Metabolism of trans fatty acids with emphasis on the effects of trans, trans-octadecadienoate on lipid composition, essential fatty acid, and prostaglandins: an overview

Biomimetic Metal-Organic Nanotubular Host for Straight-Chain Fatty Acids Recognition

Subtle structural variations among fatty acids significantly influence their biological roles and health effects. However, molecular recognition of their long, flexible, and chemically inert hydrocarbon chains remains a challenge. Inspired by natural fatty acid-binding proteins (FABPs), we designed and synthesized nanotubular metallo-cavitands, termed metal-organic pillars, through the coordination-driven assembly of pillararene-derived ligands with Ag(I) salts. These biomimetic hosts feature continuous interior channels exceeding 2.6 nm, selectively binding long-chain fatty acids through precise size and shape complementarity. Saturated and trans fatty acids, with linear conformations, are effectively encapsulated and stabilized by C-H···π and van der Waals interactions. In contrast, coiled cis-polyunsaturated fatty acids, such as docosahexaenoic acid (DHA), cannot be accommodated due to structural incompatibility. This work highlights the ability of artificial receptors to emulate the recognition capabilities of natural proteins, enabling the targeting of "bad" fatty acids associated with adverse health effects.

Elaidic acid induced hepatocyte pyroptosis via autophagy-CTSB-NLRP3 pathway

Elaidic acid (EA, C18:1 trans) is a kind of principal Trans fatty acid (TFA) and is widely found in processed food. Pyroptosis is a form of programmed cell death, distinct from apoptosis and traditional necrosis. Excessive pyroptosis could induce body injury and serious inflammation. However, the effect of EA on pyroptosis has not been reported. In the study, we found that EA exposure caused liver damage and hepatocyte pyroptosis by testing GSDMD-N, Caspase 1, IL-18, and IL-1β in mice and HepG2 cells. Further exploring the mechanisms, we found that EA-induced pyroptosis depended on Cathepsin B (CTSB)-mediated NLRP3 inflammasome activation. Cell autophagy was closely related to lysosomes. Our study revealed that EA promoted hepatocyte autophagy, and activated autophagy induced lysosomal membrane permeabilization (LMP) and CTSB leakage. Inhibition of autophagy by 3-MA mitigated the CTSB leak, reduced the activation of the NLRP3 inflammasome, and then attenuated the EA-induced pyroptosis. In summary, these results indicated that EA induced hepatocyte pyroptosis via autophagy-CTSB-NLRP3 inflammasome pathway. The study revealed new insights into the toxicity mechanism of EA.

The Association Between Circulating Trans Fatty Acids and Thyroid Function Measures in U.S. Adults

BACKGROUND

There has been controversial evidence regarding the effect of trans fatty acids (TFAs) on thyroid function in animal studies, and the epidemiological studies are lacking. We aimed to investigate the potential associations between circulating TFAs and thyroid function biomarkers in a U.S. adult population sample.

METHODS

We performed a cross-sectional survey with 626 adults aged ≥20 years who participated in the National Health and Nutrition Examination Survey (NHANES) 2009-2010. Multivariable linear regression models were constructed to elucidate the relationships between circulating concentrations of TFAs (palmitelaidic acid, vaccenic acid, elaidic acid, linoelaidic acid and the sum of the four TFAs) and a panel of thyroid function measures.

RESULTS

For 626 adults, positive associations were found between palmitelaidic acid, elaidic acid and total thyroxine (TT4), between palmitelaidic acid and total triiodothyronine (TT3), and between linolelaidic acid and thyroid stimulating hormone (TSH), while linolelaidic acid was negatively associated with free thyroxine (FT4) (all P<0.05). Besides, the four TFAs and the sum TFAs were positively associated with free triiodothyronine (FT3). Vaccenic acid, elaidic acid, linoelaidic acid and the sum TFAs were positively associated with FT3/FT4, while the four TFAs and the sum TFAs were negatively associated with FT4/TT4 (all P<0.05). In stratified analysis, the associations between thyroid function measures and the ratios remained significant in female. For men, linolelaidic acid was negatively associated with FT4 and elaidic acid and the sum TFAs were positively associated with FT3. Furthermore, the associations between TFAs and FT3/FT4 remained significant.

CONCLUSION

Our findings revealed that TFAs exposure was associated with serum biomarkers of thyroid function. More researches are needed to evaluate the long-term health outcomes of these findings.

Association of long-term consumption of repeatedly heated mix vegetable oils in different doses and hepatic toxicity through fat accumulation

BACKGROUND

Hepatic diseases are one of the chief reasons for worldwide morbidity and mortality. The increased incidence in Asian countries is driving researchers to explore preventive ways from nature. It is more practical to go with healthy routine edibles like vegetable oils to avoid environmental and chemical hepatic injuries. With the use of thermally oxidized oils overproduction of reactive oxygen species (ROS) with overwhelmed cellular antioxidants defense system results in oxidative stress, the known cause of cardiovascular diseases (CVDs), cancers and neurodegenerative disorders. Little is investigated about the effect of daily used oxidized cooking oils on hepatic function changes with oxidative stress especially in the animal model that mimics the human situation.

METHODS

In this study, healthy adult male rabbits of local strain were divided into 4 groups (n = 12). First, two sets of rabbits were treated with 1 and 2 ml/kg/day of repeatedly heated mix vegetable oils (RHMVO) respectively. The third set of rabbits was given 1 ml/kg/day of single time heated mix vegetable oils (STHMVO) and the fourth set of rabbits served as controls and fed with normal rabbit diet to for 16 weeks. Serum liver function markers including total-protein, albumin, serum glutamic-oxaloacetic transaminase (SGOT), serum glutamic-pyruvic transaminase (SGPT) and alkaline phosphatase (ALP) along with the activity of hepatic antioxidant-enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and malondialdehyde (MDA) for lipid peroxidation were compared among different groups of rabbits. Histopathological examination was performed for all four groups.

RESULTS

Significantly (p < 0.05) elevated hepatic enzymes and MDA levels, with lower total protein, serum albumin, GPx, SOD and CAT levels were found in high and low doses RHMVO treated groups, in comparison to control. In the STHMVO group, all mentioned markers were insignificantly changed. Accumulation of liver fat in low and high dose oil-treated groups was further confirmed under the microscopic examination of liver tissues, presented significant fat accumulation in liver tissues, in addition, 40-60% increased oxidative stress compared to control, in a dose-dependent manner.

CONCLUSIONS

These results conclude that consumption of thermally oxidized mix vegetable oils for longer duration can impair the liver function and destroy its histological structure significantly through fat accumulation and oxidative stress both in high as well as low doses.

Correlation of trans fatty acids with the severity of coronary artery disease lesions

BACKGROUND

Nutritional choices, which include the source of dietary fatty acids (FA), have an important significant impact on coronary artery disease (CAD). We aimed to determine on patients with CAD the relationships between Trans fatty acids (Trans FA) and different CAD associated parameters such as inflammatory and oxidative stress parameters in addition to Gensini score as a vascular severity index.

METHODS

Fatty acid profiles were established by gas chromatography from 111 CAD patients compared to 120 age-matched control group. Lipid peroxidation biomarkers, oxidative stress, inflammatory parameters and Gensini score were studied.

RESULTS

Our study showed a significant decrease of the antioxidant parameters levels such as erythrocyte glutathione peroxydase (GPx) and superoxide dismutase (SOD) activities, plasma antioxidant status (FRAP) and thiol (SH) groups in CAD patients. On the other hand, catalase activity, conjugated dienes and malondialdehyde were increased. Plasmatic and erythrocyte Trans FA were also increased in CAD patients compared to controls. Furthermore, divergent associations of these Trans FA accumulations were observed with low-density lipoprotein-cholesterol/ high-density lipoprotein-cholesterol (LDL-C/HDL-C) ratio, Apolipoprotein B (ApoB), lipid peroxidation parameters, high-sensitivity C Reactive Protein (hs-CRP), Interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α) and Gensini score. Especially, elaidic acid (C18:1 trans 9), trans C18:2 isomers and trans 11 eicosanoic acid are correlated with these parameters. Trans FA are also associated with oxidative stress, confirmed by a positive correlation between C20:1 trans 11 and GPx in erythrocytes.

CONCLUSIONS

High level of Trans FA was highly associated with the induction of inflammation, oxidative stress and lipoperoxidation which appear to be based on the vascular severity and might be of interest to assess the stage and progression of atherosclerosis. The measurement of these Trans FA would be of great value for the screening of lipid metabolism disorders in CAD patients.

The effects of trans-fatty acids on TAG regulation in mice depend on dietary unsaturated fatty acids

The aim of this study was to investigate the effects of trans-fatty acids (TFA) on liver and serum TAG regulation in mice fed diets containing different proportions of n-3, n-6 and n-9 unsaturated fatty acids (UFA) from olive (O), maize (C) or rapeseed (R) oils partially substituted or not with TFA (Ot, Ct and Rt, respectively). Male CF1 mice were fed (30 d) one of these diets. The effects of the partial substitution (1 %, w/w) of different UFA with TFA on the activity and expression of hepatic enzymes involved in lipogenesis and fatty acids oxidation were evaluated, as well as their transcription factor expressions. Some of the mechanisms involved in the serum TAG regulation, hepatic VLDL rich in TAG (VLDL-TAG) secretion rate and lipoprotein lipase (LPL) activity were assessed. In liver, TFA induced an increase in TAG content in the Ot and Rt groups, and this effect was associated with an imbalance between lipogenesis and β-oxidation. In the Ot group, exacerbated lipogenesis may be one of the mechanisms responsible for the liver steatosis induced by TFA, whereas in Rt it has been related to a decreased β-oxidation, compared with their respective controls. The enhanced hepatic VLDL-TAG secretion in the Ot and Rt groups was compensated with a differential removal of TAG by LPL enzyme in extrahepatic tissues, leading to unchanged serum TAG levels. In brief, the effects of low levels of TFA on liver and serum TAG regulation in mice depend on the dietary proportions of n-3, n-6 and n-9 UFA.

Blood fatty acid patterns are associated with prostate cancer risk in a prospective nested case-control study

BACKGROUND

Circulating fatty acids are highly correlated with each other, and analyzing fatty acid patterns could better capture their interactions and their relation to prostate cancer. We aimed to assess the associations between data-derived blood fatty acid patterns and prostate cancer risk.

METHODS

We conducted a nested case-control study in the Physicians' Health Study. Fatty acids levels were measured in whole blood samples of 476 cases and their matched controls by age and smoking status. Fatty acid patterns were identified using principal component analysis. Conditional logistic regression was used to estimate odds ratio (OR) and 95 % confidence interval (CI).

RESULTS

Two patterns explaining 40.9 % of total variation in blood fatty acid levels were identified. Pattern 1, which mainly reflects polyunsaturated fatty acid metabolism, was suggestively positively related to prostate cancer risk (ORquintile 5 vs. quintile 1 = 1.37, 95 % CI = 0.91-2.05, P trend = 0.07). Pattern 2, which largely reflects de novo lipogenesis, was significantly associated with higher prostate cancer risk (ORquintile5 vs. quintile1 = 1.63, 95 % CI = 1.04-2.55, P trend = 0.02). This association was similar across tumor stage, grade, clinical aggressiveness categories and follow-up time.

CONCLUSION

The two patterns of fatty acids we identified were consistent with known interactions between fatty acid intake and metabolism. A pattern suggestive of higher activity in the de novo lipogenesis pathway was related to higher risk of prostate cancer.

Lipotoxicity: effects of dietary saturated and transfatty acids

The ingestion of excessive amounts of saturated fatty acids (SFAs) and transfatty acids (TFAs) is considered to be a risk factor for cardiovascular diseases, insulin resistance, dyslipidemia, and obesity. The focus of this paper was to elucidate the influence of dietary SFA and TFA intake on the promotion of lipotoxicity to the liver and cardiovascular, endothelial, and gut microbiota systems, as well as on insulin resistance and endoplasmic reticulum stress. The saturated and transfatty acids favor a proinflammatory state leading to insulin resistance. These fatty acids can be involved in several inflammatory pathways, contributing to disease progression in chronic inflammation, autoimmunity, allergy, cancer, atherosclerosis, hypertension, and heart hypertrophy as well as other metabolic and degenerative diseases. As a consequence, lipotoxicity may occur in several target organs by direct effects, represented by inflammation pathways, and through indirect effects, including an important alteration in the gut microbiota associated with endotoxemia. Interactions between these pathways may perpetuate a feedback process that exacerbates an inflammatory state. The importance of lifestyle modification, including an improved diet, is recommended as a strategy for treatment of these diseases.

Ecological-level associations between highly processed food intakes and plasma phospholipid elaidic acid concentrations: results from a cross-sectional study within the European prospective investigation into cancer and nutrition (EPIC)

Elaidic acid is the main unnatural trans fatty acid isomer occurring during partial hydrogenation of vegetable oils used as ingredients for the formulation of processed foods. The main objective is to assess associations between processed food intakes and plasma phospholipid elaidic acid concentrations within the European Prospective Investigation into Cancer and Nutrition study. A cross-sectional study was used to determine fatty acid profiles in 3,003 subjects from 16 centers. Single 24-h dietary recalls (24-HDR) were collected using a standardized computerized interview program. Food intakes were computed according to their degree of processing (moderately/nonprocessed foods, processed staple foods, highly processed foods). Adjusted ecological and individual correlations were calculated between processed food intakes and plasma elaidic acid levels. At the population level, mean intakes of highly processed foods were strongly correlated with mean levels of plasma elaidic acid in men (P = 0.0016) and in women (P = 0.0012). At the individual level, these associations remained but at a much lower level in men (r = 0.08, P = 0.006) and in women (r = 0.09, P = 0.0001). The use of an averaged 24-HDR measure of highly processed food intakes is adequate for predicting mean levels of plasma elaidic acid among European populations.

The intake of high fat diet with different trans fatty acid levels differentially induces oxidative stress and non alcoholic fatty liver disease (NAFLD) in rats

BACKGROUND

Trans-fatty acids (TFA) are known as a risk factor for coronary artery diseases, insulin resistance and obesity accompanied by systemic inflammation, the features of metabolic syndrome. Little is known about the effects on the liver induced by lipids and also few studies are focused on the effect of foods rich in TFAs on hepatic functions and oxidative stress. This study investigates whether high-fat diets with different TFA levels induce oxidative stress and liver dysfunction in rats.

METHODS

Male Wistar rats were divided randomly into four groups (n = 12/group): C receiving standard-chow; Experimental groups that were fed high-fat diet included 20% fresh soybean oil diet (FSO), 20% oxidized soybean oil diet (OSO) and 20% margarine diet (MG). Each group was kept on the treatment for 4 weeks.

RESULTS

A liver damage was observed in rats fed with high-fat diet via increase of liver lipid peroxidation and decreased hepatic antioxidant enzyme activities (superoxide dismutase, catalase and glutathione peroxidase). The intake of oxidized oil led to higher levels of lipid peroxidation and a lower concentration of plasma antioxidants in comparison to rats fed with FSO. The higher inflammatory response in the liver was induced by MG diet. Liver histopathology from OSO and MG groups showed respectively moderate to severe cytoplasm vacuolation, hypatocyte hypertrophy, hepatocyte ballooning, and necroinflammation.

CONCLUSION

It seems that a strong relationship exists between the consumption of TFA in the oxidized oils and lipid peroxidation and non alcoholic fatty liver disease (NAFLD). The extent of the peroxidative events in liver was also different depending on the fat source suggesting that feeding margarine with higher TFA levels may represent a direct source of oxidative stress for the organism. The present study provides evidence for a direct effect of TFA on NAFLD.

Dietary fatty acids and the risk of hypertension in middle-aged and older women

Dietary intake of various fats may have different effects on blood pressure. We conducted a prospective cohort study to examine the association between intake of subtype and individual fatty acids (FAs) and the risk of developing hypertension among 28 100 US women aged ≥39 years and free of cardiovascular disease and cancer. Baseline intake of FAs was assessed using semiquantitative food frequency questionnaires. Incident hypertension was identified from annual follow-up questionnaires based on self-reported physician diagnosis, medication use, and blood pressure levels. A total of 13 633 women developed incident hypertension during 12.9 years of follow-up. After adjusting for demographic, lifestyle, and other dietary factors, intake of saturated FAs, monounsaturated FAs, and trans-unsaturated FAs (trans FAs) was positively associated with the risk of hypertension. The multivariable relative risks and 95% CIs of hypertension in the highest compared with the lowest quintile of intake were 1.12 (1.05 to 1.20) for saturated FAs, 1.11 (1.04 to 1.18) for monounsaturated FAs, and 1.15 (1.08 to 1.22) for trans FAs. After additional adjustment for body mass index and history of diabetes mellitus and hypercholesterolemia, these associations were attenuated and remained statistically significant only for trans FAs (relative risk in the highest quintile: 1.08; 95% CI: 1.01 to 1.15). Intake of polyunsaturated FAs, including ω3 and ω6 polyunsaturated FAs, was not significantly associated with the risk of hypertension. In conclusion, higher intake of saturated FAs, monounsaturated FAs, and trans FAs was each associated with increased risk of hypertension among middle-aged and older women, whereas only association for trans FAs remained statistically significant after adjustment for obesity-related factors.

Venous thrombosis risk: effects of palm oil and hydrogenated fat diet in rats

OBJECTIVE

We tested whether diets containing partially hydrogenated fat (PHVO, rich in trans fatty acids) or palm oil (PO, rich in saturated fat-C16 palmitic fatty acid) had different effects on the propensity for venous thrombosis, a marker of haemostatic cardiovascular risk.

METHODS

Female Wistar rats were fed normolipidic diets containing PHVO or PO during lactation, and their young male pups were fed the same diets from weaning until the 180th day of life. We evaluated platelet fatty acid composition, serum lipids, platelet aggregation, clotting time, and venous thrombus formation.

RESULTS

A significant and cumulative incorporation of trans fatty acid was observed only in the platelet lipids from the PHVO group, associated with an increased sensitivity to adenosine diphosphate (ADP) and venous thrombus formation in vivo. Platelets from rats raised on the PO diet also exhibited platelet aggregation induced by ADP and an increase in venous thrombus weight, with a concomitant increase in serum triglycerides.

CONCLUSION

The prolonged replacement of dietary hydrogenated fat by PO impaired platelet aggregability and venous thrombosis, suggesting an increased risk of thromboembolic diseases.

n-3 fatty acids prevent whereas trans-fatty acids induce vascular inflammation and sudden cardiac death

n-3 PUFA have well-recognised cardio-beneficial effects. In contrast, premature coronary deaths are associated with consumption of high levels of trans-fatty acids (TFA). The present study determined the effects of n-3 PUFA and TFA on sudden cardiac death and vascular inflammation. A rat coronary ligation model was used to study the effect of fatty acids on sudden cardiac death, whereas a mouse femoral artery ligation model was used to study compensatory vascular remodelling. Human aortic endothelial cells (HAEC) were utilised for the in vitro studies to investigate expression of inflammatory molecules. Feeding animals an n-3 PUFA-enriched diet caused a sevenfold increase in plasma n-3 PUFA compared with that of the TFA-fed group, whereas a TFA-enriched diet caused a 2.5-fold increase in plasma TFA compared with the n-3 PUFA group. Animals on a TFA diet had a lower survival rate due to sudden cardiac death and exhibited variable degrees of aortic atherosclerotic lesions. Animals on a TFA diet had diminished hindlimb collateral growth, whereas animals on the n-3 PUFA diet exhibited extensive collateral growth about ligated regions. HAEC treated with TFA (trans-18 : 2) showed significantly increased expression of intracellular adhesion molecule-1 and nitrosylation of cellular proteins than those treated with DHA (n-3 PUFA, 22 : 6). The in vivo study demonstrates that, in contrast to TFA, n-3 PUFA improve animal survival after myocardial infarction, prevent development of atherosclerotic lesions and stimulate compensatory vascular remodelling. The in vitro study demonstrates that TFA induce, while n-3 PUFA prevent, vascular inflammation.

Metabolic implications of dietary trans-fatty acids

Dietary trans-fatty acids are associated with increased risk of cardiovascular disease and have been implicated in the incidence of obesity and type 2 diabetes mellitus (T2DM). It is established that high-fat saturated diets, relative to low-fat diets, induce adiposity and whole-body insulin resistance. Here, we test the hypothesis that markers of an obese, prediabetic state (fatty liver, visceral fat accumulation, insulin resistance) are also worsened with provision of a low-fat diet containing elaidic acid (18:1t), the predominant trans-fatty acid isomer found in the human food supply. Male 8-week-old Sprague-Dawley rats were fed a 10% trans-fatty acid enriched (LF-trans) diet for 8 weeks. At baseline, 3 and 6 weeks, in vivo magnetic resonance spectroscopy (1H-MR) assessed intramyocellular lipid (IMCL) and intrahepatic lipid (IHL) content. Euglycemic-hyperinsulinemic clamps (week 8) determined whole-body and tissue-specific insulin sensitivity followed by high-resolution ex vivo 1H-NMR to assess tissue biochemistry. Rats fed the LF-trans diet were in positive energy balance, largely explained by increased energy intake, and showed significantly increased visceral fat and liver lipid accumulation relative to the low-fat control diet. Net glycogen synthesis was also increased in the LF-trans group. A reduction in glucose disposal, independent of IMCL accumulation was observed in rats fed the LF-trans diet, whereas in rats fed a 45% saturated fat (HF-sat) diet, impaired glucose disposal corresponded to increased IMCLTA. Neither diet induced an increase in IMCLsoleus. These findings imply that trans-fatty acids may alter nutrient handling in liver, adipose tissue, and skeletal muscle and that the mechanism by which trans-fatty acids induce insulin resistance differs from diets enriched with saturated fats.

A influência dos ácidos graxos trans na disfunção da célula endotelial e o possível efeito terapêutico do exercício sobre o tecido endotelial como forma de prevenção ou regressão da aterosclerose

O endotélio atua ativamente na regulação do tônus vascular, sintetizando e liberando substâncias vasoativas. A inflamação e os fatores de risco cardiovasculares alteram a homeostase vascular, levando à disfunção endotelial e possível formação de placas de ateroma. O aumento das concentrações plasmáticas de ácidos graxos livres pode causar lipotoxicidade vascular, disfunção do endotélio e, finalmente, aterosclerose. Dieta rica em lipídeos contendo ácidos graxos trans tem correlação positiva com a progressão de doenças cardiovasculares. Mudanças no estilo de vida, na adoção de dieta balanceada e atividade física são estratégias para a prevenção de doenças cardiovasculares e a reabilitação de pacientes. Nesta revisão, discutimos a influência benéfica do exercício físico em aspectos importantes da disfunção endotelial causados pelos ácidos graxos trans, incluindo evidências recentes e/ou ainda não exploradas. Discutimos também quais seriam os mecanismos envolvidos no comprometimento funcional da célula endotelial frente ao aumento de ácidos graxos trans na circulação.

Perfil lipídico tecidual de ratos alimentados com diferentes fontes lipídicas

OBJETIVO:Determinar se fontes lipídicas com diferentes razões de ácidos graxos insaturados e saturados (PUFA+MUFA)/SFA na dieta altera o perfil lipídico tecidual, a concentração de lipídios (mg/g) dos tecidos hepáticos e mesentérico e a digestibilidade lipídica. MÉTODOS: Foi realizada cromatografia gasosa para determinar o perfil de ácidos graxos nos tecidos hepático e adiposo de ratos alimentados com diferentes fontes lipídicas. O coeficiente de digestibilidade foi determinado a partir da relação entre a quantidade de lipídios consumidos e a quantidade fecal excretada. RESULTADOS:Diferentes fontes lipídicas (óleo de soja, manteiga, margarina e gorduras de porco e de peixe) não alteraram o coeficiente de digestibilidade e o peso hepático, mas alteraram a deposição de lipídios em todos os tecidos adiposos estudados. Não foi possível fazer a correlação direta entre o perfil dietário dos ácidos graxos não essenciais e sua deposição nos tecidos estudados, visto que a lipogênese de novo impede a identificação dos ácidos graxos dietários. CONCLUSÃO:Não foi constatada uma relação direta entre o perfil dietário dos ácidos graxos e sua deposição nos tecidos estudados, exceto para os ácidos graxos trans e linoléico (C18:2) que não são sintetizados no rato. Esses ácidos graxos apresentaram uma concentração tecidual diretamente proporcional àquela das fontes dietárias. Quanto à razão (PUFA+MUFA)/SFA, encontrada no tecido hepático dos diferentes grupos, observa-se que esta foi diretamente proporcional aos valores apresentados pelas fontes lipídicas dietárias. Entretanto, essa associação não foi observada nos tecidos adiposos analisados.

Ancient and modern duplication events and the evolution of stearoyl-CoA desaturases in teleost fishes

Stearoyl-CoA desaturases (SCDs) are key enzymes of fatty acid biosynthesis whose regulation underpins responses to dietary, thermal, and hormonal treatment. Although two isoforms are known to exist in the common carp and human and four in mouse, there is no coherent view on how this gene family evolved to generate functionally diverse members. Here we identify numerous new SCD homologs in teleost fishes, using sequence data from expressed sequence tag (EST) and cDNA collections and genomic model species. Phylogenetic analyses of the deduced coding sequences produced only partially resolved molecular trees. The multiple SCD isoforms were, however, consistent with having arisen by an ancient gene duplication event in teleost fishes together with a more recent duplication in the tetraploid carp and possibly also salmonid lineages. Critical support for this interpretation comes from comparison across all vertebrate groups of the gene order in the genomic environments of the SCD isoforms. Using syntenically aligned chromosomal fragments from large-insert clones of common carp and grass carp together with those from genomically sequenced model species, we show that the ancient and modern SCD duplication events in the carp lineage were each associated with large chromosomal segment duplications, both possibly linked to whole genome duplications. By contrast, the four mouse isoforms likely arose by tandem duplications. Each duplication in the carp lineage gave rise to differentially expressed SCD isoforms, either induced by cold or diet as previously shown for the recent duplicated carp isoforms or tissue specific as demonstrated here for the ancient duplicate zebrafish isoforms.

Trans fatty acids and cardiovascular health: translation of the evidence base

BACKGROUND AND AIM

The recent interest in the development of evidence-based nutrition recommendations has resulted in the development of frameworks which enable a more structured evaluation of the link between diet and chronic disease. This paper examines the application of the frameworks produced by the Scottish Intercollegiate Guidelines Network (SIGN) and the World Cancer Research Fund (WCRF), by using as a case study the association between trans unsaturated fatty acids (TFAs) and coronary heart disease. TFAs arise during industrial hydrogenation of vegetable or fish fats and oils and the natural digestion process in ruminant animals.

DATA SYNTHESIS

Numerous studies have examined the effects of TFA intake on serum lipids and lipoproteins and the association between TFA consumption and cardiovascular disease. Metabolic studies and meta-analyses show a clear and consistent association between increasing TFA intakes and an adverse lipid profile. Evidence from case-control and prospective cohort studies examining the association between TFA intakes and coronary heart disease is more heterogeneous and there are limitations in several of the studies.

CONCLUSION

While the evidence is sufficient to suggest a probable positive association between TFAs and coronary heart disease, and thus to justify a firm recommendation for a reduction in dietary TFA intake, the evaluation of the data underlines the difficulties in extrapolating the principles of evidence-based medicine to evidence-based nutrition. Furthermore, there is a paucity of research into the effects of animal-derived TFAs in amounts typically consumed in a western diet and their association with adverse lipid profiles or cardiovascular outcomes.

Effect of radical stress and ageing on the occurrence of trans fatty acids in rats fed a trans-free diet

In a previous paper, we demonstrated that tissue trans fatty acids can not only derive from the diet but also be endogenously formed. The central focus of this study was to prove that the in vivo isomerization occurs via a radical process. Two different models of radical insult were used: CCl(4) and AAPH injection to rats fed a diet completely free of trans isomers. Following this acute radical stress, a significant increase in unnatural trans fatty acid content of erythrocyte, kidney, and heart, but not liver, was observed. These results can be mainly explained by the high content, particularly in the liver, of antioxidant vitamins A and E that exhibit also an "anti-isomerizing" effect. Since during ageing cellular components are exposed to increasing radical insults, the observation of a significant trans fatty acid accumulation in 30-month-old rats could confirm that the in vivo formation of unnatural isomers is due to a radical process. Trans fatty acids can influence the physical characteristics of bilayer microdomains, affecting membrane properties and functions; thus, knowledge of biological radical species responsible for cis/trans isomerization and their possible sources can provide protective systems for preserving lipid geometry.

Dietary fat subgroups, zinc, and vegetable components are related to urine F2a-isoprostane concentration, a measure of oxidative stress, in midlife women

Smoking, diet, and physical activity may impact chronic diseases in part by promoting or attenuating oxidative stress. We evaluated associations between lifestyle factors and urine F(2a)-isoprostanes, a marker of oxidative stress in 1610 participants of the Study of Women's Health Across the Nation (SWAN). Dietary intake and physical activity were assessed at baseline and the 5th year 05 (Y05). These data were related to Y05 urinary F(2a)-isoprostane concentration with regression analyses. Median urine F(2a)-isoprostane concentration was 433 ng/L overall, 917 ng/L in smokers [inter-quartile range (IQR): 467, 1832 ng/L], and 403 ng/L in nonsmokers (IQR: 228, 709 ng/L; P < 0.0001 for difference). Higher trans fat intake was associated with higher urine F(2a)-isoprostane concentration; partial Spearman correlations (rho(x|y)) between Y05 urine F(2a)-isoprostane concentration and trans fatty acids was 0.19 (P = 0.03) in smokers and 0.13 (P < 0.0001) in nonsmokers. Increased log trans fat intake from baseline to Y05 was associated with higher concentration of log urine F(2a)-isoprostanes in nonsmokers (beta = 0.131, SE = 0.04, P = 0.0003). In nonsmokers, the partial correlation (rho(x|y)) between lutein and urine F(2a)-isoprostane concentration was -0.13 (P < 0.0001). Increased intake of log lutein from baseline to Y05 was also associated with lower log urine F(2a)-isoprostane concentration (beta = -0.096, SE = 0.03, P = 0.0005) in nonsmokers. Increased zinc intake from baseline to Y05 was associated with lower log urine F(2a)-isoprostane concentration in smokers and nonsmokers (beta = -0.346, SE = 0.14, P = 0.01), and -0.117, 0.04 (P = 0.001), respectively]. In conclusion, diet (fat subtypes, zinc, and vegetable components) and smoking were associated with urine F(2a)-isoprostanes, a marker of oxidative stress.

Trans-fatty acids induce pro-inflammatory responses and endothelial cell dysfunction

Epidemiological data indicate that there is a strong association between intake of trans-18 : 2 fatty acids (TFA) and sudden cardiac death. There is little known about the mechanisms by which TFA exert harmful effects on the cardiovascular system. The present in vitro study is the first to demonstrate the effects of membrane-incorporated C18 : 2 TFA on human aortic endothelial cell (HAEC) function. Trans-18 : 2 fatty acids were incorporated to a greater extent (2-fold) in the phospholipid fraction of endothelial cells than that of cis-18 : 2; furthermore, these fatty acids were enriched to a similar extent in the TAG fraction. Flow cytometric analysis indicated that TFA treatment of HAEC significantly increased the expression of endothelial adhesion molecules, including intercellular adhesion molecule-1 (CD54) and vitronectin receptor (CD51/CD61). Incorporation of TFA into membranes increased HAEC adhesion to fibronectin- or vitronectin-coated plates by 1.5- to 2-fold, respectively. Neutrophil and monocyte adhesion to HAEC monolayers was nearly proportional to adhesion molecule expression. TFA treatment also induced the release of monocyte chemoattractant protein-1 by nearly 3-fold in non-stimulated HAEC. Furthermore, we examined the role of TFA on in vitro angiogenic assays. Chemotactic migration of TFA-treated HAEC toward sphingosine-1-phosphate (SPP) was significantly increased compared with controls. Conversely, capillary morphogenesis of TFA-treated HAEC was significantly inhibited in response to SPP, suggesting that TFA incorporation suppresses endothelial cell differentiation. In conclusion, these in vitro studies demonstrated that TFA play a role in the induction of pro-inflammatory responses and endothelial cell dysfunction.

A Prospective Study of Trans Fatty Acids in Erythrocytes and Risk of Coronary Heart Disease

Background— High consumption of trans fat has been linked to the risk of coronary heart disease (CHD). We assessed the hypothesis that higher trans fatty acid contents in erythrocytes were associated with an elevated risk of CHD in a nested case-control study among US women.

Methods and Results— Blood samples were collected from 32 826 participants of the Nurses’ Health Study from 1989 to 1990. During 6 years of follow-up, 166 incident cases of CHD were ascertained and matched with 327 controls. Total trans fatty acid content in erythrocytes was significantly correlated with dietary intake of trans fat (correlation coefficient=0.44, P <0.01) and was associated with increased plasma low-density lipoprotein cholesterol ( P for trend =0.06), decreased plasma high-density lipoprotein cholesterol concentrations ( P for trend <0.01), and increased plasma low-density lipoprotein to high-density lipoprotein ratio ( P for trend <0.01). After adjustment for age, smoking status, and other dietary and lifestyle cardiovascular risk factors, higher total trans fatty acid content in erythrocytes was associated with an elevated risk of CHD. The multivariable relative risks (95% confidence intervals) of CHD from the lowest to highest quartiles of total trans fatty acid content in erythrocytes were 1.0 (reference), 1.6 (0.7 to 3.6), 1.6 (0.7 to 3.4), and 3.3 (1.5 to 7.2) ( P for trend <0.01). The corresponding relative risks were 1.0, 1.1, 1.3, and 3.1 ( P for trend <0.01) for a total of 18:1 trans isomers and 1.0, 1.5, 2.5, and 2.8 ( P for trend <0.01) for a total of 18:2 trans isomers.

Conclusions— These biomarker data provide further evidence that high trans fat consumption remains a significant risk factor for CHD after adjustment for covariates.

Determination of membrane lipid differences in insulin resistant diabetes mellitus type 2 in whites and blacks

OBJECTIVES

Insulin resistance in diabetes mellitus type 2 (DM2) can result from membrane lipid alterations. Blacks are at a higher risk of developing DM2; therefore, we investigated whether membrane lipid differences exist between blacks and whites and if differences contribute to impaired insulin binding in diabetes.

METHODS

Subjects were recruited from four groups: white control (n = 10), black control (n = 10), white diabetic (n = 5), and black diabetic (n = 10). Diabetic subjects who had DM2 with insulin resistance on insulin monotherapy were matched by age and sex. The following determinations were made: fasting serum glucose, fasting serum insulin, plasma lipid profile, red blood cell (RBC) membrane lipids and cholesterol, and RBC insulin binding.

RESULTS

The membrane lipid analysis showed racial differences in phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC). The plasma membrane of whites showed higher PE and lower PC levels than that in blacks. The RBC rheologic (PE/phosphatidyl serine) properties (deformability) were lower in diabetics and black subjects. The saturated nature of RBC ([sphingomyelin + PC)/(PE + phosphatidyl serine]) was the lowest in white control subjects (P < 0.056).

CONCLUSION

The combination of increased saturated/polyunsaturated fatty acids, increased saturated nature, and increased cholesterol/phospholipid can contribute to decreased membrane fluidity, resulting in insulin resistance. Also, decreased RBC deformability can make oxygen delivery through the capillaries difficult, create tissue hypoxia, and contribute to some of the known complications of diabetes. Membrane lipid alteration may be one of the reasons for a higher incidence of diabetes among blacks.

Occurrence of trans fatty acids in rats fed a trans-free diet: a free radical-mediated formation?

Trans isomers of unsaturated fatty acids are absorbed from the diet, due to their presence in diary fat and hydrogenated vegetable oils, and health concern has risen due to their effects on lipid risk factors in cardiovascular diseases. On the basis of the efficiency of the thiyl-radical-catalyzed cis/trans isomerization in vitro and the presence of many sulfur-containing compounds in the cell, the aim of this study was to demonstrate that trans geometry of lipid double bonds can be endogenously generated within membrane phospholipids. The study reports trans fatty acids occurrence in tissue and erythrocyte phospholipids of young adult rats fed a diet completely free of trans isomers. Results show that tissues are differently prone to the endogenous isomerization and that, following a free radical attack, trans fatty acids can reach very high amounts. The effectiveness of this process is considerably inhibited in the presence of all-trans retinol, confirming previous data in model membranes. Our results suggest that geometrical isomerization of unsaturated fatty acids, which causes a structural modification of membrane lipids and may influence basic membrane properties and vital biochemical functions, can occur under radical stress conditions and could be efficiently prevented by vitamin A.

Margarine consumption, asthma, and allergy in young adults: results of the German National Health Survey 1998

PURPOSE

To examine whether frequent intake of margarine is associated with allergy prevalence in adults using data of a representative national health survey.

METHODS

Data on 7124 subjects aged 18 to 79 years were obtained from the German National Health Survey 1998. Confounder-adjusted odds ratios (aOR) with 95% confidence intervals (CI) were calculated by multiple logistic regression, using the frequency of intake of low-fat butter, regular and low-fat margarine as explanatory variable in relation to frequent intake of regular butter as reference group.

RESULTS

Frequent intake of margarine of any kind was positively associated with current asthma during the past 12 months in young adults aged 18 to 29 years (aOR, 2.33; 95% CI, 1.03-5.26). In subgroup analysis, the positive association was confined to frequent intake of low-fat margarine (4.51; 1.78-11.43) or the combination of low-fat margarine and low-fat butter (4.79; 1.84-12.44). Consumption of margarine of any kind was not related to hay fever, atopic dermatitis, and atopic sensitization to inhalant allergens.

CONCLUSIONS

Frequent intake of margarine rich in n-6 PUFA is not consistently associated with allergic diseases in adults. Other constituents of low-fat margarine or certain dietary habits and lifestyle factors, characterized by use of low-fat margarine, may be related to current asthma.

Response of apolipoprotein E*3‐Leiden transgenic mice to dietary fatty acids: combining liver proteomics with physiological data

Dietary fatty acids have a profound impact on atherosclerosis, but mechanisms are not fully understood. We studied the effects of a saturated fat diet supplemented with fish oil, trans10,cis12 conjugated linoleic acid (CLA), or elaidic acid on lipid and glucose metabolism and liver protein levels of APOE*3 Leiden transgenic mice, a model for lipid metabolism and atherosclerosis. Fish oil lowered plasma and liver cholesterol and triglycerides, plasma free fatty acids, and glucose but increased plasma insulin. CLA lowered plasma cholesterol but increased plasma and liver triglycerides, plasma beta-hydroxybutyrate, and insulin. Elaidic acid lowered plasma and liver cholesterol. Proteomics identified significant regulation of 65 cytosolic and 8-membrane proteins. Many of these proteins were related to lipid and glucose metabolism, and to oxidative stress. Principal component analysis revealed that fish oil had a major impact on cytosolic proteins, and elaidic acid on membrane proteins. Correlation analysis between physiological and protein data revealed novel clusters of correlated variables, among which a metabolic syndrome cluster. The combination of proteomics and physiology gave new insights in mechanisms by which these dietary fatty acids regulate lipid metabolism and related pathways, for example, by altering protein levels of long-chain acyl-CoA thioester hydrolase and adipophilin in the liver.

Lifestyle recommendations to prevent prostate cancer, part I: time to redirect our attention?

This article provides a foundation for clinicians willing to provide lifestyle change recommendations for the prevention of prostate cancer. In part II, more general and specific lifestyle recommendations will be provided. It is imperative to provide patients with realistic and practical recommendations that are not only consistent in the medical literature, but will improve overall compliance.

Dietary trans fatty acids and composition of human atheromatous plaques

Dietary fatty acids are incorporated into atheromatous plaques mainly in the form of cholesterol esters. Physicochemical properties of the plaque (e. g. mechanical strength) depend on its fatty acid composition. Trans isomers of unsaturated fatty acids (TFA) are known to reduce the availability of fatty acid precursors for the synthesis of anticoagulant PG(1) and PG(3) prostaglandins. The present study was undertaken to determine the content of trans isomers in atheromatous plaques and to search for correlations between trans isomers in the plaque and adipose tissue. Atheromatous plaques were obtained from 31 patients who underwent surgery due to atherosclerotic stenosis of the abdominal aorta, iliac or femoral arteries. Fatty acids were extracted and separated as methyl esters using gas chromatography (GC) with an internal standard. Correlations were searched for with statistical methods, taking the level of significance as p < 0.05. We found spatial and positional isomers of sixteen- and eighteen-carbon fatty acids in plaques and adipose tissue, with elaidic acid (C18:1 trans-9) being the most abundant. Every plaque and adipose tissue sample contained linolelaidic acid (C18:2 trans-9 trans-12) which is derived exclusively from linoleic acid, as well as conjugated dienes of linoleic acid (CLA) produced during oxidative processes. The presence of trans isomers of fatty acids in the atheromatous plaque seems to be of relevance to plaque formation. Of much concern is the detection of elaidic and linolelaidic acids which adversely affect the physiologically important metabolism of eicosanoids. The TFA pool in adipose tissue has little effect on the amount of these acids in the atheromatous plaque. Apparently, the presence of TFA in atheromatous plaques is the result of processes taking place during plaque formation and maturation.

Effect of different forms of dietary hydrogenated fats on LDL particle size

BACKGROUND

Dietary trans fatty acids (FAs), which are formed during the process of hydrogenating vegetable oil, are known to increase plasma LDL-cholesterol concentrations. However, their effect on LDL particle size has yet to be investigated.

OBJECTIVE

We investigated the effect of trans FA consumption on the electrophoretic characteristics of LDL particles.

DESIGN

Eighteen women and 18 men each consumed 5 experimental diets in random order for 35-d periods. Fat represented 30% of total energy intake in each diet, with two-thirds of the fat in the form of semiliquid margarine (0.6 g trans FAs/100 g fat), soft margarine (9.4 g trans FAs/100 g fat), shortening (13.6 g trans FAs/100 g fat), stick margarine (26.1 g trans FAs/100 g fat), or butter, which was low in trans FAs (2.6 g trans FAs/100 g fat) but rich in saturated fat. LDL particle size and distribution were characterized by nondenaturing, 2-16% polyacrylamide gradient gel electrophoresis.

RESULTS

Relative to the LDL particle size observed after consumption of the butter-enriched diet, LDL particle size decreased significantly and in a dose-dependent fashion with increasing amounts of dietary trans FAs (P < 0.001). Cholesterol concentrations in large (> 260 A) and medium-sized (255-260 A) LDL particles also increased proportionately to the amount of trans FAs in the diet.

CONCLUSION

Consumption of dietary trans FAs is associated with a deleterious increase in small, dense LDL, which further reinforces the importance of promoting diets low in trans FAs to favorably affect the lipoprotein profile.

Adipose tissue alpha-linolenic acid and nonfatal acute myocardial infarction in Costa Rica

BACKGROUND

Alpha-linolenic acid may protect against cardiovascular disease. We examined the association between adipose tissue alpha-linolenic acid and nonfatal acute myocardial infarction (MI) in a population-based case-control study in Costa Rica.

METHODS AND RESULTS

The 482 case patients with a first nonfatal acute MI and 482 population control subjects were matched by age, sex, and area of residence. Fatty acids were assessed by gas-liquid chromatography in adipose tissue samples collected from all subjects. ORs and 95% CIs were calculated from multivariate conditional logistic regression models. Subjects in the top quintiles of adipose tissue alpha-linolenic acid had a lower risk of MI than those in the lowest quintile: OR (95% CI), 1.00; 0.80 (0.52 to 1.24); 0.53 (0.34 to 0.82); 0.44 (0.28 to 0.67); and 0.37 (0.24 to 0.59); test for trend, P<0.0001. This association was strengthened after adjustment for established MI risk factors, including smoking, physical activity, income, and adipose tissue linoleic acid and trans fatty acids (OR for the top versus lowest quintile, 0.23; 95% CI, 0.10 to 0.50; test for trend, P<0.0001). Further adjustment for the intake of saturated fat, fiber, alcohol, and vitamin E did not change this association (OR for the top versus lowest quintile, 0.23; 95% CI, 0.10 to 0.55; test for trend, P<0.0001).

CONCLUSIONS

The inverse association observed between alpha-linolenic acid and nonfatal acute MI suggests that consumption of vegetable oils rich in alpha-linolenic acid confers important protection against cardiovascular disease.

High 18:2 trans-fatty acids in adipose tissue are associated with increased risk of nonfatal acute myocardial infarction in costa rican adults

Trans-fatty acid intake is associated with coronary heart disease (CHD), but the atherogenic potential of individual trans-fatty acids (FA) from partially hydrogenated oils (18:1 and 18:2) or meat and dairy products (16:1 and 18:1) is unclear. Incident cases (n = 482) of a first nonfatal myocardial infarction (MI) were matched with population controls (n = 482) for age, gender and area of residence, all living in Costa Rica. Trans-FA in adipose tissue samples were assessed by gas chromatography. Odds ratios (OR) and 95% confidence intervals were calculated from conditional logistic regression models. Total adipose tissue trans-fat was positively associated with risk of MI. After adjusting for established risk factors and other confounders, the OR by quintiles of total trans-fat were 1.00, 1.34, 2.05, 2.22 and 2.94 (P-test for trend < 0.01). This association was attributed mainly to 18:2 trans-FA that were abundant in both adipose tissue and in partially hydrogenated soybean oil, margarines and baked products used by this population; OR = 1.00, 0.96, 2.09, 3.51 and 5.05 (P-test for trend < 0.001). Adipose tissue 16:1 trans-FA were also associated with MI; OR = 1.00, 1.57, 1.39, 1.34 and 2.58 (P-test for trend < 0.05). An association with 18:1 trans-FA was not detected. High 18:2 trans-FA in adipose tissue are associated with increased risk of MI. Because the use of hydrogenated oils is increasing worldwide, consumers should be aware of the harmful effects of products containing partially hydrogenated oils.

Trans-fatty acids and colon cancer

Trans-fatty acids have been hypothesized to be carcinogenic, although there are limited data in humans testing this hypothesis. In this study, we examine the association between trans-fatty acids and colon cancer using data from a case (n = 1,993)-control (n = 2,410) study conducted in Utah, Northern California, and Minnesota. Dietary data were collected using a detailed diet history questionnaire, and nutrient values were generated from the Nutrition Coordinating Center nutrient database. After adjustment for other variables, including age at diagnosis, body size, physical activity, aspirin and/or nonsteroidal anti-inflammatory drug (referred to collectively as NSAIDs) use, energy intake, and dietary fiber and calcium, we found a weak association in women [odds ratio (OR) = 1.5, 95% confidence interval (CI) = 1.1-2.0] but not in men (OR = 1.2, 95% CI = 0.9-1.7); no increased risk was observed for the cis form of the fatty acids. For men and women, slightly stronger associations were observed in those > or = 67 years of age (OR = 1.4, 95% CI = 0.9-2.1 for men; OR = 1.6, 95% CI = 1.0-2.4 for women). Those who did not use NSAIDs were at a 50% greater risk of developing colon cancer when they consumed high levels of trans-fatty acids. Women who were estrogen negative, i.e., postmenopausal not taking hormone replace therapy, had a twofold increase in risk from high levels of trans-fatty acids in the diet, while women who were estrogen positive did not experience an increased risk of colon cancer, regardless of level of trans-fatty acids consumed. We believe that these data have important public health implications. It seems prudent to avoid consuming partially hydrogenated fats, since no increased risk was observed for the cis form of fatty acids, while suggestions of increased risk from trans-fatty acids exist for subsets of the population.

Cis-trans isomerization of polyunsaturated fatty acid residues in phospholipids catalyzed by thiyl radicals

Phospholipids containing trans-unsaturated fatty acid residues are the major products of the thiyl radical attack on L-alpha-phosphatidylcholine from soybean lecithin in homogeneous solution or in liposomes (LUVET). Thiyl radicals act as the catalyst for the cis-trans isomerization, and the number of catalytic cycles depends on the reaction conditions. The presence of approximately 0.2 mM oxygen does not influence the reaction outcome but accelerates the efficiency of cis-trans isomerization in homogeneous solution. Under these conditions, the PUFA peroxidation is found to be unimportant. A detailed study of the isomerization of methyl linoleate including product studies indicates the formation of a small amount of conjugated dienes that act as inhibitors. Indeed, all-trans-retinol substantially retarded the isomerization process.