title: Effects of stereospecific positioning of fatty acids in triacylglycerol structures in native and randomized fats: a review of their nutritional implications Intake of dietary saturated fatty acids and risk of type 2 diabetes in the European Prospective Investigation into Cancer and Nutrition-Netherlands cohort: associations by types, sources of fatty acids and substitution by macronutrients Differences in the prospective association between individual plasma phospholipid saturated fatty acids and incident type 2 diabetes: the EPIC-InterAct case-cohort study The Method Quality of Cross-Over Studies Involved in Cochrane Systematic Reviews Comparing effects of soybean oil- and palm olein-based mayonnaise consumption on the plasma lipid and lipoprotein profiles in human subjects: a double-blind randomized controlled trial with cross-over design Palm olein increases plasma cholesterol moderately compared with olive oil in healthy individuals. Effects of palm olein and olive oil on serum lipids in a Chinese population: a randomized, double-blind, cross-over trial. Stearic acid-rich interesterified fat and trans-rich fat raise the LDL/HDL ratio and plasma glucose relative to palm olein in humans Overfeeding Polyunsaturated and Saturated Fat Causes Distinct Effects on Liver and Visceral Fat Accumulation in Humans The effect of incorporating fat into different components of a meal on gastric emptying and postprandial blood glucose and insulin responses. Effects of products made from a high-palmitic acid, trans-free semiliquid fat or a high-oleic acid, low-trans semiliquid fat on the serum lipoprotein profile and on C-reactive protein concentrations in humans Influence of hydrogenated fat and butter on CVD risk factors: remnant-like particles, glucose and insulin, blood pressure and C-reactive protein. Effects of diets enriched in saturated (palmitic), monounsaturated (oleic), or trans (elaidic) fatty acids on insulin sensitivity and substrate oxidation in healthy adults.
abstract: Most studies on lipid lowering diets have focused on the total content of saturated , polyunsaturated and monounsaturated fatty acids . However , the distribution of these fatty acids on the triacylglycerol ( TAG ) molecule and the molecular TAG species generated by this stereospecificity are characteristic for various native dietary TAGs . Fat r and omization or interesterification is a process involving the positional redistribution of fatty acids , which leads to the generation of new TAG molecular species . A comparison between native and r and omized TAGs is the subject of this review with regards to the role of stereospecificity of fatty acids in metabolic processing and effects on fasting lipids and postpr and ial lipemia . The positioning of unsaturated versus saturated fatty acids in the sn-2 position of TAGs indicate differences in early metabolic processing and postpr and ial clearance , which may explain modulatory effects on atherogenecity and thrombogenecity . Both human and animal studies are discussed with implication s for human health Purpose The association between dietary saturated fatty acids ( SFA ) intake and  type 2 diabetes ( T2D )  remains unclear . This study aim ed at investigating the association between SFA intake and T2D risk based on ( 1 ) individual SFA ( differing in carbon chain length ) , ( 2 ) food sources of SFA and ( 3 ) the substituting macronutrients . Methods 37,421 participants from the European Prospect i ve Investigation into Cancer and Nutrition-Netherl and s ( EPIC-NL ) cohort were included in this study . Baseline dietary intake was assessed by a vali date d food frequency question naire . T2D risks were estimated by Cox regression models adjusted for non-dietary and dietary covariates . Results 893 incident T2D cases were documented during 10.1-year follow-up . We observed no association between total SFA and T2D risk . Marginally inverse associations were found for lauric acid ( HR per 1 SD of energy% , 95 % CI 0.92 , 0.85–0.99 ) , myristic acid ( 0.89 , 0.79–0.99 ) , margaric acid ( 0.84 , 0.73–0.97 ) , odd-chain SFA ( pentadecylic plus margaric acids ; 0.88 , 0.79–0.99 ) , and cheese derived SFA ( 0.90 , 0.83–0.98 ) . Soft and liquid fats derived SFA was found related to higher T2D risk ( 1.08 , 1.01–1.17 ) . When substituting SFA by proteins , carbohydrates and polyunsaturated fatty acids , significantly higher risks of T2D were observed ( HRs per 1 energy% ranging from 1.05 to 1.15 ) . Conclusion In this Dutch population , total SFA does not relate to T2D risk . Rather , the association may depend on the types and food sources of SFA . Cheese-derived SFA and individual SFA that are commonly found in cheese , were significantly related to lower T2D risks . We can not exclude the higher T2D risks found for soft and liquid fats derived SFA and for substituting SFA with other macronutrients are influenced by residual confounding by trans fatty acids or limited intake variation in polyunsaturated fatty acids and vegetable protein Summary Background Conflicting evidence exists regarding the association between saturated fatty acids ( SFAs ) and type 2 diabetes . In this longitudinal case-cohort study , we aim ed to investigate the prospect i ve associations between objective ly measured individual plasma phospholipid SFAs and incident type 2 diabetes in EPIC-InterAct participants . Methods The EPIC-InterAct case-cohort study includes 12 403 people with incident type 2 diabetes and a representative subcohort of 16 154 individuals who were selected from a cohort of 340 234 European participants with 3·99 million person-years of follow-up ( the EPIC study ) . Incident type 2 diabetes was ascertained until Dec 31 , 2007 , by a review of several sources of evidence . Gas chromatography was used to measure the distribution of fatty acids in plasma phospholipids ( mol% ) ; sample s from people with type 2 diabetes and subcohort participants were processed in a r and om order by centre , and laboratory staff were masked to participant characteristics . We estimated country-specific hazard ratios ( HRs ) for associations per SD of each SFA with incident type 2 diabetes using Prentice-weighted Cox regression , which is weighted for case-cohort sampling , and pooled our findings using r and om-effects meta- analysis . Findings SFAs accounted for 46 % of total plasma phospholipid fatty acids . In adjusted analyses , different individual SFAs were associated with incident type 2 diabetes in opposing directions . Even-chain SFAs that were measured ( 14:0 [ myristic acid ] , 16:0 [ palmitic acid ] , and 18:0 [ stearic acid ] ) were positively associated with incident type 2 diabetes ( HR [ 95 % CI ] per SD difference : myristic acid 1·15 [ 95 % CI 1·09–1·22 ] , palmitic acid 1·26 [ 1·15–1·37 ] , and stearic acid 1·06 [ 1·00–1·13 ] ) . By contrast , measured odd-chain SFAs ( 15:0 [ pentadecanoic acid ] and 17:0 [ heptadecanoic acid ] ) were inversely associated with incident type 2 diabetes ( HR [ 95 % CI ] per 1 SD difference : 0·79 [ 0·73–0·85 ] for pentadecanoic acid and 0·67 [ 0·63–0·71 ] for heptadecanoic acid ) , as were measured longer-chain SFAs ( 20:0 [ arachidic acid ] , 22:0 [ behenic acid ] , 23:0 [ tricosanoic acid ] , and 24:0 [ lignoceric acid ] ) , with HRs ranging from 0·72 to 0·81 ( 95 % CIs ranging between 0·61 and 0·92 ) . Our findings were robust to a range of sensitivity analyses . Interpretation Different individual plasma phospholipid SFAs were associated with incident type 2 diabetes in opposite directions , which suggests that SFAs are not homogeneous in their effects . Our findings emphasise the importance of the recognition of subtypes of these fatty acids . An improved underst and ing of differences in sources of individual SFAs from dietary intake versus endogenous metabolism is needed . Funding EU FP6 programme , Medical Research Council Epidemiology Unit , Medical Research Council Human Nutrition Research , and Cambridge Lipidomics Biomarker Research Initiative Background It is possible that cross-over studies included in current systematic review s are being inadequately assessed , because the current risk of bias tools do not consider possible biases specific to cross-over design . We performed this study to evaluate whether this was being done in  cross-over studies included in Cochrane  Systematic Review s ( CSRs ) . Methods We search ed the Cochrane Library ( up to 2013 issue 5 ) for CSRs that included at least one cross-over trial . Two authors independently undertook the study selection and data extraction . A r and om sample of the CSRs was selected and we evaluated whether the cross-over trials in these CSRs were assessed according to criteria suggested by the Cochrane h and book . In addition we reassessed the risk of bias of these cross-over trials by a checklist developed form the Cochrane h and book . Results We identified 688 CSRs that included one or more cross-over studies . We chose a r and om sample of 60 CSRs and these included 139 cross-over studies . None of these CSRs undertook a risk of bias assessment specific for cross-over studies . In fact items specific for cross-over studies were seldom considered anywhere in quality assessment of these CSRs . When we reassessed the risk of bias , including the 3 items specific to cross-over trials , of these 139 studies , a low risk of bias was judged for appropriate cross-over design in 110(79 % ) , carry-over effects in 48(34 % ) and for reporting data in all stages of the trial in 114(82 % ) . Assessment of biases in cross-over trials could affect the GRADE assessment of a review ’s findings . Conclusion The current Cochrane risk of bias tool is not adequate to assess cross-over studies . Items specific to cross-over trials leading to potential risk of bias are generally neglected in CSRs . A proposed check list for the evaluation of cross-over trials is provided Background Mayonnaise is used widely in contemporary human diet with widespread use as a salad dressing or spread on breads . Vegetable oils used in its formulation may be a rich source of ω-6 PUFAs and the higher-PUFA content of mayonnaise may be beneficial in mediating a hypocholesterolemic effect . This study , therefore , evaluated the functionality of mayonnaise on cardiometabolic risk within a regular human consumption scenario . Methods Subjects underwent a r and omized double-blind crossover trial , consuming diets supplemented with 20 g/day of either soybean oil-based mayonnaise ( SB-mayo ) or palm olein-based mayonnaise ( PO-mayo ) for 4 weeks each with a 2-week wash-out period . The magnitude of changes for metabolic outcomes between dietary treatments was compared with PO-mayo serving as the control . The data was analyzed by ANCOVA using the GLM model . Analysis was adjusted for weight changes . Results Treatments result ed in significant reductions in TC ( diff = −0.25 mmol/L ; P = 0.001 ) , LDL-C ( diff = −0.17 mmol/L ; P = 0.016 ) and HDL-C ( diff = −0.12 mmol/L ; P < 0.001 ) in SB-mayo compared to PO-mayo without affecting LDL-C : HDL-C ratio ( P > 0.05 ) . Lipoprotein particle change was significant with large LDL particles increasing after PO-mayo ( diff = + 63.2 nmol/L ; P = 0.007 ) compared to SB-mayo but small LDL particles remained unaffected . Plasma glucose , apolipoproteins and oxidative stress markers remained unchanged . Conclusions Daily use with 20 g of linoleic acid-rich SB-mayo elicited reductions in TC and LDL-C concentrations without significantly changing LDL-C : HDL-C ratio or small LDL particle distributions compared to the PO-mayo diet . Trial registration This clinical trial was retrospectively registered with the National Medical Research Register , National Institute of Health , Ministry of Health Malaysia , ( NMRR-15 - 40 - 24035 ; registered on 29/01/2015 ; https://www.nmrr.gov.my/fwbPage.jsp?fwbPageId= Research ISRForm&fwbAction = Up date & fwbStep=10&pk . research ID=24035&fwbVMenu=3&fwb Research Action = Up date ) . Ethical approval was obtained from the National University of Malaysia ’s Medical Ethics Committee ( UKM 1.5.3.5/244/SPP/NN-054-2011 , approved on 25/05/2011 ) BACKGROUND Despite the high content of palmitic acid , palm olein has been shown to have a neutral effect on plasma cholesterol concentrations when compared with olive oil , which is suggested to be attributable to palmitic acid in the sn-1 and sn-3 position . In contrast , palmitic acid is in the sn-2 position in lard . OBJECTIVE The objective was to investigate the effects of a diet rich in palm olein , fractionated palm oil , olive oil , and lard on plasma blood lipids , inflammatory markers , glucose , and insulin . DESIGN A controlled double-blinded , r and omized 3 × 3 wk crossover dietary intervention study included 32 healthy men who daily replaced part of their habitual dietary fat intake with ~ 17 % of energy from palm olein , olive oil , or lard , respectively . RESULTS Compared with intake of olive oil , palm olein and lard  increased total cholesterol and LDL cholesterol ( P < 0.0001 ) . Palm olein result ed in a lower plasma triacylglycerol concentration than did olive oil ( P < 0.01 ) . No difference in effects was observed in plasma HDL-cholesterol , high-sensitivity C-reactive protein , plasminogen activator-1 , insulin , and glucose concentrations . CONCLUSIONS The current study did not support the previous finding that the effect of palm olein on total plasma cholesterol and LDL cholesterol in healthy individuals with normal plasma cholesterol concentrations is neutral compared with that of olive oil . Thus , sn-positioning was not confirmed to be important with regard to the effect on plasma cholesterol . The relatively lower plasma triacylglycerol concentration  after the palm olein diet than after the olive oil diet was unexpected . This trial is registered at clinical trials.gov as NCT00743301 BACKGROUND AND OBJECTIVES As the most widely produced edible vegetable oil , palm oil is known as to contain a high level of saturated fatty acid , which was thought to adversely affect serum lipid profiles . However , recent studies have shown no influence or benefits of palm oil on serum lipids . The potential nutritional value of palm oil is attributed to the high mono-unsaturation at the crucial sn2-position of the oil 's triacylglycerols , as with the so-called ' healthy ' olive oil ( OO ) . The aim of this study was to further test this hypothesis and evaluate the effects of consuming palm olein versus olive oil on serum lipid profiles in a Chinese population . METHODS AND STUDY DESIGN In total , 120 participants were recruited from a spinnery in Yixing city and r and omly divided into two groups ( palm olein or olive oil ) to conduct a 2 × 2 crossover trial for 2 months ' intervention with 2-week washout periods . Each participant was provided 48 g of test oil per day . At the end of each period , anthropometry , and blood lipid indices were measured to determine the effects of palm olein and olive oil . RESULTS Palm olein and olive oil consumption had no significantly different effect on BMI , on serum total cholesterol , low-density lipoprotein cholesterol , high-density lipoprotein cholesterol , triacylglycerol ( TG ) , Apo B , fasting glucose , or insulin concentrations ( all p>0.05 ) . CONCLUSIONS In a dietary crossover trial , palm olein and olive oil had no recognisably different effects on body fatness or blood lipids in a healthy Chinese population Background Dietary trans-rich and interesterified fats were compared to an unmodified saturated fat for their relative impact on blood lipids and plasma glucose . Each fat had melting characteristics , plasticity and solids fat content suitable for use as hardstock in margarine and other solid fat formulations . Methods Thirty human volunteers were fed complete , whole food diets during 4 wk periods , where total fat ( ~31 % daily energy , > 70 % from the test fats ) and fatty acid composition were tightly controlled . A crossover design was used with 3 r and omly-assigned diet rotations and repeated- measures analysis . One test fat rotation was based on palm olein ( POL ) and provided 12.0 percent of energy ( % en ) as palmitic acid ( 16:0 ) ; a second contained trans-rich partially hydrogenated soybean oil ( PHSO ) and provided 3.2 % en as trans fatty acids plus 6.5 % en as 16:0 , while the third used an interesterified fat ( IE ) and provided 12.5 % en as stearic acid ( 18:0 ) . After 4 wk the plasma lipoproteins , fatty acid profile , as well as fasting glucose and insulin were assessed . In addition , after 2 wk into each period an 8 h postpr and ial challenge was initiated in a subset of 19 subjects who consumed a meal containing 53 g of test fat . Results After 4 wk , both PHSO and IE fats significantly elevated both the LDL/HDL ratio and fasting blood glucose , the latter almost 20 % in the IE group relative to POL . Fasting 4 wk insulin was 10 % lower after PHSO ( p > 0.05 ) and 22 % lower after IE ( p < 0.001 ) compared to POL . For the postpr and ial study the glucose incremental area under the curve ( IAUC ) following the IE meal was 40 % greater than after either other meal ( p < 0.001 ) , and was linked to relatively depressed insulin and C-peptide ( p < 0.05 ) . Conclusion Both PHSO and IE fats altered the metabolism of lipoproteins and glucose relative to an unmodified saturated fat when fed to humans under identical circumstances Excess ectopic fat storage is linked to type 2 diabetes . The importance of dietary fat composition for ectopic fat storage in humans is unknown . We investigated liver fat accumulation and body composition during overfeeding saturated fatty acids ( SFAs ) or polyunsaturated fatty acids ( PUFAs ) . LIPOGAIN was a double-blind , parallel-group , r and omized trial . Thirty-nine young and normal-weight individuals were overfed muffins high in SFAs ( palm oil ) or n-6 PUFAs ( sunflower oil ) for 7 weeks .  Liver fat , visceral adipose tissue ( VAT ) , abdominal subcutaneous adipose tissue ( SAT ) , total adipose tissue , pancreatic fat , and lean tissue were assessed by magnetic resonance imaging . Transcriptomics were performed in SAT . Both groups gained similar weight . SFAs , however , markedly increased liver fat compared with PUFAs and caused a twofold larger increase in VAT than PUFAs . Conversely , PUFAs caused a nearly threefold larger increase in lean tissue than SFAs . Increase in liver fat directly correlated with changes in plasma SFAs and inversely with PUFAs . Genes involved in regulating energy dissipation , insulin resistance , body composition , and fat-cell differentiation in SAT were differentially regulated between diets , and associated with increased PUFAs in SAT . In conclusion , overeating SFAs promotes hepatic and visceral fat storage , whereas excess energy from PUFAs may instead promote lean tissue in healthy humans 1 . Three studies were carried out in each of six normal volunteers to investigate how lipid , when given at different stages during the course of a meal , affects gastric emptying and postpr and ial blood glucose and insulin concentrations . 2 . The control meal consisted of 300 ml beef consommé ( 50 kJ , 12 kcal ) , followed 20 min later by 300 g mashed potato ( 908 kJ , 217 kcal ) . In the two test meals , 60 g margarine were incorporated into either the soup or the mashed potato . 3 . The addition of margarine to either component of the meal delayed gastric emptying of the mashed potato ( P less than 0.05 ) , but the pattern varied according to the component to which the fat was added . 4 . Incorporation of fat into the soup increased the lag phase ( P less than 0.05 ) but did not influence the slope of emptying of the mashed potato , while incorporation of fat into the mashed potato reduced the slope of emptying of the mashed potato ( P less than 0.05 ) but did not influence the lag phase . 5 . Addition of fat to either component of the meal reduced postpr and ial blood glucose ( P less than 0.05 ) and insulin responses , but when the fat was incorporated in the soup , peak glucose and insulin responses were delayed as well ( P less than 0.05 ) . 6 . The results show that the effect of fat on gastric emptying and absorption of nutrients depends on when , in relation to the other components of the meal , the fat is consumed Background : Many studies have shown that trans fatty acids have unfavorable effects on the serum lipoprotein profile . In general , however , fats were compared with different functional characteristics , which lower the practical applications of the results . Objective : The major aim of this study was to compare the effects of a high-palmitic acid , trans-free semiliquid fat with those of a high-oleic acid , low-trans semiliquid fat on the serum lipoprotein profile of healthy subjects . Subjects and design : Forty-four subjects ( 33 women and 11 men ) consumed , in r and om order , two experimental diets , each for 3 weeks . Diets provided 40 energy percent ( En% ) from fat , while 15 En% was supplied by the experimental fats . At the end of each intervention period , concentrations of serum lipoproteins , C-reactive protein , glucose and insulin were measured . Results : When subjects consumed the high-oleic acid , low-trans semiliquid fat , intakes of stearic acid ( + 1.3 En% ) , oleic acid ( + 2.9 En% ) , α-linolenic acid ( + 0.1 En% ) and trans fatty acids ( + 0.6 En% ) were higher and that of palmitic acid ( −4.2 En% ) lower . Serum concentration of low-density lipoprotein cholesterol decreased by 0.34±0.39 mmol/l ( mean±s.d . ; 95 % confidence interval ( CI ) , −0.46 to −0.23 mmol/l ; P<0.001 ) and high-density lipoprotein ( HDL ) cholesterol by −0.06±0.17 mmol/l ( 95 % CI , −0.11 to −0.01 mmol/l ; P=0.021 ) . Also , the total to HDL cholesterol ratio was lower ( −0.15±0.34 ; 95 % CI , −0.25 to −0.05 ; P=0.006 ) . Other parameters did not change . Conclusions : A high-oleic acid , low-trans semiliquid fat has a more favorable effect on the serum lipoprotein profile than a trans-free semiliquid fat with comparable functional characteristics , but high in palmitic acid Dietary trans fatty acids/partially-hydrogenated fat has been associated with increased risk of developing cardiovascular disease ( CVD ) , possibly greater than predicted from changes in lipoprotein levels . To explore this issue further potential risk factors were assessed in subjects provided with each of six diets in r and omized order containing as the major source of fat : soybean oil , semi-liquid margarine , soft margarine , shortening , traditional stick margarine or butter .  Plasma fatty acid profiles reflected diet , with triglyceride and phospholipid subfractions affected to a greater extent than cholesteryl ester . Non-fasting LDL-cholesterol levels were 144+/-27 , 141+/-27 , 146+/-26 , 148+/-30 , 151+/-29 and 165+/-31 mg/dl ( P<0.001 ) and total cholesterol/HDL-cholesterol ratios were 5.50+/-1.25 , 5.54+/-1.50 , 5.69+/-1.29 , 5.82+/-1.40 , 6.11+/-1.30 and 5.94+/-1.43 ( P=0.011 ) , respectively , whereas other lipoprotein levels were not significantly different . Remnant-like particles levels were unaffected by dietary fat , either in the fasting or non-fasting state . Differences in fasting insulin and glucose levels were small and would not be predicted to have a large impact on glucose homeostasis . There was no significant effect of dietary fat type on C-reactive protein levels or blood pressure . These data suggest that , as previously demonstrated , the major CVD risk factor adversely affected by dietary trans fatty acids/partially-hydrogenated fat is LDL-cholesterol levels and total cholesterol/HDL-cholesterol ratios OBJECTIVE Diets high in total and saturated fat are associated with insulin resistance . This study examined the effects of feeding monounsaturated , saturated , and trans fatty acids on insulin action in healthy adults . RESEARCH DESIGN AND METHODS A r and omized , double-blind , crossover study was conducted comparing three controlled 4-week diets ( 57 % carbohydrate , 28 % fat , and 15 % protein ) enriched with different fatty acids in 25 healthy men and women . The monounsaturated fat diet ( M ) had 9 % of energy as C18:1cis ( oleic acid ) . The saturated fat diet ( S ) had 9 % of energy as palmitic acid , and the trans fatty acid diet ( T ) had 9 % as C18:1trans . Body weight was kept constant throughout the study . After each diet period , insulin pulsatile secretion , insulin sensitivity index ( S(I ) ) by the minimal model method , serum lipids , and fat oxidation by indirect calorimetry were measured . RESULTS Mean S(I ) for the M , S , and T diets was 3.44 + /- 0.26 , 3.20 + /- 0.26 , and 3.40 + /- 0.26 x 10(-4 ) min(-1 ) . microU(-1 ) . ml(-1 ) , respectively ( NS ) . S(I ) decreased by 24 % on the S versus M diet in overweight subjects but was unchanged in lean subjects ( NS ) . Insulin secretion was unaffected by diet , whereas total and HDL cholesterol increased significantly on the S diet . Subjects oxidized the least fat on the M diet ( 26.0 + /- 1.5 g/day ) and the most fat on the T diet ( 31.4 + /- 1.5 g/day ) ( P = 0.02 ) . CONCLUSIONS Dietary fatty acid composition significantly influenced fat oxidation but did not impact insulin sensitivity or secretion in lean individuals . Overweight individuals were more susceptible to developing insulin resistance on high-saturated fat diets
target: Current evidence on the effects of palm oil consumption on biomarkers of glucose metabolism is poor and limited to only healthy participants .
  We conclude that little or no additional benefit will be obtained by replacing palm oil with other oils rich in mono or polyunsaturated fatty acids for changes in glucose metabolism
background: INTRODUCTION Vegetable oil is an important source of fatty acids , and as palm oil being the highest consumed vegetable oil in many countries , its high saturated fatty acid content has led many concerns on cardiometabolic health .
  Dietary fatty acids has also been linked to affect glucose metabolism and insulin sensitivity .
  This systematic review is aim ed at critically evaluating the available evidence on the association of palm oil with the biomarkers of glucose metabolism as compared to other vegetable oils .