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Effect of control and modified dairy products on the susceptibility of LDL cholesterol to oxidation 1

Effect of control and modified dairy products on the susceptibility of LDL cholesterol to oxidation 1

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Interest in the development of dairy products naturally enriched in conjugated linoleic acid (CLA) exists. However, feeding regimens that enhance the CLA content of milk also increase concentrations of trans-18:1 fatty acids. The implications for human health are not yet known. This study investigated the effects of consuming dairy products natural...

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... CLA and trans-11 18:1 were incorporated into LDL lipids ( Table 7). No significant effect of the intervention was observed on the lag time for oxidation, the oxidation rate during the propagation phase, or the maximum concentrations of con- jugated dienes produced ( Table 8). ...

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... Collectively, the findings from this study suggest that dietary t11-18:1 could improve clinical response to T cell-based cancer immunotherapies. The above studies, however, need to be weighed against human clinical studies that show high levels of t11-18:1 may have similar adverse effects on blood low density lipoprotein-and high density lipoprotein-cholesterol compared with industrial TFA (Tholstrup et al. 2006;Tricon et al. 2006;Brouwer et al. 2010Brouwer et al. , 2013Gebauer et al. 2015;Stender 2015). ...
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Feeding high-grain diets is a common practice in intensive ruminant production systems to meet animal energy requirements and maximize feed efficiency. One of the consequences of these diets is trans (t)10 shifted ruminal biohydrogenation, which includes increased formation of t10-18:1 and t10, cis (c)12-conjugated linoleic acid (t10, c12-CLA) at the expense of t11-18:1 and c9, t11-CLA. In dairy cows, the t10 shift has been associated with milk fat depression. In beef cattle, the t10 shift has not been associated with negative effects on animal performance or marbling fat deposition; however, it may negatively impact meat fat eating quality by decreasing its cis monounsaturated fatty acid to saturated fatty acid ratio. Finally, the t10 shift increases t10-18:1 accumulation in ruminant-derived foods (dairy, beef, and lamb), which at high enough levels may compromise the nutritional quality of these foods. The present review will cover our current understanding of the rumen microbes involved in the t10 shift and its implications for milk fat synthesis and beef fat quality.
... However, there are four published clinical studies in which ruminant TFA-enriched dairy fats were fed. In these studies, TVA+RA-enriched butter (1-1.5% of energy intake from TVA+RA) did not alter blood glucose and insulin, HOMA-IR or glucose tolerance in healthy subjects compared with standard butters (Tholstrup et al., 2006;Tricon et al., 2006;Brown et al., 2011;Penedo et al., 2013;Werner et al., 2013). Although observational studies showed that higher circulating levels of ruminant TFA may be protective against type 2 diabetes, available data from clinical trials do not support a beneficial effect of ruminant TFA on glucose homeostasis in humans. ...
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Recent government bans on industrial trans fatty acids (TFA) in developed countries has left naturally occurring TFA from ruminant products (e.g., dairy, beef, and lamb) as the sole source of TFA in the food supply. In contrast to industrial TFA, which have undisputed adverse health effects, ruminant TFA such as trans vaccenic acid (TVA; trans11-18:1), rumenic acid (RA; cis9, trans11-18:2) and trans palmitoleic acid (TPA; trans9-16:1) have been associated with reduced risk for some diseases such as type 2 diabetes. The present review summarizes the findings from observational, animal and human studies investigating the effects of ruminant TFA on metabolic parameters related to type 2 diabetes, and provides an update on the current knowledge of their biosynthesis, intake and factors affecting their concentrations in ruminant derived foods. Overall, observational studies and a small number of animal studies suggest that ruminant TFA may be protective against type 2 diabetes, whereas the same benefits have not been observed in other animal studies or in human clinical trials. Additional clinical and mechanistic studies are needed to better understand the isomer-specific effects of ruminant TFA. Until then, production practices resulting in increased levels of this group of fatty acids in ruminant milk and meat should be carefully reconsidered.
... Amongst FAs, conjugated linoleic acids (CLAs) have been well studied in the last few decades [7][8][9][10][11], mostly in research conducted on animals and in vitro models but also due to a high interest in exploring their possible beneficial effects in humans when used as supplements or in enriched foods [12][13][14][15][16]. While most findings in animal models suggest that CLAs have a protective effect against atherosclerosis [11,[17][18][19], clinical trials are less consistent depending on the characteristics of the participants, i.e., healthy vs. subjects with risk factors or diagnosis, the CLA doses used and the duration of the intervention. ...
... Evidence from clinical trials with healthy participants is also diverse. Here, CLAs have been reported to decrease plasma triglyceride and VLDL concentrations (mixed CLAs, 5.5 g/d for 5 weeks) [27] and to decrease the expression of intercellular adhesion molecule (ICAM)-1 by monocytes (CLA9,11 or CLA10,12, 2.5 g/day for 8 weeks), although CLA10,12 induced an increased ratio of LDL-to HDL-cholesterol and of total cholesterol to HDL-cholesterol in the same study [28] but had neutral effects in other studies [12,29]. Studies using CLA9,11-enriched dairy products also showed a reduction in inflammation markers in healthy participants [30,31]. ...
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Conjugated linoleic acid (CLA) isomers may have a role in preventing atherosclerosis through the modulation of inflammation, particularly of the endothelium. However, whether low concentrations of CLAs are able to affect basal unstimulated endothelial cell (EC) responses is not clear. The aim of this study was to evaluate the effects of two CLAs (cis-9, trans-11 (CLA9,11) and trans-10, cis-12 (CLA10,12)) on the basal inflammatory responses by ECs. EA.hy926 cells (HUVEC lineage) were cultured under standard conditions and exposed to individual CLAs for 48 h. Both CLAs were incorporated into ECs in a dose-dependent manner. CLA9,11 (1 μM) significantly decreased concentrations of MCP-1 (p < 0.05), IL-6 (p < 0.05), IL-8 (p < 0.01) and RANTES (p < 0.05) in the culture medium. CLA10,12 (10 μM) decreased the concentrations of MCP-1 (p < 0.05) and RANTES (p < 0.05) but increased the concentration of IL-6 (p < 0.001). At 10 μM both CLAs increased the relative expression of the NFκβ subunit 1 gene (p < 0.01 and p < 0.05, respectively), while decreasing the relative expression of PPARα (p < 0.0001), COX-2 (p < 0.0001) and IL-6 (p < 0.0001) genes. CLA10,12 increased the relative expression of the gene encoding IκK-β at 10 μM compared with CLA9,11 (p < 0.05) and increased the relative expression of the gene encoding IκBα at 1 and 10 μM compared with linoleic acid (both p < 0.05). Neither CLA affected the adhesion of monocytes to ECs. These results suggest that low concentrations of both CLA9,11 and CLA10,12 have modest anti-inflammatory effects in ECs. Thus, CLAs may influence endothelial function and the risk of vascular disease. Nevertheless, at these low CLA concentrations some pro-inflammatory genes are upregulated while others are downregulated, suggesting complex effects of CLAs on inflammatory pathways.
... These studies were conducted in T2DM (44, 51, 66, 80), hypertension (65), metabolic syndrome (41,77), hyperlipidemia (70,73), rheumatoid arthritis (61), atherosclerosis (31), and others in healthy individuals. All studies employed a parallel design except 7 studies that applied cross-over design (48,49,67,68,70,73,75). ...
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Background The findings of trials investigating the effect of conjugated linoleic acid (CLA) administration on lipid profile are controversial. This meta-analysis of randomized controlled trials (RCTs) was performed to explore the effects of CLA supplementation on lipid profile. Methods Two authors independently searched electronic databases including PubMed, Web of Science, and Scopus until March 2022, in order to find relevant RCTs. The random effects model was used to evaluate the mean and standard deviation. Results In total, 56 RCTs with 73 effect sizes met the inclusion criteria and were eligible for the meta-analysis. CLA supplementation significantly alter triglycerides (TG) (WMD: 1.76; 95% CI: −1.65, 5.19), total cholesterols (TC) (WMD: 0.86; 95% CI: −0.42, 2.26), low-density lipoprotein cholesterols (LDL-C) (WMD: 0.49; 95% CI: −0.75, 2.74), apolipoprotein A (WMD: −3.15; 95% CI: −16.12, 9.81), and apolipoprotein B (WMD: −0.73; 95% CI: −9.87, 8.41) concentrations. However, CLA supplementation significantly increased the density lipoprotein cholesterol (HDL-C) (WMD: −0.40; 95% CI: −0.72, −0.07) concentrations. Conclusion CLA supplementation significantly improved HDL-C concentrations, however, increased concentrations of TG, TC, LDL-C, apolipoprotein A, and apolipoprotein B. Systematic review registration https://www.crd.york.ac.uk/prospero/#recordDetails, identifier: CRD42022331100.
... In contrast, studies in mice show that dietary CLA10,12 increases the expression and circulating levels of inflammatory mediators and macrophage infiltration into adipose tissue [20,21]. Clinical trials also show inconsistent results, with some studies reporting that CLA10,12 may have pro-inflammatory effects compared to CLA9,11 [22][23][24][25], while other studies show no effects and no differences between the CLAs [26,27]. ...
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Conjugated linoleic acid (CLA) isomers have been shown to possess anti-atherosclerotic properties, which may be related to the downregulation of inflammatory pathways in different cell types, including endothelial cells (ECs). However, whether different CLA isomers have different actions is not entirely clear, with inconsistent reports to date. Furthermore, in cell culture studies, CLAs have often been used at fairly high concentrations. Whether lower concentrations of CLAs are able to affect EC responses is not clear. The aim of this study was to evaluate the effects of two CLAs (cis-9, trans-11 (CLA9,11) and trans-10, cis-12 (CLA10,12)) on the inflammatory responses of ECs. ECs (EA.hy926 cells) were cultured under standard conditions and exposed to CLAs (1 to 50 μM) for 48 h. Then, the cells were cultured for a further 6 or 24 h with tumour necrosis factor alpha (TNF-α, 1 ng/mL) as an inflammatory stimulant. ECs remained viable after treatments with 1 and 10 μM of each CLA, but not after treatment with 50 μM of CLA10,12. CLAs were incorporated into ECs in a concentration-dependent manner. CLA10,12 increased the levels of ICAM-1, IL-6, and RANTES in the culture medium, while CLA9,11 had null effects. Both CLAs (1 μM) decreased the appearance of NFκB1 mRNA, but only CLA9,11 maintained this downregulation at 10 μM. CLA10,12 had no effect on THP-1 cell adhesion to ECs while significantly decreasing the percentage of ECs expressing ICAM-1 and also levels of ICAM-1 expression per cell when used at 10 µM. Although CLA9,11 did not have any effect on ICAM-1 cell surface expression, it reduced THP-1 cell adhesion to the EA.hy926 cell monolayer at both concentrations. In summary, CLA10,12 showed some pro-inflammatory effects, while CLA9,11 exhibited null or anti-inflammatory effects. The results suggest that each CLA has different effects in ECs under a pro-inflammatory condition, highlighting the need to evaluate the effects of CLA isomers independently.
... [34]. On the other hand, in a randomized human trial, intake of a VA-enriched diet for 5 weeks resulted in lower total and HDL cholesterol in healthy young men [35], while in another clinical trial, feeding both a CLA-and VA-supplemented diet found no changes in plasma lipids, insulin, or glucose in healthy young men [36]. Since lipoprotein profile in pigs is similar to humans (unlike rodents), our current swine model is a better model to study the mechanisms surrounding these findings for translation to humans. ...
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High-fat diets (HFD) have been shown to induce substantial shifts in intestinal microbial community composition and activity which are associated with adverse metabolic outcomes. Furthermore, changes in microbial composition are affected by fatty acid composition; saturated, monounsaturated (MUFA), and industrial trans fats (iTFA) adversely affect microbial diversity while polyunsaturated fats (PUFA) have been shown to have neutral effects. The effects of naturally occurring trans fats on gut microbial composition are unknown. Vaccenic acid (VA) is the most abundant naturally occurring trans fat (abundant in meat and dairy), can be elevated by altering a cow’s diet, and has been shown to have hypolipidemic effects. The aim of this study was to determine how variations of VA content in beef fat affect gut microbial composition, insulin resistance, and lipid metabolism in pigs. Low birth weight (LBW) and control pigs were fed a control or high-fat, high-carbohydrate (HFHC) diet supplemented with beef fat containing either high or low VA levels for 7 weeks. An adapted modified oral glucose tolerance test and fat challenge test were performed at 9 weeks of age following implantation of jugular catheters. Impacts on microbial composition were assessed using 16S rRNA gene amplicon sequencing. The HFHC diet containing beef fat rich in VA had a mild insulin sensitizing effect (p < 0.05, slope of curve), increased plasma HDL cholesterol (p < 0.05, +28%), reduced postprandial plasma TG (p < 0.05), and showed protection from HFHC-induced changes to gut microbial composition in LBW pigs as compared to HFHC diet containing standard beef fat. This is the first study to show effects of natural trans fats on gut dysbiosis; further studies are needed to elucidate mechanisms.
... In addition, many animal and cell culture studies have noted positive health effects of t11-18:1 including anti-inflammatory, anticarcinogenic, antiatherosclerotic, and antidiabetic effects (Field et al., 2009;Gebauer et al., 2011;Valenzuela et al., 2019). Clinical studies in humans, however, have shown that high levels of t11-18:1 may have similar adverse effects on blood low density lipoprotein-and high density lipoprotein-cholesterol compared with PHVO (Brouwer et al., 2010(Brouwer et al., , 2013Gebauer et al., 2015;Stender, 2015;Tholstrup et al., 2006;Tricon et al., 2006). In contrast to t11-18:1, very limited research has been done on effects of t10-18:1 due to its lack of commercial availability. ...
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Trans (t) fatty acids (TFA) from partially hydrogenated vegetable oils (i.e., industrial trans) have been phased out of foods in many countries due to their promotion of cardiovascular disease. This leaves ruminant-derived foods as the main source of TFA. Unlike industrial TFA where catalytic hydrogenation yields a broad distribution of isomers, ruminant TFA are enzymatically derived and can result in enrichment of specific isomers. Comparisons between industrial and ruminant TFA have often exonerated ruminant TFA due to their lack or at times positive effects on health. At extremes, however, ruminant-sourced foods can have either high levels of t10-or t11-18:1, and when considering enriched sources, t10-18:1 has properties similar to industrial TFA, whereas t11-18:1 can be converted to an isomer of conjugated linoleic acid (cis(c)9,-t11-conjugated linoleic acid), both of which have potential positive health effects. Increased t10-18:1 in meat-producing ruminants has not been associated with negative effects on live animal production or meat quality. As such, reducing t10-18:1 has not been of immediate concern to ruminant meat producers , as there have been no economic consequences for its enrichment; nevertheless at high levels, it can compromise the nutritional quality of beef and lamb. In anticipation that regulations regarding TFA may focus more on t10-18:1 in beef and lamb, the present review will cover its production, analysis, biological effects, strategies for manipulation, and regulatory policy.
... Blood samples were centrifuged, and plasma aliquots were stored at −80 °C for the measurement of lipid profile with an ILab600 chemical analyzer with kits supplied by Instrumentation Laboratory. 30 ...
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Background We have shown previously that low‐density lipoprotein (LDL) can be oxidized in the lysosomes of macrophages, that this oxidation can be inhibited by cysteamine, an antioxidant that accumulates in lysosomes, and that this drug decreases atherosclerosis in LDL receptor–deficient mice fed a high‐fat diet. We have now performed a regression study with cysteamine, which is of more relevance to the treatment of human disease. Methods and Results LDL receptor–deficient mice were fed a high‐fat diet to induce atherosclerotic lesions. They were then reared on chow diet and drinking water containing cysteamine or plain drinking water. Aortic atherosclerosis was assessed, and samples of liver and skeletal muscle were analyzed. There was no regression of atherosclerosis in the control mice, but cysteamine caused regression of between 32% and 56% compared with the control group, depending on the site of the lesions. Cysteamine substantially increased markers of lesion stability, decreased ceroid, and greatly decreased oxidized phospholipids in the lesions. The liver lipid levels and expression of cluster of differentiation 68, acetyl–coenzyme A acetyltransferase 2, cytochromes P450 (CYP)27, and proinflammatory cytokines and chemokines were decreased by cysteamine. Skeletal muscle function and oxidative fibers were increased by cysteamine. There were no changes in the plasma total cholesterol, LDL cholesterol, high‐density lipoprotein cholesterol, or triacylglycerol concentrations attributable to cysteamine. Conclusions Inhibiting the lysosomal oxidation of LDL in atherosclerotic lesions by antioxidants targeted at lysosomes causes the regression of atherosclerosis and improves liver and muscle characteristics in mice and might be a promising novel therapy for atherosclerosis in patients.
... In contrast, the results of other studies showed that cis-9, trans-11 CLA has extra beneficial effects, such as anti-inflammatory and antiatherogenic effects (Tricon et al. 2006). However, the mixture of the two CLA isomers (cis-9, trans-11 and trans-9, trans-11 CLA) had a synergistic anti-proliferation effect on a human colorectal carcinoma cell line (Zhong et al. 2012). ...
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Honeybees are the most important crop pollinators that contribute significantly to agricultural productivity and profitability worldwide. Microbiota accounts for up to 1–10% of the insect’s biomass. The intestine of European Honeybees, Apis mellifera, have diverse microbiota and are known to be occupied by approximately 70% Gram-negative bacteria, 27% Gram-positive bacteria, and 1% yeast. The native microbiota of the honeybees is known to contribute to their nutrition, growth, digestion, pathogens defense, and insecticide resistance. As with other humans and animals, intestinal dysbiosis might greatly influence these insects’ health status posing a threat to their safe existence. Lactic acid bacteria (LAB) have been discovered in abundance in the honeybee gut and are believed to be of great importance to the honeybee health. Among several symbiotic LAB species isolated from the digestive tract of honeybees, it is found that some of them have the potential to be developed as probiotics. One of the most important health benefits of probiotic LAB in honeybees is their ability to protect against several bee pathogens and contribute to honey’s antimicrobial properties. Hence, the use of probiotics in beekeeping could prevent diseases, enhance bee health, and consequently increase honey production. Although probiotic bacteria isolated from different sources could be used for honeybees, using the host bacteria, i.e., the bacteria from the honeybees’ gut microbiome community would be more desirable for their own health. In this review study, we discuss the important aspects related to Apis mellifera gut microbiome such as composition, perturbation, fermentation, and most important of all, the probiotic bacterial community, mainly LAB species residing in the gut of these insects.
... In contrast, the results of other studies showed that cis-9, trans-11 CLA has extra beneficial effects, such as anti-inflammatory and antiatherogenic effects (Tricon et al. 2006). However, the mixture of the two CLA isomers (cis-9, trans-11 and trans-9, trans-11 CLA) had a synergistic anti-proliferation effect on a human colorectal carcinoma cell line (Zhong et al. 2012). ...
Chapter
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