Effect of short-term low- and high-fat diets on low-density lipoprotein particle size in normolipidemic subjects

Very Low Calorie Ketogenic Diet: What Effects on Lipid Metabolism?

PURPOSE OF REVIEW

This review aims to critically examine how VLCKD affects plasma lipoprotein, lipid and cholesterol metabolism. Cardiovascular disease is a worldwide health problem affecting millions of people and leading to high rates of mortality and morbidity. There is a well-established association between cardiovascular disease and circulating cholesterol. Various dietary recommendations are currently available for the management of dyslipidemia.

RECENT FINDINGS

The very low-calorie ketogenic diet (VLCKD) is becoming increasingly popular as a treatment option for several pathological conditions, including dyslipidemia. In addition to being low in calories, the VLCKD's main feature is its unique calorie distribution, emphasizing a reduction in carbohydrate consumption in favor of fat as the primary calorie source. Lowering calorie intake through a VLCKD can reduce the endogenous production of cholesterol. However, if the foods consumed are from animal sources, dietary cholesterol intake may increase due to the higher fat content of animal products. When combined, these dietary practices may have opposing effects on plasma cholesterol levels. Studies investigating the impact of VLCKD on plasma cholesterol and low-density lipoprotein cholesterol levels report contradictory findings. While some studies found an increase in low-density lipoprotein cholesterol levels, others showed a decrease in total cholesterol and low-density lipoprotein cholesterol, along with an increase in high-density lipoprotein cholesterol.

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.

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.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Small dense low-density lipoprotein-lowering agents

Metabolic disorders, including obesity, diabetes, and hyperlipidemia, as well as cardiovascular diseases (CVD), particularly atherosclerosis, are still leading causes of death worldwide. Plasma levels of low-density lipoprotein (LDL) are currently being considered as a critical risk factor for the diseases mentioned above, especially atherosclerosis. Because of the heterogeneous nature of LDL, many studies have already been conducted on its subclasses, especially small dense LDL (sdLDL). According to available evidence, sdLDL levels can be considered as an ideal alternative to LDL levels for monitoring CVD and early diagnosis of atherosclerosis. Recently, several researchers have focused on factors that are able to decrease sdLDL levels and improve health quality. Therefore, the purpose of this study is to describe the production process of sdLDL particles and review the effects of pharmaceutical and dietary agents as well as lifestyle on sdLDL plasma levels. In brief, their mechanisms of action are discussed. Apparently, cholesterol and LDL-lowering compounds are also effective in the reduction of sdLDL levels. In addition, improving lipid profile, especially the reduction of triglyceride levels, appropriate regimen, and lifestyle can decrease sdLDL levels. Therefore, all the aforementioned parameters should be taken into consideration simultaneously in sdLDL levels reducing strategies.

High-Fat Diet Alleviates Neuroinflammation and Metabolic Disorders of APP/PS1 Mice and the Intervention With Chinese Medicine

Alzheimer's disease (AD) is a progressive neurodegenerative disease caused by the complex interaction of multiple mechanisms. Recent studies examining the effect of high-fat diet (HFD) on the AD phenotype have demonstrated a significant influence on both inflammation and cognition. However, different studies on the effect of high-fat diet on AD pathology have reported conflicting conclusions. To explore the involvement of HFD in AD, we investigated phenotypic and metabolic changes in an AD mouse model in response to HFD. The results indicated there was no significant effect on Aβ levels or contextual memory due to HFD treatment. Of note, HFD did moderate neuroinflammation, despite spurring inflammation and increasing cholesterol levels in the periphery. In addition, diet affected gut microbiota symbiosis, altering the production of bacterial metabolites. HFD created a favorable microenvironment for bile acid alteration and arachidonic acid metabolism in APP/PS1 mice, which may be related to the observed improvement in LXR/PPAR expression. Our previous research demonstrated that Huanglian Jiedu decoction (HLJDD) significantly ameliorated impaired learning and memory. Furthermore, HLJDD may globally suppress inflammation and lipid accumulation to relieve cognitive impairment after HFD intervention. It was difficult to define the effect of HFD on AD progression because the results were influenced by confounding factors and biases. Although there was still obvious damage in AD mice treated with HFD, there was no deterioration and there was even a slight remission of neuroinflammation. Moreover, HLJDD represents a potential AD drug based on its anti-inflammatory and lipid-lowering effects.

Effect of the Fat Eaten at Breakfast on Lipid Metabolism: A Crossover Trial in Women with Cardiovascular Risk

Recent studies point out that not only the daily intake of energy and nutrients but the time of day when they are ingested notably regulates lipid metabolism and cardiovascular risk (CVR). Therefore, the aim of the study was to assess if the type of fat ingested at breakfast can modify lipid metabolism in women with CVR. A randomized, crossover clinical trial was performed. Sixty volunteers were randomly assigned to a (A) polyunsaturated fatty acid (PUFA)-rich breakfast, (B) saturated fatty acid (SFA)-rich breakfast, or (C) monounsaturated fatty acid (MUFA)-rich breakfast. Plasma lipoprotein and apolipoprotein subfractions were determined. Our data showed that the PUFA-rich breakfast decreased lipoprotein (a) (Lp(a)), very low-density lipoproteins (VLDL), and intermediate-density lipoproteins (IDL), and increased high-density lipoproteins (HDL). A similar trend was observed for the MUFA-rich breakfast, whereas the SFA-rich breakfast, although it decreased VLDL, also increased IDL and reduced HDL. The PUFA-rich breakfast also decreased β-lipoproteins and apolipoprotein-B. In summary, varying the type of fat eaten at breakfast is enough to significantly modify the lipid metabolism of women with CVR, which can be of great relevance to establish new therapeutic strategies for the treatment of these subjects.

Effects of the low carbohydrate, high fat diet on glycemic control and body weight in patients with type 2 diabetes: experience from a community-based cohort

OBJECTIVE

The optimal diet to improve glycemia in patients with type 2 diabetes remains unclear. Low carbohydrate, high fat (LCHF) diets can improve glycemic control, but have not been investigated in real-world settings.

RESEARCH DESIGN AND METHODS

We investigated effects of the LCHF diet compared with usual care in a community-based cohort of patients with type 2 diabetes by performing a retrospective study of 49 patients who followed the LCHF diet for ≥3 months, and compared glycemic outcomes with age-matched and body mass index (BMI)-matched controls who received usual care (n=75). The primary outcome was change in A1C from baseline to the end of follow-up.

RESULTS

Compared with the usual care group, the LCHF group showed a significantly greater reduction in A1C (-1.29% (95% CI -1.75 to -0.82; p<0.001)) and body weight (-12.8 kg (95% CI -14.7 to -10.8; p<0.001) at the end of follow-up after adjusting for age, sex, baseline A1C, BMI, baseline insulin dose. Of the patients initially taking insulin therapy in the LCHF group, 100% discontinued it or had a reduction in dose, compared with 23.1% in the usual care group (p<0.001). The LCHF group also had significantly greater reduction in fasting plasma glucose (-43.5 vs -8.5 mg/mL; p=0.03) compared with usual care.

CONCLUSIONS

In a community-based cohort of type 2 diabetes, the LCHF diet was associated with superior A1C reduction, greater weight loss and significantly more patients discontinuing or reducing antihyperglycemic therapies suggesting that the LCHF diet may be a metabolically favorable option in the dietary management of type 2 diabetes.

Dietary carbohydrate intake and cardio-metabolic risk factors in type 1 diabetes

AIMS

Low-carbohydrate diet (LCD) has gained interest among individuals with diabetes as a means to manage glycaemia. We investigated the adherence to LCD in the Finnish Diabetic Nephropathy Study and whether carbohydrate restriction is associated with cardio-metabolic risk factors.

METHODS

Cross-sectional data were available from 902 individuals with type 1 diabetes (44% men, age 47 ± 13 years). Dietary data were collected twice with a 3-day diet record. Mean of the measurements was used. Carbohydrate intake <130 g/day or <26 E% was used as indication of LCD. Individuals reporting LCD were compared to sex-, diabetes duration- and eGFR-matched controls with higher carbohydrate intakes (>253 g/day or >48 E%). In the whole population, carbohydrate-to-fat ratio was calculated and its association with health variables was investigated.

RESULTS

Higher carbohydrate-to-fat ratio was associated with higher blood glucose variability, higher blood pressure, lower HDL cholesterol concentration, and in men with lower waist-to-hip ratio. LCD adherence (n = 69) was associated with lower BMI (25.6 vs. 27.8 kg/m², p = 0.030), lower variability of blood glucose measurements (0.38 vs. 0.45 mmol/l, p = 0.030), and lower diastolic blood pressure (74 vs. 79 mmHg, p = 0.048). Men reporting LCD had higher total (5.1 vs. 4.0 mmol/l, p = 0.007) and non-HDL cholesterol (3.4 vs. 2.7 mmol/l, p = 0.021). Women with LCD had higher HDL-cholesterol concentration (1.9 vs. 1.5 mmol/l, p = 0.014).

CONCLUSIONS

Reduced blood glucose variability, related to LCD, could have clinical relevance to individuals with type 1 diabetes.

Modified ketogenic diets in adults with refractory epilepsy: Efficacious improvements in seizure frequency, seizure severity, and quality of life

OBJECTIVE

This study evaluates the efficacy of a modified ketogenic diet (MKD) on seizure frequency, severity, and quality of life (QOL), as well as potential complications of MKD therapy among adults with drug-resistant epilepsy (DRE).

METHODS

Changes in seizure frequency, severity, QOL, and side effects were retrospectively examined among adults, ≥17 years of age, with DRE (≥2 antiepileptic drugs [AEDs]), after 3 months of MKD therapy. Attention was paid to medication or vagus nerve stimulator (VNS) changes as well to evaluate potential confounders.

RESULTS

A total of 60% (n = 33) of the 55 individuals reported ≥50% seizure frequency improvement, 42 (76%) reported improvement in seizure severity, and 48 (87%) reported improvement in QOL. More patients following a modified ketogenic diet - 15 g net carbohydrate daily (MKD-15) (95%) compared with a MKD-50 (69%) reported improvement in QOL (p = 0.02). Weight among the entire sample declined from 77.5 (20) kg to 73.9 (19.0) kg (p < 0.0001), and total cholesterol (TC), low density lipoprotein (LDL), and total cholesterol:high density lipoprotein (TC:HDL) increased significantly (p = 0.03, p = 0.04, and p = 0.02, respectively). Free carnitine values were available for a select number of patients, 26 (47%) at baseline, and 7 (13%) at follow-up, of which 8 (31%) at baseline, and 2 (29%) at follow-up had carnitine deficiency (<25 nmol/mL). Constipation was noted in 5 patients (9%), and no kidney stones were reported during the study period. There were no statistical differences in number or dose changes for AED or VNS during the study period.

SIGNIFICANCE

Modified ketogenic diet therapies reduce seizure frequency and severity and improve QOL among adults with DRE with few side effects outside of weight loss, a desired outcome among many adults with DRE. More restrictive MKDs may offer improved seizure severity and QOL. Modified ketogenic diet therapy increases LDL cholesterol, which may be cardioprotective if related to an increase in LDL particle size with high saturated fat intake; however, more research is needed examining LDL particle size changes among those receiving MKD therapy.

Impact of rural-urban environment on metabolic profile and response to a 5-day high-fat diet

Epidemiological studies have indicated that rural living might be protective against type 2 diabetes development. We compared the metabolic profile and response to a short-term high-fat high-calorie diet (HFD) of men with the same genetic background living in an urban and rural area of Indonesia. First, we recruited 154 Floresian male subjects (18–65 years old), of whom 105 lived in a rural area (Flores) and 49 had migrated and lived in urban area (Jakarta) for more than 1 year. The urban group had significantly higher whole-body insulin resistance (IR), as assessed by homeostatic-model-assessment of IR (HOMA-IR), [mean difference (95% CI), p-value: 0.10 (0.02–0.17), p = 0.01]. Next, we recruited 17 urban and 17 rural age-and-BMI-matched healthy-young-male volunteers for a 5-day HFD challenge. The HOMA-IR increased in both groups similarly −0.77 (−2.03–0.49), p = 0.22]. Neither rural living nor factors associated with rural living, such as current helminth infection or total IgE, were associated with protection against acute induction of IR by HFD.

Dysregulated bile acid synthesis and dysbiosis are implicated in Western diet-induced systemic inflammation, microglial activation, and reduced neuroplasticity

The goal of this study was to identify the intrinsic links that explain the effect of a Western diet (WD) on cognitive dysfunction. Specific pathogen-free, wild-type mice were fed either a control diet (CD) or a high-fat, high-sucrose WD after weaning and were euthanized at 10 mo of age to study the pathways that affect cognitive health. The results showed that long-term WD intake reduced hippocampal synaptic plasticity and the level of brain-derived neurotrophic factor mRNA in the brain and isolated microglia. A WD also activated ERK1/2 and reduced postsynaptic density-95 in the brain, suggesting postsynaptic damage. Moreover, WD-fed mice had increased inflammatory signaling in the brain, ileum, liver, adipose tissue, and spleen, which was accompanied by microglia activation. In the brain, as well as in the digestive tract, a WD reduced signaling regulated by retinoic acid and bile acids (BAs), whose receptors form heterodimers to control metabolism and inflammation. Furthermore, a WD intake caused dysbiosis and dysregulated BA synthesis with reduced endogenous ligands for BA receptors, i.e., farnesoid X receptor and G-protein-coupled bile acid receptor in the liver and brain. Together, dysregulated BA synthesis and dysbiosis were accompanied by systemic inflammation, microglial activation, and reduced neuroplasticity induced by WD.-Jena, P. K., Sheng, L., Di Lucente, J., Jin, L.-W., Maezawa, I., Wan, Y.-J. Y. Dysregulated bile acid synthesis and dysbiosis are implicated in Western diet-induced systemic inflammation, microglial activation, and reduced neuroplasticity.

The Impact of Virgin Coconut Oil and High-Oleic Safflower Oil on Body Composition, Lipids, and Inflammatory Markers in Postmenopausal Women

This randomized crossover study compared the impact of virgin coconut oil (VCO) to safflower oil (SO) on body composition and cardiovascular risk factors. Twelve postmenopausal women (58.8 ± 3.7 year) consumed 30 mL VCO or SO for 28 days, with a 28-day washout. Anthropometrics included body weight and hip and waist circumference. Fat percent for total body, android and gynoid, fat mass, and lean mass were measured using dual-energy X-ray absorptiometry. Women maintained their typical diet recording 28 days of food records during the study. Results were analyzed with SPSS v24 with significance at P ≤ .05. Comparisons are reported as paired t-test since no intervention sequence effect was observed. VCO significantly raised total cholesterol, TC (+18.2 ± 22.8 mg/dL), low-density lipoprotein (+13.5 ± 16.0 mg/dL), and high-density lipoprotein, HDL (+6.6 ± 7.5 mg/dL). SO did not significantly change lipid values. TC and HDL were significantly different between test oils. The TC/HDL ratio change showed a neutral effect of both VCO and SO. One person had adverse reactions to VCO and increased inflammation. VCO decreased IL-1β for each person who had a detected sample. The impact of VCO and SO on other cytokines varied on an individual basis. This was the first study evaluating the impact of VCO on body composition in Caucasian postmenopausal women living in the United States. Results are suggestive that individuals wishing to use coconut oil in their diets can do so safely, but more studies need to be conducted with larger sample sizes, diverse populations, and more specific clinical markers such as particle size.

Improvement of the omega 3 index of healthy subjects does not alter the effects of dietary saturated fats or n-6PUFA on LDL profiles

BACKGROUND AND AIMS

Dietary fat composition is known to modulate circulating lipid and lipoprotein levels. Although supplementation with long chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) has been shown to reduce plasma triglyceride levels, the effect of the interactions between LCn-3PUFA and the major dietary fats consumed has not been previously investigated.

METHODS

In a randomized controlled parallel design clinical intervention, we examined the effect of diets rich in either saturated fatty acids (SFA) or omega-6 polyunsaturated fatty acids (n-6PUFA) on plasma lipid levels and lipoprotein profiles (lipoprotein size, concentration and distribution in subclasses) in subjects with an adequate omega 3 index. Twenty six healthy subjects went through a four-week pre-supplementation period with LCn-3PUFA and were then randomized to diets rich in either n-6PUFA or SFA both supplemented with LCn-3PUFA.

RESULTS

The diet rich in n-6PUFA decreased low density lipoprotein (LDL) particle concentration (-8%, p=0.013) and LDL cholesterol (LDL-C) level (-8%, p=0.021), while the saturated fat rich diet did not affect LDL particle concentration or LDL-C levels significantly. Nevertheless, dietary saturated fatty acids increased LCn-3PUFA in plasma and tissue lipids compared with n-6PUFA, potentially reducing other cardiovascular risk factors such as inflammation and clotting tendency.

CONCLUSION

Improvement on the omega 3 index of healthy subjects did not alter the known effects of dietary saturated fats and n-6PUFA on LDL profiles.

Impact of a 6-week non-energy-restricted ketogenic diet on physical fitness, body composition and biochemical parameters in healthy adults

BACKGROUND

The ketogenic diet (KD) is a very low-carbohydrate, high-fat and adequate-protein diet that without limiting calories induces different metabolic adaptations, eg, increased levels of circulating ketone bodies and a shift to lipid metabolism. Our objective was to assess the impact of a 6-week non-energy-restricted KD in healthy adults beyond cohorts of athletes on physical performance, body composition, and blood parameters.

METHODS

Our single arm, before-and-after comparison study consisted of a 6-week KD with a previous preparation period including detailed instructions during classes and individual counselling by a dietitian. Compliance with the dietary regimen was monitored by measuring urinary ketones daily, and 7-day food records. All tests were performed after an overnight fast: cardiopulmonary exercise testing via cycle sprioergometry, blood samples, body composition, indirect calorimetry, handgrip strength, and questionnaires addressing complaints and physical sensations.

RESULTS

Forty-two subjects aged 37 ± 12 years with a BMI of 23.9 ± 3.1 kg/m² completed the study. Urinary ketosis was detectable on 97% of the days, revealing very good compliance with the KD. Mean energy intake during the study did not change from the habitual diet and 71.6, 20.9, and 7.7% of total energy intake were from fat, protein, and carbohydrates, respectively. Weight loss was -2.0 ± 1.9 kg (P < 0.001) with equal losses of fat-free and fat mass. VO₂peak and peak power decreased from 2.55 ± 0.68 l/min to 2.49 ± 0.69 l/min by 2.4% (P = 0.023) and from 241 ± 57 W to 231 ± 57 W by 4.1% (P < 0.001), respectively, whereas, handgrip strength rose slightly from 40.1 ± 8.8 to 41.0 ± 9.1 kg by 2.5% (P = 0.047). The blood lipids TG and HDL-C remained unchanged, whereas total cholesterol and LDL-C increased significantly by 4.7 and 10.7%, respectively. Glucose, insulin, and IGF-1 dropped significantly by 3.0, 22.2 and 20.2%, respectively.

CONCLUSIONS

We detected a mildly negative impact from this 6-week non-energy-restricted KD on physical performance (endurance capacity, peak power and faster exhaustion). Our findings lead us to assume that a KD does not impact physical fitness in a clinically relevant manner that would impair activities of daily living and aerobic training. However, a KD may be a matter of concern in competitive athletes.

TRIAL REGISTRATION

DRKS00009605, registered 08 January 2016.

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

Background

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

Objective

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

Methods

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

Results

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

Conclusions

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

Trial registration

Clinicaltrials.gov NCT00895141.

Diet, lipids, and cardiovascular disease

PURPOSE OF REVIEW

Modulation of diet is the primary lifestyle approach for reducing cardiovascular disease (CVD) risk, with a major focus of current guidelines being to lower LDL cholesterol by reducing intake of saturated fatty acids. However, dietary effects on lipid-related CVD risk factors extend beyond LDL cholesterol, with growing emphasis on the prevention and management of atherogenic dyslipidemia, which includes elevated triglyceride, small dense LDL, and reduced HDL cholesterol, and which is associated with excess adiposity and insulin resistance. We here review recent studies of dietary macronutrient effects on CVD risk that may act through effects on plasma lipid and lipoprotein metabolism.

RECENT FINDINGS

Effects of reducing saturated fatty acids on CVD risk have been evaluated both in terms of the replacement macronutrient(s) and the food and dietary context in which the macronutrients are consumed. Although weight loss remains the most important goal for reducing cardiometabolic risk among overweight and obese individuals, a variety of lines of evidence support limitation of added sugars and processed starches for improving features of atherogenic dyslipidemia.

SUMMARY

Increasing understanding of the complexity of nutrient-disease relationships has shifted the framework for CVD prevention from a focus on macronutrient content of diets to foods and dietary patterns.

[Nutritional therapy in the obese patient with insulin resistance and cardiovascular risk]

Currently, each of the different scientific societies advocate one kind or another nutritional recommendations for patients with vascular risk. This variety of diets on the one hand enrich the nutritional therapeutic possibilities, but on the other can lead to some confusion, both for the patient and for the professional that advises. Furthermore, most studies assessing vascular risk mention a "diet" without defining or specifying to which kind of diet they refer, thereby introducing an important bias in the results of those studies. In fact, some of them bear a degree of contradiction. This review aims to shed some light on such a controversial topic.

Interaction between Common Genetic Variants and Total Fat Intake on Low-Density Lipoprotein Peak Particle Diameter: A Genome-Wide Association Study

BACKGROUND/AIM

Total fat intake has an important impact on the low-density lipoprotein (LDL) peak particle diameter (LDL-PPD) and may interact with nutrient-sensitive single nucleotide polymorphisms (SNPs). The objective was to examine whether there is suggestive evidence of SNP × dietary fat intake interaction effects influencing the LDL-PPD in the Quebec Family Study (QFS) in order to generate hypotheses to be tested in larger studies.

METHODS

SNPs from a genome-wide association study (GWAS) using Illumina Human610-Quad BeadChip, total fat intake derived from a 3-day weighted food record, and SNP × total fat intake interaction effects were examined on LDL-PPD in 541 QFS subjects.

RESULTS

The GWAS analyses 29 identified independent SNP × total fat intake interaction effects on the LDL-PPD at p < 10(-5), including SNPs in the following genes: ABCG2, CPA3, FNBP1, KCNQ3, NBAS, NCALD, OPRL1, NKAIN2, SH3BGRL2, SOX5, and SUSD4.

CONCLUSIONS

This observational study suggests that multiple SNPs interact with dietary fat intake to influence variation in the LDL-PPD.

Effect of pistachio consumption on plasma lipoprotein subclasses in pre-diabetic subjects

BACKGROUND AND AIMS

Nuts have been demonstrated to improve several cardiovascular risk factors and the lipid profile in diabetic and pre-diabetic subjects. However, analysis of conventional serum lipid profiles does not completely explain the atherogenic risk associated with pre-diabetes. We therefore investigated whether chronic consumption of pistachio modifies the lipoprotein subclasses to a healthier profile in pre-diabetic subjects.

METHODS AND RESULTS

Randomized cross-over clinical trial in 54 subjects with pre-diabetes. Subjects consumed a pistachio-supplemented diet (PD, 50% carbohydrates, 33% fat, including 57 g/d of pistachios daily) and a control diet (CD, 55% carbohydrates, 30% fat) for 4 months each, separated by a 2-week wash-out. Diets were isocaloric and matched for protein, fiber and saturated fatty acids. Nuclear magnetic resonance (NMR) was performed to determine changes in plasma lipoprotein subclasses. Small low-density lipoprotein particles (sLDL-P) significantly decreased after pistachio consumption compared to the nut-free diet (P = 0.023). The non-high-density lipoprotein particles (non-HDL-P i.e. VLDL-P plus LDL-P) significantly decreased under the PD compared to CD (P = 0.041). The percentage of sHDL-P increased by 2.23% after the PD compared with a reduction of 0.08% after the CD (P = 0.014). Consequently, the overall size of HDL-P significantly decreased in the PD (P = 0.007).

CONCLUSION

Chronic pistachio consumption could modify the lipoprotein particle size and subclass concentrations independently of changes in total plasma lipid profile, which may help to explain the decreased risk of cardiovascular disease and mortality associated with those individuals who frequently consumed nuts.

REGISTRATION NUMBER

This study is registered at www.clinicaltrials.gov as NCT01441921.

Impact of milk consumption on cardiometabolic risk in postmenopausal women with abdominal obesity

Background

The impact of dairy intake on cardiometabolic risk factors associated with metabolic syndrome (MetS) needs further research.

Objective

To investigate the impact of milk consumption on a wide array of cardiometabolic risk factors associated with MetS (blood lipids, cholesterol homeostasis, glucose homeostasis, systemic inflammation, blood pressure, endothelial function) in postmenopausal women with abdominal obesity.

Methods

In this randomized, crossover study, 27 women with abdominal obesity consumed two 6-week diets based on the National Cholesterol Education Program (NCEP), one with 3.2 servings/d of 2% fat milk per 2000 kcal (MILK) and one without milk or other dairy (NCEP). The macronutrient composition of both diets was comparable (55% carbohydrates, 15% proteins, 30% fat and 10% saturated fat).

Results

The MILK diet had no significant effect on LDL-C, triglycerides, LDL size, CRP and cell adhesion molecule concentrations and on indicators of insulin sensitivity. The MILK diet reduced HDL-C, adiponectin, endothelin and fasting glucose levels as well blood pressure (all P ≤ 0.01), but those changes were comparable to those seen with the NCEP milk-free diet (all between-diet P ≥ 0.07). Finally, the MILK diet was associated with lower VLDL apolipoprotein B fractional catabolic rate (−13.4%; P = 0.04) and plasma sterol concentrations (−12.0%; P = 0.04) compared with the control NCEP milk-free diet.

Conclusions

These data suggest that short-term consumption of low fat milk in the context of a prudent NCEP diet has no favorable nor deleterious effect on cardiometabolic risk factors associated with MetS in postmenopausal women with abdominal obesity.

Electronic supplementary material

The online version of this article (doi:10.1186/1475-2891-14-12) contains supplementary material, which is available to authorized users.

Saturated Fats Versus Polyunsaturated Fats Versus Carbohydrates for Cardiovascular Disease Prevention and Treatment

The effects of saturated fatty acids (SFAs) on cardiovascular disease (CVD) risk are modulated by the nutrients that replace them and their food matrices. Replacement of SFAs with polyunsaturated fatty acids has been associated with reduced CVD risk, although there is heterogeneity in both fatty acid categories. In contrast, replacement of SFAs with carbohydrates, particularly sugar, has been associated with no improvement or even a worsening of CVD risk, at least in part through effects on atherogenic dyslipidemia, a cluster of traits including small, dense low-density lipoprotein particles. The effects of dietary SFAs on insulin sensitivity, inflammation, vascular function, and thrombosis are less clear. There is growing evidence that SFAs in the context of dairy foods, particularly fermented dairy products, have neutral or inverse associations with CVD. Overall dietary patterns emphasizing vegetables, fish, nuts, and whole versus processed grains form the basis of heart-healthy eating and should supersede a focus on macronutrient composition.

The role of advanced lipid testing in the prediction of cardiovascular disease

Advanced lipid testing has been suggested by some experts to identify patients with substantial residual risk for more aggressive targeting of lifestyle and pharmacologic therapies. It measures the subpopulation of lipoproteins and apolipoproteins, which include lipoprotein (a), apolipoprotein A-I, and apolipoprotein B, and measures of lipoprotein particle composition such as LDL particle (LPL-P) and HDL particle (HDL-P) number and size. Obesity is associated with smaller LDL-P and HDL-P sizes. Moderate weight loss via fasting/calorie restriction is associated with LDL-P size increase, whereas moderate weight loss via endurance exercise is associated with HDL-P size increase. Diets high in carbohydrates are associated with a more atherogenic advanced lipoprotein profile characterized by smaller LDL-P and HDL-P sizes. In summary, lifestyle changes such as weight loss, exercise, and dietary modification correlate with improvement in the profile of advanced lipoproteins. Regrettably, therapies targeting HDL and HDL composition have been disappointing to date.

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

BACKGROUND

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

METHODS AND FINDINGS

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

CONCLUSIONS

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

Alternate day fasting and endurance exercise combine to reduce body weight and favorably alter plasma lipids in obese humans

OBJECTIVE

This study examined whether the combination of alternate day fasting (ADF) plus exercise produces superior changes in body composition and plasma lipid levels when compared to each intervention alone.

DESIGN AND METHODS

Obese subjects (n = 64) were randomized to 1 of 4 groups for 12 weeks: 1) combination (ADF plus endurance exercise), 2) ADF, 3) exercise, or 4) control.

RESULTS

Body weight was reduced (P < 0.05) by 6 ± 4 kg, 3 ± 1 kg, and 1 ± 0 kg in the combination, ADF, and exercise groups, respectively. Fat mass and waist circumference decreased (P < 0.001), while lean mass was retained in the combination group. Low-density lipoprotein (LDL) cholesterol decreased (12 ± 5%, P < 0.05) and high-density lipoprotein (HDL) cholesterol increased (18 ± 9%, P < 0.05) in the combination group only. LDL particle size increased (P < 0.001) by 4 ± 1 Å and 5 ± 1 Å in the combination and ADF groups, respectively. The proportion of small HDL particles decreased (P < 0.01) in the combination group only.

CONCLUSIONS

These findings suggest that the combination produces superior changes in body weight, body composition, and lipid indicators of heart disease risk, when compared to individual treatments.

Mouse models and techniques for the isolation of the diabetic endothelium

Understanding the molecular mechanisms underlying diabetic endothelial dysfunction is necessary in order to improve the cardiovascular health of diabetic patients. Previously, we described an in vivo, murine model of insulin resistance induced by feeding a high-fat diet (HFD) whereby the endothelium may be isolated by fluorescence-activated cell sorting (FACS) based on Tie2-GFP expression and cell-surface staining. Here, we apply this model to two new strains of mice, ScN/Tie2-GFP and ApoE(−/−)/Tie2-GFP, and describe their metabolic responses and endothelial isolation. ScN/Tie2-GFP mice, which lack a functional toll-like receptor 4 (TLR4), display lower fasting glucose and insulin levels and improved glucose tolerance compared to Tie2-GFP mice, suggesting that TLR4 deficiency decreases susceptibility to the development of insulin resistance. ApoE(−/−)/Tie2-GFP mice display elevated glucose and cholesterol levels versus Tie2-GFP mice. Endothelial isolation by FACS achieves a pure population of endothelial cells that retain GFP fluorescence and endothelial functions. Transcriptional analysis of the aortic and muscle endothelium isolated from ApoE(−/−)/Tie2-GFP mice reveals a reduced endothelial response to HFD compared to Tie2-GFP mice, perhaps resulting from preexisting endothelial dysfunction in the hypercholesterolemic state. These mouse models and endothelial isolation techniques are valuable for assessing diabetic endothelial dysfunction and vascular responses in vivo.

Dietary Fructus Schisandrae extracts and fenofibrate regulate the serum/hepatic lipid-profile in normal and hypercholesterolemic mice, with attention to hepatotoxicity

Background

Schisandra, a globally distributed plant, has been widely applied to health care products. Here, we investigated the effects of dietary intake of Fructus Schisandrae chinensis (FSC), both aqueous and ethanolic extracts (AqFSC, EtFSC), on serum/hepatic lipid contents in normal diet (ND)- and high-fat/cholesterol/bile salt diet (HFCBD)-fed mice.

Methods

Male ICR mice were fed with ND or HFCBD, supplemented with 1 and 4% of AqFSC and EtFSC, respectively, or 0.1% fenofibrate, for 13 days. Lipids were determined according to the manufacture’s instructions.

Results

EtFSC, but not AqFSC, significantly elevated hepatic triglyceride (TG) in mice fed with ND. Feeding mice with HFCBD increased serum total cholesterol (TC), high density lipoprotein (HDL) and low density lipoprotein (LDL) levels as well as alanine aminotransferase (ALT) activity. Supplementation with AqFSC, EtFSC or fenofibrate significantly reduced hepatic TC and TG levels. However, AqFSC and EtFSC supplementation increased serum HDL and LDL levels in mice fed with HFCBD. Fenofibrate increased serum HDL and reduced serum LDL contents in hypercholesterolemic mice. EtFSC reduced, but fenofibrate elevated, serum ALT activity in both normal and hypercholesterolemic mice. While fenofibrate reduced serum TC, TG, and HDL levels in mice fed with ND, it increased serum HDL and reduced serum LDL and TC levels in mice fed with HFCBD. Hepatomegaly was found in normal and hypercholesterolemic mice fed with diet supplemented with fenofibrate.

Conclusions

Feeding mice with AqFSC and EtFSC ameliorated the HFCBD-induced hepatic steatosis. In addition, EtFSC may offer protection against hepatic injury in hypercholesterolemic mice.

Regulation of low-density lipoprotein subfractions by carbohydrates

PURPOSE OF REVIEW

This article aims at reviewing the recent findings that have been made concerning the crosstalk of carbohydrate metabolism with the generation of small, dense low-density lipoprotein (LDL) particles, which are known to be associated with an adverse cardiovascular risk profile.

RECENT FINDINGS

Studies conducted during the past few years have quite unanimously shown that the quantity of carbohydrates ingested is associated with a decrease of LDL particle size and an increase in its density. Conversely, diets that aim at a reduction of carbohydrate intake are able to improve LDL quality. Furthermore, a reduction of the glycaemic index without changing the amount of carbohydrates ingested has similar effects. Diseases with altered carbohydrate metabolism, for example, type 2 diabetes, are associated with small, dense LDL particles. Finally, even the kind of monosaccharide the carbohydrate intake consists of is important concerning LDL particle size: fructose has been shown to alter the LDL particle subclass profile more adversely than glucose in many recent studies.

SUMMARY

LDL particle quality, rather than its quantity, is affected by carbohydrate metabolism, which is of clinical importance, in particular, in the light of increased carbohydrate consumption in today's world.

A review of the role of apolipoprotein C-II in lipoprotein metabolism and cardiovascular disease

The focus of this review is on the role of apolipoprotein C-II (apoC-II) in lipoprotein metabolism and the potential effects on the risk of cardiovascular disease (CVD). We searched PubMed/Scopus for articles regarding apoC-II and its role in lipoprotein metabolism and the risk of CVD. Apolipoprotein C-II is a constituent of chylomicrons, very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein (HDL). Apolipoprotein C-II contains 3 amphipathic α-helices. The lipid-binding domain of apoC-II is located in the N-terminal, whereas the C-terminal helix of apoC-II is responsible for the interaction with lipoprotein lipase (LPL). At intermediate concentrations (approximately 4 mg/dL) and in normolipidemic subjects, apoC-II activates LPL. In contrast, both an excess and a deficiency of apoC-II are associated with reduced LPL activity and hypertriglyceridemia. Furthermore, excess apoC-II has been associated with increased triglyceride-rich particles and alterations in HDL particle distribution, factors that may increase the risk of CVD. However, there is not enough current evidence to clarify whether increased apoC-II causes hypertriglyceridemia or is an epiphenomenon reflecting hypertriglyceridemia. A number of pharmaceutical interventions, including statins, fibrates, ezetimibe, nicotinic acid, and orlistat, have been shown to reduce the increased apoC-II concentrations. An excess of apoC-II is associated with increased triglyceride-rich particles and alterations in HDL particle distribution. However, prospective trials are needed to assess if apoC-II is a CVD marker or a risk factor in high-risk patients.

Traditional dietary recommendations for the prevention of cardiovascular disease: do they meet the needs of our patients?

The characteristics of patients with CVD have changed: whereas smoking prevalence declines, obesity and metabolic syndrome are on the rise. Unfortunately, the traditional low-fat diet for the prevention of cardiovascular disease (CVD) still seems to be the “mainstream knowledge” despite contradicting evidence. But lowering LDL-cholesterol by the wrong diet even may be counterproductive, if sd-LDL is raised and HDL is lowered. New insights into the pathophysiology of insulin resistance and its influence on the effects of dietary changes have led to a better approach: (1) the higher a patient's insulin resistance, the more important is the glycemic load of the diet. (2) Fat quality is much more important than fat quantity. (3) The best principle for a reduced calorie intake is not fat counting, but a high volume diet with low energy density, which means fibre rich vegetables and fruits. (4) And finally, satiation and palatability of a diet is very important: there is no success without the patient's compliance. Thus, the best approach to the dietary prevention of CVD is a Mediterranean style low-carb diet represented in the LOGI pyramid. Dietary guidelines for the prevention of CVD should to be revised accordingly.