Effects of cardiovascular lifestyle change on lipoprotein subclass profiles defined by nuclear magnetic resonance spectroscopy

Saturated Fatty Acids Consumed in Smoothies Increase Glucose and Metabolic Load Index in Young Adults Compared to Polyunsaturated Omega-3-Fatty Acids

Introduction: Chronic diets high in saturated fat (SF) and omega-6-fatty acids (O6FAs) elevate fasting triglycerides (TRGs) and glucose (GLU). Postprandial TRGs, GLU, and Metabolic Load Index (MLI) are better predictors of disease risk compared to fasting levels alone. Conversely, diets high in omega-3 fatty acids (O3FAs) may be cardioprotective. Unfortunately, many existing postprandial studies are not standardized to body weight and given in an amount individuals would typically consume in their daily lives; the MLI is not calculated, and varying types of fat content are not examined. Therefore, we sought to determine whether SF, O3FAs, or O6FAs altered postprandial TRGs, GLU, and MLI from a standardized mixed meal. Methods: Fifteen individuals (6 M and 9 F) visited the laboratory three times, separated by at least 48 h, to consume HFM smoothies with varying FA composition (SF, high O6FAs, and high O3FAs). The smoothies were standardized to 12 kcal/kg body weight, 63% total fat, and 0.72 g/kg sugar. TRGs and GLU were collected at baseline and at 2 h and 4 h postprandially; the MLI was calculated by summing the TRG and GLU responses at each time point. Results: There was a significant increase in TRGs across time points (p < 0.001). For TRGs, there was a trend toward a significant interaction between smoothie type and time (p = 0.06) due to the increase in TRGs in the SF compared to the O3FA smoothie. There was an increase in postprandial GLU that varied across smoothie types (p = 0.036). Taken together, the MLI was elevated in the SF smoothie compared to the O3FAs at 2 h (p = 0.041). Conclusion: A SF smoothie in the morning elevated the metabolic load compared to an O3FA smoothie. Mechanisms of action in the competing clearance of TRGs and GLU warrant further investigation.

Consumption of Eggs Alone or Enriched with Annatto (Bixa orellana L.) Does Not Increase Cardiovascular Risk in Healthy Adults-A Randomized Clinical Trial, the Eggant Study

Most atherosclerotic cardiovascular diseases can be prevented by modifying lifestyles, including unhealthy diets. Eggs contain important carotenoids that may impact cardiovascular risk. The lipid nature of eggs can improve the bioavailability of other carotenoids, such as Annatto (Bixa orellana L.), with reported antioxidant properties. Although numerous studies have shown that there is no association between egg consumption and cardiovascular risk, there is still controversy. In addition, there is limited information about Annatto's effects on human health. This study evaluated the association between egg consumption and its enrichment with Annatto in lipid biomarkers of cardiovascular disease. In a parallel clinical trial, one hundred and five (n = 105) men and women were randomized by age, sex, and body mass index (BMI), and distributed into three groups. Subjects consumed daily, for 8 weeks, either two eggs, two eggs with Annatto, or two egg whites. Plasma lipids were measured by enzymatic colorimetric methods, plasma apolipoproteins and lipoprotein subfractions and size by nuclear magnetic resonance. There were no differences between groups in age, sex, and BMI. No significant changes were found over time or between groups in plasma triglycerides, LDL cholesterol, HDL cholesterol, apolipoprotein (apo) A1, apo B, or lipoprotein subfraction concentrations. In healthy adults, the intake of two eggs a day, or two eggs with Annatto for eight weeks, did not generate adverse changes in cardiovascular risk markers.

Impact of α-Linolenic Acid, the Vegetable ω-3 Fatty Acid, on Cardiovascular Disease and Cognition

Given the evidence of the health benefits of plant-based diets and long-chain n-3 (ω-3) fatty acids, there is keen interest in better understanding the role of α-linolenic acid (ALA), a plant-derived n-3 fatty acid, on cardiometabolic diseases and cognition. There is increasing evidence for ALA largely based on its major food sources (i.e., walnuts and flaxseed); however, this lags behind our understanding of long-chain n-3 fatty acids. Meta-analyses of observational studies have shown that increasing dietary ALA is associated with a 10% lower risk of total cardiovascular disease and a 20% reduced risk of fatal coronary heart disease. Three randomized controlled trials (RCTs) [AlphaOmega trial, Prevención con Dieta Mediterránea (PREDIMED) trial, and Lyon Diet Heart Study] all showed benefits of diets high in ALA on cardiovascular-related outcomes, but the AlphaOmega trial, designed to specifically evaluate ALA effects, only showed a trend for benefit. RCTs have shown that dietary ALA reduced total cholesterol, LDL cholesterol, triglycerides, and blood pressure, and epidemiologic studies and some trials also have shown an anti-inflammatory effect of ALA, which collectively account for, in part, the cardiovascular benefits of ALA. A meta-analysis reported a trend toward diabetes risk reduction with both dietary and biomarker ALA. For metabolic syndrome and obesity, the evidence for ALA benefits is inconclusive. The role of ALA in cognition is in the early stages but shows promising evidence of counteracting cognitive impairment. Much has been learned about the health benefits of ALA and with additional research we will be better positioned to make strong evidence-based dietary recommendations for the reduction of many chronic diseases.

Divergence of Cardiovascular Biomarkers of Lipids and Subclinical Myocardial Injury Among Rheumatoid Arthritis Patients With Increased Inflammation

OBJECTIVE

Patients with rheumatoid arthritis (RA) are 1.5 times more likely to develop cardiovascular disease (CVD) attributed to chronic inflammation. A decrease in inflammation in patients with RA is associated with increased low-density lipoprotein (LDL) cholesterol. This study was undertaken to prospectively evaluate the changes in lipid levels among RA patients experiencing changes in inflammation and determine the association with concomitant temporal patterns in markers of myocardial injury.

METHODS

A total of 196 patients were evaluated in a longitudinal RA cohort, with blood samples and high-sensitivity C-reactive protein (hsCRP) levels measured annually. Patients were stratified based on whether they experienced either a significant increase in inflammation (an increase in hsCRP of ≥10 mg/liter between any 2 time points 1 year apart; designated the increased inflammation cohort [n = 103]) or decrease in inflammation (a decrease in hsCRP of ≥10 mg/liter between any 2 time points 1 year apart; designated the decreased inflammation cohort [n = 93]). Routine and advanced lipids, markers of inflammation (interleukin-6, hsCRP, soluble tumor necrosis factor receptor II), and markers of subclinical myocardial injury (high-sensitivity cardiac troponin T [hs-cTnT], N-terminal pro-brain natriuretic peptide) were measured.

RESULTS

Among the patients in the increased inflammation cohort, the mean age was 59 years, 81% were women, and the mean RA disease duration was 17.9 years. The average increase in hsCRP levels was 36 mg/liter, and this increase was associated with significant reductions in LDL cholesterol, triglycerides, total cholesterol, apolipoprotein (Apo B), and Apo A-I levels. In the increased inflammation cohort at baseline, 45.6% of patients (47 of 103) had detectable circulating hs-cTnT, which further increased during inflammation (P = 0.02). In the decreased inflammation cohort, hs-cTnT levels remained stable despite a reduction in inflammation over follow-up. In both cohorts, hs-cTnT levels were associated with the overall estimated risk of CVD.

CONCLUSION

Among RA patients who experienced an increase in inflammation, a significant decrease in routinely measured lipids, including LDL cholesterol, and an increase in markers of subclinical myocardial injury were observed. These findings highlight the divergence in biomarkers of CVD risk and suggest a role in future studies examining the benefit of including hs-cTnT for CVD risk stratification in RA.

Reference values assessment in a Mediterranean population for small dense low-density lipoprotein concentration isolated by an optimized precipitation method

Background

High serum concentrations of small dense low-density lipoprotein cholesterol (sd-LDL-c) particles are associated with risk of cardiovascular disease (CVD). Their clinical application has been hindered as a consequence of the laborious current method used for their quantification.

Objective

Optimize a simple and fast precipitation method to isolate sd-LDL particles and establish a reference interval in a Mediterranean population.

Materials and methods

Forty-five serum samples were collected, and sd-LDL particles were isolated using a modified heparin-Mg²⁺ precipitation method. sd-LDL-c concentration was calculated by subtracting high-density lipoprotein cholesterol (HDL-c) from the total cholesterol measured in the supernatant. This method was compared with the reference method (ultracentrifugation). Reference values were estimated according to the Clinical and Laboratory Standards Institute and The International Federation of Clinical Chemistry and Laboratory Medicine recommendations. sd-LDL-c concentration was measured in serums from 79 subjects with no lipid metabolism abnormalities.

Results

The Passing–Bablok regression equation is y = 1.52 (0.72 to 1.73) + 0.07x (−0.1 to 0.13), demonstrating no significant statistical differences between the modified precipitation method and the ultracentrifugation reference method. Similarly, no differences were detected when considering only sd-LDL-c from dyslipidemic patients, since the modifications added to the precipitation method facilitated the proper sedimentation of triglycerides and other lipoproteins. The reference interval for sd-LDL-c concentration estimated in a Mediterranean population was 0.04–0.47 mmol/L.

Conclusion

An optimization of the heparin-Mg²⁺ precipitation method for sd-LDL particle isolation was performed, and reference intervals were established in a Spanish Mediterranean population. Measured values were equivalent to those obtained with the reference method, assuring its clinical application when tested in both normolipidemic and dyslipidemic subjects.

Lifestyle modification interventions differing in intensity and dietary stringency improve insulin resistance through changes in lipoprotein profiles

Objective

Metabolic dysfunction characterized by insulin resistance (IR) is an important risk factor for type‐2 diabetes and coronary artery disease (CAD). The aim of this study was to determine if clinical lifestyle interventions differing in scope and intensity improve IR, defined by the lipoprotein IR (LPIR) score, in individuals differing in the severity of metabolic dysfunction.

Methods

Subjects with diagnosed type‐2 diabetes, CAD or significant risk factors participated in one of two clinical lifestyle modification interventions: (i) intensive non‐randomized programme with a strict vegetarian diet (n = 90 participants, 90 matched controls) or (ii) moderate randomized trial following a Mediterranean‐style diet (n = 89 subjects, 58 controls). On‐treatment and intention‐to‐treat analyses assessed changes over 1 year in LPIR, lipoprotein profiles and metabolic risk factors in intervention participants and controls in both programmes.

Results

In the on‐treatment analysis, both interventions led to weight loss: [−8.9% (95% CI, −10.3 to −7.4), intensive programme; −2.8% (95% CI, −3.8 to −1.9), moderate programme; adjusted P < 0.001] and a decrease in the LPIR score [−13.3% (95% CI, −18.2 to −8.3), intensive; −8.8% (95% CI, −12.9 to −4.7), moderate; adjusted P < 0.01] compared with respective controls. Of the six lipoprotein parameters comprising LPIR, only large very‐low‐density lipoprotein particle concentrations decreased significantly in participants compared with controls in both programmes [−26.3% (95% CI, −43.0 to −9.6), intensive; −14.2% (95% CI, −27.4 to −1.0), moderate; P < 0.05]. Intention‐to‐treat analysis confirmed and strengthened the primary results.

Conclusion

A stringent lifestyle modification intervention with a vegetarian diet and a moderate lifestyle modification intervention following a Mediterranean diet were both effective for improving IR defined by the LPIR score.

Gene expression profiling during intensive cardiovascular lifestyle modification: Relationships with vascular function and weight loss

Heart disease and related sequelae are a leading cause of death and healthcare expenditure throughout the world. Although many patients opt for surgical interventions, lifestyle modification programs focusing on nutrition and exercise have shown substantial health benefits and are becoming increasing popular. We conducted a year-long lifestyle modification program to mediate cardiovascular risk through traditional risk factors and to investigate how molecular changes, if present, may contribute to long-term risk reduction. Here we describe the lifestyle intervention, including clinical and molecular data collected, and provide details of the experimental methods and quality control parameters for the gene expression data generated from participants and non-intervention controls. Our findings suggest successful and sustained modulation of gene expression through healthy lifestyle changes may have beneficial effects on vascular health that cannot be discerned from traditional risk factor profiles. The data are deposited in the Gene Expression Omnibus, series GSE46097 and GSE66175.

Effect of relative weight group change on nuclear magnetic resonance spectroscopy derived lipoprotein particle size and concentrations among adolescents

OBJECTIVE

To examine whether longitudinal changes in relative weight category (as indicated by change in body mass index [BMI] classification group) were associated with changes in nuclear magnetic resonance (NMR)-derived lipoprotein particles among US youth.

STUDY DESIGN

Secondary analysis of data from a clustered randomized controlled trial. BMI and fasting blood samples were obtained from 2069 participants at the start of the 6th grade and end of the 8th grade. BMI was categorized as normal weight, overweight, or obese at both time points. Lipoprotein particle profiles were measured with NMR spectroscopy at both time points. Regression models were used to examine changes in relative weight group and change in lipoprotein variables.

RESULTS

A total of 38% of participants changed relative weight category (BMI group) during the 2.5-year study period. Low-density lipoprotein (LDL) cholesterol and non-high-density lipoprotein (HDL) cholesterol decreased almost universally, but more with improved BMI category. There were adverse effects on LDL size and total LDL particles, HDL size, and cholesterol for participants who remained obese or whose relative weight group worsened. Changes in relative category had no impact on HDL particles.

CONCLUSION

Improvement in relative weight group from 6th to 8th grade was associated with favorable changes in non-HDL cholesterol, very low-density lipoprotein size, LDL size, HDL size, and LDL particles but had no effect on HDL particles. Findings indicate that an improvement in relative weight group between 6th and 8th grade had an effect on NMR-derived particles sizes and concentrations among a large group of adolescents, which overrepresented low-income minorities.

Intensive Cardiovascular Risk Reduction Induces Sustainable Changes in Expression of Genes and Pathways Important to Vascular Function

Background—

Healthy lifestyle changes are thought to mediate cardiovascular disease risk through pathways affecting endothelial function and progression of atherosclerosis; however, the extent, persistence, and clinical significance of molecular change during lifestyle modification are not well known. We examined the effect of a rigorous cardiovascular disease risk reduction program on peripheral blood gene expression profiles in 63 participants and 63 matched controls to characterize molecular responses and identify regulatory pathways important to cardiovascular health.

Methods and Results—

Dramatic changes in dietary fat intake (−61%; P <0.001 versus controls) and physical fitness (+34%; P <0.001) led to significant improvements in cardiovascular disease risk factors. Analysis of variance with false discovery rate correction for multiple testing ( P <0.05) identified 26 genes after 12 weeks and 143 genes after 52 weeks that were differentially expressed from baseline in participants. Controls showed little change in cardiovascular disease risk factors or gene expression. Quantitative reverse transcription polymerase chain reaction validated differential expression for selected transcripts. Lifestyle modification effectively reduced expression of proinflammatory genes associated with neutrophil activation and molecular pathways important to vascular function, including cytokine production, carbohydrate metabolism, and steroid hormones. Prescription medications did not significantly affect changes in gene expression.

Conclusions—

Successful and sustained modulation of gene expression through lifestyle changes may have beneficial effects on the vascular system not apparent from traditional risk factors. Healthy lifestyles may restore homeostasis to the leukocyte transcriptome by downregulating lactoferrin and other genes important in the pathogenesis of atherosclerosis.

Clinical Trial Registration—

URL: www.clinicaltrials.gov . Unique identifier: NCT01805492

Reduction in dietary trans fat intake is associated with decreased LDL particle number in a primary prevention population

BACKGROUND AND AIMS

Increased trans fat intake has been associated with an increased risk of cardiovascular disease (CVD). While the effect of trans fat on traditional lipids is known, it's association with LDL particle number (LDL-P), a novel marker of CVD risk, has not been established. The purpose of this study was to determine the association between trans fat intake and LDL-P over 1-year among individuals participating in a lifestyle intervention trial.

METHODS AND RESULTS

Family members (N = 400, 33% male, mean age 48 ± 13) of patients hospitalized with CVD who participated in a 1-year randomized controlled primary prevention lifestyle intervention trial and had complete dietary data and LDL-P measures at baseline and 1-year. Change in trans fat as a percentage of total diet and mean absolute change in LDL-P at 1-year was assessed using multivariate adjusted linear regression models. At baseline, there was a significant positive correlation between dietary trans fat intake and LDL-P (Beta = 37, p = 0.04). For every 1 percent change in trans fat intake there was a 27 nmol/L change in LDL-P (Beta = 27, p = 0.04) over 1-year which was independent of baseline predictors and confounders (age, sex, smoking, statin use, waist size and physical activity; Beta = 30, p = 0.03).

CONCLUSION

A reduction in trans fat intake over 1-year was significantly associated with a reduction in LDL-P independent of potential confounders. Healthcare providers should reinforce the beneficial impact of a healthy diet, and in particular modifications in trans fat intake on improving lipid profiles.

Effect of fatty and lean fish intake on lipoprotein subclasses in subjects with coronary heart disease: a controlled trial

BACKGROUND

Fish oil intake reduces serum triglycerides; however, little is known about the effects of dietary fish intake on lipoprotein subclasses.

OBJECTIVE

We aimed at assessing the effect of fatty and lean fish intake on the lipoprotein subclasses in an intervention study.

METHODS

The intervention study included 33 patients with coronary heart disease, who were aged 61.0 ± 5.8 (mean ± SD) years. The subjects were randomly assigned to a fatty fish (n = 11), lean fish (n = 12), or control (n = 10) diet for 8 weeks. Fish diets included at least 4 fish meals per week. Subjects in the control group consumed lean beef, pork, and chicken. Lipoprotein subclasses and their lipid components were determined by nuclear magnetic resonance spectroscopy.

RESULTS

Concentrations of n-3 fatty acids and docosahexaenoic acid increased in the fatty fish group. The concentrations of cholesterol, cholesterol esters, and total lipids in very large high-density lipoproteins (HDLs) increased in the fatty fish group (overall difference P = .005, P = .002, and P = .007, respectively; false discovery rate P = .04, P = .04, and P = .05, respectively). The mean size of HDL particles increased in the fatty fish group (9.8 ± 0.3 nm at baseline and 9.9 ± 0.4 nm at end of study; overall difference P = .004, false discovery rate P = .04). The fish diets did not affect very-low-density lipoprotein or low-density lipoprotein size.

CONCLUSION

Fatty fish intake at least 4 times per week increases HDL particle size which might have beneficial effect in patients with coronary heart disease.

Cardiometabolic risk reduction in an intensive cardiovascular health program

BACKGROUND AND AIMS

Insulin and leptin are important markers of insulin resistance and vascular inflammation in metabolic and cardiovascular diseases. This study evaluated changes in circulating levels of insulin and leptin during a cardiovascular health program to improve our understanding of cardiometabolic risk reduction.

METHODS AND RESULTS

Participants (n=76) completed a prospective, nonrandomized program designed to stabilize or reverse progression of coronary artery disease through dietary changes, exercise, stress management, and group support. Controls (n=76) were matched to participants based on age, gender, and disease status. Traditional cardiovascular risk factors were assessed at baseline, 12 weeks, and 52 weeks by standard methods. Dietary data were collected by 72-h recall and evaluated by Food Processor® v8.4.0. Ultrasensitive insulin and leptin levels were measured by radioimmunoassay. Participants successfully reduced their total caloric intake from >2000 calories per day to ≈ 1700 calories per day (p<0.05 compared to controls), lowered daily fat intake by >60% (p<0.001 compared to controls), and increased carbohydrate intake by >30% (p<0.001). Repeated-measures ANOVA indicated significant beneficial changes (p<0.001 compared to controls) in plasma insulin (-19%) and leptin (-33%) during the lifestyle program, as well as improvement in traditional cardiovascular risk factors. Response was similar between men and women for most risk factors and was not markedly influenced by medication use.

CONCLUSION

Lifestyle changes focusing on diet, physical activity, and stress reduction can successfully modify both cardiovascular and metabolic risk factors, with the potential to mediate cardiometabolic risk through beneficial anti-inflammatory and anti-oxidative effects on the vasculature.

Genetic associations with lipoprotein subfractions provide information on their biological nature

Adverse levels of lipoproteins are highly heritable and constitute risk factors for cardiovascular outcomes. Hitherto, genome-wide association studies revealed 95 lipid-associated loci. However, due to the small effect sizes of these associations large sample numbers (>100 000 samples) were needed. Here we show that analyzing more refined lipid phenotypes, namely lipoprotein subfractions, can increase the number of significantly associated loci compared with bulk high-density lipoprotein and low-density lipoprotein analysis in a study with identical sample numbers. Moreover, lipoprotein subfractions provide novel insight into the human lipid metabolism. We measured 15 lipoprotein subfractions (L1-L15) in 1791 samples using (1)H-NMR (nuclear magnetic resonance) spectroscopy. Using cluster analyses, we quantified inter-relationships among lipoprotein subfractions. Additionally, we analyzed associations with subfractions at known lipid loci. We identified five distinct groups of subfractions: one (L1) was only marginally captured by serum lipids and therefore extends our knowledge of lipoprotein biochemistry. During a lipid-tolerance test, L1 lost its special position. In the association analysis, we found that eight loci (LIPC, CETP, PLTP, FADS1-2-3, SORT1, GCKR, APOB, APOA1) were associated with the subfractions, whereas only four loci (CETP, SORT1, GCKR, APOA1) were associated with serum lipids. For LIPC, we observed a 10-fold increase in the variance explained by our regression models. In conclusion, NMR-based fine mapping of lipoprotein subfractions provides novel information on their biological nature and strengthens the associations with genetic loci. Future clinical studies are now needed to investigate their biomedical relevance.

High-fat meal effect on LDL, HDL, and VLDL particle size and number in the Genetics of Lipid-Lowering Drugs and Diet Network (GOLDN): an interventional study

Background

Postprandial lipemia (PPL) is likely a risk factor for cardiovascular disease but these changes have not been well described and characterized in a large cohort. We assessed acute changes in the size and concentration of total and subclasses of LDL, HDL, and VLDL particles in response to a high-fat meal. Participants (n = 1048) from the Genetics of Lipid-Lowering Drugs and Diet Network (GOLDN) Study who ingested a high-fat meal were included in this analysis. Lipids were measured at 0 hr (fasting), 3.5 hr, and 6 hr after a standardized fat meal. Particle size distributions were determined using nuclear magnetic resonance spectroscopy. Analyses were stratified by baseline triglycerides (normal vs. elevated) and gender. The effect of PPL on changes in lipoprotein subclasses was assessed using repeated measures ANOVA.

Results

Postprandially, LDL-C, HDL-C, VLDL-C, and triglycerides increased regardless of baseline triglyceride status, with the largest increases in VLDL-C and TG; however, those with elevated triglycerides demonstrated larger magnitude of response. Total LDL particle number decreased over the 6-hour time interval, mostly from a decrease in the number of small LDL particles. Similarly, total VLDL particle number decreased due to reductions in medium and small VLDL particles. Large VLDL particles and chylomicrons demonstrated the largest increase in concentration. HDL particles demonstrated minimal overall changes in total particle number.

Conclusions

We have characterized the changes in LDL and VLDL particle number, and their subclass patterns following a high-fat meal.

Lipid-lowering therapy: who can benefit?

Cardiovascular disease (CVD) is the leading cause of death in the US. Despite the decline in CVD-associated mortality rates in recent years, coronary heart disease (CHD) still causes one in every six deaths in this country. Because most CHD risk factors are modifiable (eg, smoking, hypertension, obesity, onset of type 2 diabetes, and dyslipidemia), cardiovascular risk can be reduced by timely and appropriate interventions, such as smoking cessation, diet and lifestyle changes, and lipid-modifying therapy. Dyslipidemia, manifested by elevated low-density lipoprotein cholesterol (LDL-C), is central to the development and progression of atherosclerosis, which can be silent for decades before triggering a first major cardiovascular event. Consequently, dyslipidemia has become a primary target of intervention in strategies for the prevention of cardiovascular events. The guidelines of the Adult Treatment Panel (ATP) III, updated in 2004, recommend therapeutic lifestyle changes and the use of lipid-lowering medications, such as statins, to achieve specific LDL-C goals based on a person’s global cardiovascular risk. For high-risk individuals, such as patients with CHD and diabetic patients without CHD, an LDL-C target of < 100 mg/dL is recommended, and statin therapy should be considered to help patients achieve this goal. If correctly dosed in appropriate patients, currently approved statins are generally safe and provide significant cardiovascular benefits in diverse populations, including women, the elderly, and patients with diabetes. A recent primary prevention trial also showed that statins benefit individuals traditionally not considered at high risk of CHD, such as those with no hyperlipidemia but elevated C-reactive protein. Additional evidence suggests that statins may halt or slow atherosclerotic disease progression. Recent evidence confirms the pivotal role of statins in primary and secondary prevention.

Obesity, weight loss and conditional cardiovascular risk factors

Obesity is a pathological condition aggregating a substantial number of proatherogenic factors, such as insulin resistance, type 2 diabetes mellitus, dyslipidaemia and hypertension. In addition to these classic cardiometabolic risk factors, atherosclerosis may be aggravated by other non-classic factors, which are characterized as conditional, including homocysteine, fibrinogen, lipoprotein(a), LDL particle size and high-sensitivity CRP. Some of these biomarkers are disturbed in obesity because of a combination of dietary factors, hypertrophic adipose tissue, low-grade inflammation, insulin resistance and other parameters under investigation. For the reduction of these risk factors, weight loss exceeding 10-20% of the initial body weight is probably necessary, achieved through either conventional lifestyle measures or more drastic interventions such as bariatric surgery. It has been shown that certain well-balanced diets, such as the Mediterranean diet, constitute a means of improving in a concerted manner the levels of CRP, fibrinogen, homocysteine and small dense LDL particles, regardless of weight loss. The significance of considering these factors in weight management intervention is an issue that needs further investigation.

Short term effects of a low-carbohydrate diet in overweight and obese subjects with low HDL-C levels

BACKGROUND

The aim of this study was to evaluate short-term effects of a low-carbohydrate diet in overweight and obese subjects with low HDL-C levels.

METHODS

Overweight (BMI between 25-30 kg/m2) or obese (BMI over 30 kg/m2) subjects with low HDL-C levels (men with HDL-C <1.03, women <1.29 mmol/l) were invited to the study. A 1400 kcal 75-gram carbohydrate (CHO) diet was given to women and an 1800 kcal 100-gram CHO diet was given to men for four weeks. The distribution of daily energy of the prescribed diet was 21-22% from CHO, 26-29% from protein and 49-53% from fat. Subjects completed a three-day dietary intake record before each visit. Anthropometric indices, body fat ratio, blood lipids, glucose and insulin were measured. Baseline and week-four results were compared with a Wilcoxon signed ranks test.

RESULTS

Twenty-five women and 18 men participated. Basal median LDL-C level of men was 3.11 and basal median LDL-C level of women was 3.00 mmol/l. After four weeks of a low-carbohydrate diet, the median energy intake decreased from 1901 to 1307 kcal/day, daily energy from carbohydrate from 55% to 33%, body weight from 87.7 to 83.0 kg and HDL-C increased from 0.83 to 0.96 mmol/l in men (p < 0.002, for all). After four weeks of a low-carbohydrate diet, the median energy intake tended to decrease (from 1463 to 1243 kcal, p = 0.052), daily energy from carbohydrate decreased from 53% to 30% (p < 0.001) and body weight decreased from 73.2 to 70.8 kg (p < 0.001) in women, but HDL-C did not significantly change (from 1.03 to 1.01 mmol/l, p = 0.165). There were significant decreases in body mass index, waist circumference, body fat ratio, systolic blood pressure, total cholesterol, triglyceride and insulin levels in all subjects.

CONCLUSIONS

HDL-C levels increased significantly with energy restriction, carbohydrate restriction and weight loss in men. HDL-C levels didn't change in women in whom there was no significant energy restriction but a significant carbohydrate restriction and a relatively small but significant weight loss. Our results suggest that both energy and carbohydrate restriction should be considered in overweight and obese subjects with low HDL-C levels, especially when LDL-C levels are not elevated.