 nuclear translocation and the activity of NAD(P)H quinone oxidoreductase (NQO1) were increased significantly after treatment of astrocytes with tert-butylhydroquinone (tBHQ), resveratrol, or curcumin, at 20-50μM. Incubation of tBHQ, resveratrol, and curcumin in the growth medium in the absence of astrocytes caused the accumulation of H(2)O(2). Treatment of cells with either glutathione or metmyoglobin was found to decrease Nrf2 translocation and NQO1 activity induced by polyphenols by up to 40 and 60%, respectively. Addition of both glutathione and metmyoglobin to growth medium decreased Nrf2 translocation and NQO1 activity by up to 100 and 80%, respectively. In conclusion, because metmyoglobin, in the presence of polyphenols and glutathione, is known to interact with H(2)O(2), semiquinones, and quinones, the up-regulation of the antioxidant defense of the cells through activation of the Nrf2 transcription factor, paradoxically, occurs via the generation of H(2)O(2) and polyphenol-oxidized species generated from the exogenous microenvironment of the cells.
Department of Pharmaceutics, School of Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel.
To determine the stomach bioreactor capability for food oxidation or antioxidation, rats were fed red turkey meat cutlets (meal A) or red turkey meat cutlets and red wine concentrate (meal B). The hydroperoxides (LOOH) and malondialdehyde (MDA) levels of the stomach contents were evaluated during and after digestion; the postprandial plasma MDA level was also evaluated. In independently fed rats, the stomach LOOH concentration fell substantially 90 min following the meal, and the addition of red wine polyphenols enhanced LOOH reduction 3-fold. A similar trend was obtained for MDA. After pyloric ligation, the stomach contents of rats fed red meat homogenate showed >2-fold increases in LOOH and MDA accumulation. The postprandial plasma MDA level increased significantly by 50% following meal A and was maintained or even fell by 34% below basal level following meal B. The findings show that consumption of partially oxidized food could increase lipid peroxidation in the stomach and the absorption of cytotoxic lipid peroxidation products into the body. The addition of antioxidants such as red wine polyphenols to the meal may alter these outcomes. These findings explain the potentially harmful effects of oxidized fats in foods and the important benefit of consuming dietary polyphenols during the meal.
A novel function of red wine polyphenols in humans: prevention of absorption of cytotoxic lipid peroxidation products.
Department of Pharmaceutics, David R. Bloom Center of Pharmacy, School of Pharmacy, the Hebrew University of Jerusalem, Jerusalem, Israel.
Current evidence supports a contribution of polyphenols to the prevention of cardiovascular disease, but their mechanisms of action are not understood. We investigated the impact of red wine polyphenols on postprandial cytotoxic lipid peroxidation products (MDA) levels in humans. In a randomized, crossover study, the effect of red wine polyphenols on postprandial levels of plasma and urine MDA was investigated. Three meals of 250 g turkey cutlets supplemented by water (A); soaked in red wine after heating plus 200 ml of red wine (B); or soaked in red wine prior to heating plus 200 ml of red wine (C) were administered to 10 healthy volunteers. Subject baseline plasma levels of MDA were 50 +/- 20 nM. After a meal of turkey meat cutlets, plasma MDA levels increased by 160 nM (P<0.0001); after (B) there was a 75% reduction in the absorption of MDA (P<0.0001). However, after (C), the elevation of plasma MDA was completely prevented (P<0.0001). Similar results were obtained for MDA accumulation in urine. Our study suggests that red wine polyphenols exert a beneficial effect by the novel new function, absorption inhibition of the lipotoxin MDA. These findings explain the potentially harmful effects of oxidized fats found in foods and the important benefit of dietary polyphenols in the meal.
Lipid peroxidation and coupled vitamin oxidation in simulated and human gastric fluid inhibited by dietary polyphenols: health implications.
Department of Food Science, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
The Western diet contains large quantities of oxidized lipids, because a large proportion of the food in the diet is consumed in a fried, heated, processed, or stored form. We investigated the reaction that could occur in the acidic pH of the stomach and accelerate the generation of lipid hydroperoxides and cooxidation of dietary vitamins. To estimate the oxygen content in the stomach after food consumption, oxygen released from masticated bread (20 g) into deoxygenated water (100 mL) was measured. Under these conditions, the oxygen concentration rose by 250 microM and reached a full oxygen saturation. The present study demonstrated that heated red meat homogenized in human gastric fluid, at pH 3.0, generated hydroperoxides and malondialdehyde. The cross-reaction between free radicals produced during this reaction cooxidized vitamin E, beta-carotene, and vitamin C. Both lipid peroxidation and cooxidation of vitamin E and beta-carotene were inhibited at pH 3.0 by red wine polyphenols. Ascorbic acid (44 mg) at a concentration that represented the amount that could be ingested during a meal inhibited lipid peroxidation only slightly. Red wine polyphenols failed to prevent ascorbic acid oxidation significantly but, in conjunction with ascorbic acid, did inhibit lipid peroxidation. In the presence of catechin, a well-known polyphenol found in red wine, ascorbic acid at pH 3.0 works in a synergistic manner preventing lipid peroxidation and beta-carotene cooxidation. The present data may explain the major benefits to our health and the crucial role of consuming food products rich in dietary antioxidants such as fruits, vegetables, red wines, or green tea during the meal.
Department of Food Science, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
Our recent study demonstrated the potential of gastric fluid at pH 3.0 to accelerate lipid peroxidation and cooxidation of dietary constituents in the stomach medium. Metmyoglobin is known to catalyze the breakdown of lipid hydroperoxides to free radicals, a reaction that could enhance the propagation step and general lipid peroxidation. During this reaction, a part of the free radicals is autoreduced by metmyoglobin. At pH 3.0, metmyoglobin at low concentration was almost 7 x 10(4) times as effective as at pH 7.0 in enhancing the rate of lipid peroxidation. Our study demonstrated that metmyoglobin, at a low concentration (approximately 1:30), as compared with that of the hydroperoxides in the lipid system, worked prooxidatively increasing the amounts of linoleate hydroperoxides. However, at a high concentration (approximately 1:3), metmyoglobin acted antioxidatively and decomposed hydroperoxides, whose concentrations then remained at zero for a long time. Catechin, a known polyphenol, supports the inversion of metmyoglobin catalysis, from prooxidation to antioxidation. The antioxidative activity of the couple metmyoglobin-catechin was better at pH 3.0 than at pH 7.0, indicating that this reaction is more dependent on metmyoglobin than on catechin. During this reaction, catechin or quercetin not only donates reducing equivalents to prevent lipid peroxidation but also prevents the destruction and polymerization of metmyoglobin. The results of this research highlighted the important and possible reactions of heme proteins and polyphenols as couple antioxidants, working as hydroperoxidases or as pseudo-peroxidases. We hypothesize that the occurrence of these reactions in the stomach could have an important impact on our health and might help to better explain the health benefits of including foods rich in polyphenol antioxidants in the meal, especially when consuming red meat.
Lipid peroxidation by "free" iron ions and myoglobin as affected by dietary antioxidants in simulated gastric fluids.
Department of Food Science, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
Grilled red turkey muscle (Doner Kabab) is a real "fast food" containing approximately 200 microM hydroperoxides, homogenized in simulated gastric fluid and oxidized more rapidly at pH 3.0 than at pH 5.0, after 180 min, producing 1200 and 600 microM hydroperoxides, respectively. The effects of "free" iron ions and metmyoglobin, two potential catalyzers of lipid peroxidation in muscle foods, were evaluated for linoleic acid peroxidation at pH 3.0 of simulated gastric fluid. The prooxidant effects of free iron ions on linoleic acid peroxidation in simulated gastric fluid was evaluated in the presence of ascorbic acid. At low concentrations of ascorbic acid, the effects were prooxidative, which was reversed at high concentrations. In the presence of metmyoglobin, ascorbic acid with or without free iron enhanced the antioxidative effect. Lipid peroxidation by an iron-ascorbic acid system was inhibited totally by 250-500 microM catechin at pH 3.0. The catechin antioxidant effect was determined also in the iron-ascorbic acid system containing metmyoglobin. In this system, catechin totally inhibited lipid peroxidation at a concentration 20-fold lower than without metmyoglobin. The ability of catechin to inhibit lipid peroxidation was also determined at a low pH with beta-carotene as a sensitive target molecule for oxidation. The results show that a significant protection was achieved only with almost 100-fold higher antioxidant concentration. Polyphenols from different groups were determined for the antioxidant activity at pH 3.0. The results show a high antioxidant activity of polyphenols with orthodihydroxylated groups at the B ring, unsaturation, and the presence of a 4-oxo group in the heterocyclic ring, as demonstrated by quercetin.
Department of Food Science, ARO Volcani Center, Bet Dagan 50250, Israel.
A number of natural phenolic compounds display antioxidant and cell protective effects in cell culture models, yet in some studies show prooxidant and cytotoxic effects. Pancreatic beta-cells have been reported to exhibit particular sensitivity to oxidative stress, a factor that may contribute to the impaired beta-cell function characteristic of diabetes. The aim of this study was to examine the potential of natural phenolics to protect cultured pancreatic beta-cells (betaTC1 and HIT) from H(2)O(2) oxidative stress. Exposure of cells to H(2)O(2) led to significant proliferation inhibition. Contrary to what one should expect, simultaneous exposure to H(2)O(2) and the phenolics, quercetin (10-100 microM), catechin (50-500 microM), or ascorbic acid (100-1000 microM), led to amplification of proliferation inhibition. At higher concentrations, these compounds inhibited proliferation, even in the absence of added H(2)O(2). This prooxidant effect is attributable to the generation of H(2)O(2) through interaction of the added phenolic compounds with as yet undefined componenets of the culture media. On the other hand, inclusion of metmyoglobin (30 microM) in the culture medium significantly reduced the prooxidant impact of the phenolics. Under these conditions, quercetin and catechin significantly protected the cells against oxidative stress when these components were present during the stress period. Furthermore, significant cell protection was observed upon preincubation of cells with chrysin, quercetin, catechin, or caffeic acid (50 microM, each) prior to application of oxidative stress. It is concluded that provided artifactual prooxidant effects are avoided, preincubation of beta-cells with relatively hydrophobic natural phenolics can confer protection against oxidative stress.
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Am J Public Health. 2012 Aug 16;: 22897596
Ross D. Whitehead and David I. Perrett are with the Perception Lab, School of Psychology, and Gozde Ozakinci is with the School of Medicine, University of St Andrews, Fife, UK. Ian D. Stephen is with the School of Psychology, University of Nottingham, Malaysia Campus, Kuala Lumpur.
We agree that fruit and vegetable consumption is likely to confer health benefits by substituting refined carbohydrates, saturated fats, and other foodstuffs that are unambiguously deleterious to health. We argue, though, that fruit and vegetables convey additional active benefits to human health. While it is true that trials have consistently indicated that the impact of antioxidant supplement intake is null or negative, these studies highlight an overly reductionist approach. There exist important synergistic relationships between antioxidants(1); therefore, high-dose supplementation of a circumscribed subset of phytochemicals is unlikely to be beneficial. Breakdown products of some antioxidants are themselves toxic,(2) and because these antioxidants are readily expended by oxidizing agents when reserves of alternate endogenous antioxidants are low, administering high doses of single antioxidants could inadvertently precipitate oxidative tissue damage. As an example of the synergic relationships that exist, α-tocopherol oxidation toxicity is mitigated by carotenoids.(3)(Am J Public Health. Published online ahead of print August 16, 2012: e1. doi:10.2105/AJPH.2012.300942).
Institute of Food Chemistry, Gottfried Wilhelm Leibniz University, Hannover, Germany. firstname.lastname@example.org
The powerful action of antioxidants in preventing premature lipid oxidation in food suggests that the same compounds, when consumed with the daily diet, could unfold antioxidative/anti-aging effects in the human body. Therefore, it has been hypothesized that antioxidants are helpful in preventing various diseases. More detailed chemical and physiological examination of antioxidants shows, however, that the extrapolation of in vitro data to in vivo behavior may be misleading. Indeed, such a procedure fails to take into account the mismatch between most in vitro models (e.g., cell cultures) and in vivo systems. For example, the physiological relevance of pro-oxidative and other physiological activities of antioxidants have been largely underestimated. Actually, contrary to the antioxidant hypothesis, clinical trials testing the health benefits of dietary antioxidants have reported rather mixed or negative results. Many clinical studies have not taken into account the nutrikinetic and nutridynamic nature of antioxidants. Further, oxidative stress is not only an inevitable event in a healthy human cell, but responsible for the functioning of vital metabolic processes, such as insulin signaling and erythropoietin production. In the light of recent physiological studies it appears more advisable to maintain the delicate redox balance of the cell than to interfere with the antioxidant homeostasis by a non-physiological, excessive exogenous supply of antioxidants in healthy humans.
National Institute of Food Science and Technology, University of Agriculture, Faisalabad, Pakistan. email@example.com
Coinage of terms like nutraceuticals, functional, and pharma foods has diverted the attention of human beings to where they are seeking more natural cures. Though pharmaceutical drugs have been beneficial for human health and have cured various diseases but they also impart some side effects. Numerous plants have been tested for their therapeutic potential; Nigella sativa, commonly known as black cumin, is one of them. It possesses a nutritional dense profile as its fixed oil (lipid fraction), is rich in unsaturated fatty acids while essential oil contains thymoquinone and carvacrol as antioxidants. N. sativa seeds also contain proteins, alkaloids (nigellicines and nigelledine), and saponins (alpha-hederin) in substantial amounts. Recent pharmacological investigations suggested its potential role, especially for the amelioration of oxidative stress through free radical scavenging activity, the induction of apoptosis to cure various cancer lines, the reduction of blood glucose, and the prevention of complications from diabetes. It regulates hematological and serological aspects and can be effective in dyslipidemia and respiratory disorders. Moreover, its immunopotentiating and immunomodulating role brings balance in the immune system. Evidence is available supporting the utilization of Nigella sativa and its bioactive components in a daily diet for health improvement. This review is intended to focus on the composition of Nigella sativa and to elaborate its possible therapeutic roles as a functional food to prevent an array of maladies.
Institute of Chemical Engineering, Biotechnology and Environmental Technology, Faculty of Engineering, University of Southern Denmark, DK-5230 Odense M, Denmark. firstname.lastname@example.org
Galactolipids are a class of compounds widely found in the plant kingdom, including edible plants, and are an important part of the cell membranes. Galactolipids in plants consists mainly of monogalactosyldiacylglycerols and digalactosyldiacylglycerols containing one or two saturated and/or unsaturated fatty acids linked to the glycerol moiety. Several galactolipids have been shown to possess in vitro and/or in vivo anti-tumor promoting activity and anti-inflammatory activity. Recently, it has been demonstrated that the galactolipid, 1,2-di-O-alpha-linolenoyl-3-O-beta-D-galactopyranosyl-sn-glycerol (1), may be important for the anti-inflammatory activity of dog rose (Rosa canina), a medicinal plant with documented effect on anti-inflammatory diseases such as arthritis. This galactolipid also occurs in relative high concentrations in certain legumes (e.g., common bean, pea), leaf vegetables (e.g., kale, leek, parsley, perilla and spinach), stem vegetables (e.g., asparagus, broccoli, brussels sprouts), and fruit vegetables (e.g., chilli, bell pepper, pumpkin). Furthermore, compound 1 has been isolated from spinach and several medicinal plants by bioassay-guided fractionation as a galactolipid with possible cancer preventive effects. In this review, the bioactivity of galactolipids is discussed and their potential role in human diet as important nutraceuticals. Moreover, recent patents on the bioactivity of specific galactolipids and inventions making use of this knowledge are presented and discussed.
Department of Biochemistry, Memorial University of Newfoundland, St.John's, NL, Canada A1B 3X9.
Lipids are a major component of food and important structural and functional constituents of cells in biological systems. However, this diverse group of substances is prone to oxidation through various pathways. Their oxidative stability depends on a number of intrinsic and extrinsic factors, including the unsaturation of their fatty acids, composition of minor components, environment conditions, delivery techniques and use of antioxidants, among others. Lipid oxidation has detrimental effects on both food quality and human health, and efforts must be made to minimize oxidation and improve oxidative stability of lipid products. Antioxidant strategy has been successfully employed in the food industry for quality preservation of the food products and in the medicinal industry for risk reduction of numerous oxidative stress-mediated diseases. This tutorial review will provide important knowledge about lipid oxidation, including the mechanism and factors involved in oxidation, as well as strategies for improving oxidative stability of lipids.
Eur J Clin Nutr. 2010 Feb 24;: 20179727
The effect of dietary phytosphingosine on cholesterol levels and insulin sensitivity in subjects with the metabolic syndrome.
Department of General Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands.
Background:Sphingolipids, like phytosphingosine (PS) are part of cellular membranes of yeasts, vegetables and fruits. Addition of PS to the diet decreases serum cholesterol and free fatty acid (FFA) levels in rodents and improves insulin sensitivity.Objective:To study the effect of dietary supplementation with PS on cholesterol and glucose metabolism in humans.Methods:Twelve men with the metabolic syndrome (MetS)(according to the International Diabetes Federation (IDF) criteria; age 51+/-2 years (mean+/-s.e.m.); body mass index (BMI) 32+/-1 kg/m(2)) were randomly assigned to 4 weeks of PS (500 mg twice daily) and 4 weeks of placebo (P) in a double-blind cross-over study, with a 4-week wash-out period between both interventions. At the end of each intervention anthropometric measures and serum lipids were measured and an intravenous glucose tolerance test (IVGTT) was performed.Results:Phytosphingosine did not affect body weight and fat mass compared with P. PS decreased serum total cholesterol (5.1+/-0.3 (PS) vs 5.4+/-0.3 (P) mmol/l; P<0.05) and low-density lipoprotein (LDL)-cholesterol levels (3.1+/-0.3 (PS) vs 3.4+/-0.3 (P) mmol/l; P<0.05), whereas it did not alter serum triglyceride and high-density lipoprotein (HDL)-cholesterol levels. In addition, PS lowered fasting plasma glucose levels (6.2+/-0.3 (PS) vs 6.5+/-0.3 (P) mmol/l; P<0.05). PS increased the glucose disappearance rate (K-value) by 9.9% during the IVGTT (0.91+/-0.06 (PS) vs 0.82+/-0.05 (P)%/min; P<0.05) at similar insulin levels, compared with P, thus implying enhanced insulin sensitivity. PS induced only minor gastrointestinal side effects.Conclusion:Dietary supplementation of PS decreases plasma cholesterol levels and enhances insulin sensitivity in men with the MetS.European Journal of Clinical Nutrition advance online publication, 24 February 2010; doi:10.1038/ejcn.2009.154.
J Agric Food Chem. 2010 Feb 24;: 20178390
Department of Nutritional Sciences, Faculty of Medicine, FitzGerald Building, University of Toronto, 150 College Street, Toronto, Ontario, Canada M5S 3E2.
Dietary guidelines around the world recommend the increased consumption of fruits and vegetables as good sources of antioxidant phytochemicals for the prevention of chronic diseases. Red raspberries are a common and important fruit in the Western diet due to their content of essential nutrients and beneficial phytochemicals. Anthocyanins and ellagitannins are polyphenolic compounds and the major antioxidant phytochemicals present in raspberries. Whereas individual phytochemical constituents of raspberries have been studied for their biological activities, human intervention studies using whole berries are lacking in the literature. The nutritional and phytochemical compositions of red raspberries and their absorption, metabolism, and biological activity are reviewed. Finally, future directions of research are also identified.
Department of Medical Biochemistry, Medical University of Białystok, Białystok, Poland. email@example.com
Wharton's jelly is a myxomatous substance which surrounds the umbilical cord vessels protecting them against extension, bending, twisting and compression. Very low number of cells in this tissue produce high amounts of extracellular matrix; collagen, hyaluronate and proteoglycans which bind large quantities of peptide growth factors (PGFs). Preeclampsia (the most common pregnancy-associated syndrome) is accompanied by a significant reduction in hyaluronate and a concomitant increase in sulphated glycosaminoglycans/proteoglycans content in Wharton's jelly. Such a phenomenon corresponds to an 'early ageing' of this tissue. We have evaluated the lipid composition of Wharton's jelly and its alteration in preeclampsia. Thin layer chromatography and high-performance liquid chromatography were employed. It was found that Wharton's jelly contains free fatty acids (FFA), mono-, di- and triacylglycerols, free cholesterol and its esters. The characteristic feature is the presence of relatively high amounts of unsaturated fatty acids, including those (C18:2 and C18:3) which are nutritionally essential. Preeclampsia is associated with a slight increase in the total fatty acid content in Wharton's jelly and with marked changes in the proportional relationships between various lipids. A distinct decrease in the amounts of FFA was observed with a concomitant increase in monoacylglycerols and cholesterol esters. At least in some cases the effects exerted by PGFs are mediated by the lipid second messengers. Thus it is possible that alterations in lipid compounds of Wharton's jelly may participate in the deregulation of various cell functions, including overproduction of sulphated glycosaminoglycans or down-regulation of enzymes which participate in their degradation.
Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study.
Tommy Jonsson, Yvonne Granfeldt, Bo Ahren, Ulla-Carin Branell, Gunvor Palsson, Anita Hansson, Margareta Soderstrom, Staffan Lindeberg
ABSTRACT: BACKGROUND: Our aim was to compare the effects of a Paleolithic ('Old Stone Age') diet and a diabetes diet as generally recommended on risk factors for cardiovascular disease in patients with type 2 diabetes not treated with insulin. METHODS: In a randomized cross-over study, 13 patients with type 2 diabetes, 3 women and 10 men, were instructed to eat a Paleolithic diet based on lean meat, fish, fruits, vegetables, root vegetables, eggs and nuts; and a Diabetes diet designed in accordance with dietary guidelines during two consecutive 3-month periods. Outcome variables included changes in weight, waist circumference, serum lipids, C-reactive protein, blood pressure, glycated haemoglobin (HbA1c), and areas under the curve for plasma glucose and plasma insulin in the 75g oral glucose tolerance test. Dietary intake was evaluated by use of 4-day weighed food records. RESULTS: Study participants had on average a diabetes duration of 9 years, a mean HbA1c of 6,6 % units by Mono-S standard and were usually treated with metformin alone (3 subjects) or metformin in combination with a sulfonylurea (3 subjects) or a thiazolidinedione (3 subjects). Mean average dose of metformin was 1031 mg per day. Compared to the diabetes diet, the Paleolithic diet resulted in lower mean values of HbA1c (-0.4% units, p=0.01), triacylglycerol (-0.4 mmol/L, p=0.003), diastolic blood pressure (-4 mmHg, p=0.03), weight (-3 kg, p=0.01), BMI (-1 kg/m2, p=0.04) and waist circumference (-4 cm, p=0.02), and higher mean values of high density lipoprotein cholesterol (+0.08 mmol/L, p=0.03). The Paleolithic diet was mainly lower in cereals and dairy products, and higher in fruits, vegetables, meat and eggs, as compared with the Diabetes diet. Further, the Paleolithic diet was lower in total energy, energy density, carbohydrate, dietary glycemic load, saturated fatty acids and calcium, and higher in unsaturated fatty acids, dietary cholesterol and several vitamins. Dietary GI was slightly lower in the Paleolithic diet (GI=50) than in the Diabetic diet (GI=55). CONCLUSIONS: Over a 3-month study period, a Paleolithic diet improved glycemic control and several cardiovascular risk factors compared to a Diabetes diet in patients with type 2 diabetes. Trial registration ClinicalTrials.gov NCT00435240.
J Dairy Sci. 2009 Jul ;92 (7):3040-8 19528581
Odor compounds in cheese made from the milk of cows supplemented with extruded linseed and alpha-tocopherol.
UR370 Qualité des Produits Animaux, Institut National de la Recherche Agronomique, Theix, F63122 Saint-Genès Champanelle, France.
Three diets for cows were used to evaluate the effect of extruded linseed (EL) or extruded linseed plus alpha-tocopherol (ELVE) supplementation of a maize silage diet (CO) on the odor-active compounds of Saint-Nectaire cheese. Cheese odor and flavor profiles were studied by sensory analysis. The volatile compounds were extracted by purge and trap and separated by gas chromatography. The odor compounds were detected and identified using an 8-way olfactometric device and a mass spectrometer. Twenty-nine volatile compounds were considered as contributing to the odor of Saint-Nectaire cheese. Half the compounds identified were known to be lipid degradation products but not all of them were affected by the diet. Among the markers of unsaturated fatty acid degradation, hexanal was not affected, whereas heptanal was increased more by the ELVE diet (6 times) than by the EL (3 times) diet. The ELVE diet led to cheeses with butanoic acid and heptanal odor peaks that were, respectively, 2 and 6 times higher than with the CO diet, which explained the lower milk odor and flavor scores obtained by sensory analysis on ELVE cheese. Although the cheese-making date had a greater effect than the diet on the aromatic profiles of the cheese, principal component analysis showed that the differences between cheeses obtained on the 3 diets were repeatable. The EL diet successfully enhanced cheese nutritional value without noticeably changing its flavor. alpha-Tocopherol supplementation was found to be unnecessary, as no oxidized odor was found.