Article

Effects of Repeated Heating of Cooking Oils on Antioxidant Content and Endothelial Function

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Abstract

Reusing cooking oil in food preparation, especially during deep-frying, is a common practice to save costs. Repeated heating of the oil accelerates oxidative degradation of lipids, forming hazardous reactive oxygen species and depleting the natural antioxidant contents of the cooking oil. Long-term ingestion of foods prepared using reheated oil could severely compromise one’s antioxidant defense network, leading to pathologies such as hypertension, diabetes and vascular inflammation. The detrimental effects of reheated oil consumption extend beyond mere oxidative assault to cellular antioxidant shield. In this review, we have examined the experimental and clinical effects related to the intake of reheated oil on antioxidant contents, membrane lipid peroxidation and endothelial function. Understanding the mechanisms underlying the pathology associated with intake of repeatedly heated oil will help to set a reference for assessing the safety of cooking oil. Finally, considering the potential hazard of repeatedly heating oil, this article aims to further increase awareness of the general public regarding the health risks associated with these oils.

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... Furthermore, during frying, the heated oil undergoes deterioration due to various chemical reactions like thermal oxidation, and thermally-oxidized oil induced oxidative stress [18]. Studies that examined the relationship of oxidative stress and endothelial dysfunction reported that oxidative stress was involved in the pathogenesis of endothelial dysfunction, one of the biological mechanisms responsible for the development of hypertension [19][20][21][22]. ...
... During frying, heated oil undergoes deterioration due to the exposure of oil to high temperatures in the presence of air and moisture [35,36]. Thermally-oxidized oil generates free radicals which in turn react with nitric oxide (NO), causing activation of peroxynitrite, which propagates the chain of lipid peroxidation [18,21,37] . Also, it has been reported that hypertensive individuals have high levels of malondialdehyde (MDA), a breakdown product of lipid peroxidation and a known marker of oxidative stress [18,38]. ...
... In this study, we found high prevalence of hypertension with deep and shallow fried food, but not with pan and stir fried food. When oil is exposed to deep-frying temperature, it leads to a series of physicochemical changes such as production of volatile and non-volatile compounds, which affect the properties of oil and fried food [21,35,40]. Also, deep-frying generates toxic compounds such as hydroperoxides, aldehydes, and other free radicals. ...
Article
Background/objectives: Few epidemiological studies examined the association between fried food intake and hypertension. This study examined whether fried food intake was associated with higher prevalence of prehypertension and hypertension combined in a cross-sectional study of the Filipino Women's Diet and Health Study (FiLWHEL). Subjects/methods: This study included a total of 428 women aged 20-57 years who have ever been married to Korean men. Prehypertension was defined as 120 - < 140 mmHg of SBP or 80 - < 90 mmHg of DBP and hypertension as SBP ≥ 140 mmHg or DBP ≥ 90 mmHg. Fried food intake was assessed using one-day 24-hour recall. Fried foods were categorized into total, deep/shallow and pan/stir fried foods. The odds ratio (OR)s and 95% confidence interval (CI)s were calculated using multivariate logistic regression. Results: The prevalence of prehypertension and hypertension combined was 41.36% in this population. High fried food intake was associated with high prevalence of prehypertension and hypertension combined. The odds of having prehypertension and hypertension was higher in the 3rd tertile of fried food intake among fried food consumers compared to non-fried food consumers (OR = 2.46, 95% CI = 1.24, 4.87; P for trend = 0.004). Separate analysis for types of frying showed that deep and shallow fried food intake was associated with prevalence of prehypertension and hypertension combined for comparing the 3rd tertile vs. non-fried food consumers (OR = 2.93; 95% CI = 1.57-5.47; P for trend = < 0.001). Conclusions: This study showed the evidence that high fried food intake was significantly associated with high prevalence of prehypertension and hypertension combined among Filipino women married to Korean men.
... Two or more vegetable oils are mixed at different proportion to get blended oils for different nutritional and processing purpose [3]. Vegetable oils are the healthier choice relative to animal fats in view of their fatty acid contents and cholesterol-free nature [4]. Studies on edible oils remain one of the prime areas of research, and nowadays people are much health-conscious. ...
... Oxidation of long chain fatty acids causes neuromyopathic disease both in infant and adults [15,25]. Consumption of lipids containing excessive free radicals may cause alterations in the redox state of human body, leading to lipid peroxidation [4]. Unstable free radicals tend to stabilize themselves by abstracting electrons from membrane lipids to start a self-propagating chain reaction causing structural rearrangement of the lipids. ...
... The rate of bond cleavage increases until the molecule gets stabilized. Oxidative damage to lipid structures eventually leads to disorganization and dysfunction of, as well as damage to membranes, enzymes and proteins [4,26]. ...
... These intermediates are rapidly broken down into reactive free radicals. All these chemical changes reduce the quality, texture and nutritional value of cooking oils (6,7). Therefore, quantitative data are required to assess the effects of heating and repeated heating of different edible oils on humanhealth. ...
... Therefore, natural antioxidants in oils can affect the ultimate quality and nutritional value of oils. However, antioxidants are highly heat-labile: hence, destruction of antioxidants during heating is unavoidable (6). The resistance and stability of antioxidants in different cooking oils to thermal oxidation are highly variable (9). ...
... The formation of phenolic compounds with repeated heating, which does not possess antioxidant capacities, could be the reason for this outcome. Further, it is proven that there is a significantly high formation of free radicals and oxidants in oils with repeated heating (6). ...
... Two or more vegetable oils are mixed at different proportion to get blended oils for different nutritional and processing purpose [3]. Vegetable oils are the healthier choice relative to animal fats in view of their fatty acid contents and cholesterol-free nature [4]. Studies on edible oils remain one of the prime areas of research, and nowadays people are much health-conscious. ...
... Oxidation of long chain fatty acids causes neuromyopathic disease both in infant and adults [15,25]. Consumption of lipids containing excessive free radicals may cause alterations in the redox state of human body, leading to lipid peroxidation [4]. Unstable free radicals tend to stabilize themselves by abstracting electrons from membrane lipids to start a self-propagating chain reaction causing structural rearrangement of the lipids. ...
... The rate of bond cleavage increases until the molecule gets stabilized. Oxidative damage to lipid structures eventually leads to disorganization and dysfunction of, as well as damage to membranes, enzymes and proteins [4,26]. ...
Chapter
Edible plant oils play a vital role in daily diets of people worldwide. Stability against oxidation is the major factor limiting the application of most edible plant oils for cooking and processing. Most native plant oils vary greatly in their stability to oxidation depending on their composition. Oxidative stability of edible plant oils has been extensively studied to find out the ways of improving their stability against oxidation to widen their application. Synthetic antioxidants are effective to improve the oxidative stability of these oils, however, recently, following the evidences on possible toxicities of synthetic antioxidants, the use of natural plant sources as antioxidant is gaining interest. In addition, modification of composition of the oils through genetic modification is another successful means to improve the oxidative stability of these oils. This chapter focuses on the mechanism and factors of oxidation and ways of improving oxidative stability of oils.
... RCO consumption has been validated to be detrimental to health by numerous studies. The practice of RCO has been linked to causing genotoxic, mutagenic and carcinogenic potentials, along with, promoting increased blood pressure (Ganesan et al., 2019;Leong, Ng, Jaarin & Mustafa, 2015;Perumalla & Subramanyam, 2016). According to Aziz, Elias, and Sabran (2018), and Kalogianni et al. (2016), it is a common practice among Malaysian food operators to reheat cooking oil and to fry food repeatedly using the same oil for several days. ...
... Reheated cooking oil (RCO) refers to the practice of reusing cooking oil in multiple frying sessions (Leong et al., 2015). Cooking oil primarily serves as the medium of heat exchange; however; as much as 45% of oil ends up in the final fried product (Orthoefer & List, 2007). ...
... Frying of food should not be heated above 180℃, for any longer than 24 hours of continuous heating (Chen, Chiu, Cheng, Hsu, & Kuo, 2013). When cooking oil is reheated excessively, the chemical reactions enhance, causing rapid degradation to the cooking oil both chemically and physically (Leong et al., 2015). ...
... Consumption of foods fried with reheated oil in production for the long term can affect human health. The content of free fatty acids and the occurrence of free radicals can cause pathological disorders such as hypertension, diabetes and vascular inflammation [15]. ...
... The process of hydrolysis of vegetable oil is increased due to the increase in temperature and with the presence of water in fat. [15], [16]. Table 4 shows the result of the statistical test (P> 0,05) that indicate that free fatty acid oil in fried chicken processing is significantly different with fresh oil. ...
... Many studies have shown that using cooking oil repeatedly results in production of hazardous radicals such as peroxides and polar compounds (Murwani, unpublished data) [14]. Long-term consumption of foods prepared using reheated oil could severely hamper the antioxidant defence network, leading to pathologies such as hypertension, diabetes, and vascular inflammation [13,15,16]. ...
... This activity was further reduced in RO peanuts (16.92% reduction). The reduction in antioxidant activity could be because of the partial loss of antioxidant compounds in the heated cooking oil [16,27]. The reduction in antioxidant activity of FO peanut or RO peanuts was compensated after they were processed into peanut sauce, with their antioxidant activity increasing significantly (34.65% to 48.07% and 27.53% to 34.77%, respectively). ...
Article
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Vegetables are essential in our diet to maintain health, partly due to their antioxidant properties. A well-known Javanese salad called “Pecel” is prepared by boiling the vegetables and dressed with seasoned peanut sauce. Cooking can reduce or improve the antioxidant properties of foods; therefore, the purpose of this study was to evaluate the effects of brief water boiling (1 min), steaming (1 min), and water blanching (20 s) of the Javanese Pecel vegetables, with or without the peanut sauce. We assessed the in vitro antioxidant capacity and lipid peroxidation inhibition of the salad samples prepared using each cooking method. Six vegetables, i.e., Sesbania grandiflora (turi) flower, Amaranthus hybridus L. (spinach), Carica papaya (papaya) leaves, Cosmos caudatus L. (kenikir) leaves, Vigna unguiculata ssp. Sesquipedalis (yard-long beans), and Vigna radiata (mung-bean) sprouts were cooked by boiling or steaming for 1 min or blanching for 20 s. Peanut (Arachis hypogaea), the raw material for peanut sauce, was fried in either fresh palm oil or repeatedly used palm oil. Our results revealed that the highest antioxidant capacity (percent inhibition of DPPH radicals) was observed following boiling for 1 min in case of spinach (41.94±9.8%), papaya (59.04±5.35%), kenikir (54.93%±6.32%), and yard-long beans (70.21±8.91%); steaming for 1 min in case of turi flower (60.25±3.63%); and blanching for 20 s in case of mung-bean sprouts (49.27±3.69%). Peanut sauce prepared by frying peanuts in fresh or repeatedly used palm oil reduces the natural antioxidant and lipid peroxidation inhibition properties. However, seasoning the peanut sauce with fresh garlic and lime leaves can restore the lost antioxidant properties. Our study provides the first and clear evidence of the optimal cooking method for Pecel vegetables and sheds light on the wisdom behind the existing traditional cooking method.
... During repeated conventional heating, the degradation of triglycerides and the formation of fatty acids were observed by increased acid values (Halim et al., 2016;Adejumo et al., 2015). With microwave heating, the amount of fatty acids increased (Taghvaei et al., 2014) and then these fatty acids degraded to hydro peroxides which were further converted to secondary oxidation products and lower acid values (Leong et al., 2015). The acid values for corn oil showed greater degradation with microwave radiation exposure compared to soybean oil, which confirmed the oxidative stability of soybean oil (Adejumo et al., 2015). ...
... This fact led to the representation of rancidity of oil in terms of the p-anisidine value (p-AV) and total oxidation value (TOTOX value). The p-anisidine value of edible oil samples determines the amount of hydro peroxides as well as the aldehydic and ketonic forms of products (Leong et al., 2015). During conventional heating, p-anisidine values were increased by 31.53% and 24.83% for corn oil and soybean oil, respectively. ...
Article
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The effects of conventional and microwave heating on the oxidative properties of corn and soybean oil were evaluated. The results showed that acid value, peroxide value, oxidative indices, total oxidation value, and p-anisidine values changed significantly with the rise in temperature (p < 0.05). The peroxide and p-anisidine values for corn oil (PV: 50.670 meqO2/kg, p-AV: 8.248) were greater than soybean oil (PV: 41.694 meqO2/kg, p-AV: 7.566) for conventional heating. The peroxide and p-anisidine values for soybean oil (PV: 6.545 meqO2/kg, p-AV: 76.539) were greater compared to corn oil (PV: 5.074 meqO2/kg, p-AV: 65.360) for microwave heating. The results concluded that microwave heating had a greater impact on the chemical degradation of the fatty acids of the oil. The FT-IR spectra showed peak changes at 3743 cm-1 and 1739 cm-1 and confirmed the rancidity of the oils from microwave heating due to the formation of secondary oxidation products. It was concluded that corn oil showed more oxidative changes compared to soybean oil.
... Consequently, the activated molecules break down the esterified bond of triacylglycerides to generate glycerol, free fatty acids monocyglyceride and diacyglycerides. Simultaneously, high temperature persuades polymerization of hydrolysis product and form high molecular weight cyclic fatty acid monomer and diamer (Leong et al., 2015). ...
... Vitamin E, tocotrienols isomers and tocopherols are the major antioxidants in cooking oil. The constancy of vitamin E isomers differs during heating because it is determined by the type of cooking oil and the content of vitamin E (Leong et al., 2015). Thus, the effect of heating on the total antioxidant content of the three oil Figure 3. ...
Article
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Deep frying is the process of immersing food in hot oil at a temperature of approximately 180°C. During deep frying, different chemical reactions are taking place, resulting in changes in the physicochemical properties of the frying oil, eventually leading to harmful health effects on the consumers. Nevertheless, based on economic feasibility, both the domestic and industrial levels tend to repeatedly use edible oils for deep frying. Thus, the current study aimed to evaluate physicochemical and nutritional parameters of commercially available coconut oil, palm oil and sunflower oil and to investigate the effect of repeated deep frying for the physicochemical and nutritional parameters of the studied oil samples. Thereby, the optimum number of frying cycles for each type of oil was also investigated. In order to achieve that, using coconut, palm and sunflower oils, potato and fish were fried separately for five repeated frying cycles. As per the results, regardless of the frying material, the relative density, colour, peroxide value, free fatty acid value of coconut oil, palm oil, and sunflower oil were increased significantly with increase the number of frying cycles whereas the smoke point and moisture content was found to be significantly decreased. In contrast, the number of cycles suitable for repeated frying is varying upon the frying material. Accordingly, coconut oil has proven to be used for three frying cycles of potato and five frying cycles of fish: palm oil for one frying of potato and two fryings of fish without adversely altering their physicochemical and nutritional properties. Conferring to the obtained results, the use of unsaturated oil like sunflower oil on repeated frying is not recommended.
... Frying is one of the most popular culinary operations practiced in both industrial and domestic food preparation procedures which develop unique sensory characteristics in the food (Leong et al., 2015). During repeated frying, oil undergoes a series of reactions namely hydrolysis, autoxidation, thermal oxidation, isomerisation, and polymerization (Abiona et al., 2011). ...
Article
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The effect of extracts of pomegranate (Punica granatum L.) peel, rosemary and oregano on the oxidative stability of Coconut Oil (CO), Virgin Coconut Oil (VCO), Palm oil (PO), Sunflower Oil (SO) and Sesame Oil (SSO) during deep frying (170 ± 5 °C/10 min) was determined. These five locally available edible oils were used for frying standard size potato strips in the presence of three different antioixdative extracts namely, pomegranate pee, oregano and rosemary extracts at 2% (w/w) level. A sample of oil used for frying (10 mL) was collected into a glass vial, flushed with nitrogen and stored at -18°C until analysis. Frying was repeated twice more with the same oil. Oil devoid of any extract was used as the control. The samples were analysed for peroxide value (PV) and thiobarbituric acid reactive substances (TBARS). Results revealed that both PV and TBARS values gradually increased with the frying cycle across all oil systems tested indicating a gradual rise of oxidation of oils with use. The order of oxidative stability of oils followed the order: SO< SSO< PO< CO< VCO. A significant (p<0.05) inhibition of oxidation was observed in all oil systems tested as a result of the plant extracts incorporated into oils during deep frying. The least resistance against oxidation was observed in SSO which is predominantly rich in unsaturated fatty acids while VCO exhibited the highest level of resistance. Results further revealed that the pomegranate peel powder exerted the strongest antioxidant activity compared to that of the oregano and rosemary extracts.
... In the food industry, the chemical structures of cooking oil change after repeated heating (e.g., deep frying) likely due to increases in saturated fatty acids [3,4]. Prior studies [5,6] have also indicated that oil when rotational Brownian motion is dominant. According to the Stokes-Einstein-Debye relation [37], the diffusivity of rotational Brownian motion is inversely proportional to the cubic bead diameter. ...
Article
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Viscosity is an important property of liquids. A viscosity change of aqueous substances that deviates from their normal levels usually implies a compromise in quality due to degradation or microorganism proliferation. Monitoring of macro-scale viscosity can be simply realized by various conventional tools, such as rotational viscometers, capillary tubes, falling bodies, and so forth. Nevertheless, today, micro-volume viscosity measurement remains a challenging endeavor, resulting in rare, expensive, or difficult-to-obtain samples not very well studied. For this reason, a novel technique for micro-viscosity based on rotational Brownian motion is presented in this paper. Janus microbeads were made by coating fluorescent polystyrene beads with gold film. Taking advantage of the bead configuration of half gold/half fluorescence, the rotational Brownian signal was expressed in terms of blinking fluorescent intensity. The characteristic correlation time was derived from the blinking intensity of trace amounts of a selected medium over a certain time period, and results were correlated with viscosity. Given a volume of only 2 μL for each measurement, calibration of a series of glycerol–water mixtures (100%–1% (v/v) water content) yielded good agreement with the expected viscosity predictions over the range of 0.8–574.8 cP. Five common oil products, including lubricant oil, baby oil, food oil, olive oil, and motor oil, were further investigated to demonstrate the feasibility and practicability of the proposed technique. Data measured by the rotational Brownian motion-based diffusometer were comparable with those measured by a commercial rotational viscometer. The method also explicitly showed viscosity degradation after the oils were heated at a high temperature of over 100 °C for 10 min. Evaluation proved the proposed Janus microbead-enabled rotational diffusometric technique to be a promising approach for rapid and micro-scale viscosity measurement.
... 34 Vitamin E banyak terdapat pada telur, ikan, udang, dan minyak. Hubungan pengaruh yang lemah antara asupan vitamin E terhadap fungsi paru diduga karena pada saat proses pengolahan makanan sumber vitamin E tersebut diolah dengan suhu tinggi secara berulang-ulang, hal tersebut akan mengurangi konsentrasi kandungan vitamin E dan mengubah bentuk asam lemaknya, sehingga akan mengurangi efek antioksidan dari vitamin E. 35,36,37 ...
Article
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Asap rokok merupakan salah satu sumber radikal bebas eksogen yang dapat menyebabkan kerusakan sel yang mengakibatkan penurunan fungsi paru. Vitamin C dan E merupakan antioksidan yang dapat menghambat aktivitas senyawa oksidan. Tujuan dari penelitian ini adalah mengetahui perbedaan kondisi fungsi paru, asupan vitamin C, asupan vitamin E pada perokok aktif dan non perokok, serta pengaruh asupan vitamin C dan E terhadap kondisi fungsi paru. Desain penelitian yang digunakan adalah cross sectional. Variabel yang diukur meliputi asupan vitamin C dan E dengan Semi Quantitative-Food Frequency Questionnaire (SQ-FFQ) serta kondisi fungsi paru dengan handheld spirometer. Sampel penelitian ini terdiri dari 63 sampel perokok dan 63 sampel non perokok. Hasil uji menunjukkan fungsi paru dan asupan vitamin C berbeda signifikan (p=0,00), sedangkan asupan vitamin E (p=0,29) tidak berbeda signifikan antara perokok aktif dan non perokok. Hasil analisis menunjukkan adanya pengaruh asupan vitamin C (p=0,00; r=0,63) dan vitamin E (p=0,015; r=0,22) terhadap kondisi fungsi paru. Terdapat perbedaan asupan vitamin C dan fungsi paru pada perokok dan non perokok, serta adanya pengaruh asupan vitamin C dan E terhadap fungsi paru.
... The study recorded higher blood pressure and ACE activity as the plasma NO and HO-1 decreased. NO, an endothelium-derived relaxing factor is involved in the regulation of homeostasis of the vascular system to maintain its integrity [Leong et al., 2015]. A reduction in the level of NO compromises the integrity of the vascular system. ...
Article
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Cooking oils are an integral part of a human diet as they are used in almost all types of culinary practices. They serve as sources of lipids with a significant nutritive value and health benefits which can be attributed to their fatty acid compositions and biological antioxidants. However, cooking oils are usually subjected to thermal oxidation which occurs when fresh cooking oil is heated at high temperatures during various food preparations. Repeated use of cooking oils in the commercial food industry is also common to maximize profit. Thermal oxidation of edible oils had since attracted great attention of nutritionist and researchers given the deteriorative effect such as generation of very cytotoxic compounds, loss of carotenoid, phenolics and vitamins thus reducing the overall antioxidant properties of the oils. Furthermore, several
... Ketika terjadi pemanasan berulang pada minyak, terjadi perubahan fisik dari minyak termasuk peningkatan kekentalan dan warna menjadi lebih gelap, yang juga merubah komposisi asam lemak pada minyak.Pemanasan juga mengakibatkan reaksi kimia seperti oksidasi, hidrolisis dan polimerasi yang menghasilkan beberapa produk oksidatif (Jaarin and Kamisah, 2012 (Leong et al, 2015). ...
Article
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p> Fast food consumption including used of repeated heating-oil, causing various of health problems, especially the formation of free radicals characterized by elevated MDA levels. Pomegranates have many therapeutic functions, especially as antioxidants that scavenges free radical of oxidative stress thus improving the quality of spermatozoa. The aim of this study was to see the effect of pomegranate juice to reduce oxidative stress and improve sperm motility. This study used 24 rats divided into 4 groups, namely KN, KP, JD1 and JD2. The mean MDA content (nmol / ml) in KN, KP, JD1 and JD2 was 23.35; 8,53; 12.15; and 12,83 followed by Kruskal-Wallis test obtained p value 0,021 (p <0,05). The quality of spermatozoa includes the motility of spermatozoa which distinguished 4 criteria: fast moving spermatozoa and straight forward (criteria 1), spermatozoa move slowly / difficult to go straight (criteria 2), street spermatozoa (criteria 3) and immobile spermatozoa (criteria 4). Mean percentage (%) number of spermatozoa criteria 1 on KN, KP, JD1, and JD2 among others 41,6; 18.2; 38; and 62.2. Mean percentage (%) number of spermatozoa criteria 2 on KN, KP, JD1, and JD2 among others 4,4; 21.8; 15.6 and 14.2. Mean of percentage (%) motility of spermatozoa criteria 3 on KN, KP, JD1, and JD2 among others 10.6; 24.8; 11.2 and 15.2, while for criteria 4 is 21.8; 37.2; 40.4; and 13.8. Statistical test for sperm motility using ANOVA one way, on criteria 1, 2, 3 and 4 each got p value 0,000; 0.010; 0,000; and 0.000, which means the administration of pomegranate juice shows the effect on the motility of spermatozoa. </p
... Study postulated that the termal oxidation of heated oil together with destruction of vitamin E 7 were the attributed factors for heated oilinduced of CVD. Thermal oxidation and antioxidant deficiency generate free radicals that might cause vascular inflammation 8,9 that predisposed to vascular dysfunction leading to both hypertension and athrosclerosis. ADD-X is a plant crude extracts prepared from the Rutaceae family rich in polyphenols. ...
Article
Palm oil is chief vegetable oil usually consumed worldwide. The consumption of repeatedly heated palm oil produces detrimental effect that attributes to the development of cardiovascular diseases. This study was aimed to determine the effects of ADD-X and repeatedly heated palm oil mixed with 2% cholesterol diet on cardiac, inflammatory biomarkers and histogical changes in ovarectmized rats. Based on the administration of food, animals were divided into 7 groups with 6 rats each. All groups of the animals were ovariectomized except sham after anesthetized. The study was conducted for 6 months. Group I-Sham control fed with Normal rat chow (Sham); Group II-fed with Normal rat chow [Ovx (n)]; Group III-fed with 2% cholesterol chow [Ovx (c)]; Group IV-fed with 2% cholesterol chow mixed with five times heated palm oil (5HPO); Group V-fed with 2% cholesterol chow mixed with five times heated palm oil and ADD-X extract (5HPO-X); Group VI-fed with 2% cholesterol chow mixed with ten times heated palm oil (10HPO); Group VII fed with 2% cholesterol chow mixed with ten times heated palm oil and ADD-X extract (10HPO-X). The rats were sacrificed at the end of the study; blood was collected for cardiac and inflammatory biomarkers. The cardiac tissues of all groups were obtained for biochemical parameters and processed for histopathological examinations. Five times (5HPO) and ten times heated (10HPO) palm oil caused a significant (p<0.05) increase in the level of cardiac lactate dehydrogenase (LDH), troponin (Trp), serum C-reactive protein (CRP), Tumour necrosis factor-α (TNF-α), free fatty acids and triglycerides with increase in cardiac weight compared to control. The changes in the biochemical parameters and cardiac weight were significantly (p<0.05) attenuated by ADD-X supplementation to the heated oil. The histological sections of the heart showed presence of cardiac necrosis in the 5HPO and 10HPO. These histological changes were reduced with ADD-X supplementation. The consumption of repeatedly heated palm oil increases LDL, troponin, CRP, TNFα, triglyceride, FFA, heart weight and cause cardiac necrosis in the post menopausal rat models. Those changes were attenuated by ADDX supplementation. © 2016, International Journal of Toxicological and Pharmacological Research. All rights reserved.
... They contain triacylglycerol ( esters of glycerol with long chain C 12 to C 18 saturated and unsaturated fatty acids) as their major component along with polyphenols, aldehydes, sterols , antioxidants, vitamins, a variety of volatile compounds and others as minor components. Edible oils are physiologically vital constituents of human diet and life (Eckey 1954 Leong et al. 2015) . They provide energy, essential fatty acids necessary to raise high density lipoprotein and serve as a carrier of fat soluble vitamins and antioxidants. ...
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The oxidative degradability of the unsaturated fat components in edible vegetable oils affect their nutrient value, storage stability, reusability and high temperature culinary applications. In the present investigation thermal and thermooxidative stabilities and decomposition enthalpies of refined and virgin oils of gingely, ground nut, coconut and sunflower in air and N 2 were simultaneously analysed by nonisothermal gravimetry and differential thermal analysis to optimize their process, use and storage conditions for stability and reusability. These oils which registered a negligible mass loss at ≤200 o C degraded exothermically in air by three step pathway and endothermically in N 2 by a single step. Their thermal stabilities decreased in the order groundnut>gingely> sunflower>coconut and sunflower>groundnut> gingely>coconut in N 2 , and groundnut> gingely> coconut>sunflower and gingely>groundnut> coconut> sunflower in air for refined and virgin grades respectively. Their level of saturated and unsaturated fats were also analysed from the recorded thermograms.
... In many parts of the world including Asia, oil is repeatedly used for food preparation to minimize the cost [10,21]. This practice is not only limited to homes but also observed in restaurants and other large-scale food preparing industries as well as the informal food sector [22,23]. When cooling the oil from the hightemperature solubility of the oxygen in oil increases. ...
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Objectives: Palm olein, which is the fractionated form of palm oil, is commonly used as cooking oil in Sri Lanka. Processing of crude oil degrades α-tocopherol as does exposure to high heat during cooking. This study was aimed to determine the content and heat degradation of α-tocopherol in Sri Lankan commercially available palm olein. Method: Four different brands of Sri Lankan commercially available palm olein (100 mL) were heated to 180°C for 10 minutes. The oil was subsequently cooled and reheated five times and assayed in duplicate. Between each cycle of reheating oil was left in room temperature to cool for 5 hours. Fresh palm olein and the heated samples were analyzed for α-tocopherol content using reversed-phase High-pressure liquid chromatography (HPLC) (Shimadzu, Japan). Results: The mean α-tocopherol content in unheated palm olein was 3.02 ± 0.35 ppm, with no significant differences between brands. Heating Palm olein for 10 minutes resulted in 56.6% reduction in α-tocopherol compared to unheated oil. Reheating resulted in further reduction with a 100% loss by the fourth time. Conclusion: The Sri Lankan commercially available palm olein did not provide expected α-tocopherol content, and is not a good source of dietary α-tocopherol. Further analysis is required to quantify α-tocopherol content. Since reheating further reduced α-tocopherol levels, repeated frying during cooking is likely to result in a minimal level of α-tocopherol being provided through palm olein to the diet.
... Double bonds, are electron-withdrawing groups existed in unsaturated fatty acids, will cause adjacent carbon being oxidized to form carbonyl, then to form aldehyde finally. Besides, some monomers, dimers, trimers and high-molecular-weight compounds will be generated in deeply oxidized WCO (Choe and Min, 2007;Leong et al., 2015). As can be inferred, this process would augment the concentration of carbonyl without reducing acid values but shorten the alkyl chains of fatty acids, causing carbonyl absorption peak raised rapidly in the infrared spectrum (Jamal et al., 2020;Sun et al., 2017;. ...
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Prompting high content of reclaimed asphalt pavement (RAP) to be used in road building and maintenance has drawn great attention. The application of rejuvenators is an efficient way to ensure the performance of recycled asphalt mixtures. However, as various types of rejuvenators emerging, limited understanding about rejuvenation poses challenges to put effective ones into use. For precisely evaluating the performance of rejuvenators, plenty of studies were conducted to ascertain the fundamental mechanism of rejuvenating from the microscopic view. This paper provides an overview of studies focusing on the change inside asphalt after adding rejuvenators. Chemical compositions of rejuvenators were collected as basic information. Both laboratorial experiments and molecular dynamic simulations were investigated to not only compare the effectiveness of several rejuvenators but also explain the rejuvenating mechanism. Finally, functional groups of rejuvenator structures were comprehensively examined to provide global understanding about how chemical compositions influence the efficacy of rejuvenators. This review highlights that the essential capacity of a true rejuvenator is to disturb asphaltene agglomerations. Besides, the molecular structures of rejuvenators will not only affect their deagglomerating abilities but also the performances of diffusion and durability. It has been found that gel-permeation chromatography (GPC) analysis is effective in evaluating the performance of rejuvenators, while Fourier transform infrared spectroscopy (FT-IR) and SARA (saturates, aromatics, resins and asphaltenes) analysis are only suitable for assessing asphalt oxidization. In addition, comparing some tests can only detect changes, molecular dynamic simulation can reveal the mechanism both of data and vision. The results of this work can provide comprehensive knowledge for the evaluation and development of rejuvenators.
... Indeed, it is important to highlight the health impacts imposed by detection of high peroxide in cooking oil used by food premise handlers as they were part of the communities and being the responsible party who were preparing food products for consumers. Long-term uptake of foods cooked by the usage of rancid oil could significantly have an effect on antioxidant defence of an individual and potentially lead to diseases such as hypertension, diabetes and vascular inflammation (13). Nevertheless, there is still a gap that could be filled up in order to increase awareness on health issues associated with consumption of oxidised oils. ...
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Introduction: The repeatedly heating cooking oil in preparation of fried food has become a main dietary habit among Malaysian which can cause health impacts on humans. The peroxide value (PV) can be applied to identify cooking oil's quality through the oxidative change that takes place in fats or oils. High peroxide value indicates bad quality of cooking oil. This research was conducted to identify the awareness and practice of repeatedly heating cooking oil among food premise operators and to determine the peroxide value in repeatedly heating cooking oil samples. Methods: A total of 124 food premise operators in Bukit Mertajam, Penang, participated in this research. A face-to-face interview was carried out by using the structured questionnaire for data collection to obtain socio-demographics information as well as awareness and practice of repeatedly heating cooking oil among respondents. The peroxide values analysis was performed on five samples of respondent's most favourable brands of cooking oil by using io-dometric titration method. Results: Majority of respondents had moderate awareness (53.2%) and practice (50.0%) level regarding repeatedly heating cooking oil. The PV analysis showed that the peroxide value begin to exceed the AOCS standard limit of 10 meqO 2 /kg following the 5 th cycles of frying. Conclusion: Relevant actions need to be taken by the governmental food authorities to address this issue and ensure safe consumption of fried foods by consumers.
... The study recorded higher blood pressure and ACE activity as the plasma NO and HO-1 decreased. NO, an endothelium-derived relaxing factor is involved in the regulation of homeostasis of the vascular system to maintain its integrity [Leong et al., 2015]. A reduction in the level of NO compromises the integrity of the vascular system. ...
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Cooking oils are integral part of human diet as they are used in almost all type of culinary practices. They serve as sources of lipid with significant nutritive value and health benefits which can be attributed to their fatty acid compositions and biological antioxidants. However, cooking oils are usually subjected to thermal oxidation which occurs when fresh cooking oil is heated at high temperatures during various food preparations. Repeated use of cooking oils in the commercial food industry is also common to maximize profit. Thermal oxidation of edible oils had since attracted great attention of nutritionist and researchers given the deteriorative effect such as generation of very cytotoxic compounds, loss of carotenoid, phenolics and vitamins thus reducing the overall antioxidant properties of the oils. Furthermore, several in vivo studies had suggested that consumption of thermally oxidized cooking oils might not be healthy as it might negatively influence the lipid profile [increased low density lipoprotein (LDL), decreased high density lipoprotein (HDL) and elevated cholesterol level], haematological system [alteration in concentration of heamoglobin (Hb), packed cell volume (PCV), white blood cell (WBC) count, neutrophil and lymphocyte counts], kidney function, and induce lipid peroxidation and oxidative stress which have been associated with the pathogenesis of various degenerative diseases. Therefore, thermal oxidation seems not to provide any health benefit, as it deteriorates cooking oils and the consumption of the oils may predispose consumers to various disease conditions that may ensue from free radical generation, thereby having deleterious effect on human health. Key words: thermal oxidation; cooking oils; antioxidant properties; health concerns.
... The immature mesocarp contains large amount of chlorophyll and less carotene then ripens fruit (Khan et al. 2020). Chemically palm oil is highly saturated with fatty acids, about 50% esterified with glycerol (Leong, et al. 2015). Palm oil is semisolid at room temperature (Nor and Yusoff 2000). ...
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In an attempt to explore the harmful effect of oxidative edible palm oil on body mass, cardiac alterations, and lipid profile in albino mice, an experiment using 24 mice was carried out divided into groups I, II, III, and fed with a normal diet, fresh and reused oxidized palm respectively. The result from the study showed that the mice in groups II and III indicated a considerable proliferation (p<0.05) within body mass. The total cholesterol of control (group I) were (54.12 ± 2.15 U/L), in fresh palm oil (group II) mice were (69.05 ± 8.53 U/L) while in reused oxidized oils show fundamentally influences in lipid profile. Cholesterol levels were (89.37 ± 8.26 U/L) Confirmed increase (p<0.05) levels of Cholesterol. Triglyceride (U/L) Level in (Group 1) control was (21.12±1.25U/L) in (Group II) fresh palm feed was (39.8750 ± 5.33U/L) and in (Group C) reused oxidized palm oil feed was (56.50 ± 5.24U/L) demonstrated major rise (p<0.05) in triglyceride. HDL levels in (Group I) control were (82.01 ±0.31 U/L).in (group II) fresh palm oil feed were (82.45 ± 4.01 U/L) while in (Group III) reused oxidized palm oil feed was (105.97±3.31 U/L). The group (III) demonstrated a noteworthy increase (p<0.05) in the HDL level. LDL levels in (Group I) control were (82.01 ±0.31 U/L).in (group II) fresh palm oil feed were (82.45 ± 4.01 U/L) while in (Group III) reused oxidized palm oil feed was (105.97±3.31 U/L). The group (III) demonstrated a noteworthy increase (p<0.05) in the LDL level. The histological reading demonstrated that the cardiac cells of the reused oxidized palm oil feeding group demonstrated vacuole and congested myocardial condition in papillary in heart muscles. The reused oxidized palm oil has adverse effects and should be discouraged.
... In addition, UFO contains toxic compound formed during high temperature heating like hydroperoxides and aldehydes. When these compounds ingested through consumed food, they may be responsible for increasing blood pressure (hypertension) and attributable to cardiovascular diseases and diabetes (Leong et al., 2015;Jaarin et al., 2018). Repeatedly heated cooking oils even produce carcinogenic compounds such as polycyclic aromatic hydrocarbons that relate to the incidence of tumor and cancer diseases (Ganesan et al., 2017). ...
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Used frying oil (UFO) has a great potential as feedstock for biodiesel production. This study aims to develop an artificial neural network (ANN) model to predict biodiesel yield produced from base-catalyzed transesterification of UFO. The experiment was performed with 100 mL of UFO at three different molar ratios (oil:methanol) (namely 1:4, 1:5, and 1:6), conducted with reaction temperatures of 30 to 55oC (raised by 5oC), and reaction time of 0.25, 0.5, 1, 2, 3, 6, 8, and 10 minutes. Prediction model was based on ANN model consisting of three layers with 27 combinations of three activation functions (tansig, logsig, purelin). All activation function architectures were trained using Levenberg- Marquardt train type with 126 data set (87.5%) and learning rate of 0.001. Model validation used 18 data set (12.5%) measured at reaction time of 8 min. Results showed that two ANN models with activation function of logsig-purelin-logsig and purelin-logsig-tansig be the best with RRMSE of 2.41% and 2.44% with R2 of 0.9355 and 0.9391, respectively. Predictions of biodiesel yield using ANN models are significantly better than those of first-order kinetics.
... Reused cooking oil contains high trans isomers saturated fatty acids. Due to several reheating process, unsaturated fatty acid undergo chemical changes that generated several oxidized products, leading to deleterious effects on the vascular function (Leong et al., 2015). This research also used egg yolk, which contains 13,2 gram monounsaturated fatty acid, 3,4 gram polyunsaturated fatty acid, 8,7 gram saturated fatty acid, and 1.120 mg per 100 gram of fresh egg yolk (Faitarone et al., 2013). ...
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It is well established that regular exercise has many positive benefits on health. Exercise at the appropriate intensity and level has been shown to improve lipid profile and reduce the risk of cardiovascular disease. This study investigates the effect of swimming training on total cholesterol levels and body weight in male Wistar rats. Thirty rats weighing 150-200 grams were randomly divided into one control (C) and two treatment groups (ST=swimming training, SED=sedentary activity). Rats in control (C) group were fed a standard diet, while rats in both treatment groups were fed high-fat diet-induced hypercholesterolemia for three weeks. Rats in ST were then swim-trained at moderate intensity for 30 minutes/day, six days a week for three weeks, and rats in SED were left without exercise stimuli. Body weight was measured weekly. At the end of the experimental period, intracardiac blood samples were drawn to measure the total cholesterol level. Findings revealed that rats’ bodyweight (p=0,045) and blood cholesterol (p=0,034) in ST group were significantly lower compared to SED. It indicates that swimming exercise is shown to be effective in weight loss and reducing blood cholesterol level in hypercholesterolemic rats.
... This reaction causes rancidity in the oil [1]. The use of cooking oil that has been contaminated or has damaged physico-chemical properties can cause long-term disease [2,3] because 5% -40% of cooking oil is left on food. which is obtained by frying. ...
... To improve the cost, vegetable oil is being repeatedly heated and used. These oils are being reused till it is thrown away and put back with fresh oil [6] . Oil containing seeds, fruits and nuts are used to obtain the vegetable oil. ...
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In recent years, adulteration has become a global issue. Edible oil is obtained from both plant and animal source. Edible oil is not a food group but they are essential for human consumption as they provide essential nutrients. Edible oils are being used as ingredients in food, for frying medium, salad dressing, for the formulation food products and also for baking. The fats of animal sources include butter, ghee and fish oils. These edible oils are mostly used to enhance the flavor of the food. In recent days the edible oil is being adulterated to increase the production cost which affects the authenticity of the fats and oils. Some of the edible oils are being mixed and adulterated with low quality and low-cost vegetable oil to achieve more profit. Adulteration of edible oil leads to various health hazards. Where mustard oil is being adulterated with argemone oil it has shown the effect of gall bladder cancer. There is an immediate need to maintain the authenticity of oils and fats and also to improve various detection methods. This review paper focuses on various detection methods for analyzing and quantifying the adulterants in edible oils. Various methods such as spectroscopic, chromatographic and other techniques have been employed. IR was more time-consuming process when compared with NMR. HPLC was found to be easy to handle and had high resolution and was rapid. Raman spectroscopy is a quick method for detecting the impure mixtures. GC was stable technique of detecting the adulterations in EVOO. The adulterants cause various ill effects which includes gall bladder cancer, stomach problems, damage to liver and epidemic dropsy.
... In order to monitor the rancidity of oil, the p-anisidine value (p-AnV) and the total oxidation value (totox) are being determined (Saeed & Naz, 2019). The p-anisidine value indicates secondary oxidation products (Leong et al., 2015;Patsioura et al., 2017). ...
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Refined sunflower oil has dissimilar shelf life compared to cold-pressed sunflower oil, which increases the use of refined oil, and it is more abundant in the diet. On the other hand, the production of cold-pressed oils does not require chemical processing. Moreover, these oils contain significant amounts of bioactive components with a beneficial health effect. Breeders are trying to create new sunflower hybrids for the production of cold-pressed oil with improved oxidative characteristics. This study aims to examine the rancidity of 24 cold-pressed sunflower oils of new hybrids under accelerated thermal stability test conditions (Rancimat and Schaal oven tests) and to compare the obtained results with refined sunflower oil. According to investigated oxidative parameters, the most similar to refined sunflower oil was the H20 sample with the induction period determined by the Rancimat test of 9.55 ± 0.00 h, compared to 9.49 ± 0.00 h, obtained in refined sunflower oil. The total oxidation value of the H20 sample amounted to 3.26 ± 0.12, while in refined sunflower oil this value was 2.12 ± 1.73.
... The differentiation in all of those data could be attributed to one or/and more of the following reasons: 1) the type of the vegetable oil, 2) the technology used for oil extraction and preparation, and 3) method of analysis. In this attention, Earl et al., (2005) and Leong et al., (2015) reported that during refining, the bleaching and steam deodorisation processes partially/completely remove some of the valuable components including phenolics. The amounts retained in the refined oils depend on the conditions of refining. ...
... The quality of fried food products also depends on the nutritive value of the oil used in frying. The changes in chemical properties of frying oil eventually bring about changes in the value of fried food; use of frying oil repeatedly generates unwanted components such as conjugated diene, triene, FFAs, peroxides, cyclic compounds, ketones, aldehydes, and alcohols which may result in production of carcinogenic or toxic compound [8,9] and consequent health risk. This can reduce the sensory, functional, and nutritive value of oils [10]. ...
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This study investigated the effects of mixing Moringa oleifera seed oil with soybean ( Glycine max ) seed oil in enhancing the physical and chemical properties of soybean oil during repetitive frying. Different blends (100:0, 50:50, and 70:30) of soybean and M. oleifera seed oils were formulated, while soybean oil served as control. All these oil samples were used for frying potato ( Ipomoea batatas ) slices. The quality of the fried oil samples was evaluated by determining the smoke point, refractive index (RI), viscosity, colour, peroxide value, iodine value, and free fatty acid (FFA). The range of values obtained were smoke point (158.7–172.3°C), RI (1.46–1.49°C), colour (6.0–9.42), viscosity (0.41–2.13 mm ² /s), peroxide value (0.93–5.16 meq/kg), iodine value (87.16–64.71 mg/100 g), and FFA (0.3–1.95%), for different blends of soybean and M. oleifera seed oils and control. In terms of changes in the chemical and physical properties, during frying, soybean/ M. oleifera seed oil mix of 70:30 had the lowest reduction in iodine value (87.56–68.73 mg/100 g), lowest increase in peroxide value (0.93–1.86 meq/kg) and FFA value (0.3–0.65%), while no changes in RI (1.47°C) was observed. The study revealed that mixing of soybean seed oil with M. oleifera seed oil at a ratio of 70:30 enhanced the physical and chemical properties of the soybean oil after two repetitive frying.
... WCO is made following the frying process with a variety of edible animal and vegetable oils [12]. Depending on the amount of activity of the frying process, WCO degrades at different rates [13]. According to Asli et al. [14], the primary chemical components of WCO are oleic acid (43.67%), palmitic acid (38.35%), and linoleic acid (11.39%), as indicated in Table 1. ...
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Many academics have been looking for alternatives to asphalt binders, such as alternative binders for hot mix asphalt (HMA), as a result of increasing environmental restrictions and the rising expense of asphalt binders. The goal of this study was to investigate if bioasphalt might be used as a binder instead of petroleum-based asphalt. Mechanical tests such as Marshall Stability, resilient modulus, and dynamic creep were used to evaluate if there was any improvement in the performance of an asphalt mixture incorporating waste cooking oil (WCO) at various percentages (0, 1.5, and 3%) by weight of the binder. Marshall Stability, resilience modulus, and dynamic creep performance all improved with the addition of 1.5% WCO to the bituminous mixture. Furthermore, the 1.5% WCO mixture had the maximum creep stiffness, with a 36% improvement in resisting permanent deformation as compared to the conventional mixture. As a result of the benefits of this type of waste material in improving the mechanical performance of asphalt mixtures, recycling this waste material will be a suitable technique in waste materials recycling. .
... The immature mesocarp contains large amount of chlorophyll and less carotene then ripens fruit (Khan et al. 2020). Chemically palm oil is highly saturated with fatty acids, about 50% esterified with glycerol (Leong, et al. 2015). Palm oil is semisolid at room temperature (Nor and Yusoff 2000). ...
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The practice of using cooking oils that are heated repeatedly is common to reduce the expenses of food preparation. However, this will result in lipid peroxidation, which generates compounds that are toxic to human health. Prolonged consumption of oxidized oils may affect the lipid metabolism, which generates free radicals and products that will lead to pro-inflammatory pathways. A number of cellular, animal and clinical studies revealed the effects of oxidized oils on inflammatory responses. By-products of lipid peroxidation, including trans, trans-2,4-decadienal (2.4-De), 4-hydroxy-2-hexenals (4-HHE) and malonaldehyde (MDA) can be found significantly in samples treated with oxidized oils. Besides, the release of inflammatory biomarkers or cytokines will be induced due to the enhanced degree of oxidative stress. Inflammation has been acknowledged to be linked to increased risk of cancer. Therefore, the consumption of repeatedly heated oils, which have higher level of oxidation may potentially lead to cancer progression. The possible cancer risk induced by the dietary intake of the pro-inflammatory oxidized oils, and methodology considerations and limitations of studies related to cancer risk induced by pro-inflammatory oxidized oils will be also discussed in this review.
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Objective: Cooking oils (edible oils) are vegetable oils which are extensively used for cooking in India. These edible oils are rich in triglycerides, sterol, tocoferol, carotenes and pigments. Upon frying, edible oils gives rise to formation of free radicals and other harmful agents. The degraded products of oils generated while cooking produce unfavorable effects. The present study was designed to evaluate the effects of reused edible oils (sunflower oil and palm oil) on vital organs of experimental animals. Materials and Methods: Wistar rats were fed fresh and reused edible oils - sunflower oil and palm oil (15 gm oil/100gm of feed consumed) and control group received normal food and water for a period of 8 weeks. The parameters studied include changes in physicochemical properties of reused oils, change in body weight of animals, plasma lipid profile, biochemical parameters and histopathological examination. Results: The result showed the change in physicochemical characteristics of reused oils. The animals fed with fresh and reused palm oil significant increase the body weight while reused sunflower oil fed group showed decrease significantly. The biochemical parameters, SGPT (serum glutamate–pyruvate transaminase), SGOT (serum glutamate- oxaloacetate transaminase), and ALP (alkaline phoshphatase) were increased in reused oils fed groups. The histopathological study showed the change in size of liver, heart, kidney and testes cells in reused oil groups. Conclusions: From the present study, it can be concluded that reused sunflower oil and palm oil, can be toxic and can cause considerable damage to the vital organs of the experimental animals.
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Oxidative stress plays a critical role in the pathophysiology of a wide range of diseases including cancer. This view has broadened significantly with the recent discoveries that reactive oxygen species initiated lipid peroxidation leads to the formation of potentially toxic lipid aldehyde species such as 4-hydroxy-trans-2-nonenal (HNE), acrolein, and malondialdehyde which activate various signaling intermediates that regulate cellular activity and dysfunction via a process called redox signaling. The lipid aldehyde species formed during synchronized enzymatic pathways result in the posttranslational modification of proteins and DNA leading to cytotoxicity and genotoxicty. Among the lipid aldehyde species, HNE has been widely accepted as a most toxic and abundant lipid aldehyde generated during lipid peroxidation. HNE and its glutathione conjugates have been shown to regulate redox-sensitive transcription factors such as NF-κB and AP-1 via signaling through various protein kinase cascades. Activation of redox-sensitive transcription factors and their nuclear localization leads to transcriptional induction of several genes responsible for cell survival, differentiation, and death. In this review, we describe the mechanisms by which the lipid aldehydes transduce activation of NF-κB signaling pathways that may help to develop therapeutic strategies for the prevention of a number of inflammatory diseases.
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A study to measure frying quality and stability of rice bran oil (RBO) compared to palm olein (PO) was conducted. The oils were used to fry French fries continuously for six hours a day up to five days at a temperature of 185 ± 5°C. Oil samples were collected and analyzed for free fatty acid (FFA), peroxide value (PV), smoke point, p-anisidine value (p-AV), iodine value (IV) and colour. At the end of the frying period for both oil samples, FFA, PV, colour and p-AV were increased whereas the IV and smoke point decreased. The rate of FFA formation of RBO was slightly lower which increased from 0.142% to 0.66% compared to PO which was from 0.079% to 0.93%. The PV of RBO showed consistent increased from 3.9 meq/kg to 13.4 meq/kg whereas PO with initial value at 3.4 meq/kg increased to 34.6 meq/kg on the fifth day. Smoke point of RBO and PO progressively dropped from 235°C to 188°C and 220°C to 178°C, respectively. The level of p-AV for RBO increased from 12.19 to 32.65 from the initial to the end of frying day whereas PO had higher rate of changes in p-AV which was from 10.45 to 60.75. The IV decreased over frying time where IV of RBO decreased from 94.5 to 66.5 while IV of PO decreased from 50.9 to 44.6. The colour of RBO showed increased in redness and yellowness but PO was darker at the end of the frying trial. In general, RBO showed better stability than the PO in deep frying of French fries.
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DNA adducts are a major cause of DNA mutation and DNA mutation-related diseases, but the simultaneous identification of multiple DNA adducts has been a challenge for a decade. An adductome approach using consecutive liquid chromatography and double mass spectrometry after micrococcal nuclease treatment has paved the way to demonstrations of numerous DNA adducts in a single experiment and is expected to contribute to the comprehensive understanding of overall environmental and endogenous exposures to possible mutagens in individuals. In this report we applied an adductome approach to gastric mucosa samples taken at the time of a gastrectomy for gastric cancer in Lujiang, China, and in Hamamatsu, Japan. Seven lipid peroxidation-related DNA adducts (1,N6-etheno-2'-deoxyadenosine [εdA], butanone-etheno-2'-deoxycytidine [BεdC], butanone-etheno-2'-deoxy-5-methylcytidine [BεmedC], butanone- etheno-2'-deoxyadenosine [BεdA], heptanone-etheno-2'-deoxycytidine [HεdC], heptanone-etheno-2'-deoxyadenosine [HεdA], and heptanone-etheno- 2'-deoxyguanosine [HεεdG]) were identified in a total of 22 gastric mucosa samples. The levels of these adducts ranged from 0 to 30,000 per 10(9)bases. Although the presence of Helicobacter pylori DNA in the mucosa was not related to these adducts level, the levels of BεdC,BεdA, and HεdA were higher in the Japanese gastric mucosa samples. The profiles of these 7 adduct levels among the 21 cases were capable of discriminating between the possible origins (China or Japan) of the gastric mucosa samples. Our report is the first demonstration of lipid peroxidation-related DNA adducts in the human stomach, and the present observations warrant further investigation in the context of the significance of DNA adducts in human gastric carcinogenesis.
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Hypercholesterolaemia, increase in lipid peroxidation and hyperhomocysteinaemia may contribute to the pathogenesis of atherosclerosis. This study was performed to examine the effects of repeatedly heated palm oil mixed with 2% cholesterol diet on atherosclerosis in oestrogen-deficient postmenopausal rats. Ovariectomy causes disruption of tunica intima layer of the rat aorta simulating a postmenopausal condition in females. Twenty-four ovariectomized female Sprague-Dawley rats were divided into four groups. The control group received 2% cholesterol diet without palm oil. A diet with 2% cholesterol content fortified with fresh, once-heated and five-times-heated palm oil was given to the other treatment groups. The rats were sacrificed at the end of 4 months of study and the aortic arch tissue was processed for histomorphometry and electron microscopy. On observation, there was disruption of the intimal layer of the ovariectomized rat aorta. There was no obvious ultrastructural change in the aorta of the rats fed with fresh palm oil. The ultrastructural changes were minimal with once-heated palm oil, in which there was a focal disruption of the endothelial layer. The focal disruption was more pronounced with five-times-heated palm oil. The results of this study show that the ingestion of fresh palm oil may have a protective effect on the aorta but such a protective action may be lost when the palm oil is repeatedly heated. The study may be clinically important for all postmenopausal women who are susceptible to atherosclerosis.
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This study was carried out to investigate the effects of a dietary oxidized oil on lipid metabolism in rats, particularly the desaturation of fatty acids. Two groups of rats were fed initially for a period of 35 d diets containing 10% of either fresh oil or thermally treated oil (150 degrees C, 6 d). The dietary fats used were markedly different for lipid peroxidation products (peroxide value: 94.5 vs. 3.1 meq O2/kg; thiobarbituric acid-reactive substances: 230 vs. 7 micromol/kg) but were equalized for their fatty acid composition by using different mixtures of lard and safflower oil and for tocopherol concentrations by individual supplementation with DL-alpha-tocopherol acetate. In the second period which lasted 16 d, the same diets were supplemented with 10% linseed oil to study the effect of the oxidized oil on the desaturation of alpha-linolenic acid. During the whole period, all the rats were fed identical quantities of diet by a restrictive feeding system in order to avoid a reduced food intake in the rats fed the oxidized oil. Body weight gains and food conversion rates were only slightly lower in the rats fed the oxidized oil compared to the rats fed the fresh oil. Hence, the effects of lipid peroxidation products could be studied without a distortion by a marked reduced food intake and growth. To assess the rate of fatty acid desaturation, the fatty acid composition of liver and heart total lipids and phospholipids was determined and ratios between product and precursor of individual desaturation reactions were calculated. Rats fed the oxidized oil had reduced ratios of 20:4n-6/18:2n-6, 20:5n-3/18:3n-3, 20:4n-6/20:3n-6, and 22:6n-3/22:5n-3 in liver phospholipids and reduced ratios of 20:4n-6/18:2n-6, 22:5n-3/18:3n-3, and 22:6n-3/18:3n-3 in heart phospholipids. Those results suggest a reduced rate of desaturation of linoleic acid and alpha-linolenic acid by microsomal delta4-, delta5-, and delta6-desaturases. Furthermore, liver total lipids of rats fed the oxidized oil exhibited a reduced ratio between total monounsaturated fatty acids and total saturated fatty acids, suggesting a reduced delta9-desaturation. Besides those effects, the study observed a slightly increased liver weight, markedly reduced tocopherol concentrations in liver and plasma, reduced lipid concentrations in plasma, and an increased ratio between phospholipids and cholesterol in the liver. Thus, the study demonstrates that feeding an oxidized oil causes several alterations of lipid and fatty acid metabolism which might be of great physiologic relevance.
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The responsiveness of the rat aorta after chronic consumption of 15% (wt/wt) fresh and thermally oxidized palm oil diets was studied under standard organ bath procedures. Aortic rings from the oxidized oil-fed group showed significantly (P < 0.05) enhanced vascular responses to noradrenaline and potassium chloride when compared with the control and fresh palm oil-fed groups. The maximum tensions were 285.10 +/- 30 mg/mg tissue weight for the oxidized oil-fed group and 148.98 +/- 36 mg/mg for the control in response to noradrenaline. The fresh oil-fed group produced maximum tension of 133.9 +/- 20 mg/mg which was not significantly different from the control. The trend was similar with potassium chloride. The maximum tensions were 206.31 +/- 25 mg/mg for the oxidized oil-fed group and 93.33 +/- 13 mg/mg for the control group. The fresh oil-fed group produced maximum tension of 109.31 +/- 7.8 mg/mg which was not significantly different from the control. Relaxation to acetylcholine was significantly (P < 0.01) attenuated in the aortic rings obtained from the oxidized palm oil-fed group when compared with the control and fresh palm oil-fed groups. The percentage maximum relaxations to acetylcholine were 28.1 +/- 6.7% in the oxidized oil-fed group, 71.4 +/- 6.0% in control and 78.2 +/- 6.0% in the fresh oil-fed groups. The relaxation in the fresh oil-fed group was not significantly different from control. These results suggest that functional changes occur in rat blood vessels after chronic consumption of thermally oxidized palm oil.
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The effects of non-fried and fried virgin olive and sunflower oils on rat liver microsomal compositional features have been investigated. In addition, plasma antioxidants (alpha-tocopherol and ubiquinone 9) were investigated as well as the possible oxidative modifications suffered by virgin olive and sunflower oils during the frying process. The frying process decreased the content of alpha-tocopherol and phenolics in the oils and increased total polar materials. Sunflower oil was affected to a greater extent than olive oil. In rats, the intake of fried oil led to higher levels of lipid peroxidation and a lower concentration of plasma antioxidants. Microsomal fatty acid and antioxidant profiles were also altered. It seems that a strong relationship exists between the loss of antioxidants and the production of toxic compounds in the oils after frying and the extent of the peroxidative events in microsomes, which were also different depending on the fat source. The highly unsaturated sunflower oil was less resistant to the oxidative stress produced by frying and led to a higher degree of lipid peroxidation in liver microsomes in vivo than virgin olive oil.
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This paper reviews the properties of natural antioxidant in vegetable oil which is one of the most significant active components that plays an important role in reducing fat oxidation. Frying is widely used in food industry and household cooking which leads to degradation of oil that induces important chemical changes in oils, specifically oxidation, polymerization, isomerism, hydrolysis and cyclization. Effective control over the limitation of the above reaction is technically done by the simplest way of the natural antioxidant in the oil. Antioxidants reduce the oxidative stress in cells damage and health problems including cancers, degenerative diseases, cardiovascular diseases, inflammatory diseases etc. This study reveals the stability and efficiency of natural antioxidants present in sunflower oil, groundnut oil, soya bean oil palm oil, sesame oil, rice bran oil and corn oil and the changes on heating.
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Changes in antioxidant properties and degradation of bioactives in palm oil (PO) and rice bran oil (RBO) during deep-frying were investigated. The alpha (α)-tocopherol, gamma (γ)-tocotrienol and γ-oryzanol contents of the deep-fried oils were monitored using high performance liquid chromatography, and antioxidant activity was determined using 2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activity. Results revealed that the antioxidant activity of PO decreased significantly (p < 0.05), while that of RBO was preserved after deep-frying of fries. As expected, the concentration of α-tocopherol in PO and γ-tocotrienol in both PO and RBO decreased significantly (p < 0.05) with increased frying. Results also showed that γ-tocotrienol was found to be more susceptible to degradation compared to that of α-tocopherol in both PO and RBO. Interestingly, no significant degradation of α-tocopherol was observed in RBO. It is suggested that the presence of γ-oryzanol and γ-tocotrienol in RBO may have a protective effect on α-tocopherol during deep-frying.
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Oxidative stress is associated with the pathogenesis of cardiovascular diseases. The process of deep-fat frying in dietary cooking oil plays a role in the generation of free radicals. In this study, palm olein heated to 180 °C was tested for its effect on the activity of blood pressure-regulating enzymes and lipid peroxidation. Forty-two adult male Sprague-Dawley rats were equally assigned into 6 groups.The first group was fed with normal rat chow as the control group, and the subsequent groups were fed with rat chow fortified with 15% weight/weight of the following: fresh palm olein, palm olein heated once, palm olein heated twice, palm olein heated 5 times, or palm olein heated 10 times. The duration of feeding was 6 months. Fatty acid analyses of oil were performed using gas chromatography. Peroxide values were determined using standard titration. Plasma was collected for biochemical analyses. Repeatedly heated palm olein increased the levels of peroxide, angiotensin-converting enzyme, and lipid peroxidation as well as reduced the level of heme oxygenase. Fresh palm olein and palm olein heated once had lesser effects on lipid peroxidation and a better effect on the activity of blood pressure-regulating enzymes than repeatedly heated palm olein. Repeatedly heated palm olein may negatively affect the activity of blood pressure-regulating enzymes and increase lipid peroxidation.
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The changes in regular canola oil as affected by frying temperature were studied. French fries were fried intermittently in canola oil that was heated for 7h daily over seven consecutive days. Thermo-oxidative alterations of the oil heated at 185±5 or 215±5°C were measured by total polar components (TPC), anisidine value (AV), color components formation, and changes in fatty acid composition and tocopherols. Results showed that TPC, AV, color and trans fatty acid content increased significantly (P<0.05) as a function of frying temperature and time. The oil polyunsaturated fatty acids (PUFA) decreased in direct proportion to frying temperature and time. After 7days of frying, the amount of PUFA was reduced by half and the trans isomers contribution increased 2.5 times during frying at 215°C. Of the parameters assessed, total polar component and color had the highest correlation, with correlation coefficients of 0.9650 and 0.9302 for frying at 215 and 185°C, respectively. TPC formation correlated inversely with the reduction of tocopherols.
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Repeated heating of soy oil may promote lipid peroxidation. Oxidized unsaturated fatty acids may contribute to the pathogenesis of atherosclerosis, especially in estrogen-deficient states. This study was performed to explore the deleterious effects of repeatedly heated soy oil on the development of atherosclerosis using ovariectomized rats, which represent an estrogen-deficient state. Twenty-four female Sprague-Dawley rats were ovariectomized and were divided equally into four groups. The control group was fed with 2% cholesterol diet without any oil. The three treatment groups each received 2% cholesterol diet fortified with fresh, once-heated or five-times-heated (repeatedly heated) soy oil, respectively. Serum thiobarbituric acid reactive substances (TBARS), lipid profile and homocysteine levels were measured prior to ovariectomy and at the end of four months. Ovariectomized rats treated with repeatedly heated soy oil showed significant increases in lipid peroxidation and low-density lipoprotein (LDL) levels. Treatment with once-heated or repeatedly heated soy oil caused a significant increase in total cholesterol, while fresh soy oil caused significant reduction in homocysteine level as compared to other groups. Repeatedly heated soy oil caused significant increases in TBARS and LDL as compared to fresh oil. The higher level of homocysteine in the ovariectomized rats fed with repeatedly heated oil, as compared to those fed with fresh oil, also suggests the repeatedly heated oil contributes to the development of atherosclerosis. Importantly, the protective effect of the soy oil may be lost once it was being repeatedly heated. In conclusion, the consumption of repeatedly heated oil may predispose to atherosclerosis in estrogen-deficient states.
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A therosclerosis and the associated adverse complications of cardiovascular disease are major causes of morbidity and mortality in people living a Western lifestyle. A role for excess cholesterol in the pathophysiology of atherosclerosis is clear. However, additional mechanisms driving the relevant pathological changes in a chronic disease such as atherosclerosis are those that constitute the acute inflammatory response.1 The essential elements of a physiological, and regulated, inflammatory response starts with stimulated endothelium,2 displaying adhesive molecules for circulating white blood cells. This is accompanied by localized production of cell type–specific agonists for adherent monocytes, neutrophils, or lymphocytes by the activated endothelium.3 These agonists then activate the migratory instruction set of adherent or rolling cells positioned to receive both adhesion- and agonist-related stimuli from activated vascular endothelial cells.4 Lipid oxidation products formed by virtually every vascular cell type participate in orchestrating these processes. We also have recently come to appreciate that the inflammatory process is actively limited by activation of a resolution phase, often via generation of structurally specific oxidized lipids whose function is to orchestrate resolution of inflammation.5 The overall goal of this review series is to place recent observations and insights in rapidly developing areas of lipid oxidation into the framework of cardiovascular disease. Enzymatic and free radical oxidation have prominent roles in cardiovascular disease through their oxidative modification of existing molecules. Lipids are primary targets of this modification because they are the primary repository of oxidizable olefinic or double bonds. Oxidized lipids are best understood as oxygenated arachidonic acid products, the prostaglandins, leukotrienes, and thromboxane A2, that have diverse and potent effects throughout the inflammatory and reparative responses. These oxidized lipid mediators are …
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Human clinical trials have demonstrated the cardiovascular protective properties of peanuts and peanut oil in decreasing total and low density lipoprotein cholesterol (LDL-C) without reducing high density lipoprotein cholesterol (HDL-C). The cardiovascular effects of the nonlipid portion of peanuts has not been evaluated even though that fraction contains arginine, flavonoids, folates, and other compounds that have been linked to cardiovascular health. The objective of this study was to evaluate the effects of fat free peanut flour (FFPF), peanuts, and peanut oil on cardiovascular disease (CVD) risk factors and the development of atherosclerosis in male Syrian golden hamsters. Each experimental diet group was fed a high fat, high cholesterol diet with various peanut components (FFPF, peanut oil, or peanuts) substituted for similar metabolic components in the control diet. Tissues were collected at week 0, 12, 18, and 24. Total plasma cholesterol (TPC), LDL-C, and HDL-C distributions were determined by high-performance gel filtration chromatography, while aortic total cholesterol (TC) and cholesteryl ester (CE) were determined by gas liquid chromatography. Peanuts, peanut oil, and FFPF diet groups had significantly (P < 0.05) lower TPC, non-HDL-C than the control group beginning at about 12 wk and continuing through the 24-wk study. HDL-C was not significantly different among the diet groups. Peanut and peanut component diets retarded an increase in TC and CE. Because CE is an indicator of the development of atherosclerosis this study demonstrated that peanuts, peanut oil, and FFPF retarded the development of atherosclerosis in animals consuming an atherosclerosis inducing diet.
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Ingestion of deep-frying oil has been reported to cause physiologic and histologic changes in experimental animals' tissue, increase the oxidative stress, and possibly lead to death. The purpose of this study was to investigate the effect of deep-frying oil on oxidative stress and blood pressure in spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats. Deep-frying oil was prepared by frying fresh soybean oil at 180 +/- 5 degrees C for 8 h each day, for 4 consecutive days. Male SHR and WKY rats were fed diets containing 15% fresh soybean oil or deep-frying oil (DO) for 10 wk. Rats ingesting the DO diet had lower feed efficiency and higher relative liver and kidney weights but deep frying had no significant influence on blood pressure in WKY or SHR rats. The DO diet had no effect on plasma renin activity, aldosterone content, or tissue angiotension-I-converting enzyme activity. WKY rats fed the DO diet showed significantly increased urinary thromboxane B(2) and 8-iso-prostaglandin F(2alpha) excretion, but not urinary 6-keto-prostaglandin F(1alpha) excretion. Diets containing deep-frying oil resulted in increased plasma thiobarbituric acid-reactive substances and nitric oxide contents and decreased plasma total antioxidant capacity in SHR and WKY rats. The ingestion of deep-frying oil seemed not to influence blood pressure or its related parameters, but altered eicosanoid metabolism and elevated oxidative stress in SHR and WKY rats.
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Palm oil used worldwide contains considerable amounts of antioxidants, namely, vitamin E and carotenes. The purpose of the study was to observe the effect of heated palm oil on blood pressure and observe the cardiac histological changes in rats. Forty male Sprague Dawley rats were divided equally into four groups and given treatment as follows: (i) basal diet (control group); (ii) basal diet fortified with 15% weight/weight (w/w) fresh palm oil (FPO); (iii) basal diet fortified with 15% w/w palm oil heated five times (5HPO); (iv) basal diet fortified with 15% w/w palm oil heated ten times (10HPO). Treatment duration was 16 weeks. Blood pressure was measured at baseline and at monthly intervals for 4 months using the tail-cuff method. After 16 weeks of study, the rats were killed and the hearts were taken out. The specimens were sectioned longitudinally and stained with hematoxylin and eosin for light microscopy. The FPO group did not show any significant changes in blood pressure and histological study. There was a significant increase (p <0.05) in blood pressure in the 5HPO and 10HPO groups. However, blood pressure in the 10HPO group was higher than in the 5HPO group. Histological sections of the heart showed necrosis in cardiac tissue in the 5HPO and 10HPO groups with the latter group showing more damage. Fresh palm oil has no deleterious effects on blood pressure and cardiac tissue but prolonged consumption of repeatedly heated palm oil may result in an increase in blood pressure level with necrosis of cardiac tissue.
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The effects of short-term feeding of mutagen containing, heated deep-frying oils on urinary and faecal mutagenicity, plasma clinical biochemical parameters, peroxidative effects and cell proliferative indices in the gastro-intestinal tract were determined in rats. Repeatedly used frying oils [a saturated fatty acid-rich coconut oil (CO) and a polyunsaturated fatty acid (PUFA)-rich (greater than 60% PUFA) vegetable frying oil (PO)] were administered to groups of seven rats at a level of 10% (by weight) in the diet for 4 wk; control groups were fed equal amounts of the unheated oils. Both heated oils showed direct-acting mutagenicity to Salmonella tester strain TA97; heated PO was also mutagenic to strain TA100. Both heated CO and heated PO contained detectable amounts of thiobarbituric acid-reactive substances (TBA-RS). In heated PO, hydroperoxides of linoleic acid were also present. In groups fed heated oils the mutagenicity of urine and faeces to strain TA97 was not found to be increased in comparison with the control groups. Faecal mutagenicity to strain TA100 was also unaffected by consumption of heated oils. Urinary excretion of TA100 mutagens was significantly increased in rats fed heated PO. Plasma alkaline phosphatase activity was clearly raised in rats fed heated PO, in comparison with rats fed unheated oils or heated CO. In addition, other clinical biochemical plasma parameters showed a tendency to be increased in rats fed heated PO, indicating hepatic and renal cellular toxicity. Urinary and faecal excretion of thiobarbituric acid-reactive substances (TBA-RS) were also slightly, but not significantly, increased in rats fed heated PO. Feeding heated CO to rats did not result in increased plasma enzyme activities and excretion of TBA-RS, nor in increased cell proliferation in gastro-intestinal tissues. Cell proliferation of the oesophageal tissues were slightly, but significantly, increased in rats fed heated PO, in comparison with the group fed unheated PO. Tissues of the glandular stomach and colon/rectum did not show significantly enhanced cell proliferation in the group fed heated PO. The results obtained in this study indicated that consumption of heated oils containing TA100 mutagens and oxidation products of linoleic acid produced indications of cellular damage to liver and kidneys, and increased urine mutagenicity, as well as enhanced cell proliferation in the oesophagus.
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Young and aging rats were fed for different periods (10, 90, 180 and 365 days) diets containing 15% of fresh or heated soybean oil. Thiobarbituric reactive substances (TBA-RS), lipofuscin, superoxide dismutase (SOD), vitamin A, vitamin E and microsomal and mitochondrial fatty acids in liver, brain and serum were measured. Heated oil diets induced significant increase of TBA-RS levels in liver, with earlier effects in aging rats and affected SOD activity in aging rats only after a long period of feeding. Circulating and stored vitamin A were reduced in both young and aging rats, with earlier effects in young animals. Serum and liver vitamin E was significantly reduced in all test groups. The results indicate that heated unsaturated oil produces reduction in the antioxidative defense system and that vitamin E status is the earliest indicator of the oxidative effect regardless of age.
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Disturbance of the balance between the production of reactive oxygen species such as superoxide; hydrogen peroxide; hypochlorous acid; hydroxyl, alkoxyl, and peroxyl radicals; and antioxidant defenses against them produces oxidative stress, which amplifies tissue damage by releasing prooxidative forms of reactive iron that are able to drive Fenton chemistry and lipid peroxidation and by eroding away protective sacrificial antioxidants. The body has a hierarchy of defense strategies to deal with oxidative stress within different cellular compartments, and superimposed on these are gene-regulated defenses involving the heat-shock and oxidant stress proteins.
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We examined whether oxidized lipids in the diet determine the levels of oxidized lipid in human postprandial serum chylomicrons. After we fed subjects control corn oil containing low quantities of oxidized lipid, the levels of conjugated dienes in the chylomicron fraction were low (9.67 +/- 0.92 nmol/mumol triglyceride), and no thiobarbituric acid-reactive substances (TBARS) could be detected. However, when subjects were fed a highly oxidized oil, the conjugated diene content in chylomicrons was increased 4.7-fold to 46 +/- 5.63 nmol/mumol triglyceride, with 0.140 +/- 0.03 nmol TBARS/mumol triglyceride. When subjects were fed medium-oxidized oil, the degree of oxidation of the chylomicron lipids was moderately increased (21.86 +/- 2.03 nmol conjugated dienes/mumol triglyceride). Additionally, we found that chylomicrons isolated after ingestion of oxidized oil were more susceptible to CuSO4 oxidation than chylomicrons isolated after ingestion of the control oil. The lag time for oxidation decreased from 4.30 +/- 0.40 to 3.24 +/- 0.51 hours (P < .05). These data demonstrate that in humans dietary oxidized lipids are absorbed by the small intestine, incorporated into chylomicrons, and appear in the bloodstream, where they contribute to the total body pool of oxidized lipid.
Article
Studies have indicated that oxidized lipoproteins may play a role in atherosclerosis. We have recently demonstrated that the levels of oxidized lipoproteins in the circulation can be directly correlated to the quantity of oxidized lipids in the diet. The present study tested the hypothesis that dietary oxidized lipids accelerate the development of atherosclerosis. For 12 to 14 weeks, 36 male New Zealand White rabbits were fed a low-cholesterol (0.25%) diet containing either 5% unoxidized corn oil (control diet) or 5% oxidized corn oil (oxidized-lipid diet). Serum cholesterol levels increased to a similar extent in both groups, with the majority of the cholesterol in the beta-migrating very low density lipoprotein (beta-VLDL) fraction. Beta-VLDL from control animals contained 3.86+/- 0.57 versus 9.07 +/- 2.14 nmol conjugated dienes per micromol cholesterol (P<.05) in rabbits fed the oxidized-lipid diet. No difference in oxidized lipid levels was detected in LDL. Most important, feeding a diet rich in oxidized-lipid resulted in a 100% increase in fatty streak lesions in the aorta. Additionally, rabbits that were fed the oxidized-lipid++ diet had a >100% increase in total cholesterol in the pulmonary artery that was primarily due to an increase in cholesteryl ester. Oxidized lipids are frequently present in the typical US diet, and our results suggest that consumption of these foods may be an important risk factor for atherosclerosis.
Article
Much has been written about the potential role of antioxidants in the prevention of atherosclerosis. To assess the short-term effect of a single high-fat meal with and without pretreatment with antioxidant vitamins on endothelial function in healthy, normocholesterolemic subjects. Observer-blinded randomized trial. University hospital. Twenty healthy, normocholesterolemic (total and low-density lipoprotein cholesterol <5.2 mmol/L and <3.4 mmol/L [<200 mg/dL and <130 mg/ dL], respectively), male (7) and female (13) hospital employee volunteers, aged 24 to 54 years. Three randomly administered breakfasts: (1) a high-fat meal (3766 J [900 calories], 50 g of fat); (2) a low-fat meal (3766 J [900 calories], 0 g of fat); and (3) a high-fat meal and pretreatment with oral administration of vitamins C (1 g) and E (800 IU) (high-fat meal with vitamins). A subgroup of 10 subjects also ate the low-fat meal with the same vitamin pretreatment (low-fat meal with vitamins). High-resolution ultrasound assessed flow-mediated (endothelium-dependent) brachial artery vasodilation measured as percent diameter change before and hourly for 6 hours following each meal. Flow-mediated vasodilation fell from a mean+/-SD of 20%+/-8% before to 12%+/-6%, 10%+/-6%, and 8%+/-9% at 2, 3, and 4 hours, respectively, after the high-fat meal (P<.001). No significant changes in flow-mediated vasodilation occurred after the low-fat meal, high-fat meal with vitamins, or low-fat meal with vitamins. The change in flow-mediated vasodilation after the low-fat and high-fat meals correlated inversely with the 2-hour postprandial change in triglyceride levels (r=-0.54; P<.001). A single high-fat meal transiently reduces endothelial function for up to 4 hours in healthy, normocholesterolemic subjects, probably through the accumulation of triglyceride-rich lipoproteins. This decrease is blocked by pretreatment with antioxidant vitamins C and E, suggesting an oxidative mechanism.
Article
The purpose of this study was to test the hypothesis that intake of used cooking fat is associated with impaired endothelial function. Diets containing high levels of lipid oxidation products may accelerate atherogenesis, but the effect on endothelial function is unknown. Flow-mediated endothelium-dependent dilation and glyceryl trinitrate-induced endothelium-independent dilation of the brachial artery were investigated in 10 men. Subjects had arterial studies before and 4 h after three test meals: 1) a meal (fat 64.4 g) rich in cooking fat that had been used for deep frying in a fast food restaurant; 2) the same meal (fat 64.4 g) rich in unused cooking fat, and 3) a corresponding low fat meal (fat 18.4 g) without added fat. Endothelium-dependent dilation decreased between fasting and postprandial studies after the used fat meal (5.9 +/- 2.3% vs. 0.8 +/- 2.2%, p = 0.0003), but there was no significant change after the unused fat meal (5.3 +/- 2.1% vs. 6.0 +/- 2.5%) or low fat meal (5.3 +/- 2.3% vs. 5.4 +/- 3.3%). There was no significant difference in endothelium-independent dilation after any of the meals. Plasma free fatty acid concentration did not change significantly during any of the meals. The level of postprandial hypertriglyceridemia was not associated with change in endothelial function. Ingestion of a meal rich in fat previously used for deep frying in a commercial fast food restaurant resulted in impaired arterial endothelial function. These findings suggest that intake of degradation products of heated fat contribute to endothelial dysfunction.
Article
The aim of the present study was to examine the effect of reducing saturated fat in the diet, or partly replacing it with unsaturated fat, on the serum lipoprotein profile of human subjects. The study had two intervention periods, 8 weeks (phase 1) and 52 weeks (phase 2). In phase 1, total fat was reduced from 31 to 25% energy (polyunsaturated fatty acids (PUFA):saturated fatty acids (SFA) ratio increased from 0.2 to 0.4) by reducing the quantity of coconut fat (CF) in the diet from 17.8 to 9.3% energy intake. In phase 2, subjects were randomised to groups A and B. In group A total fat was reduced from 25 to 20% energy (PUFA:SFA ratio increased from 0.4 to 0.7) by reducing the quantity of CF in the diet from 9.3 to 4.7% total energy intake. In group B, the saturated fat content in the diet was similar to group A. In addition a test fat (a mixture of soyabean oil and sesame oil, PUFA:monosaturated fatty acids ratio 2) contributed 3.3% total energy intake and total fat contributed 24% energy intake (PUFA:SFA ratio increased from 0.7 to 1.1). At the end of phase 1, there was a 7.7% reduction in cholesterol (95% CI -3.6, -12.2) and 10.8% reduction in LDL (95% CI -4.9, -16.5) and no significant change in HDL and triacylglycerol. At the end of phase 2, the reduction in cholesterol in both groups was only about 4% (95% CI -12, 3.2) partly due the concomitant rise in HDL. The reduction in LDL at 52 weeks was significantly higher in group B (group A mean reduction 11%, 95% CI -20.1, -2.0 and group B mean reduction 16.2% 95% CI -23.5, -8.9). In phase 2, triacylglycerol levels showed a mean reduction of 6.5% in group 2A and a mean increase of 8.2% in group 2B. The reduction of saturated fat in the diet is associated with a lipoprotein profile that would be expected to reduce cardiovascular risk. The reduction of dietary saturated fat with partial replacement of unsaturated fat brings about changes in total cholesterol, HDL- and LDL-cholesterol that are associated with a lower cardiovascular risk.
We have examined the plasma levels of the lipid peroxidation products 4-hydroxy-nonenal and malondialdehyde in a carefully controlled study of age and sex-matched subjects with rheumatoid arthritis in whom potentially confounding influences such as disease modifying anti-rheumatic drugs (DMARDs), self-medication and vitamin supplements were eliminated. The plasma concentrations of the antioxidants uric acid and vitamin E were also measured. The results reveal a strong and consistent inverse correlation between the levels of lipid peroxidation products in the plasma and erythrocyte sedimentation rate (ESR). There is no indication that vitamin E or urate function as the major antioxidant agent in arthritis, as has been suggested in more seriously affected patients. It is concluded that there is no evidence that vitamin E is more important, and urate less important as an antioxidant in mild arthritis. The correlation between lipid peroxidation and ESR suggests a more complex relationship than has been assumed.
Article
In the present work, virgin olive oil, sunflower oil and a vegetable shortening were used as cooking oils for the deep-frying and pan-frying of potatoes, for eight successive sessions, under the usual domestic practice. Several chemical and physicochemical parameters (acidic value, peroxide value, total polar artefacts, total phenol content and triglyceride fatty acyl moiety composition) were assayed during frying operations in order to evaluate the status of the frying oils, which were found within expected ranges similar to those previously reported. The oil fatty acids were effectively protected from oxidation by the natural antioxidants. The frying oil absorption by the potatoes was quantitated within 6.1-12.8%, depending on the oil type and the frying process. The retention of α- and (β + γ)-tocopherols during the eight fryings ranged from 85-90% (first frying) to 15-40% (eighth frying), except for the (β + γ)-tocopherols of sunflower oil, which almost disappeared after the sixth frying. The deterioration during the successive frying of several phenolic species present in virgin olive oil is reported for the first time. The retention of total phenolics ranged from 70-80% (first frying) to 20-30% (eighth frying). Tannic acid, oleuropein and hydroxytyrosol-elenolic acid dialdeydic form showed remarkable resistance in all frying sessions in both frying methods, while hydroxytyrosol and hydroxytyrosol-elenolic acid were the faster eliminated. The deterioration of the other phenolic species account for 40-50% and 20-30% for deep-frying and pan-frying, respectively, after three to four frying sessions, which are the most usual in the household kitchen. Deep-frying resulted in better recoveries of all the parameters examined. The correlation of the deterioration rate of the phenolic compounds and tocopherols during frying is discussed and the nutritional aspects of the natural antioxidant intake, through the oil absorbed by the potatoes, are evaluated.