Effects of high-fat and low-fat diets rich in monounsaturated fatty acids on serum lipids, LDL size and indices of lipid peroxidation in healthy non-obese men and women when consumed under controlled conditions

Cis-monounsaturated fatty acids inhibit ferroptosis through downregulation of transferrin receptor 1

Ferroptosis, a form of cell death mediated by lipid peroxidation, is implicated in various pathological processes. Although monounsaturated fatty acids (MUFAs) can inhibit ferroptotic lipid peroxidation, the underlying structural mechanism of this antagonistic effect remains poorly understood. We hypothesized that MUFAs with different structures (including chain length, conformation, and double bond position) may affect their regulatory effect on ferroptosis. In this study, 11 MUFAs with varying structures were screened to identify those with an inhibitory effect on ferroptosis. Results from 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazoliumbromide assays indicated that only exogenous MUFAs with cis-conformation and centered double bond could inhibit ferroptosis. Meanwhile, it was found that suppressing the expression of SCD1 and SCD5 genes could sensitize cells to ferroptosis indicating the protective role of endogenous MUFA against ferroptosis. Additionally, western blot analysis revealed that cis-MUFAs with centered double bond downregulated the protein levels of transferrin receptor 1. Flow cytometry confirmed that these MUFAs led to decreases in intracellular iron, reactive oxygen species, and lipid peroxides. It was also found that SCD1 inhibitor could enhance ferroptosis inducer-mediated tumor suppression both in vivo and in vitro. Overall, these findings shed light on the particular structural features of MUFAs that contribute to their ferroptosis-resistant properties and suggest the potential therapeutic relevance of natural MUFAs in a range of ferroptosis-related diseases.

Effect of carbohydrate-restricted dietary interventions on LDL particle size and number in adults in the context of weight loss or weight maintenance: a systematic review and meta-analysis

BACKGROUND

LDL particle size and number (LDL-P) are emerging lipid risk factors. Nonsystematic reviews have suggested that diets lower in carbohydrates and higher in fats may result in increased LDL particle size when compared with higher-carbohydrate diets.

OBJECTIVES

This study aimed to systematically review available evidence and conduct meta-analyses of studies addressing the association of carbohydrate restriction with LDL particle size and LDL-P.

METHODS

We searched 6 electronic databases on 4 January, 2021 for randomized trials of any length that reported on dietary carbohydrate restriction (intervention) compared with higher carbohydrate intake (control). We calculated standardized mean differences (SMDs) in LDL particle size and LDL-P between the intervention and control groups of eligible studies, and pooled effect sizes using random-effects models. We performed prespecified subgroup analyses and examined the effect of potential explanatory factors. Internal validity and publication bias were assessed using Cochrane's risk-of-bias tool and funnel plots, respectively. Studies that could not be meta-analyzed were summarized qualitatively.

RESULTS

This review summarizes findings from 38 randomized trials including a total of 1785 participants. Carbohydrate-restricted dietary interventions were associated with an increase in LDL peak particle size (SMD = 0.50; 95% CI: 0.15, 0.86; P < 0.01) and a reduction in LDL-P (SMD = -0.24; 95% CI: -0.43, -0.06; P = 0.02). The effect of carbohydrate-restricted dietary interventions on LDL peak particle size appeared to be partially explained by differences in weight loss between intervention groups and exploratory analysis revealed a shift from small dense to larger LDL subclasses. No statistically significant association was found between carbohydrate-restricted dietary interventions and mean LDL particle size (SMD = 0.20; 95% CI: -0.29, 0.69; P = 0.37).

CONCLUSIONS

The available evidence indicates that dietary interventions restricted in carbohydrates increase LDL peak particle size and decrease the numbers of total and small LDL particles.This review was registered at www.crd.york.ac.uk/prospero/ as CRD42020188745.

The effects of fat consumption on low-density lipoprotein particle size in healthy individuals: a narrative review

Cardiovascular disease (CVD) is the number one contributor to death in the United States and worldwide. A risk factor for CVD is high serum low-density lipoprotein cholesterol (LDL-C) concentrations; however, LDL particles exist in a variety of sizes that may differentially affect the progression of CVD. The small, dense LDL particles, compared to the large, buoyant LDL subclass, are considered to be more atherogenic. It has been suggested that replacing saturated fatty acids with monounsaturated and polyunsaturated fatty acids decreases the risk for CVD. However, certain studies are not in agreement with this recommendation, as saturated fatty acid intake did not increase the risk for CVD, cardiovascular events, and/or mortality. Furthermore, consumption of saturated fat has been demonstrated to increase large, buoyant LDL particles, which may explain, in part, for the differing outcomes regarding fat consumption on CVD risk. Therefore, the objective was to review intervention trials that explored the effects of fat consumption on LDL particle size in healthy individuals. PubMed and Web of Science were utilized during the search process for journal articles. The results of this review provided evidence that fat consumption increases large, buoyant LDL and/or decreases small, dense LDL particles, and therefore, influences CVD risk.

The effects of long-term moderate exercise and Western-type diet on oxidative/nitrosative stress, serum lipids and cytokines in female Sprague Dawley rats

Purpose

Regular exercise reduces obesity and the risk of cardiovascular disease. However, health-promoting benefits of physical activity are commonly associated with increased inflammation and oxidative stress. Here, we tested whether constant moderate exercise is able to prevent or attenuate the oxidative/nitrosative stress, inflammation, and serum lipids in lean and obese rats.

Methods

Four-month-old female Sprague Dawley rats received standard or a high-fat diet. Animals were subjected to a physical activity protocol, consisting of 30 min forced treadmill exercise for 5 consecutive days per week during 10 months. Baseline and sedentary (non-exercised) rats were used as controls. Lipids, oxidized low-density lipoprotein cholesterol, nitric oxide metabolites, and pro- and anti-inflammatory markers were measured in blood collected upon euthanasia.

Results

At variance to young baseline control rats, 14-month-old animals fed normal diet had increased plasma lipid levels, including total cholesterol and triglycerides, which were further elevated in rats that consumed a high-fat diet. While treadmill exercise did not lower the amount of serum lipids in standard diet group, forced physical activity reduced non-high-density lipoprotein cholesterol in response to high-fat diet feeding. Exercised rats fed standard diet or high-fat diet had lower abundancy of nitric oxide metabolites, which coincided with increased levels of oxidized low-density lipoprotein cholesterol. Accordingly, the amount of nitric oxide metabolites correlated inversely with oxidized low-density lipoprotein cholesterol and homo-arginine. Exercise significantly reduced inflammatory cytokines in high-fat diet fed rats only.

Conclusion

Our study suggests that regular exercise alters the equilibrium between oxidative and anti-oxidative compounds and reduces pro-inflammatory cytokines.

Fatty acid profile as affected by fat depot and the sex category of Polish Holstein-Friesian × Limousin fattening cattle fed silage ad libitum

This study was designed to compare the fatty acid profiles of four types of fat depots from bulls, steers, and heifers. All animals were Polish Holstein-Friesian and Limousin crossbreds fattened semi-intensively-silage at libitum and concentrate in the amount corresponding to 30% of their net energy requirements. The fatty acid profile in intramuscular, intermuscular, and external and internal fat was determined. The intramuscular fat of bulls was most abundant in total PUFAs and n-6 PUFAs, and functional fatty acids C 18:2, C 20:4, and C 22:5 in comparison with steers and heifers. Regardless of sex category, intramuscular and external fat were characterized by higher levels of UFAs and a more desirable MUFA/SFA ratio than the remaining fat types. It should also be noted that external fat was more abundant in CLA than other fat types, and that the highest CLA content was found in bull fat, compared with the remaining sex categories of cattle.

Consumption of High-Oleic Soybean Oil Improves Lipid and Lipoprotein Profile in Humans Compared to a Palm Oil Blend: A Randomized Controlled Trial

Partially hydrogenated oils (PHO) have been removed from the food supply due to adverse effects on risk for coronary heart disease (CHD). High-oleic soybean oils (HOSBO) are alternatives that provide functionality for different food applications. The objective of this study was to determine how consumption of diets containing HOSBO compared to other alternative oils, with similar functional properties, modifies LDL cholesterol (LDLc) and other risk factors and biomarkers of CHD. A triple-blind, crossover, randomized controlled trial was conducted in humans (n = 60) with four highly-controlled diets containing (1) HOSBO, (2) 80:20 blend of HOSBO and fully hydrogenated soybean oil (HOSBO+FHSBO), (3) soybean oil (SBO), and (4) 50:50 blend of palm oil and palm kernel oil (PO + PKO). Before and after 29 days of feeding, lipids/lipoproteins, blood pressure, body composition, and markers of inflammation, oxidation, and hemostasis were measured. LDLc, apolipoprotein B (apoB), NonHDL-cholesterol (HDLc), ratios of total cholesterol (TC)-to-HDLc and LDLc-to-HDL cholesterol, and LDL particle number and small LDL particles concentration were lower after HOSBO and HOSBO+FHSBO compared to PO (specific comparisons p < 0.05). Other than TC:HDL, there were no differences in lipid/lipoprotein markers when comparing HOSBO+FHSBO with HOSBO. LDLc and apoB were higher after HOSBO compared to SBO (p < 0.05). PO + PKO increased HDLc (p < 0.001) and apolipoprotein AI (p < 0.03) compared to HOSBO and HOSBO+FHSBO. With the exception of lipid hydroperoxides, dietary treatments did not affect other CHD markers. HOSBO, and blends thereof, is a PHO replacement that results in more favorable lipid/lipoprotein profiles compared to PO + PKO (an alternative fat with similar functional properties).

The Polymorphisms of the Peroxisome-Proliferator Activated Receptors' Alfa Gene Modify the Aerobic Training Induced Changes of Cholesterol and Glucose

Background: PPARα is a transcriptional factor that controls the expression of genes involved in fatty acid metabolism, including fatty acid transport, uptake by the cells, intracellular binding, and activation, as well as catabolism (particularly mitochondrial fatty acid oxidation) or storage. PPARA gene polymorphisms may be crucial for maintaining lipid homeostasis and in this way, being responsible for developing specific training-induced physiological reactions. Therefore, we have decided to check if post-training changes of body mass measurements as well as chosen biochemical parameters are modulation by the PPARA genotypes. Methods: We have examined the genotype and alleles’ frequencies (described in PPARA rs1800206 and rs4253778 polymorphic sites) in 168 female participants engaged in a 12-week training program. Body composition and biochemical parameters were measured before and after the completion of a whole training program. Results: Statistical analyses revealed that PPARA intron 7 rs4253778 CC genotype modulate training response by increasing low-density lipoproteins (LDL) and glucose concentration, while PPARA Leu162Val rs1800206 CG genotype polymorphism interacts in a decrease in high-density lipoproteins (HDL) concentration. Conclusions: Carriers of PPARA intron 7 rs4253778 CC genotype and Leu162Val rs1800206 CG genotype might have potential negative training-induced cholesterol and glucose changes after aerobic exercise.

The effect of periodic energy restriction on growth performance, serum biochemical indices, and meat quality in sheep

Energy is a key factor regulated by the neuroendocrine system. The objective of this study was to compare growth performance, serum biochemical indices, carcass traits, meat quality, and nutrient composition of lambs fed restricted metabolizable energy (ME) intakes to mimic the seasonal changes of the natural grasslands of northwest China. Nineteen male Dorper × Small Tailed Han lambs were assigned to treatments, control (CON) fed at 1.0 MJ/W0.75 × d-1 throughout the 180 d study, and restricted ME (RES) fed by sequentially restricting ME every 30 d (0.56, 0.84, 1.0, 0.84, 0.56, and 0.28 MJ/W0.75 × d-1). Lambs were harvested at the end of the study. Lambs fed the CON diet demonstrated higher (P < 0.05) average daily gain (ADG) compared with RES-fed lambs (158.79 and 57.01 g/d, for CON and RES, respectively), although ADG were lower in each period with the last period being a negative ADG for RES-fed lambs resulting in a loss of body weight. Both treatments demonstrated lower ADG in the last 3 study periods compared with the first 2 periods, which may be explained by cold stress (<-3 °C) increasing the lamb's energy requirement. Feeding lambs a restricted ME diet resulted in lower (P < 0.05) blood serum glucose, triglycerides, total protein, calcium, phosphorus, immunoglobulin G, immunoglobulin M, and immunoglobulin A concentrations compared with CON-fed lambs, but both treatments were similar (P > 0.05) for cholesterol and high-density lipoprotein-cholesterol. Feeding lambs a restricted ME diet increased (P < 0.05) meat pH, while reducing the cooked meat rate compared with CON-fed lambs. Thus, the carcass yield, rib eye muscle area, and shear force were lower (P < 0.05) for RES-fed lambs compared with CON-fed lambs. The meat water concentration was higher (P < 0.05), whereas the concentrations of dry matter, crude fat, crude protein, and carbohydrate were lower (P < 0.05) for lambs fed a RES ME diet compared to CON-fed lambs. These results demonstrate that sequentially restricting ME intake, as natural grasslands might experience during seasonal forage quality and quantity changes, resulted in a reduction of body weight because lambs were mobilizing body reserves as a source of ME. The reduction in concentrations of key serum nutrients, as well as carcass traits and meat composition, demonstrate the body is responding to the meet the lambs ME requirements, which has implications for both meat quality and the animal's physiological functions.

Dietary fats and F2-isoprostanes: A review of the clinical evidence

Evidence supports that a high dietary fat intake increases oxidative stress and the risk of diet-induced metabolic disorders such as obesity, diabetes and cardiovascular diseases. F₂-isoprostanes (F₂-isoP) are formed by the non-enzymatic oxidation of arachidonic acid and are widely used as reliable biomarkers of oxidative stress in clinical studies. Dietary fats may influence F₂-isoP levels, as they (1) are metabolic substrates for their formation, (2) modify the lipid composition of tissues, and (3) affect the plasma lipoprotein concentrations which are involved in F₂-isoP transport. This review examined the latest clinical evidence on how dietary fats can affect blood circulation and excretion of F₂-isoP in individuals with healthy or deteriorated metabolic profiles. Clinical studies reported that saturated or monounsaturated fat-rich diets did not affect F₂-isoP levels in adults with healthy or deteriorated metabolic profiles. Though, ω-3 polyunsaturated fatty acids decreased F₂-isoP levels in numerous studies, whereas trans-fatty acids raised F₂-isoP excretion. Yet, the reported heterogeneous results reveal important considerations, such as the health status of the participants, the biological fluids used to determine F₂-isoP, the analytical methods employed and the specific F₂-isoP isomers detected. Therefore, future clinical studies should be designed in order to consider these issues in the studies of the effects of fat intake on oxidative stress.

The effects of daily intake timing of almond on the body composition and blood lipid profile of healthy adults

BACKGROUND/OBJECTIVES

Timing of almond intake during a day may result differently in the perspectives of body composition and changes of lipid profile. The current study was conducted to compare the effects of daily almond intake as a preload versus as a snack on body composition, blood lipid profile, and oxidative and inflammation indicators among young Korean adults aged 20-39 years old.

SUBJECTS/METHODS

Participants were randomly assigned to one of three groups: a pre-meal almond group (PM), a snack almond group (SN) in which participants were instructed to consume 56 g of almonds either as a preload before meals or as a snack between meals, respectively, and a control group (CL) in which participants were provided high-carbohydrate iso-caloric control food. Measurements were performed at baseline, weeks 8 and 16.

RESULTS

A total of 169 (M 77/F 92) out of the 227 participants completed the study between June 2014 and June 2015 (n = 58 for PM; 55 for SN; and 56 for CL). A significant decrease in body fat mass was observed in the PM group at both weeks 8 and 16 compared with the CL. There were significant intervention effects on changes of body fat mass (P = 0.025), body fat percentages (P = 0.019), and visceral fat levels (P < 0.001). Consuming almonds as a daily snack reduced the levels of total cholesterol (P = 0.043) and low-density lipoprotein (LDL) cholesterol (P = 0.011) without changing high-density lipoprotein (HDL) cholesterol compared with the CL.

CONCLUSION

Almond consumption as a preload modified body fat percentages, whereas snacking on almonds between meals improved blood lipid profiles. This trial was registered at ClinicalTrials.gov as NCT03014531.

Effects of a very high saturated fat diet on LDL particles in adults with atherogenic dyslipidemia: A randomized controlled trial

Background

Previous studies have shown that increases in LDL-cholesterol resulting from substitution of dietary saturated fat for carbohydrate or unsaturated fat are due primarily to increases in large cholesterol-enriched LDL, with minimal changes in small, dense LDL particles and apolipoprotein B. However, individuals can differ by their LDL particle distribution, and it is possible that this may influence LDL subclass response.

Objective

The objective of this study was to test whether the reported effects of saturated fat apply to individuals with atherogenic dyslipidemia as characterized by a preponderance of small LDL particles (LDL phenotype B).

Methods

Fifty-three phenotype B men and postmenopausal women consumed a baseline diet (55%E carbohydrate, 15%E protein, 30%E fat, 8%E saturated fat) for 3 weeks, after which they were randomized to either a moderate carbohydrate, very high saturated fat diet (HSF; 39%E carbohydrate, 25%E protein, 36%E fat, 18%E saturated fat) or low saturated fat diet (LSF; 37%E carbohydrate, 25%E protein, 37%E fat, 9%E saturated fat) for 3 weeks.

Results

Compared to the LSF diet, consumption of the HSF diet resulted in significantly greater increases from baseline (% change; 95% CI) in plasma concentrations of apolipoprotein B (HSF vs. LSF: 9.5; 3.6 to 15.7 vs. -6.8; -11.7 to -1.76; p = 0.0003) and medium (8.8; -1.3 to 20.0 vs. -7.3; -15.7 to 2.0; p = 0.03), small (6.1; -10.3 to 25.6 vs. -20.8; -32.8 to -6.7; p = 0.02), and total LDL (3.6; -3.2 to 11.0 vs. -7.9; -13.9 to -1.5; p = 0.03) particles, with no differences in change of large and very small LDL concentrations. As expected, total-cholesterol (11.0; 6.5 to 15.7 vs. -5.7; -9.4 to -1.8; p<0.0001) and LDL-cholesterol (16.7; 7.9 to 26.2 vs. -8.7; -15.4 to -1.4; p = 0.0001) also increased with increased saturated fat intake.

Conclusions

Because medium and small LDL particles are more highly associated with cardiovascular disease than are larger LDL, the present results suggest that very high saturated fat intake may increase cardiovascular disease risk in phenotype B individuals. This trial was registered at clinicaltrials.gov (NCT00895141).

Trial registration

Clinicaltrials.gov NCT00895141.

Oilseeds native to the Cerrado have fatty acid profile beneficial for cardiovascular health

ABSTRACT Objective: To assess and compare the fatty acid composition of edible seeds and a nut native to the Cerrado (Brazilian savannah) to that of traditional oilseeds. Methods: Baru almonds, Cerrado cashew nuts, and pequi almonds were extracted from the fruits using appropriate equipment. All edible seeds and nuts were roasted, except for the Brazil nut. The sample lipids were extracted via cold pressing. The fatty acids were esterified, and the fatty acid esters were analyzed by gas chromatography. Results: The native and traditional edible seeds and nuts contain mostly monounsaturated fatty acids (42.72 g to 63.44 g/100 g), except for the Brazil nut, which showed predominance of polyunsaturated fatty acids (45.48 g/100 g). Pequi almond had the highest saturated fatty acid content (36.14 g/100 g). The fatty acids with the highest concentration were oleic and linoleic acids, and palmitic acid was also found in considerable concentration in the oilseeds studied. The Cerrado cashew nut and the traditional cashew nut have similar fatty acid profiles. As for the ratio of ω-6 to ω-3, the baru almond showed the highest ratio, 9:1, which was the closest to the recommended intake of these fatty acids. Conclusion: The fatty acid profile of the edible seeds and nuts native to the cerrado is similar to those of traditional oilseeds. We suggest the inclusion of native oilseeds in the diet aiming at reducing the risk of cardiovascular disease, especially the baru almond and the cerrado cashew nut, due to the fact they have high ratio of monounsaturated fatty acids to saturated fatty acids.

Oxidative stress in relation to diet and physical activity among premenopausal women

Higher levels of oxidative stress, as measured by F2-isoprostanes, have been associated with chronic diseases such as CVD and some cancers. Improvements in diet and physical activity may help reduce oxidative stress; however, previous studies regarding associations between lifestyle factors and F2-isoprostane concentrations have been inconsistent. The aim of this cross-sectional study was to investigate whether physical activity and intakes of fruits/vegetables, antioxidant nutrients, dietary fat subgroups and alcohol are associated with concentrations of F2-isoprostane and the major F2-isoprostane metabolite. Urinary F2-isoprostane and its metabolite were measured in urine samples collected at enrolment from 912 premenopausal women (aged 35-54 years) participating in the Sister Study. Physical activity, alcohol consumption and dietary intakes were self-reported via questionnaires. With adjustment for potential confounders, the geometric means of F2-isoprostane and its metabolite were calculated according to quartiles of dietary intakes, alcohol consumption and physical activity, and linear regression models were used to evaluate trends. Significant inverse associations were found between F2-isoprostane and/or its metabolite and physical activity, vegetables, fruits, vitamin C, α-carotene, vitamin E, β-carotene, vitamin A, Se, lutein+zeaxanthin and long-chain n-3 fatty acids. Although trans fats were positively associated with both F2-isoprostane and its metabolite, other dietary fat subgroups including SFA, n-6 fatty acids, n-3 fatty acids, MUFA, PUFA, short-chain n-3 fatty acids, long-chain n-3 fatty acids and total fat were not associated with either F2-isoprostane or its metabolite. Our findings suggest that lower intake of antioxidant nutrients and higher intake of trans fats may be associated with greater oxidative stress among premenopausal women.

A metabolomics approach to the identification of biomarkers of sugar-sweetened beverage intake

BACKGROUND

The association between sugar-sweetened beverages (SSBs) and health risks remains controversial. To clarify proposed links, reliable and accurate dietary assessment methods of food intakes are essential.

OBJECTIVE

The aim of this present work was to use a metabolomics approach to identify a panel of urinary biomarkers indicative of SSB consumption from a national food consumption survey and subsequently validate this panel in an acute intervention study.

DESIGN

Heat map analysis was performed to identify correlations between ¹H nuclear magnetic resonance (NMR) spectral regions and SSB intakes in participants of the National Adult Nutrition Survey (n = 565). Metabolites were identified and receiver operating characteristic (ROC) analysis was performed to assess sensitivity and specificity of biomarkers. The panel of biomarkers was validated in an acute study (n = 10). A fasting first-void urine sample and postprandial samples (2, 4, 6 h) were collected after SSB consumption. After NMR spectroscopic profiling of the urine samples, multivariate data analysis was applied.

RESULTS

A panel of 4 biomarkers-formate, citrulline, taurine, and isocitrate-were identified as markers of SSB intake. This panel of biomarkers had an area under the curve of 0.8 for ROC analysis and a sensitivity and specificity of 0.7 and 0.8, respectively. All 4 biomarkers were identified in the SSB sample. After acute consumption of an SSB drink, all 4 metabolites increased in the urine.

CONCLUSIONS

The present metabolomics-based strategy proved to be successful in the identification of SSB biomarkers. Future work will ascertain how to translate this panel of markers for use in nutrition epidemiology.

Baru almond improves lipid profile in mildly hypercholesterolemic subjects: a randomized, controlled, crossover study

BACKGROUD AND AIM

The usual consumption of nuts reduces cardiovascular diseases (CVD) risk by improving serum lipids and oxidation status. Baru almonds (Dipteryxalata Vog.), a native species of Brazilian Savannah, have considerable contents of monounsaturated fatty acids (MUFA), dietary fiber, vitamin E and zinc, which could exert positive effects in serum lipids and markers of oxidation. However, there is no study about the effect of their consumption on human health. Thus, the aim of this study was to evaluate the effect of baru almonds supplementation on lipid profile and oxidation of mildly hypercholesterolemic subjects.

METHODS AND RESULTS

A randomized, crossover, placebo controlled study was performed with 20 mildly hypercholesterolemic subjects (total cholesterol (TC) mean ±SEM = 5.8 ± 0.2 mmol/L). The assay had 2 periods of 6 weeks each and a 4-week washout period between the treatments. Subjects were randomly allocated in alternated periods receiving the following treatments per period: supplementation with 20 g/day of baru almonds or placebo (1 corn starch capsule/day). Compared to placebo, supplementation of baru almonds reduced TC (-8.1 ± 2.4%, P = 0.007), low-density lipoprotein cholesterol (LDL-c) (-9.4 ± 2.4%, P = 0.006) and non-high-density lipoprotein cholesterol (non-HDL-c) (-8.1 ± 3.0%, P = 0.013). There were no significant changes on the oxidation biomarkers evaluated.

CONCLUSION

Dietary supplementation of mildly hypercholesterolemic subjects with baru almonds improved serum lipid parameters, so that this food might be included in diets for reducing the CVD risk.

CLINICAL TRIAL REGISTRY

Brazilian Registry of Clinical Trials (ReBEC) (website: http://www.ensaiosclinicos.gov.br). Register number: RBR-4zdy9p.

Effect of the amount and type of dietary fat on cardiometabolic risk factors and risk of developing type 2 diabetes, cardiovascular diseases, and cancer: a systematic review

The effects of both the amount and quality of dietary fat have been studied intensively during the past decades. Previously, low-fat diets were recommended without much attention to the quality of fat, whereas there is general emphasis on the quality of fat in current guidelines. The objective of this systematic review (SR) was to assess the evidence of an effect of the amount and type of dietary fat on body weight (BW), risk factors, and risk of non-communicable diseases, that is, type 2 diabetes (T2DM), cardiovascular diseases (CVD), and cancer in healthy subjects or subjects at risk for these diseases. This work was performed in the process of updating the fourth edition of the Nordic Nutrition Recommendations from 2004. The literature search was performed in October 2010 covering articles published since January 2000. A complementary search was done in February 2012 covering literature until December 2011. Two authors independently selected articles for inclusion from a total of about 16,000 abstracts according to predefined criteria. Randomized controlled trials (RCT) and prospective cohort studies (PCS) were included as well as nested case-control studies. A few retrospective case-control studies were also included when limited or no data were available from other study types. Altogether 607 articles were quality graded and the observed effects in these papers were summarized. Convincing evidence was found that partial replacement of saturated fat (SFA) with polyunsaturated fat (PUFA) or monounsaturated fat (MUFA) lowers fasting serum/plasma total and LDL cholesterol concentrations. The evidence was probable for a decreasing effect of fish oil on concentration of serum/plasma total triglycerides as compared with MUFA. Beneficial effect of MUFA both on insulin sensitivity and fasting plasma/serum insulin concentration was considered as probable in comparisons of MUFA and carbohydrates versus SFA, whereas no effect was found on fasting glucose concentration in these comparisons. There was probable evidence for a moderate direct association between total fat intake and BW. Furthermore, there was convincing evidence that partial replacement of SFA with PUFA decreases the risk of CVD, especially in men. This finding was supported by an association with biomarkers of PUFA intake; the evidence of a beneficial effect of dietary total PUFA, n-6 PUFA, and linoleic acid (LA) on CVD mortality was limited suggestive. Evidence for a direct association between total fat intake and risk of T2DM was inconclusive, whereas there was limited-suggestive evidence from biomarker studies that LA is inversely associated with the risk of T2DM. However, there was limited-suggestive evidence in biomarker studies that odd-chain SFA found in milk fat and fish may be inversely related to T2DM, but these associations have not been supported by controlled studies. The evidence for an association between dietary n-3 PUFA and T2DM was inconclusive. Evidence for effects of fat on major types of cancer was inconclusive regarding both the amount and quality of dietary fat, except for prostate cancer where there was limited-suggestive evidence for an inverse association with intake of ALA and for ovarian cancer for which there was limited-suggestive evidence for a positive association with intake of SFA. This SR reviewed a large number of studies focusing on several different health outcomes. The time period covered by the search may not have allowed obtaining the full picture of the evidence in all areas covered by this SR. However, several SRs and meta-analyses that covered studies published before year 2000 were evaluated, which adds confidence to the results. Many of the investigated questions remain unresolved, mainly because of few studies on certain outcomes, conflicting results from studies, and lack of high quality-controlled studies. There is thus an evident need of highly controlled RCT and PCS with sufficient number of subjects and long enough duration, specifically regarding the effects of the amount and quality of dietary fat on insulin sensitivity, T2DM, low-grade inflammation, and blood pressure. New metabolic and other potential risk markers and utilization of new methodology in the area of lipid metabolism may provide new insight.

Low carbohydrate versus isoenergetic balanced diets for reducing weight and cardiovascular risk: a systematic review and meta-analysis

BACKGROUND

Some popular weight loss diets restricting carbohydrates (CHO) claim to be more effective, and have additional health benefits in preventing cardiovascular disease compared to balanced weight loss diets.

METHODS AND FINDINGS

We compared the effects of low CHO and isoenergetic balanced weight loss diets in overweight and obese adults assessed in randomised controlled trials (minimum follow-up of 12 weeks), and summarised the effects on weight, as well as cardiovascular and diabetes risk. Dietary criteria were derived from existing macronutrient recommendations. We searched Medline, EMBASE and CENTRAL (19 March 2014). Analysis was stratified by outcomes at 3-6 months and 1-2 years, and participants with diabetes were analysed separately. We evaluated dietary adherence and used GRADE to assess the quality of evidence. We calculated mean differences (MD) and performed random-effects meta-analysis. Nineteen trials were included (n = 3209); 3 had adequate allocation concealment. In non-diabetic participants, our analysis showed little or no difference in mean weight loss in the two groups at 3-6 months (MD 0.74 kg, 95%CI -1.49 to 0.01 kg; I2 = 53%; n = 1745, 14 trials; moderate quality evidence) and 1-2 years (MD 0.48 kg, 95%CI -1.44 kg to 0.49 kg; I2 = 12%; n = 1025; 7 trials, moderate quality evidence). Furthermore, little or no difference was detected at 3-6 months and 1-2 years for blood pressure, LDL, HDL and total cholesterol, triglycerides and fasting blood glucose (>914 participants). In diabetic participants, findings showed a similar pattern.

CONCLUSIONS

Trials show weight loss in the short-term irrespective of whether the diet is low CHO or balanced. There is probably little or no difference in weight loss and changes in cardiovascular risk factors up to two years of follow-up when overweight and obese adults, with or without type 2 diabetes, are randomised to low CHO diets and isoenergetic balanced weight loss diets.

Margarines fortified with α-linolenic acid, eicosapentaenoic acid, or docosahexaenoic acid alter the fatty acid composition of erythrocytes but do not affect the antioxidant status of healthy adults

We aimed to investigate the effects of increased intake of α-linolenic acid (ALA), EPA, or DHA incorporated into a food matrix on the fatty acid composition of erythrocytes and on biomarkers of oxidant/antioxidant status. To this end, a controlled dietary study was conducted in 74 healthy men and women. The participants were randomly assigned to 1 of 3 interventions in which margarines fortified with either 10 weight percent ALA, EPA, or DHA ethyl esters replaced their normal spread for 6 wk. The total intakes of ALA, EPA, and DHA were 4.4, 2.2, and 2.3 g/d, respectively. Consuming EPA increased the erythrocyte proportion of EPA (394%) and the omega-3 index (sum of EPA and DHA, 38%). Consumption of DHA increased erythrocyte DHA (91%), the omega-3 index (98%), and EPA (137%). The omega-3 index increased to a significantly greater extent in the DHA group than in the EPA group. ALA did not increase erythrocyte EPA or the omega-3 index. We found no change in plasma uric acid or antioxidant capacity in any of the groups. Plasma malondialdehyde (MDA) increased with the EPA and DHA interventions. All 3 interventions decreased erythrocyte linoleic acid hydroperoxides but did not affect their MDA concentrations. In conclusion, the intake of both isolated EPA and DHA incorporated into margarine resulted in an enhanced incorporation of EPA and DHA into erythrocytes. Our findings indicate that DHA is quantitatively superior to EPA in view of the EPA+DHA tissue incorporation and also that 4 g/d ALA is not sufficient to increase the omega-3 index over a 6-wk period.

Effects of a rapeseed oil-enriched hypoenergetic diet with a high content of α-linolenic acid on body weight and cardiovascular risk profile in patients with the metabolic syndrome

In therapy of the metabolic syndrome, the optimal dietary approach with regard to its macronutrient composition and metabolically favourable food components, such as the plant-derived n-3 fatty acid α-linolenic acid (ALA), is still a matter of debate. We investigated the effects of a hypoenergetic diet with low energy density (ED) enriched in rapeseed oil, resulting in high MUFA content and an ALA intake of 3·5 g/d on body weight and cardiovascular risk profile in eighty-one patients with the metabolic syndrome in comparison with an olive oil diet rich in MUFA, but with a low ALA content. After a 6-month dietary intervention, body weight was significantly reduced in the rapeseed oil and olive oil groups ( − 7·8 v. − 6·0 kg; P < 0·05). There were significant decreases in systolic blood pressure, total cholesterol and LDL-cholesterol, and insulin levels in both groups (P < 0·05). For all of these changes, no inter-group differences were observed. After the rapeseed oil diet, diastolic blood pressure declined more than after the olive oil diet (P < 0·05 for time × group interaction). Furthermore, concentrations of serum TAG were significantly reduced after the high ALA intake, but not in the low ALA group (P < 0·05 for time × group interaction). In conclusion, our dietary food pattern with a low ED and high intakes of MUFA and ALA may be a practical approach for long-term dietary treatment in patients with the metabolic syndrome, leading to weight reduction and an improvement in the overall cardiovascular risk profile.

PPARγ2 gene Pro12Ala and PPARα gene Leu162Val single nucleotide polymorphisms interact with dietary intake of fat in determination of plasma lipid concentrations

BACKGROUND/AIMS

The peroxisome proliferator-activated receptors (PPARs) are transcriptional regulators of lipid metabolism, activated by unsaturated fatty acids. We investigated independent and interactive effects of PPARγ2 gene PPARG Pro12Ala (rs1801282) andPPARαgene PPARA Leu162Val (rs1800206) genotypes with dietary intake of fatty acids on concentrations of plasma lipids in subjects of whom 47.5% had metabolic syndrome.

METHODS

The RISCK study is a parallel design, randomised controlled trial. Plasma lipids were quantified at baseline after a 4-week high saturated fatty acids diet and after three parallel 24-week interventions with reference (high saturated fatty acids), high monounsaturated fatty acids and low-fat diets. Single nucleotide polymorphisms were genotyped in 466 subjects.

RESULTS

At baseline, the PPARG Ala12allele was associated with increased plasma total cholesterol (n = 378; p = 0.04), LDL cholesterol (p = 0.05) and apoB (p =0.05) after adjustment for age, gender and ethnicity. At baseline, PPARA Leu162Val × PPARG Pro12Ala genotype interaction did not significantly influence plasma lipid concentrations. After dietary intervention, gene-gene interaction significantly influenced LDL cholesterol (p =0.0002) and small dense LDL as a proportion of LDL (p = 0.005) after adjustments.

CONCLUSIONS

Interaction between PPARG Pro12Ala and PPARA Leu162Val genotypes may influence plasma LDL cholesterol concentration and the proportion as small dense LDL after a high monounsaturated fatty acids diet.

Effects of dietary cold-pressed turnip rapeseed oil and butter on serum lipids, oxidized LDL and arterial elasticity in men with metabolic syndrome

Background

Rapeseed oil is the principal dietary source of monounsaturated and n-3 polyunsaturated fatty acids in the Northern Europe. However, the effect of rapeseed oil on the markers of subclinical atherosclerosis is not known. The purpose of this study was to compare the effects of dietary intake of cold-pressed turnip rapeseed oil (CPTRO) and butter on serum lipids, oxidized LDL and arterial elasticity in men with metabolic syndrome.

Methods

Thirty-seven men with metabolic syndrome completed an open and balanced crossover study. Treatment periods lasted for 6 to 8 weeks and they were separated from each other with an eight-week washout period. Subjects maintained their normal dietary habits and physical activity without major variations. The daily fat adjunct consisted either of 37.5 grams of butter or 35 mL of Virgino^R CPTRO. Participants were asked to spread butter on bread on the butter period and to drink CPTRO on the oil period. The fat adjunct was used as such without heating or frying.

Results

Compared to butter, administration of CPTRO was followed by a reduction of total cholesterol by 8% (p < 0.001) and LDL cholesterol by 11% (p < 0.001). The level of oxidized LDL was 16% lower after oil period (p = 0.024). Minimal differences in arterial elasticity were not statistically significant.

Conclusion

Cold-pressed turnip rapeseed oil had favourable effects on circulating LDL cholesterol and oxidized LDL, which may be important in the management of patients at high cardiovascular risk.

Trial registration

ClinicalTrial.gov NCT01119690