Carbohydrate restriction alters lipoprotein metabolism by modifying VLDL, LDL, and HDL subfraction distribution and size in overweight men

HDL-Cholesterol Subfraction Dimensional Distribution Is Associated with Cardiovascular Disease Risk and Is Predicted by Visceral Adiposity and Dietary Lipid Intake in Women

HDL-cholesterol quality, including cholesterol distribution in HDL subfractions, is emerging as a key discriminant in dictating the effects of these lipoproteins on cardiovascular health. This study aims at elucidating the relationship between cholesterol distribution in HDL subfractions and CVD risk factors as well as diet quality and energy density in a population of pre- and postmenopausal women. Seventy-two women aged 52 ± 6 years were characterized metabolically and anthropometrically. Serum HDL-C subfractions were quantified using the Lipoprint HDL System. Cholesterol distribution in large HDL subfractions was lower in overweight individuals and study participants with moderate to high estimated CVD risk, hypertension, or insulin resistance. Cholesterol distribution in large, as opposed to small, HDL subfractions correlated negatively with insulin resistance, circulating triglycerides, and visceral adipose tissue (VAT). VAT was an independent positive and negative predictor of cholesterol distribution in large and small HDL subfractions, respectively. Furthermore, an increase in energy intake could predict a decrease in cholesterol levels in large HDL subfractions while lipid intake positively predicted cholesterol levels in small HDL subfractions. Cholesterol distribution in HDL subfractions may represent an additional player in shaping CVD risk and a novel potential mediator of the effect of diet on cardiovascular health.

A pragmatic low carbohydrate diet intervention changes neither carbohydrate consumption nor glycemia in adolescents and young adults with type 1 diabetes in a randomized trial

OBJECTIVE

Despite enthusiasm for low carbohydrate diets (LCDs) among patients with type 1 diabetes (T1DM), no prospective study has investigated outcomes in adolescent T1DM. We aimed to quantify a pragmatic LCD intervention's impact on glycemia, lipidemia, and quality of life (QOL) in adolescents with T1DM.

RESEARCH DESIGN AND METHODS

At an academic center, we randomized 39 patients with T1DM aged 13-21 years to one of three 12-week interventions: an LCD, an isocaloric standard carbohydrate diet (SCD), or general diabetes education without a prescriptive diet. Glycemic outcomes included glycosylated hemoglobin (HbA1c) and continuous glucose monitoring.

RESULTS

There were no significant differences in glycemic, lipidemic, or QOL parameters between groups at any timepoint. Median HbA1c was similar at baseline between groups and did not change appreciably (7.9%-8.4% in LCDs, 7.9%-7.9% in SCDs, and 8.2%-7.8% in controls). Change in carbohydrate consumption was minimal with only one participant reaching target carbohydrate intake.

CONCLUSIONS

This pragmatic LCD intervention did not alter carbohydrate consumption or glycemia. Although this study was unable to evaluate a highly controlled LCD, it indicates that adolescents are unlikely to implement an educational LCD intervention in routine clinic settings. Thus, this approach is unlikely to effectively mitigate hyperglycemia in adolescents.

Quantitative NMR-Based Lipoprotein Analysis Identifies Elevated HDL-4 and Triglycerides in the Serum of Alzheimer’s Disease Patients

Alzheimer’s disease (AD) is the most common form of dementia in the elderly and has been associated with changes in lipoprotein metabolism. We performed quantitative lipoprotein analysis in a local cohort of cognitively impaired elderly and control subjects using standardized nuclear magnetic resonance (NMR) spectroscopy. A commercially available quantitative NMR-based assay covering 112 lipoprotein main and subtype variables was used to investigate blood serum samples from a moderate cohort size of 161 persons (71 female, 90 male), including measures of quality control. Additionally, clinical metadata and cerebrospinal fluid AD biomarkers were collected and used for analysis. High-density lipoprotein (HDL) HDL-4 subfraction levels were mostly high in female individuals with mild cognitive impairment (MCI), followed by AD. Low-density lipoprotein (LDL) LDL-2 cholesterol was slightly elevated in male AD patients. HDL-2 apolipoprotein Apo-A1, HDL-2 phospholipids, and HDL-3 triglycerides were highly abundant in AD and MCI women compared to men. When considering clinical biomarkers (Aβ, tau), very low-density lipoprotein (VLDL) VLDL-1 and intermediate-density lipoprotein (IDL) triglycerides were substantially higher in AD compared to MCI. In addition, triglyceride levels correlated positively with dementia. Different lipoprotein serum patterns were identified for AD, MCI, and control subjects. Interestingly, HDL-4 and LDL-2 cholesterol parameters revealed strong gender-specific changes in the context of AD-driven dementia. As gender-based comparisons were based on smaller sub-groups with a low n-number, several statistical findings did not meet the significance threshold for multiple comparisons testing. Still, our finding suggests that serum HDL-4 parameters and various triglycerides correlate positively with AD pathology which could be a read-out of extended lipids traveling through the blood-brain barrier, supporting amyloid plaque formation processes. Thereof, we see herein a proof of concept that this quantitative NMR-based lipoprotein assay can generate important and highly interesting data for refined AD diagnosis and patient stratification, especially when larger cohorts are available.

Time-restricted eating with or without low-carbohydrate diet reduces visceral fat and improves metabolic syndrome: A randomized trial

Overconsumption of carbohydrate-rich food combined with adverse eating patterns contributes to the increasing incidence of metabolic syndrome (MetS) in China. Therefore, we conducted a randomized trial to determine the effects of a low-carbohydrate diet (LCD), an 8-h time-restricted eating (TRE) schedule, and their combination on body weight and abdominal fat area (i.e., primary outcomes) and cardiometabolic outcomes in participants with MetS. Compared with baseline, all 3-month treatments significantly reduce body weight and subcutaneous fat area, but only TRE and combination treatment reduce visceral fat area (VFA), fasting blood glucose, uric acid (UA), and dyslipidemia. Furthermore, compared with changes of LCD, TRE and combination treatment further decrease body weight and VFA, while only combination treatment yields more benefits on glycemic control, UA, and dyslipidemia. In conclusion, without change of physical activity, an 8-h TRE with or without LCD can serve as an effective treatment for MetS (ClinicalTrials.gov: NCT04475822).

Sugar-Sweetened Beverage Consumption and Plasma Lipoprotein Cholesterol, Apolipoprotein, and Lipoprotein Particle Size Concentrations in US Adults

BACKGROUND

Prospective cohort studies have found a relation between sugar-sweetened beverage (SSB) consumption (sodas and fruit drinks) and dyslipidemia. There is limited evidence linking SSB consumption to emerging features of dyslipidemia, which can be characterized by variation in lipoprotein particle size, remnant-like particle (RLP), and apolipoprotein concentrations.

OBJECTIVES

To examine the association between SSB consumption and plasma lipoprotein cholesterol, apolipoprotein, and lipoprotein particle size concentrations among US adults.

METHODS

We examined participants from the Framingham Offspring Study (FOS; 1987-1995, n = 3047) and the Women's Health Study (1992, n = 26,218). Concentrations of plasma LDL cholesterol, apolipoprotein B (apoB), HDL cholesterol, apolipoprotein A1 (apoA1), triglyceride (TG), and non-HDL cholesterol, as well as total cholesterol:HDL cholesterol ratio and apoB:apoA1 ratio, were quantified in both cohorts; concentrations of apolipoprotein E, apolipoprotein C3, RLP-TG, and RLP cholesterol (RLP-C) were measured in the FOS only. Lipoprotein particle sizes were calculated from nuclear magnetic resonance signals for lipoprotein particle subclass concentrations (TG-rich lipoprotein particles [TRL-Ps]: very large, large, medium, small, and very small; LDL particles [LDL-Ps]: large, medium, and small; HDL particles [HDL-Ps]: large, medium, and small). SSB consumption was estimated from food frequency questionnaire data. We examined the associations between SSB consumption and all lipoprotein and apoprotein measures in linear regression models, adjusting for confounding factors such as lifestyle, diet, and traditional lipoprotein risk factors.

RESULTS

SSB consumption was positively associated with LDL cholesterol, apoB, TG, RLP-TG, RLP-C, and non-HDL cholesterol concentrations and total cholesterol:HDL cholesterol and apoB:apoA1 ratios; and negatively associated with HDL cholesterol and apoA1 concentrations (P-trend range: <0.0001 to 0.008). After adjustment for traditional lipoprotein risk factors, SSB consumers had smaller LDL-P and HDL-P sizes; lower concentrations of large LDL-Ps and medium HDL-Ps; and higher concentrations of small LDL-Ps, small HDL-Ps, and large TRL-Ps (P-trend range: <0.0001 to 0.001).

CONCLUSIONS

Higher SSB consumption was associated with multiple emerging features of dyslipidemia that have been linked to higher cardiometabolic risk in US adults.

Universal Barcoding Predicts In Vivo ApoE-Independent Lipid Nanoparticle Delivery

To predict whether preclinical lipid nanoparticle (LNP) delivery will translate in humans, it is necessary to understand whether the mechanism used by LNPs to enter cells is conserved across species. In mice, non-human primates, and humans, LNPs deliver RNA to hepatocytes by adsorbing apolipoprotein E (ApoE), which binds low-density lipoprotein receptor (LDLR). A growing number of LNPs can deliver RNA to nonhepatocytes, suggesting that ApoE- and LDLR-independent interactions could affect LNP tropism. To evaluate this hypothesis, we developed a universal DNA barcoding system that quantifies how chemically distinct LNPs deliver small interfering RNA in any mouse model, including genetic knockouts. We quantified how 98 different LNPs targeted 11 cell types in wildtype, LDLR^-/-, very low-density lipoprotein receptor, and ApoE^-/- mice, studying how these genes, which traffic endogenous lipids, affected LNP delivery. These data identified a novel, stereopure LNP that targets Kupffer cells, endothelial cells, and hepatocytes in an ApoE-independent manner. These results suggest that non-ApoE interactions can affect the tropism of LNP-RNA drugs.

The role of adiposity, diet and inflammation on the discordance between LDL-C and apolipoprotein B

BACKGROUND AND AIMS

While low-density lipoprotein cholesterol (LDL-C) is a good predictor of atherosclerotic cardiovascular disease, apolipoprotein B (ApoB) is superior when the two markers are discordant. We aimed to determine the impact of adiposity, diet and inflammation upon ApoB and LDL-C discordance.

METHODS AND RESULTS

Machine learning (ML) and structural equation models (SEMs) were applied to the National Health and Nutrition Examination Survey to investigate cardiometabolic and dietary factors when LDL-C and ApoB are concordant/discordant. Mendelian randomisation (MR) determined whether adiposity and inflammation exposures were causal of elevated/decreased LDL-C and/or ApoB. ML showed body mass index (BMI), dietary saturated fatty acids (SFA), dietary fibre, serum C-reactive protein (CRP) and uric acid were the most strongly associated variables (R² = 0.70) in those with low LDL-C and high ApoB. SEMs revealed that fibre (b = -0.42, p = 0.001) and SFA (b = 0.28, p = 0.014) had a significant association with our outcome (joined effect of ApoB and LDL-C). BMI (b = 0.65, p = 0.001), fibre (b = -0.24, p = 0.014) and SFA (b = 0.26, p = 0.032) had significant associations with CRP. MR analysis showed genetically higher body fat percentage had a significant causal effect on ApoB (Inverse variance weighted (IVW) = Beta: 0.172, p = 0.0001) but not LDL-C (IVW = Beta: 0.006, p = 0.845).

CONCLUSION

Our data show increased discordance between ApoB and LDL-C is associated with cardiometabolic, clinical and dietary abnormalities and that body fat percentage is causal of elevated ApoB.

Modification of High-Density Lipoprotein Functions by Diet and Other Lifestyle Changes: A Systematic Review of Randomized Controlled Trials

High-density lipoprotein (HDL) functional traits have emerged as relevant elements that may explain HDL antiatherogenic capacity better than HDL cholesterol levels. These properties have been improved in several lifestyle intervention trials. The aim of this systematic review is to summarize the results of such trials of the most commonly used dietary modifications (fatty acids, cholesterol, antioxidants, alcohol, and calorie restriction) and physical activity. Articles were screened from the Medline database until March 2021, and 118 randomized controlled trials were selected. Results from HDL functions and associated functional components were extracted, including cholesterol efflux capacity, cholesteryl ester transfer protein, lecithin-cholesterol acyltransferase, HDL antioxidant capacity, HDL oxidation status, paraoxonase-1 activity, HDL anti-inflammatory and endothelial protection capacity, HDL-associated phospholipase A2, HDL-associated serum amyloid A, and HDL-alpha-1-antitrypsin. In mainly short-term clinical trials, the consumption of monounsaturated and polyunsaturated fatty acids (particularly omega-3 in fish), and dietary antioxidants showed benefits to HDL functionality, especially in subjects with cardiovascular risk factors. In this regard, antioxidant-rich dietary patterns were able to improve HDL function in both healthy individuals and subjects at high cardiovascular risk. In addition, in randomized trial assays performed mainly in healthy individuals, reverse cholesterol transport with ethanol in moderate quantities enhanced HDL function. Nevertheless, the evidence summarized was of unclear quality and short-term nature and presented heterogeneity in lifestyle modifications, trial designs, and biochemical techniques for the assessment of HDL functions. Such findings should therefore be interpreted with caution. Large-scale, long-term, randomized, controlled trials in different populations and individuals with diverse pathologies are warranted.

Effect of a 90 g/day low-carbohydrate diet on glycaemic control, small, dense low-density lipoprotein and carotid intima-media thickness in type 2 diabetic patients: An 18-month randomised controlled trial

Aim

This study explored the effect of a moderate (90 g/d) low-carbohydrate diet (LCD) in type 2 diabetes patients over 18 months.

Methods

Ninety-two poorly controlled type 2 diabetes patients aged 20–80 years with HbA1c ≥7.5% (58 mmol/mol) in the previous three months were randomly assigned to a 90 g/d LCD r traditional diabetic diet (TDD). The primary outcomes were glycaemic control status and change in medication effect score (MES). The secondary outcomes were lipid profiles, small, dense low-density lipoprotein (sdLDL), serum creatinine, microalbuminuria and carotid intima-media thickness (IMT).

Results

A total of 85 (92.4%) patients completed 18 months of the trial. At the end of the study, the LCD and TDD group consumed 88.0±29.9 g and 151.1±29.8 g of carbohydrates, respectively (p < 0.05). The 18-month mean change from baseline was statistically significant for the HbA1c (-1.6±0.3 vs. -1.0±0.3%), 2-h glucose (-94.4±20.8 vs. -18.7±25.7 mg/dl), MES (-0.42±0.32 vs. -0.05±0.24), weight (-2.8±1.8 vs. -0.7±0.7 kg), waist circumference (-5.7±2.7 vs. -1.9±1.4 cm), hip circumference (-6.1±1.8 vs. -2.9±1.7 cm) and blood pressure (-8.3±4.6/-5.0±3 vs. 1.6±0.5/2.5±1.6 mmHg) between the LCD and TDD groups (p<0.05). The 18-month mean change from baseline was not significantly different in lipid profiles, sdLDL, serum creatinine, microalbuminuria, alanine aminotransferase (ALT) and carotid IMT between the groups.

Conclusions

A moderate (90 g/d) LCD showed better glycaemic control with decreasing MES, lowering blood pressure, decreasing weight, waist and hip circumference without adverse effects on lipid profiles, sdLDL, serum creatinine, microalbuminuria, ALT and carotid IMT than TDD for type 2 diabetic patients.

A Cross-Sectional Study on the Dietary Pattern Impact on Cardiovascular Disease Biomarkers in Malaysia

We conducted this cross-sectional population study with a healthy multi-ethnic urban population (n = 577) in Malaysia, combining nutritional assessments with cardiometabolic biomarkers defined by lipid, atherogenic lipoproteins, inflammation and insulin resistance. We found diametrically opposing associations of carbohydrate (246·6 ± 57·7 g, 54·3 ± 6·5%-TEI) and fat (total = 64·5 ± 19·8 g, 31·6 ± 5·5%-TEI; saturated fat = 14·1 ± 2·7%-TEI) intakes as regards waist circumference, HDL-C, blood pressure, glucose, insulin and HOMA2-IR as well as the large-LDL and large-HDL lipoprotein particles. Diets were then differentiated into either low fat (LF, <30% TEI or <50 g) or high fat (HF, >35% TEI or >70 g) and low carbohydrate (LC, <210 g) or high carbohydrate (HC, >285 g) which yielded LFLC, LFHC, HFLC and HFHC groupings. Cardiometabolic biomarkers were not significantly different (P > 0.05) between LFLC and HFLC groups. LFLC had significantly higher large-LDL particle concentrations compared to HFHC. HOMA-IR2 was significantly higher with HFHC (1·91 ± 1·85, P < 0·001) versus other fat-carbohydrate combinations (LFLC = 1·34 ± 1·07, HFLC = 1·41 ± 1·07; LFHC = 1·31 ± 0·93). After co-variate adjustment, odds of having HOMA2-IR >1.7 in the HFHC group was 2.43 (95% CI: 1·03, 5·72) times more compared to LFLC while odds of having large-LDL <450 nmol/L in the HFHC group was 1.91 (95% CI: 1·06, 3·44) more compared to latter group. Our data suggests that a HFHC dietary combination in Malaysian adults is associated with significant impact on lipoprotein particles and insulin resistance.

Health Benefits of Indoor Cycling: A Systematic Review

Background and Objectives: Indoor cycling is one of the most practiced activities in fitness centers for most people regardless of their physical conditioning level. Several studies have analyzed the effect of indoor cycling on several parameters related to health, such as maximal oxygen consumption, blood pressure, body composition, as well as biochemical markers such as HDL or LDL. However, no study has synthesized all health benefits associated with the indoor cycling practice in the form of a systematic review and established guidelines or recommendations. Therefore, the aim of this manuscript was to conduct a systematic review of published studies about the benefits of indoor cycling training and to establish recommendations for coaches, researchers, and practitioners. Materials and Methods: The PRISMA guidelines were followed to conduct the current systematic review. A systematic search was performed to retrieve relevant published articles until January 2019 using the following keywords: ‘indoor cycling’, ‘indoor bicycle’, and ‘spinning exercise’. Information about participants, intervention, comparisons, outcomes, and study design (PICOS) was extracted. Results: A total of 300 studies were initially identified. After the revision process, 13 of them were included. The total sample size of the studies was 372 (306 women). Results revealed that indoor cycling may improve aerobic capacity, blood pressure, lipid profile, and body composition. These enhancements may be achieved as standalone intervention or combined with other physical exercises or diet. Conclusions: The combination of indoor cycling and diet is recommended to improve the lipid profile, lose weight, and reduce blood pressure. Furthermore, indoor cycling alone may also enhance aerobic capacity. Given the lack of randomized controlled trials, these conclusions should be taken with caution.

Targeting the Warburg effect for cancer treatment: Ketogenic diets for management of glioma

Gliomas are a highly heterogeneous tumor, refractory to treatment and the most frequently diagnosed primary brain tumor. Although the current WHO grading system (2016) demonstrates promise towards identifying novel treatment modalities and better prediction of prognosis over time, to date, existing targeted and mono therapy approaches have failed to elicit a robust impact on disease progression and patient survival. It is possible that tumor heterogeneity as well as specifically targeted agents fail because redundant molecular pathways in the tumor make it refractory to such approaches. Additionally, the underlying metabolic pathology, which is significantly altered during neoplastic transformation and tumor progression, is unaccounted for. With several molecular and metabolic pathways implicated in the carcinogenesis of CNS tumors, including glioma, we postulate that a systemic, broad spectrum approach to produce robust targeting of relevant and multiple molecular and metabolic regulation of growth and survival pathways, critical to the modulation of hallmarks of carcinogenesis, without clinically limiting toxicity, may provide a more sustained impact on clinical outcomes compared to the modalities of treatment evaluated to date. The objective of this review is to examine the emerging hallmark of reprogramming energy metabolism of the tumor cells and the tumor microenvironment during carcinogenesis, and to provide a rationale for exploiting this hallmark and its biological capabilities as a target for secondary chemoprevention and treatment of glioma. This review will primarily focus on interventions to induce ketosis to target the glycolytic phenotype of many cancers, with specific application to secondary chemoprevention of low grade glioma- to halt the progression of lower grade tumors to more aggressive subtypes, as evidenced by reduction in validated intermediate endpoints of disease progression including clinical symptoms.

Genetic associations with lipoprotein subfraction measures differ by ethnicity in the multi-ethnic study of atherosclerosis (MESA)

A recent genome-wide association study associated 62 single nucleotide polymorphisms (SNPs) from 43 genomic loci, with fasting lipoprotein subfractions in European-Americans (EAs) at genome-wide levels of significance across three independent samples. Whether these associations are consistent across ethnicities with a non-European ancestry is unknown. We analyzed 15 lipoprotein subfraction measures, on 1677 African-Americans (AAs), 1450 Hispanic-Americans (HAs), and 775 Chinese-Americans (CHN) participating in the multi-ethnic study of atherosclerosis (MESA). Genome-wide data were obtained using the Affymetrix 6.0 and Illumina HumanOmni chips. Linear regression models between genetic variables and lipoprotein subfractions were adjusted for age, gender, body mass index, smoking, study center, and genetic ancestry (based on principal components), and additionally adjusted for Mexican/Non-Mexican status in HAs. A false discovery rate correction was applied separately within the results for each ethnicity to correct for multiple testing. Power calculations revealed that we did not have the power for SNP-based measures of association, so we analyzed phenotype-specific genetic risk scores (GRSs), constructed as in the original genome-wide analysis. We successfully replicated all 15 GRS-lipoprotein associations in 2527 EAs. Among the 15 significant GRS-lipoprotein associations in EAs, 11 were significant in AAs, 13 in HAs, and 1 in CHNs. Further analyses revealed that ethnicity differences could not be explained by differences in linkage disequilibrium, lipid lowering drugs, diabetes, or gender. Our study emphasizes the importance of ethnicity (here indexing genetic ancestry) in genetic risk for CVD and highlights the need to identify ethnicity-specific genetic variants associated with CVD risk.

Evidence that supports the prescription of low-carbohydrate high-fat diets: a narrative review

Low-carbohydrate high-fat (LCHF) diets are a highly contentious current topic in nutrition. This narrative review aims to provide clinicians with a broad overview of the effects of LCHF diets on body weight, glycaemic control and cardiovascular risk factors while addressing some common concerns and misconceptions. Blood total cholesterol and LDL-cholesterol concentrations show a variable, highly individual response to LCHF diets, and should be monitored in patients adhering to this diet. In contrast, available evidence from clinical and preclinical studies indicates that LCHF diets consistently improve all other markers of cardiovascular risk-lowering elevated blood glucose, insulin, triglyceride, ApoB and saturated fat (especially palmitoleic acid) concentrations, reducing small dense LDL particle numbers, glycated haemoglobin (HbA_1c) levels, blood pressure and body weight while increasing low HDL-cholesterol concentrations and reversing non-alcoholic fatty liver disease (NAFLD). This particular combination of favourable modifications to all these risk factors is a benefit unique to LCHF diets. These effects are likely due in part to reduced hunger and decreased ad libitum calorie intake common to low-carbohydrate diets, allied to a reduction in hyperinsulinaemia, and reversal of NAFLD. Although LCHF diets may not be suitable for everyone, available evidence shows this eating plan to be a safe and efficacious dietary option to be considered. LCHF diets may also be particularly beneficial in patients with atherogenic dyslipidaemia, insulin resistance, and the frequently associated NAFLD.

Effects of High Protein and Balanced Diets on Lipid Profiles and Inflammation Biomarkers in Obese and Overweight Women at Aerobic Clubs: A Randomized Clinical Trial

BACKGROUND

We studied the effects of high protein (HP) and balanced diets (BDs) on lipid profiles, and high-sensitive C-reactive protein (hs-CRP) levels in obese and overweight women.

METHODS

In a parallel designed randomized controlled clinical trial, 60 healthy women with body mass index ≥25 kg/m², aged 20-46 years, enrolled in an 8-week investigation at aerobic clubs. They were categorized into two groups (HP and BDs), randomly. Fasting lipid profile and hs-CRP levels were evaluated at the beginning and end of the trial. We assessed dietary intake by 3-day records and also used SPSS (version 18; SPSS Inc., Chicago, IL, USA) for data analyzing.

RESULTS

Fifty-six participants completed the intervention. Concentrations of low-density lipoprotein cholesterol (P < 0.001 in BD group vs. P =0.023 in HP group) and high-density lipoprotein cholesterol (P < 0.001 in BD group vs. P =0.002 in HP group) increased significantly in both groups. Circulating triglycerides levels increased in both intervention grows, but the change in the HP group was not significant compared with the other group (P = 0.007 in BD group vs. P =0.099 in HP group). Whereas total cholesterol concentration decreased but not significantly so (P = 0.53 in BD group vs. P =0.73 in HP group). There were marginally significant decreases in the hs-CRP levels due to both diets (P = 0.057 in BD group vs. P =0.086 in HP group); however, there were no significant differences between the groups.

CONCLUSIONS

Administration of HP and BD in overweight and obese women with regular aerobic exercise showed improvement in lipid profiles and hs-CRP levels within the groups, but there were no significant differences between groups.

Age, APOE and sex: Triad of risk of Alzheimer's disease

Age, apolipoprotein E ε4 (APOE) and chromosomal sex are well-established risk factors for late-onset Alzheimer's disease (LOAD; AD). Over 60% of persons with AD harbor at least one APOE-ε4 allele. The sex-based prevalence of AD is well documented with over 60% of persons with AD being female. Evidence indicates that the APOE-ε4 risk for AD is greater in women than men, which is particularly evident in heterozygous women carrying one APOE-ε4 allele. Paradoxically, men homozygous for APOE-ε4 are reported to be at greater risk for mild cognitive impairment and AD. Herein, we discuss the complex interplay between the three greatest risk factors for Alzheimer's disease, age, APOE-ε4 genotype and chromosomal sex. We propose that the convergence of these three risk factors, and specifically the bioenergetic aging perimenopause to menopause transition unique to the female, creates a risk profile for AD unique to the female. Further, we discuss the specific risk of the APOE-ε4 positive male which appears to emerge early in the aging process. Evidence for impact of the triad of AD risk factors is most evident in the temporal trajectory of AD progression and burden of pathology in relation to APOE genotype, age and sex. Collectively, the data indicate complex interactions between age, APOE genotype and gender that belies a one size fits all approach and argues for a precision medicine approach that integrates across the three main risk factors for Alzheimer's disease.

Relevance of liver fat to the impact of dietary extrinsic sugars on lipid metabolism

In contrast to the decline in mortality from many non-infectious, chronic diseases in the UK, death from liver disease has increased exponentially in men and women over the past 40 years. This is primarily because of the over consumption of alcohol, but also the increased prevalence of obesity, which is linked to early pathology through the accumulation of liver fat. Supra-physiological intakes of fructose-containing sugar can produce acute, adverse effects on lipid metabolism, and deliver excess energy that increases bodyweight and the deposition of fat in sites other than adipose tissue, including the liver. This review addresses the variable metabolic origins of liver fat, and the key importance of postprandial lipid metabolism in this respect. The effects of supra-physiological intakes of sugar are also considered in context of the real world and established threshold for the adverse effects of sugar on cardio-metabolic risk factors. The review concludes that while the average intake of sugar in the UK falls well below this critical threshold, intakes in subgroups of adults, and especially adolescents, may be cause for concern. There is also evidence to suggest that raised liver fat, acquired, in part, through an impaired removal of postprandial lipaemia, can increase sensitivity to the adverse effects of sugar at all ages.

One Egg per Day Improves Inflammation when Compared to an Oatmeal-Based Breakfast without Increasing Other Cardiometabolic Risk Factors in Diabetic Patients

There is concern that egg intake may increase blood glucose in patients with type 2 diabetes mellitus (T2DM). However, we have previously shown that eggs reduce inflammation in patients at risk for T2DM, including obese subjects and those with metabolic syndrome. Thus, we hypothesized that egg intake would not alter plasma glucose in T2DM patients when compared to oatmeal intake. Our primary endpoints for this clinical intervention were plasma glucose and the inflammatory markers tumor necrosis factor (TNF)-α and interleukin 6 (IL-6). As secondary endpoints, we evaluated additional parameters of glucose metabolism, dyslipidemias, oxidative stress and inflammation. Twenty-nine subjects, 35–65 years with glycosylated hemoglobin (HbA1c) values <9% were recruited and randomly allocated to consume isocaloric breakfasts containing either one egg/day or 40 g of oatmeal with 472 mL of lactose-free milk/day for five weeks. Following a three-week washout period, subjects were assigned to the alternate breakfast. At the end of each period, we measured all primary and secondary endpoints. Subjects completed four-day dietary recalls and one exercise questionnaire for each breakfast period. There were no significant differences in plasma glucose, our primary endpoint, plasma lipids, lipoprotein size or subfraction concentrations, insulin, HbA1c, apolipoprotein B, oxidized LDL or C-reactive protein. However, after adjusting for gender, age and body mass index, aspartate amino-transferase (AST) (p < 0.05) and tumor necrosis factor (TNF)-α (p < 0.01), one of our primary endpoints were significantly reduced during the egg period. These results suggest that compared to an oatmeal-based breakfast, eggs do not have any detrimental effects on lipoprotein or glucose metabolism in T2DM. In contrast, eggs reduce AST and TNF-α in this population characterized by chronic low-grade inflammation.

Genomic determinants of triglyceride and cholesterol distribution into lipoprotein fractions in the rat

The plasma profile of major lipoprotein classes and its subdivision into particular fractions plays a crucial role in the pathogenesis of atherosclerosis and is a major predictor of coronary artery disease. Our aim was to identify genomic determinants of triglyceride and cholesterol distribution into lipoprotein fractions and lipoprotein particle sizes in the recombinant inbred rat set PXO, in which alleles of two rat models of the metabolic syndrome (SHR and PD inbred strains) segregate together with those from Brown Norway rat strain. Adult male rats of 15 PXO strains (n = 8–13/strain) and two progenitor strains SHR-Lx (n = 13) and BXH2/Cub (n = 18) were subjected to one-week of high-sucrose diet feeding. We performed association analyses of triglyceride (TG) and cholesterol (C) concentrations in 20 lipoprotein fractions and the size of major classes of lipoprotein particles utilizing 704 polymorphic microsatellite markers, the genome-wide significance was validated by 2,000 permutations per trait. Subsequent in silico focusing of the identified quantitative trait loci was completed using a map of over 20,000 single nucleotide polymorphisms. In most of the phenotypes we identified substantial gradient among the strains (e.g. VLDL-TG from 5.6 to 66.7 mg/dl). We have identified 14 loci (encompassing 1 to 65 genes) on rat chromosomes 3, 4, 7, 8, 11 and 12 showing suggestive or significant association to one or more of the studied traits. PXO strains carrying the SHR allele displayed significantly higher values of the linked traits except for LDL-TG and adiposity index. Cholesterol concentrations in large, medium and very small LDL particles were significantly associated to a haplotype block spanning part of a single gene, low density lipoprotein receptor-related protein 1B (Lrp1b). Using genome-wide association we have identified new genetic determinants of triglyceride and cholesterol distribution into lipoprotein fractions in the recombinant inbred panel of rat model strains.

Bioelectrocatalytic sensor for triglycerides in human skin sebum based on enzymatic cascade reaction of lipase, glycerol kinase and glycerophosphate oxidase

We report the development of an electrochemical biosensor for the quantification of triglycerides in human skin sebum, based on a multienzyme cascade reaction. The presence of excessive triglycerides in human sebum is one of the leading causes of various skin ailments. However, to the best of our knowledge, no bioelectrocatalytic approach for the quantification of sebum triglycerides has been made. In order to develop triglyceride biosensor, we fabricated a multienzyme-associated electrode incorporating lipase, glycerol kinase, and glycerophosphate oxidase. Enzymes were deposited by electrostatic force and further stabilized via crosslinking between enzymes and polymer matrices. The enzyme-modified biosensing electrode maintained its bioelectrocatalytic activity for five days. An additional constraint was the limited solubility of sebum triglycerides in aqueous electrolytes, impeding the analysis. To address this issue, triglyceride samples were prepared in the form of micelles, enabling efficient sample preparation for biosensor signaling. Calibration tests revealed that the designed assay had a detection range of 15-200mg/dL of micellar triglyceride, which covered the required determination range. The developed biosensing approach was successfully used to determine triglyceride concentrations in real sebum samples of unknown triglyceride content.

Sex-specific associations between screen time and lipoprotein subfractions

BACKGROUND

Time spent in sedentary activities (such as watching television) has previously been associated with several risk factors for cardiovascular disease (CVD) such as increased low-density lipoprotein cholesterol (LDL-C). Little is known about associations with lipoprotein subfractions. Using television and computer screen time in hours per day as a measure of sedentary time, we examined the association of screen time with lipoprotein subfractions.

METHODS

Data were used from men and women forming the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study population. Mixed linear models specified lipoprotein measures as the outcome, and screen time as the predictor for fourteen lipoprotein subfraction measures, and included age, smoking status, pedigree, and fat, carbohydrate daily alcohol and energy intake as covariates. Analyses were run separately for men (n = 623) and women (n = 671). A step-down Bonferroni correction was applied to results. The analysis was repeated for significant results (p < .05), additionally controlling for body mass index (BMI) and moderate and vigorous physical activity.

RESULTS

Linear models indicated that screen time was associated with five lipoprotein parameters in women: the concentration of large VLDL particles (p = .01), LDL particle number (p = .01), concentration of small LDL particles (p = .04), the concentration of large HDL particles (p = .04), and HDL diameter (p = .02). All associations remained after controlling for moderate or vigorous physical activity and BMI.

CONCLUSIONS

We show that sedentary time is associated with lipoprotein measures, markers of cardiometabolic disease, independently of physical activity and BMI, in women but not men.

Dengue virus capsid protein interacts specifically with very low-density lipoproteins

Dengue affects millions of people worldwide. No specific treatment is currently available, in part due to an incomplete understanding of the viral components' interactions with host cellular structures. We tested dengue virus (DENV) capsid protein (C) interaction with low- and very low-density lipoproteins (LDL and VLDL, respectively) using atomic force microscopy-based force spectroscopy, dynamic light scattering, NMR and computational analysis. Data reveal a specific DENV C interaction with VLDL, but not LDL. This binding is potassium-dependent and involves the DENV C N-terminal region, as previously observed for the DENV C-lipid droplets (LDs) interaction. A successful inhibition of DENV C-VLDL binding was achieved with a peptide drug lead. The similarities between LDs and VLDL, and between perilipin 3 (DENV C target on LDs) and ApoE, indicate ApoE as the molecular target on VLDL. We hypothesize that DENV may form lipoviroparticles, which would constitute a novel step on DENV life cycle.

FROM THE CLINICAL EDITOR

Using atomic force microscopy-based force spectroscopy, dynamic light scattering, NMR, and computational analysis, these authors demonstrate that dengue viral capsid proteins (DENV C) bind to very low density lipoprotein surfaces, but not to LDLs, in a potassium-dependent manner. This observation suggests the formation of lipo-viroparticles, which may be a novel step in its life cycle, and may offer potential therapeutic interventions directed to this step.

Genetic variants associated with VLDL, LDL and HDL particle size differ with race/ethnicity

Specific constellations of lipoprotein particle features, reflected as differences in mean lipoprotein particle diameters, are associated with risk of insulin resistance (IR) and cardiovascular disease (CVD). The associations of lipid profiles with disease risk differ by race/ethnicity, the reason for this is not clear. We aimed to examine whether there were additional genetic differences between racial/ethnic groups on lipoprotein profile. Genotypes were assessed using the Affymetrix 6.0 array in 817 related Caucasian participants of the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN). Association analysis was conducted on fasting mean particle diameters using linear models, adjusted for age, sex and study center as fixed effects, and pedigree as a random effect. Replication of associations reaching P < 1.97 × 10(-05) (the level at which we achieved at least 80% power to replicate SNP-phenotype associations) was conducted in the Caucasian population of the Multi-Ethnic Study of Atherosclerosis (MESA; N = 2,430). Variants which replicated across both Caucasian populations were subsequently tested for association in the African-American (N = 1,594), Chinese (N = 758), and Hispanic (N = 1,422) populations of MESA. Variants in the APOB gene region were significantly associated with mean VLDL diameter in GOLDN, and in the Caucasian and Hispanic populations of MESA, while variation in the hepatic lipase (LIPC) gene was associated with mean HDL diameter in both Caucasians populations only. Our findings suggest that the genetic underpinnings of mean lipoprotein diameter differ by race/ethnicity. As lipoprotein diameters are modifiable, this may lead new strategies to modify lipoprotein profiles during the reduction of IR that are sensitive to race/ethnicity.

A Mediterranean-style low-glycemic-load diet increases plasma carotenoids and decreases LDL oxidation in women with metabolic syndrome

Thirty-five women with metabolic syndrome and high plasma low-density lipoprotein (LDL) cholesterol (≥100 mg/dl) participated in a dietary intervention consisting of a Mediterranean-style low-glycemic-load diet for 12 weeks. Participants were randomly allocated to consume diet only (n=15) or diet plus a medical food containing soy protein and plant sterols (n=20). Plasma concentrations of carotenoids, lipoprotein subfractions and oxidized LDL (OxLDL) were measured. Independent of treatment, women had a significant increase in plasma lutein (P<.0001) and β-carotene (P<.0001), while plasma lycopene was reduced (P<.05) after 12 weeks. Low-density lipoprotein cholesterol was reduced from 138±35 to 114±33 mg/dl (P<.0001). In addition, decreases were observed in the atherogenic subfractions: large very low-density lipoprotein (P<.05), small LDL (P<.00001) and medium high-density lipoprotein (P<.05). Oxidized LDL was significantly reduced by 12% in both groups (P<.01). Changes in OxLDL were inversely correlated with plasma lutein (r=-.478, P<.0001). The data indicate that women complied with the dietary regimen by increasing fruits and vegetable intake. Decreased consumption of high-glycemic foods frequently co-consumed with lycopene-rich tomato sauce such as pasta and pizza may be responsible for the lowering of this carotenoid in plasma after 12 weeks. These results also suggest that plasma lutein concentrations may protect against oxidative stress by reducing the concentrations of OxLDL.

Low HDL cholesterol is associated with increased atherogenic lipoproteins and insulin resistance in women classified with metabolic syndrome

Both metabolic syndrome (MetS) and elevated LDL cholesterol (LDL-C) increase the risk for cardiovascular disease (CVD). We hypothesized that low HDL cholesterol (HDL-C) would further increase CVD risk in women having both conditions. To assess this, we recruited 89 women with MetS (25-72 y) and LDL-C ≥ 2.6 mmol/L. To determine whether plasma HDL-C concentrations were associated with dietary components, circulating atherogenic particles, and other risk factors for CVD, we divided the subjects into two groups: high HDL-C (H-HDL) (≥ 1.3 mmol/L, n = 32) and low HDL-C (L-HDL) (< 1.3 mmol/L, n = 57). Plasma lipids, insulin, adiponectin, apolipoproteins, oxidized LDL, Lipoprotein(a), and lipoprotein size and subfractions were measured, and 3-d dietary records were used to assess macronutrient intake. Women with L-HDL had higher sugar intake and glycemic load (P < 0.05), higher plasma insulin (P < 0.01), lower adiponectin (P < 0.05), and higher numbers of atherogenic lipoproteins such as large VLDL (P < 0.01) and small LDL (P < 0.001) than the H-HDL group. Women with L-HDL also had larger VLDL and both smaller LDL and HDL particle diameters (P < 0.001). HDL-C was positively correlated with LDL size (r = 0.691, P < 0.0001) and HDL size (r = 0.606, P < 0.001), and inversely correlated with VLDL size (r = -0.327, P < 0.01). We concluded that L-HDL could be used as a marker for increased numbers of circulating atherogenic lipoproteins as well as increased insulin resistance in women who are already at risk for CVD.

Efeito da dieta hipoenergética sobre a composição corporal e nível sérico lipídico de mulheres adultas com sobrepeso

OBJETIVO: Verificar o efeito de 12 semanas de dieta hipocalórica sobre a composição corporal e o nível sérico lipídico de mulheres adultas com sobrepeso. MÉTODOS: A amostra foi composta por vinte mulheres (23,80, desvio-padrão de 2,73 anos) da academia Westfit-Bangu, divididas randomicamente em dois grupos de dez: grupo controle e grupo dieta hipoenergética. Foi realizada uma avaliação da composição corporal (massa corporal, percentual de gordura, índice de massa corporal e massa magra) e do nível sérico lipídico (colesterol total, triglicerídeos, lipoproteína de baixa densidade, lipoproteína de alta densidade e lipoproteínas de muito baixa densidade). Utilizou-se a estatística descritiva (média e desvio-padrão) e o teste t de Student na análise inter e intragrupos. O nível de significância foi de p<0,05. RESULTADOS: O grupo dieta hipoenergética apresentou reduções significativas (p<0,05) nas variáveis antropométricas (massa corporal, percentual de gordura, índice de massa corporal e massa magra) e nas variáveis lipídicas (triglicerídios, colesterol total, lipoproteína de baixa densidade e lipoproteínas de muito baixa densidade). Quanto à variável: lipoproteína de alta densidade, foi observada uma redução, porém não significativa. CONCLUSÃO: A partir dos resultados apresentados pode-se concluir que a dieta hipoenergética foi uma excelente opção no tratamento da obesidade e no controle do nível sérico dos lipídeos, contribuindo desta forma, para a redução dos riscos cardiovasculares na população estudada.

Carbohydrate restriction favorably alters lipoprotein metabolism in Emirati subjects classified with the metabolic syndrome

BACKGROUND AND AIMS

Carbohydrate restriction (CR) has been shown to improve dyslipidemias associated with metabolic syndrome (MetS). We evaluated the effects of CR on lipoprotein subfractions and apolipoproteins in Emirati adults classified with the MetS.

METHODS AND RESULTS

39 subjects (15 men/24 women) were randomly allocated to a CR diet [20-25% energy from carbohydrate (CHO)] for 12 wk (CRD group) or a combination treatment consisting of CRD for 6 wk followed by the American Heart Association diet (50-55% CHO, AHA group) for an additional 6 wk. All subjects reduced body weight, LDL cholesterol and triglycerides (P<0.01). At baseline all subjects had low concentrations of medium VLDL and total HDL particles associated with the very low plasma triglycerides and HDL cholesterol in this population. After 12 wk, the large VLDL subfraction was decreased over time for subjects in the CRD group (P<0.01) while these changes were not observed in those subjects who changed to the AHA diet. The number of medium and small LDL particles decreased for all subjects rendering a less atherogenic lipoprotein profile. In agreement with these results, a significant decrease in apolipoprotein (apo) B was observed (P<0.01). The medium HDL subfraction and apo A-II, which can be considered pro-atherogenic, were also decreased over time in the CRD group only.

CONCLUSIONS

These results suggest that weight loss favorably affects lipoprotein metabolism and that the CRD had a better effect on atherogenic VLDL and HDL than the low fat diet recommended by AHA.

The relationship between high density lipoprotein subclass profile and plasma lipids concentrations

HDL particles posses multiple antiatherogenic activities and the identification and differentiation of individual HDL subclasses may be useful in documentation and understanding of metabolic changes of different HDL subclasses. The major plasma lipids exist and are transported in the form of lipoprotein complexes. Hence, alterations in plasma lipids levels can interfere with the composition, content, and distribution of plasma lipoprotein subclasses that affect atherosclerosis risk. The research review major discussed the relationship between plasma lipids levels and HDL subclasses distribution. The general shift toward smaller size of HDL particle size in HTG, HCL and MHL subjects, and the changes were more prominent with the elevation of TG and TC levels which imply that HDL maturation might be abnormal and RCT pathway might be weaken, and these changes were more seriously in MHL subjects. Plasma contents of small sized HDL particles significantly higher, whereas those of large sized HDL particles were significantly lower with elevation of TG/HDL-C and TC/HDL-C ratios. Increased in the TC/HDL-C ratio alone did not influence the distributions of HDL subclasses significantly when the TG/HDL-C ratio was low (TG/HDL-C ≤ 2.5). Hence, the TG/HDL-C ratio might be more sensitive to reflect the alteration of HDL subclass distribution than the TC/HDL-C ratio. In LDL-C/HDL-C ≤ 2.3 group, the pattern of distribution in HDL subclass was in agreement with the normolipidemic subjects. Moreover, considering the relative ease of measuring TC/HDL-C, TG/HDL-C and LDL-C/HDL-C ratios, as opposed to measuring HDL subclasses, these 3 ratios together may be a good indicator of HDL subclass distribution. The protective effect of increased apoA-I levels against the reduction of HDL_2b caused by elevated TG concentration. On one hand, plasma HDL-C and apoA-I appear to play a coordinated role in the assembly of HDL particles and the determination of their contents among the total subjects. On the other hand, the apoA-I level might be a more powerful factor than HDL-C to influence the distribution of HDL subclasses in hyperlipidemic subjects. At the same time, from point of HDL subclasses distribution, the plasma lipids, apos concentrations and apos ratios should be considered while assessing the CHD risk. Abnormality of HDL subclasses distribution may result in accelerated atherosclerosis, therapeutic normalization of attenuated antiatherogenic HDL function in terms of both particle number and distribution of HDL particles is the target of innovative pharmacological approaches to large-sized HDL particles rising, including enhanced apoA-I levels.

Improvements in LDL particle size and distribution by short-term alternate day modified fasting in obese adults

Alternate day modified fasting (ADMF) beneficially modulates several indicators of CHD risk, but its effects on LDL particle size have never been tested. Accordingly, we examined the effects of ADMF on LDL particle size and distribution in obese adults. Sixteen obese subjects participated in a 10-week trial with three consecutive phases: (1) 2-week control phase; (2) 4-week ADMF controlled feeding phase; (3) 4-week ADMF self-selected feeding phase. After 8 weeks of diet, body weight and waist circumference were reduced (P < 0·05) by 5·6 (sem 0·9) kg and 4·0 (sem 0·9) cm, respectively. LDL-cholesterol and TAG concentrations decreased (P < 0·05) by 25 (sem 10) % and 32 (sem 6) %, respectively. Peak LDL particle size increased (P < 0·05) from 266 (sem 1) to 268 (sem 1) Å. Additionally, the proportion of small LDL particles decreased (P < 0·05) from 13 (sem 2) % to 9 (sem 3) %, while the proportion of large LDL particles increased (P < 0·05) from 68 (sem 4) % to 76 (sem 4) % post-treatment. These findings suggest that ADMF is an effective diet strategy for increasing LDL particle size and decreasing the proportion of small, dense LDL particles in obese adults.

Comparison of a reduced carbohydrate and reduced fat diet for LDL, HDL, and VLDL subclasses during 9-months of weight maintenance subsequent to weight loss

OBJECTIVES

This study compared LDL, HDL, and VLDL subclasses in overweight or obese adults consuming either a reduced carbohydrate (RC) or reduced fat (RF) weight maintenance diet for 9 months following significant weight loss.

METHODS

Thirty-five (21 RC; 14 RF) overweight or obese middle-aged adults completed a 1-year weight management clinic. Participants met weekly for the first six months and bi-weekly thereafter. Meetings included instruction for diet, physical activity, and behavior change related to weight management. Additionally, participants followed a liquid very low-energy diet of approximately 2092 kJ per day for the first three months of the study. Subsequently, participants followed a dietary plan for nine months that targeted a reduced percentage of carbohydrate (approximately 20%) or fat (approximately 30%) intake and an energy intake level calculated to maintain weight loss. Lipid subclasses using NMR spectroscopy were analyzed prior to weight loss and at multiple intervals during weight maintenance.

RESULTS

Body weight change was not significantly different within or between groups during weight maintenance (p>0.05). The RC group showed significant increases in mean LDL size, large LDL, total HDL, large and small HDL, mean VLDL size, and large VLDL during weight maintenance while the RF group showed increases in total HDL, large and small HDL, total VLDL, and large, medium, and small VLDL (p<0.05). Group*time interactions were significant for large and medium VLDL (p>0.05).

CONCLUSION

Some individual lipid subclasses improved in both dietary groups. Large and medium VLDL subclasses increased to a greater extent across weight maintenance in the RF group.

Metabolic syndrome prevalence, dietary intake, and cardiovascular risk profile among overweight and obese adults 18-50 years old from the United Arab Emirates

BACKGROUND

The prevalence of diabetes mellitus is among the highest worldwide, and metabolic syndrome predisposes to diabetes.

METHODS

We recruited 227 overweight/obese Emirati adults living in the city of Al-Ain, Emirati of Abu Dhabi to screen for the metabolic syndrome and to assess for the most relevant criteria for the metabolic syndrome in this population. We identified subjects as having the metabolic syndrome if they had three of the following characteristics: Waist circumference (WC) >88 cm in women and >102 cm in men; plasma glucose >5.5 mmol/L; blood pressure >130/85 mmHg, triglycerides (TG) >1.7 mmol/L, and high-density lipoprotein cholesterol (HDL-C) <1.0 mmol/L in men and <1.3 mmol/L in women. In addition to features of metabolic syndrome, lipoprotein subfractions and 24-hour dietary recalls were assessed in a random sample of participants.

RESULTS

A total of 92 subjects (40.5%) were classified as having metabolic syndrome. The most relevant clinical criteria associated with metabolic syndrome were large WC, high blood pressure, and low HDL-C. Only 7% of subjects had TG >1.7 mmol/L, whereas 95% had plasma LDL-C >2.6 mmol/L. In addition, subjects presented low concentrations of medium very-low-density lipoprotein (VLDL) and small HDL subfractions in agreement with low concentrations of HDL-C and TG. Dietary analysis revealed high-energy consumption, with diets high in total carbohydrates, fat, and simple sugars. In addition, subjects were sedentary with only 14% of the population engaged in physical activity.

CONCLUSIONS

The high prevalence of metabolic syndrome among overweight/obese Emirati adults predisposes this population to increased risk for developing diabetes and cardiovascular disease. Public health involvement targeting poor dietary habits and exercise programs among Emirati citizens is urgently needed.

Analysis of cholesterol levels in lipoprotein(a) with anion-exchange chromatography

We previously established an analysis method for determining the cholesterol levels of five major lipoprotein classes [HDL, LDL, intermediate density lipoprotein (IDL), VLDL, and chylomicrons] in serum by an anion-exchange (AEX)-HPLC method, but lipoprotein(a) [Lp(a)], a well-known risk factor for atherosclerotic diseases, was not determinable. Therefore, we established new AEX-HPLC separation conditions for analyzing the cholesterol levels of six lipoprotein classes, including Lp(a). Serum lipoproteins were separated by HPLC with a diethylaminoethyl-ligand nonporous polymer-based column by elution with a stepwise gradient of the sodium perchlorate concentration. In this improved method, HDL, LDL, IDL, VLDL, chylomicrons, and Lp(a) were each eluted from the column. The cholesterol levels of the eluted lipoproteins were measured enzymatically by a postcolumn reaction. The within-day assay and between-day assay coefficients of variation for the lipoprotein cholesterol levels were in the ranges of 0.29-11.86% and 0.57-11.99%, respectively. The Lp(a) cholesterol levels determined by AEX-HPLC were significantly correlated with the amounts of Lp(a) protein measured by an immunoturbidimetry method available commercially (r = 0.9503, P < 0.0001). Taken together, this AEX-HPLC method may be effectively applied to the analysis of serum lipoproteins with high levels of Lp(a).

Carbohydrate restriction, as a first-line dietary intervention, effectively reduces biomarkers of metabolic syndrome in Emirati adults

The prevalence of diabetes mellitus (DM) in the United Arab Emirates is among the highest world-wide. Metabolic syndrome (MetS) predisposes individuals to DM; therefore, dietary interventions targeting MetS biomarkers are a high priority. We evaluated whether a carbohydrate-restricted diet (CRD) could effectively be used as a first-line therapy intervention in adult Emirati to improve the characteristics of MetS. A total of 39 participants (14 men, 25 women) 18-50 y, classified with MetS, followed a CRD (20-25% carbohydrate, 50-55% fat, 25-30% protein energy distribution). After 6 wk, 19 participants were randomly switched to the AHA diet (55% carbohydrate, 25-30% fat, 15-20% protein) whereas 20 participants continued with the CRD diet for an additional 6 wk. Fasting plasma lipids, 24-h dietary recalls, body composition, anthropometrics, blood pressure (BP), glucose, insulin, and plasma markers of inflammation were measured at baseline, wk 6, and wk 12. Dietary analysis indicated high compliance. At wk 6, the CRD (n = 39) resulted in decreased body weight (-13%), waist circumference (-4.5%), body fat (-10.6%), and plasma triglycerides (TG) (-38.7%) (P < 0.001). Significant decreases in LDL cholesterol, BP, glucose, insulin, and inflammatory markers and increases in adiponectin (P < 0.05) also occurred. After 12 wk, positive changes persisted for all participants, independent of diet. However, body weight and plasma TG and insulin were lower in the CRD (P < 0.05) group than in the CRD + AHA group. Results from this study suggest that a 6-wk CRD can effectively be used as a first-line diet therapy to rapidly improve features of MetS and cardiovascular risk in adult Emirati.

Carbohydrate restriction (with or without additional dietary cholesterol provided by eggs) reduces insulin resistance and plasma leptin without modifying appetite hormones in adult men

Carbohydrate-restricted diets (CRDs) have been shown to reduce body weight, whereas whole egg intake has been associated with increased satiety. The purpose of this study was to evaluate the effects of additional dietary cholesterol and protein provided by whole eggs while following a CRD on insulin resistance and appetite hormones. Using a randomized blind parallel design, subjects were allocated to an egg (640 mg/d additional dietary cholesterol) or placebo (0 mg/d additional dietary cholesterol) group for 12 weeks while following a CRD. There were significant reductions in fasting insulin (P < .025) and fasting leptin concentrations (P < .01) for both groups, which were correlated with the reductions in body weight and body fat (P < .05 and P < .01, respectively). Both groups reduced insulin resistance as measured by the homeostatic model assessment of insulin resistance (P < .025). There was a significant decrease in serum glucose levels observed after the intervention. We did not observe the expected increases in plasma ghrelin levels associated with weight loss, suggesting a mechanism by which subjects do not increase appetite with CRD. To confirm these results, the subjective measures of satiety using visual analog scale showed that both groups felt more "full" (P < .05), "satisfied" (P < .001), and "wanted to eat less" (P < .001) after the intervention. These results indicate that inclusion of eggs in the diet (additional dietary cholesterol) did not modify the multiple beneficial effects of CRD on insulin resistance and appetite hormones.

Eggs distinctly modulate plasma carotenoid and lipoprotein subclasses in adult men following a carbohydrate-restricted diet

We previously reported that carbohydrate restriction (CR) (10-15% en) during a weight loss intervention lowered plasma triglycerides (TG) by 45% in male subjects (P<.001). However, those subjects with a higher intake of cholesterol provided by eggs (640 mg additional cholesterol, EGG group) had higher concentrations of high-density lipoprotein (HDL) cholesterol (P<.0001) than the individuals consuming lower amounts (0 mg of additional cholesterol, SUB group). The objectives of the present study were to evaluate whether CR and egg intake (1) modulate circulating carotenoids and (2) affect the concentrations of plasma apolipoproteins (apo), lipoprotein size and subfraction distribution. CR decreased the number of large and medium very low-density lipoprotein cholesterol subclasses (P<.001), while small low-density lipoprotein (LDL) were reduced (P<.001). In agreement with these observations, a decrease in apo B (P<.01) was observed. In addition, CR resulted in a 133% increase in apo C-II and a 65% decrease in apo C-III (P<.0001). Although an increase of the larger LDL subclass was observed for all subjects, the EGG group had a greater increase (P<.05). The EGG group also presented a higher number of large HDL particles (P<.01) compared to the SUB group. Regarding carotenoids, CR resulted in no changes in dietary or plasma alpha- or beta-carotene and beta-cryptoxanthin, while there was a significant reduction in both dietary and plasma lycopene (P<.001). In contrast, dietary lutein and zeaxanthin were increased during the intervention (P<.05). However, only those subjects from the EGG group presented higher concentrations of these two carotenoids in plasma, which were correlated with the higher concentrations of large LDL observed in the EGG group. These results indicate that CR favorably alters VLDL metabolism and apolipoprotein concentrations, while the components of the egg yolk favor the formation of larger LDL and HDL leading to an increase in plasma lutein and zeaxanthin.

Short-term changes in lipoprotein subclasses and C-reactive protein levels of hypertriglyceridemic adults on low-carbohydrate and low-fat diets

Diets designed to promote weight loss and improve atherogenic lipid profiles traditionally include a reduction in total fat and, in particular, saturated fats. This study was designed to test the efficacy of a low-fat diet vs a carbohydrate (CHO)-restricted (low-CHO) diet in hypertriglyceridemic patients on lipid profile, weight loss, high-sensitivity C-reactive protein (hs-CRP), and satiety. Twenty-eight hypertriglyceridemic subjects (based on fasting triacylglycerol [TG] levels exceeding 1.69 mmol/L) were randomized to either the low-CHO or low-fat diet for 8 weeks. Fasting bloods were acquired at weeks 0 and 8 and analyzed for lipids and hs-CRP. Body weight and other anthropometric measures were also obtained. Three random 24-hour food recalls were used to assess compliance during the trial and 2 recalls before randomization to permit individualized dietary education. A significant time-by-treatment interaction was observed (P = .045), wherein the small low-density lipoprotein cholesterol concentrations were reduced by 46% in the low-CHO-assigned subjects and increased by 36% for those assigned the low-fat plan. The observed decrease in TG (18%) among low-CHO subjects, in contrast to the 4% increase for low-fat group, was not significant, nor were there significant differences in hs-CRP, overall dietary compliance, satiety, or the magnitude of body weight loss between groups (low-CHO group, -3.8% vs low-fat group, -1.6%). Favorable reductions in small low-density lipoprotein concentrations after 8 weeks suggest that a moderately restricted carbohydrate diet (20% CHO as energy) can promote a less atherogenic lipid profile when compared to the low-fat diet.

Use of cereal fiber to facilitate adherence to a human caloric restriction program

BACKGROUND AND AIMS

Caloric restriction (CR) attenuates biological aging in animal models but there is little information on the feasibility and efficacy of CR regimens in humans. We examined the effects of consuming an insoluble cereal fiber supplement on ability to sustain CR over 1 year in healthy overweight adults.

METHODS

In 34 healthy overweight women and men (BMI 25-30 kg/m2, age 20-42 yr), a 30% CR regimen meeting national recommendations for dietary fiber was provided for 24 weeks, and for an additional 24 weeks subjects were counseled to prepare the same regimen at home. During 5-10 weeks of CR, subjects were randomized to consume an extra 20 g/day of dietary fiber from a high fiber cereal (+F) or to not consume additional fiber (-F). After this time, all subjects were encouraged to consume the extra fiber. Outcomes included adherence to the provided and self-prepared CR regimens (energy intake determined using doubly labeled water), changes in body weight, and self-reported satisfaction with the amount of consumed food.

RESULTS

During 5-10 weeks of CR when all food was provided, both +F and -F groups were highly adherent to the CR regimen and there was no significant difference between groups in energy intake (p=0.51), weight change (p=0.96), or satisfaction with amount of provided food (p=0.08). During self-prepared CR from 25 to 48 weeks, mean adherence was lower than during the food-provided phase and there was a significant association between fiber intake and % CR (r=0.69, p<0.001), decreased BMI (r=- 0.38, p=0.04) and satisfaction with the amount of consumed food (r=0.59, p=0.002).

CONCLUSIONS

A high fiber cereal intake may facilitate CR in humans self-selecting their own food; longer-term intervention studies are needed to confirm these findings.

Moderate carbohydrate, moderate protein weight loss diet reduces cardiovascular disease risk compared to high carbohydrate, low protein diet in obese adults: A randomized clinical trial

Background

To evaluate the metabolic effects of two weight loss diets differing in macronutrient composition on features of dyslipidemia and post-prandial insulin (INS) response to a meal challenge in overweight/obese individuals.

Methods

This study was a parallel-arm randomized 4 mo weight loss trial. Adults (n = 50, 47 ± 7 y) matched on BMI (33.6 ± 0.6 kg/m², P = 0.79) consumed energy restricted diets (deficit ~500 kcal/d): PRO (1.6 g.kg^-1.d^-1 protein and < 170 g/d carbohydrate) or CHO (0.8 g.kg^-1.d^-1 protein and > 220 g/d carbohydrate) for 4 mos. Meal challenges of respective diets were utilized for determination of blood lipids and post-prandial INS and glucose response at the beginning and end of the study.

Results

There was a trend for PRO to lose more weight (-9.1% vs. -7.3%, P = 0.07) with a significant reduction in percent fat mass compared to CHO (-8.7% vs. -5.7%; P = 0.03). PRO also favored reductions in triacylglycerol (-34% vs. -14%; P < 0.05) and increases in HDL-C (+5% vs. -3%; P = 0.05); however, CHO favored reduction in LDL-C (-7% vs. +2.5%; P < 0.05). INS responses to the meal challenge were improved in PRO compared to CHO (P < 0.05) at both 1 hr (-34.3% vs. -1.0%) and 2 hr (-9.2% vs. +46.2%), an effect that remained significant after controlling for weight or fat loss (both P < 0.05).

Conclusion

A weight loss diet with moderate carbohydrate, moderate protein results in more favorable changes in body composition, dyslipidemia, and post-prandial INS response compared to a high carbohydrate, low protein diet suggesting an additional benefit beyond weight management to include augmented risk reduction for metabolic disease.

Unlimited energy, restricted carbohydrate diet improves lipid parameters in obese children

BACKGROUND

Childhood obesity is a leading health concern. We have previously demonstrated the effectiveness of a restricted-carbohydrate, unlimited energy diet for weight reduction in elementary school-aged children. To our knowledge, there are no studies that have looked at the effect of this diet on lipid profiles in elementary school-aged children. Therefore, the objective of this pilot study was to examine the effect of a restricted-carbohydrate, unlimited protein, unlimited energy diet on lipid profiles in obese children 6 to 12 years of age.

METHODS

Overweight children (body mass index >97%) referred to our obesity clinic were treated with a restricted-carbohydrate (<30 grams daily), unlimited protein, and unlimited energy diet. Weight, height, body mass index, and fasting lipid profiles were obtained at baseline and at 10 weeks on each patient.

RESULTS

Twenty-seven patients were enrolled in our study, with a total of 18 patients returning for our 10 week follow-up (67%). The study group included 10 males and 8 females, with an age range of 6 to 12 years. Both total serum cholesterol and triglyceride levels showed a significant reduction; 24.2 (P = 0.018) and 56.9 (P = 0.015) mg/dL, respectively.

CONCLUSIONS

We have demonstrated a significant decrease in total cholesterol and triglycerides in elementary school-aged children after 10 weeks of a restricted-carbohydrate, unlimited protein, and unlimited energy diet. We suggest that this diet may decrease cardiovascular risk factors in obese children. Long-term studies will be needed to substantiate these data.

Low-carbohydrate, high-protein diets revisited

PURPOSE OF REVIEW

There has been continued interest in the physiological, nutritional and clinical aspects of low-carbohydrate diets. This review will discuss the effects on appetite regulation, metabolic parameters, body weight and body composition, the role of glycemic index and glycemic load, as well as long-term outcomes.

RECENT FINDINGS

Low-carbohydrate, high-protein diets appear to improve satiety through their actions on measures of adiposity and gut peptides that influence appetite and caloric intake. Specific macronutrients such as low glycemic index carbohydrates and dietary protein impact appetite, calorie intake and metabolic parameters independent of weight loss. Long-term data, however, continue to support that total weight loss among low-carbohydrate dieters is not significantly different from low-fat dieters. The long-term safety of low-carbohydrate, high-protein diets on cardiovascular disease risk remains undetermined.

SUMMARY

Low-carbohydrate, high-protein diets may be an effective choice for weight loss, enhanced satiety and improved metabolic parameters.

Eggs modulate the inflammatory response to carbohydrate restricted diets in overweight men

Background

Carbohydrate restricted diets (CRD) consistently lower glucose and insulin levels and improve atherogenic dyslipidemia [decreasing triglycerides and increasing HDL cholesterol (HDL-C)]. We have previously shown that male subjects following a CRD experienced significant increases in HDL-C only if they were consuming a higher intake of cholesterol provided by eggs compared to those individuals who were taking lower concentrations of dietary cholesterol. Here, as a follow up of our previous study, we examined the effects of eggs (a source of both dietary cholesterol and lutein) on adiponectin, a marker of insulin sensitivity, and on inflammatory markers in the context of a CRD.

Methods

Twenty eight overweight men [body mass index (BMI) 26–37 kg/m²] aged 40–70 y consumed an ad libitum CRD (% energy from CHO:fat:protein = 17:57:26) for 12 wk. Subjects were matched by age and BMI and randomly assigned to consume eggs (EGG, n = 15) (640 mg additional cholesterol/day provided by eggs) or placebo (SUB, n = 13) (no additional dietary cholesterol). Fasting blood samples were drawn before and after the intervention to assess plasma lipids, insulin, adiponectin and markers of inflammation including C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1(VCAM-1).

Results

Body weight, percent total body fat and trunk fat were reduced for all subjects after 12 wk (P < 0.0001). Increases in adiponectin were also observed (P < 0.01). Subjects in the EGG group had a 21% increase in this adipokine compared to a 7% increase in the SUB group (P < 0.05). Plasma CRP was significantly decreased only in the EGG group (P < 0.05). MCP-1 levels were decreased for the SUB group (P < 0.001), but unchanged in the EGG group. VCAM-1, ICAM-1, TNF-α, and IL-8 were not modified by CRD or eggs.

Conclusion

A CRD with daily intake of eggs decreased plasma CRP and increased plasma adiponectin compared to a CRD without eggs. These findings indicate that eggs make a significant contribution to the anti-inflammatory effects of CRD, possibly due to the presence of cholesterol, which increases HDL-C and to the antioxidant lutein which modulates certain inflammatory responses.