Individual variability in cardiovascular disease risk factor responses to low-fat and low-saturated-fat diets in men: body mass index, adiposity, and insulin resistance predict changes in LDL cholesterol

Macadamia nut effects on cardiometabolic risk factors: a randomised trial

We sought to examine the effects of daily consumption of macadamia nuts on body weight and composition, plasma lipids and glycaemic parameters in a free-living environment in overweight and obese adults at elevated cardiometabolic risk. Utilising a randomised cross-over design, thirty-five adults with abdominal obesity consumed their usual diet plus macadamia nuts (~15 % of daily calories) for 8 weeks (intervention) and their usual diet without nuts for 8 weeks (control), with a 2-week washout. Body composition was determined by bioelectrical impedance; dietary intake was assessed with 24-h dietary recalls. Consumption of macadamia nuts led to increased total fat and MUFA intake while SFA intake was unaltered. With mixed model regression analysis, no significant changes in mean weight, BMI, waist circumference, percent body fat or glycaemic parameters, and non-significant reductions in plasma total cholesterol of 2⋅1 % (-4⋅3 mg/dl; 95 % CI -14⋅8, 6⋅1) and low-density lipoprotein (LDL-C) of 4 % (-4⋅7 mg/dl; 95 % CI -14⋅3, 4⋅8) were observed. Cholesterol-lowering effects were modified by adiposity: greater lipid lowering occurred in those with overweight v. obesity, and in those with less than the median percent body fat. Daily consumption of macadamia nuts does not lead to gains in weight or body fat under free-living conditions in overweight or obese adults; non-significant cholesterol lowering occurred without altering saturated fat intake of similar magnitude to cholesterol lowering seen with other nuts. Clinical Trial Registry Number and Website: NCT03801837 https://clinicaltrials.gov/ct2/show/NCT03801837?term = macadamia + nut&draw = 2&rank = 1.

Saturated Fat and Cardiovascular Health: Phenotype and Dietary Factors Influencing Interindividual Responsiveness

PURPOSE OF REVIEW

Recent inconsistencies in nutrition research studies examining the influence of saturated fat (SFA) on cardiovascular disease (CVD) risk have led to substantial scientific debate and increased public confusion. This review will summarize metabolic characteristics and food-based factors that underlie interindividual responsiveness to SFA consumption.

RECENT FINDINGS

The magnitude of postprandial blood lipid responses to SFA intake is dependent on a number of individual factors including age, sex, and adiposity status. Further, the metabolic effects of SFA intake are influenced by the specific types of SFAs and the food matrix within which they are contained. Importantly, results from research examining the effects of SFA on CVD risk should be interpreted with consideration of the comparator nutrient (i.e., carbohydrate, monounsaturated fat, polyunsaturated fat). A more nuanced understanding of the multitude of factors mediating the influence of SFA on lipid metabolism and CVD risk might help resolve the current controversy and inform more precise personalized recommendations for future dietary guidelines.

Baseline Insulin Resistance Is a Determinant of the Small, Dense Low-Density Lipoprotein Response to Diets Differing in Saturated Fat, Protein, and Carbohydrate Contents

Individual responses to diet vary but causes other than genetics are poorly understood. This study sought to determine whether baseline values of homeostasis model assessment (HOMA-IR) was related to changes in small, dense low-density lipoprotein (sdLDL, i.e., LDL₄, d = 1.044–1.063 g/mL) amounts quantified by isopycnic density profiling, in mildly hypercholesterolemic subjects (n = 27) consuming one of three low saturated fatty acid (SFA) diets: Dietary Approaches to Stop Hypertension (DASH), Beef in an Optimal Lean Diet (BOLD) and BOLD plus extra protein (BOLD+) when compared to a higher-SFA healthy American diet (HAD). The diets were consumed in random order for 5 wk, with 1 wk between diets. BOLD+ reduced fractional abundance (%) LDL₄ (p < 0.05) relative to HAD, DASH and BOLD, and reductions in % LDL₄ correlated with reductions in triglycerides (p = 0.044), total cholesterol (p = 0.014), LDL cholesterol (p = 0.004) and apolipoprotein B (p < 0.001). Responses to the four diets were similar (~12% decrease in % LDL₄, p = 0.890) in the lower (<2.73 median) HOMA-IR subgroup but differed across diet conditions in the higher HOMA-IR subgroup (p = 0.013), in which % LDL₄ was reduced with BOLD+ (−11%), was unchanged in BOLD and increased with the HAD (8%) and DASH (6%) diets (p < 0.05 for BOLD+ vs. HAD). Individual responses to diet interventions are influenced by presence and degree of insulin resistance as measured by HOMA-IR.

The homeoviscous adaptation to dietary lipids (HADL) model explains controversies over saturated fat, cholesterol, and cardiovascular disease risk

SFAs play the leading role in 1 of the greatest controversies in nutrition science. Relative to PUFAs, SFAs generally increase circulating concentrations of LDL cholesterol, a risk factor for atherosclerotic cardiovascular disease (ASCVD). However, the purpose of regulatory mechanisms that control the diet-induced lipoprotein cholesterol dynamics is rarely discussed in the context of human adaptive biology. We argue that better mechanistic explanations can help resolve lingering controversies, with the potential to redefine aspects of research, clinical practice, dietary advice, public health management, and food policy. In this paper we propose a novel model, the homeoviscous adaptation to dietary lipids (HADL) model, which explains changes in lipoprotein cholesterol as adaptive homeostatic adjustments that serve to maintain cell membrane fluidity and hence optimal cell function. Due to the highly variable intake of fatty acids in humans and other omnivore species, we propose that circulating lipoproteins serve as a buffer to enable the rapid redistribution of cholesterol molecules between specific cells and tissues that is necessary with changes in dietary fatty acid supply. Hence, circulating levels of LDL cholesterol may change for nonpathological reasons. Accordingly, an SFA-induced raise in LDL cholesterol in healthy individuals could represent a normal rather than a pathologic response. These regulatory mechanisms may become disrupted secondarily to pathogenic processes in association with insulin resistance and the presence of other ASCVD risk factors, as supported by evidence showing diverging lipoprotein responses in healthy individuals as opposed to those with metabolic disorders such as insulin resistance and obesity. Corresponding with the model, we suggest alternative contributing factors to the association between elevated LDL cholesterol concentrations and ASCVD, involving dietary factors beyond SFAs, such as an increased endotoxin load from diet-gut microbiome interactions and subsequent chronic low-grade inflammation that interferes with fine-tuned signaling pathways.

The Effect of Inflammation and Insulin Resistance on Lipid and Lipoprotein Responsiveness to Dietary Intervention

Lipids and lipoproteins are major targets for cardiovascular disease (CVD) prevention. Findings from a limited number of clinical trials suggest diet-induced atherogenic lipoprotein lowering can be altered in the presence of chronic low-grade inflammation or insulin resistance. This review summarizes results from randomized controlled trials that have examined diet-induced changes in lipids/lipoproteins by inflammatory or insulin sensitivity status. In addition, mechanisms to explain these clinical observations are explored. Post hoc analyses of data from a limited number of randomized controlled trials suggest attenuation of diet-induced lipid/lipoprotein lowering in individuals with inflammation and/or insulin resistance. These findings are supported by experimental studies showing that inflammatory stimuli and hyperinsulinemia alter genes involved in endogenous cholesterol synthesis and cholesterol uptake, reduce cholesterol efflux, and increase fatty acid biosynthesis. Further a priori defined research is required to better characterize how chronic low-grade inflammation and insulin resistance modulate lipid and lipoprotein responsiveness to guide CVD risk reduction in individuals presenting with these phenotypes.

RETRACTED ARTICLE: Dietary metabotype modelling predicts individual responses to dietary interventions

Habitual consumption of poor quality diets is linked directly to risk factors for many non-communicable diseases. This has resulted in the vast majority of countries and the World Health Organization developing policies for healthy eating to reduce the prevalence of non-communicable diseases in the population. However, there is mounting evidence of variability in individual metabolic responses to any dietary intervention. We have developed a method for applying a pipeline for understanding interindividual differences in response to diet, based on coupling data from highly controlled dietary studies with deep metabolic phenotyping. In this feasibility study, we create an individual Dietary Metabotype Score (DMS) that embodies interindividual variability in dietary response and captures consequent dynamic changes in concentrations of urinary metabolites. We find an inverse relationship between the DMS and blood glucose concentration. There is also a relationship between the DMS and urinary metabolic energy loss. Furthermore, we use a metabolic entropy approach to visualize individual and collective responses to dietary interventions. Potentially, the DMS offers a method to target and to enhance dietary response at the individual level, thereby reducing the burden of non-communicable diseases at the population level.

The Role of the Gut Microbiome in Predicting Response to Diet and the Development of Precision Nutrition Models. Part II: Results

The gut microbiota is increasingly implicated in the health and metabolism of its human host. The host's diet is a major component influencing the composition and function of the gut microbiota, and mounting evidence suggests that the composition and function of the gut microbiota influence the host's metabolic response to diet. This effect of the gut microbiota on personalized dietary response is a growing focus of precision nutrition research and may inform the effort to tailor dietary advice to the individual. Because the gut microbiota has been shown to be malleable to some extent, it may also allow for therapeutic alterations of the gut microbiota in order to alter response to certain dietary components. This article is the second in a 2-part review of the current research in the field of precision nutrition incorporating the gut microbiota into studies investigating interindividual variability in response to diet. Part I reviews the methods used by researchers to design and carry out such studies as well as analyze the results subsequently obtained. Part II reviews the findings of these studies and discusses the gaps in our current knowledge and directions for future research. The studies reviewed provide the current understanding in this field of research and a foundation from which we may build, utilizing and expanding upon the methods and results they present to inform future studies.

BMI modifies the effect of dietary fat on atherogenic lipids: a randomized clinical trial

BACKGROUND

SFA intake increases LDL cholesterol whereas PUFA intake lowers it. Whether the lipid response to dietary fat differs between normal-weight and obese persons is of relevance to dietary recommendations for obese populations.

OBJECTIVES

We compared the effect of substituting unsaturated fat for saturated fat on LDL cholesterol and apoB concentrations in normal-weight (BMI ≤ 25 kg/m2) and obese (BMI: 30-45) subjects with elevated LDL cholesterol.

METHODS

We randomly assigned 83 men and women (aged 21-70 y) stratified by BMI (normal: n = 44; obese: n = 39) and elevated LDL cholesterol (mean ± SD, normal weight 4.6 ± 0.9 mmol/L; obese 4.4 ± 0.8 mmol/L) to either a PUFA diet enriched with oil-based margarine ( n = 42) or an SFA diet enriched with butter (n = 41) for 6 wk.

RESULTS

Seven-day dietary records showed differences of ∼9 energy percent (E%) in SFA and ∼4 E% in PUFA between the SFA and PUFA groups. In the total study population, the PUFA diet compared with the SFA diet lowered LDL cholesterol (-0.31 mmol/L; 95% CI: -0.47, -0.15 mmol/L, compared with 0.32 mmol/L; 95% CI: 0.18, 0.47 mmol/L; P < 0.001) and apoB (-0.08 g/L; 95% CI: -0.11, -0.05 g/L, compared with 0.07 g/L; 95% CI: 0.03, 0.10 g/L; P < 0.001). Tests of the BMI × diet interaction were significant for total cholesterol, LDL cholesterol, and apoB ( P values ≤ 0.009). In normal-weight compared with obese participants post-hoc comparisons found that the respective changes in LDL cholesterol were 9.7% (95% CI: 5.3%, 14.2%) compared with 5.3% (95% CI: -0.7%, 11.2%), P = 0.206, in the SFA group, and -10.4% (95% CI: -15.2%, -5.7%) compared with -2.3% (95% CI: -7.4%, 2.8%), P = 0.020, in the PUFA group. ApoB changes were 7.5% (95% CI: 3.5%, 11.4%) compared with 3.0% (95% CI: -1.7%, 7.7%), P = 0.140, in the SFA group, and -8.9% (95% CI: -12.6%, -5.2%) compared with -3.8% (95% CI: -6.3%, -1.2%), P = 0.021, in the PUFA group. Responses to dietary fat were not associated with changes in polyprotein convertase subtisilin/kexin type 9 concentrations.

CONCLUSIONS

BMI modifies the effect of PUFAs compared with SFAs, with smaller improvements in atherogenic lipid concentrations in obese than in normal-weight individuals, possibly supporting adjustment of dietary recommendations according to BMI. This trial was registered with www.clinicaltrials.gov as NCT02589769.

Body Mass Index Z-Score Modifies the Association between Added Sugar Intake and Arterial Stiffness in Youth with Type 1 Diabetes: The Search Nutrition Ancillary Study

The relationship between added sugar and arterial stiffness in youth with type 1 diabetes (T1D) has not been well-described. We used data from the SEARCH for Diabetes in Youth Study (SEARCH), an ongoing observational cohort study, to determine the association between added sugar and arterial stiffness in individuals diagnosed with T1D <20 years of age (n = 1539; mean diabetes duration of 7.9 ± 1.9 years). Added sugar intake was assessed by a food frequency questionnaire, and arterial stiffness measures included pulse wave velocity (PWV) and augmentation index. Separate multivariate linear regression models were used to evaluate the association between added sugar and arterial stiffness. Separate interaction terms were included to test for effect modification by body mass index (BMI) z-score and physical activity (PA). Overall, there was no association between added sugar and arterial stiffness (P > 0.05); however, the association between added sugar and arterial stiffness differed by BMI z-score (P for interaction = 0.003). For participants with lower BMI z-scores, added sugar intake was positively associated with PWV trunk measurements, whereas there was no association for those who had a higher BMI z-score. PA did not significantly modify the association between added sugar and arterial stiffness. Further research is needed to determine the longitudinal relationship and to confirm that obesity differentially affects this association.

Dietary fat composition: replacement of saturated fatty acids with PUFA as a public health strategy, with an emphasis on α-linolenic acid

SFA intakes have decreased in recent years, both in Ireland and across other European countries; however a large proportion of the population are still not meeting the SFA recommendation of &lt;10% of total energy (TE). High SFA intakes have been associated with increased CVD and type-2 diabetes (T2D) risk, due to alterations in cholesterol homoeostasis and adipose tissue inflammation. PUFA, in particular EPA and DHA, have been associated with health benefits, including anti-inflammatory effects. It is well established that dietary fat composition plays an important role in biological processes. A recent review of evidence suggests that replacement of SFA with PUFA has potential to reduce risk of CVD and T2D. The public health and molecular impact of EPA and DHA have been well-characterised, while less is known of effects of α-linolenic acid (ALA). The current dietary guideline for ALA is 0·5% TE; however evidence from supplementation trials suggests that benefit is observed at levels greater than 2 g/d (0·6-1% TE). This review highlights the gap in the evidence base relating to effects of the replacement of SFA with ALA, identifying the need for randomised controlled trials to determine the optimal dose of ALA substitution to define the efficacy of dietary fat modification with ALA.

A Pecan-Rich Diet Improves Cardiometabolic Risk Factors in Overweight and Obese Adults: A Randomized Controlled Trial

Evidence from observational and intervention studies has shown a high intake of tree nuts is associated with a reduced risk of cardiovascular disease (CVD), mortality from type 2 diabetes (T2DM), and all-cause mortality. However, there is limited data regarding their effects on indicators of cardiometabolic risk other than hypercholesterolemia, and little is known about the demonstrable health benefits of pecans (Carya illinoensis (Wangenh.) K.Koch). We conducted a randomized, controlled feeding trial to compare the effects of a pecan-rich diet with an isocaloric control diet similar in total fat and fiber content, but absent nuts, on biomarkers related to CVD and T2DM risk in healthy middle-aged and older adults who are overweight or obese with central adiposity. After 4 weeks on a pecan-rich diet, changes in serum insulin, insulin resistance (HOMA-IR) and beta cell function (HOMA-β) were significantly greater than after the control diet (p < 0.05). Pecan consumption also lowered the risk of cardiometabolic disease as indicated by a composite score reflecting changes in clinically relevant markers. Thus, compared to the control diet, the pecan intervention had a concurrent and clinically significant effect on several relevant markers of cardiometabolic risk.

Substitution of dietary ω-6 polyunsaturated fatty acids for saturated fatty acids decreases LDL apolipoprotein B-100 production rate in men with dyslipidemia associated with insulin resistance: a randomized controlled trial

Background

The substitution of omega (ω)-6 (n-6) polyunsaturated fatty acids (PUFAs) for saturated fatty acids (SFAs) is advocated in cardiovascular disease prevention. The impact of this substitution on lipoprotein metabolism in subjects with dyslipidemia associated with insulin resistance (IR) remains unknown.

Objective

In men with dyslipidemia and IR, we evaluated the impact of substituting ω-6 PUFAs for SFAs on the in vivo kinetics of apolipoprotein (apo) B-containing lipoproteins and on the intestinal expression of key genes involved in lipoprotein metabolism.

Design

Dyslipidemic and IR men (n = 36) were recruited for this double-blind, randomized, crossover, controlled trial. Subjects consumed, in a random order, a fully controlled diet rich in SFAs (SFAs: 13.4% of energy; ω-6 PUFAs: 4.0%) and a fully controlled diet rich in ω-6 PUFAs (SFAs: 6.0%; ω-6 PUFAs: 11.3%) for periods of 4 wk, separated by a 4-wk washout period. At the end of each diet, the in vivo kinetics of apoB-containing lipoproteins were measured and the intestinal expression of key genes involved in lipoprotein metabolism was quantified in duodenal biopsies taken from each participant.

Results

The substitution of ω-6 PUFAs for SFAs had no impact on TRL apoB-48 fractional catabolic rate (Δ = -3.8%, P = 0.7) and production rate (Δ = +1.2%, P = 0.9), although it downregulated the intestinal expression of the microsomal triglyceride transfer protein (Δ = -18.4%, P = 0.006) and apoB (Δ = -16.6%, P = 0.005). The substitution of ω-6 PUFAs for SFAs decreased the LDL apoB-100 pool size (Δ = -7.8%; P = 0.005). This difference was attributed to a reduction in the LDL apoB-100 production rate after the substitution of ω-6 PUFAs for SFAs (Δ = -10.0%; P = 0.003).

Conclusions

This study demonstrates that the substitution of dietary ω-6 PUFAs for SFAs decreases the production and number of LDL particles in men with dyslipidemia and IR. This trial was registered at clinicaltrials.gov as NCT01934543.

Association Between Plasma Trans-Fatty Acid Concentrations and Measures of Glucose Homeostasis and Cardiovascular Risk Factors in Adults in NHANES 1999-2000

There is limited evidence on the association between plasma trans-fatty acids (TFAs) and cardiometabolic risk factors. Therefore, we examined the association between plasma TFA concentrations and glucose homeostasis and cardiovascular (CV) risk factors in adult Americans from the 1999 to 2000 National Health and Nutrition Examination Survey participants. Derivatized TFAs were separated by capillary gas chromatography. Of the 1678 participants, 46.5% were men. The mean age was 50.5 years overall, with no significant difference between men and women ( P = .101). In age-, sex- and race-adjusted analyses, mean waist circumference, fat-free mass, fat mass, C-peptide, insulin, hemoglobin A_1c (HbA_1c), homeostatic model assessment of insulin resistance (HOMA-IR), serum triglycerides (TGs), and total cholesterol (TC) increased across increasing quarters of TFAs (for all P < .001), while mean serum high-density lipoprotein cholesterol decreased across increasing quarters of plasma TFAs ( P < .001). In multivariable adjusted linear regressions, there remained significant positive associations between all plasma TFAs and body mass index, waist circumference, fat-free mass, fat mass, C-peptide, insulin, fasting blood glucose, HOMA-IR, HbA_1c, TGs, low-density lipoprotein cholesterol, and TC ( P < .001). In conclusion, our findings support a possible association between plasma TFAs concentrations and measures of glucose homeostasis and several CV risk factors.

Inclusion of Almonds in a Cholesterol-Lowering Diet Improves Plasma HDL Subspecies and Cholesterol Efflux to Serum in Normal-Weight Individuals with Elevated LDL Cholesterol

Background: Almonds may increase circulating HDL cholesterol when substituted for a high-carbohydrate snack in an isocaloric diet, yet little is known about the effects on HDL biology and function.Objective: The objective was to determine whether incorporating 43 g almonds/d in a cholesterol-lowering diet would improve HDL subspecies and function, which were secondary study outcomes.Methods: In a randomized, 2-period, crossover, controlled-feeding study, a diet with 43 g almonds/d (percentage of total energy: 51% carbohydrate, 16% protein, and 32% total and 8% saturated fat) was compared with a similar diet with an isocaloric muffin substitution (58% carbohydrate, 15% protein, and 26% total and 8% saturated fat) in men and women with elevated LDL cholesterol. Plasma HDL subspecies and cholesterol efflux from J774 macrophages to human serum were measured at baseline and after each diet period. Diet effects were examined in all participants (n = 48) and in normal-weight (body mass index: <25; n = 14) and overweight or obese (≥25; n = 34) participants by using linear mixed models.Results: The almond diet, compared with the control diet, increased α-1 HDL [mean ± SEM: 26.7 ± 1.5 compared with 24.3 ± 1.3 mg apolipoprotein A-I (apoA-I)/dL; P = 0.001]. In normal-weight participants, the almond diet, relative to the control diet, increased α-1 HDL (33.7 ± 3.2 compared with 28.4 ± 2.6 mg apoA-I/dL), the α-1 to pre-β-1 ratio [geometric mean (95% CI): 4.3 (3.3, 5.7) compared with 3.1 (2.4, 4.0)], and non-ATP-binding cassette transporter A1 cholesterol efflux (8.3% ± 0.4% compared with 7.8% ± 0.3%) and decreased pre-β-2 (3.8 ± 0.4 compared with 4.6 ± 0.4 mg apoA-I/dL) and α-3 (23.5 ± 0.9 compared with 26.9 ± 1.1 mg apoA-I/dL) HDL (P < 0.05). No diet effects were observed in the overweight or obese group.Conclusions: Substituting almonds for a carbohydrate-rich snack within a lower-saturated-fat diet may be a simple strategy to maintain a favorable circulating HDL subpopulation distribution and improve cholesterol efflux in normal-weight individuals with elevated LDL cholesterol. This trial was registered at clinicaltrials.gov as NCT01101230.

Comparison of the impact of SFAs from cheese and butter on cardiometabolic risk factors: a randomized controlled trial

Background: Controversies persist concerning the association between intake of dietary saturated fatty acids (SFAs) and cardiovascular disease risk.Objective: We compared the impact of consuming equal amounts of SFAs from cheese and butter on cardiometabolic risk factors.Design: In a multicenter, crossover, randomized controlled trial, 92 men and women with abdominal obesity and relatively low HDL-cholesterol concentrations were assigned to sequences of 5 predetermined isoenergetic diets of 4 wk each separated by 4-wk washouts: 2 diets rich in SFAs (12.4-12.6% of calories) from either cheese or butter; a monounsaturated fatty acid (MUFA)-rich diet (SFAs: 5.8%, MUFAs: 19.6%); a polyunsaturated fatty acid (PUFA)-rich diet (SFAs: 5.8%, PUFAs: 11.5%); and a low-fat, high-carbohydrate diet (fat: 25%, SFAs: 5.8%).Results: Serum HDL-cholesterol concentrations were similar after the cheese and butter diets but were significantly higher than after the carbohydrate diet (+3.8% and +4.7%, respectively; P < 0.05 for both). LDL-cholesterol concentrations after the cheese diet were lower than after the butter diet (-3.3%, P < 0.05) but were higher than after the carbohydrate (+2.6%), MUFA (+5.3%), and PUFA (+12.3%) diets (P < 0.05 for all). LDL-cholesterol concentrations after the butter diet also increased significantly (from +6.1% to +16.2%, P < 0.05) compared with the carbohydrate, MUFA, and PUFA diets. The LDL-cholesterol response to treatment was significantly modified by baseline values (P-interaction = 0.02), with the increase in LDL cholesterol being significantly greater with butter than with cheese only among individuals with high baseline LDL-cholesterol concentrations. There was no significant difference between all diets on inflammation markers, blood pressure, and insulin-glucose homeostasis.Conclusions: The results of our study suggest that the consumption of SFAs from cheese and butter has similar effects on HDL cholesterol but differentially modifies LDL-cholesterol concentrations compared with the effects of carbohydrates, MUFAs, and PUFAs, particularly in individuals with high LDL cholesterol. In contrast, SFAs from either cheese or butter have no significant effects on several other nonlipid cardiometabolic risk factors. This trial was registered at clinicaltrials.gov as NCT02106208.

Metabolic Phenotyping of Diet and Dietary Intake

Nutrition provides the building blocks for growth, repair, and maintenance of the body and is key to maintaining health. Exposure to fast foods, mass production of dietary components, and wider importation of goods have challenged the balance between diet and health in recent decades, and both scientists and clinicians struggle to characterize the relationship between this changing dietary landscape and human metabolism with its consequent impact on health. Metabolic phenotyping of foods, using high-density data-generating technologies to profile the biochemical composition of foods, meals, and human samples (pre- and postfood intake), can be used to map the complex interaction between the diet and human metabolism and also to assess food quality and safety. Here, we outline some of the techniques currently used for metabolic phenotyping and describe key applications in the food sciences, ending with a broad outlook at some of the newer technologies in the field with a view to exploring their potential to address some of the critical challenges in nutritional science.

Phenotypic factors influencing the variation in response of circulating cholesterol level to personalised dietary advice in the Food4Me study

Individual response to dietary interventions can be highly variable. The phenotypic characteristics of those who will respond positively to personalised dietary advice are largely unknown. The objective of this study was to compare the phenotypic profiles of differential responders to personalised dietary intervention, with a focus on total circulating cholesterol. Subjects from the Food4Me multi-centre study were classified as responders or non-responders to dietary advice on the basis of the change in cholesterol level from baseline to month 6, with lower and upper quartiles defined as responder and non-responder groups, respectively. There were no significant differences between demographic and anthropometric profiles of the groups. Furthermore, with the exception of alcohol, there was no significant difference in reported dietary intake, at baseline. However, there were marked differences in baseline fatty acid profiles. The responder group had significantly higher levels of stearic acid (18 : 0, P=0·034) and lower levels of palmitic acid (16 : 0, P=0·009). Total MUFA (P=0·016) and total PUFA (P=0·008) also differed between the groups. In a step-wise logistic regression model, age, baseline total cholesterol, glucose, five fatty acids and alcohol intakes were selected as factors that successfully discriminated responders from non-responders, with sensitivity of 82 % and specificity of 83 %. The successful delivery of personalised dietary advice may depend on our ability to identify phenotypes that are responsive. The results demonstrate the potential use of metabolic profiles in identifying response to an intervention and could play an important role in the development of precision nutrition.

Comprehensive Analysis of Established Dyslipidemia-Associated Loci in the Diabetes Prevention Program

BACKGROUND

We assessed whether 234 established dyslipidemia-associated loci modify the effects of metformin treatment and lifestyle intervention (versus placebo control) on lipid and lipid subfraction levels in the Diabetes Prevention Program randomized controlled trial.

METHODS AND RESULTS

We tested gene treatment interactions in relation to baseline-adjusted follow-up blood lipid concentrations (high-density lipoprotein [HDL] and low-density lipoprotein-cholesterol, total cholesterol, and triglycerides) and lipoprotein subfraction particle concentrations and size in 2993 participants with pre-diabetes. Of the previously reported single-nucleotide polymorphism associations, 32.5% replicated at P<0.05 with baseline lipid traits. Trait-specific genetic risk scores were robustly associated (3×10^-4>P>1.1×10^-16) with their respective baseline traits for all but 2 traits. Lifestyle modified the effect of the genetic risk score for large HDL particle numbers, such that each risk allele of the genetic risk scores was associated with lower concentrations of large HDL particles at follow-up in the lifestyle arm (β=-0.11 µmol/L per genetic risk scores risk allele; 95% confidence interval, -0.188 to -0.033; P=5×10^-3; P_interaction=1×10^-3 for lifestyle versus placebo), but not in the metformin or placebo arms (P>0.05). In the lifestyle arm, participants with high genetic risk had more favorable or similar trait levels at 1-year compared with participants at lower genetic risk at baseline for 17 of the 20 traits.

CONCLUSIONS

Improvements in large HDL particle concentrations conferred by lifestyle may be diminished by genetic factors. Lifestyle intervention, however, was successful in offsetting unfavorable genetic loading for most lipid traits.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique Identifier: NCT00004992.

Impact of avocado-enriched diets on plasma lipoproteins: A meta-analysis

BACKGROUND

Optimizing plasma lipoproteins is the primary goal of pharmacotherapy and diet interventions in people at risk for cardiovascular diseases. Avocados offer a rich source of monounsaturated fat and may pose beneficial effects on the lipid profile.

OBJECTIVE

We aimed to perform a meta-analysis of randomized clinical trials assessing the impact of avocados on TC, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol, and/or triglycerides (TG).

METHODS

We searched PUBMED, Cumulative Index to Nursing and Allied Health Literature, Index to Nursing and Allied Health Literature, and the Cochrane Database of Systemic Reviews from their inception to February 2015. The weighted mean difference from baseline was calculated for all endpoints. Subgroup analyses were performed to assess heterogeneity, and funnel plots inspected to assess publication bias.

RESULTS

Ten unique studies (n = 229) were included. Avocado consumption significantly reduced TC, LDL-C, and TG by -18.80 mg/dL (95% confidence interval [CI], -24.56 to -13.05; I(2), 46.9%), -16.50 mg/dL (95% CI, -22.91 to -10.10; I(2), 72.5%), -27.20 mg/dL (95% CI, -44.41 to -9.99; I(2), 91.1%) respectively. High-density lipoprotein cholesterol decreased nonsignificantly by -0.18 mg/dL (95% CI, -3.23 to 2.88; I(2), 84.8%).

CONCLUSION

Avocado-substituted diets significantly decrease TC, LDL-C, and TG levels. Substituting dietary fats with avocados versus adding to the free diet should be the primary recommendation strategy. Larger trials looking at the impact of avocados on major adverse cardiovascular events are warranted.

Effect of 12 Weeks High Oleic Peanut Consumption on Cardio-Metabolic Risk Factors and Body Composition

Epidemiological evidence indicates an inverse association between nut consumption and obesity, inflammation, hyperlipidaemia and glucose intolerance. We investigated effects of high oleic peanut consumption vs. a nut free diet on adiposity and cardio-metabolic risk markers. In a randomised cross-over design, 61 healthy subjects (65 ± 7 years, body mass index (BMI) 31 ± 4 kg/m²) alternated either high oleic peanuts (15%-20% of energy) or a nut free diet for 12 weeks. Body composition and mass, waist circumference, C-reactive protein (CRP), lipids, glucose and insulin were assessed at baseline and after each phase. Repeated measures analysis of variance (ANOVA) compared the two diets. Consistent with other nut studies, there were no differences in lipids, CRP, glucose and insulin with peanut consumption. In contrast, some reports have demonstrated benefits, likely due to differences in the study cohort. Energy intake was 10% higher (853 kJ, p < 0.05), following peanut consumption vs. control, attributed to a 30% increase in fat intake (p < 0.001), predominantly monounsaturated (increase 22 g, p < 0.05). Despite greater energy intake during the peanut phase, there were no differences in body composition, and less than predicted increase (0.5 kg) in body weight for this additional energy intake, possibly due to incomplete nutrient absorption and energy utilisation.

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.

Diets high in protein or saturated fat do not affect insulin sensitivity or plasma concentrations of lipids and lipoproteins in overweight and obese adults

BACKGROUND

Previous human studies reported inconsistent effects of dietary protein and branched-chain amino acids (BCAAs) on insulin action and glucose metabolism. Similarly, it is unclear whether saturated fat (SF) intake influences these metabolic variables.

OBJECTIVE

The objective of this study was to test the effects of high [30% of energy (%E)] vs. moderate (20%E) intakes of protein (primarily whey) on insulin action and lipid and lipoprotein concentrations in the context of both high (15%E) and low (7%E) SF diets.

METHODS

The study was conducted as a randomized controlled trial in 158 overweight and obese men and women. After a 4-wk baseline diet [55%E carbohydrate, 15%E protein, 30%E fat (7%E SF)], participants were randomly assigned to 4 wk of either the baseline diet or 1 of 4 test diets containing 35%E carbohydrate and either 20%E or 30%E protein and either 7%E or 15%E SF. Frequently sampled i.v. glucose tolerance tests were administered after each dietary period.

RESULTS

Other than significantly higher fasting glucose concentrations for high vs. moderate protein intakes with a low-fat diet (difference ± SE: 0.47 ± 0.14 mmol/L; P = 0.001), there were no significant effects of dietary protein or SF on glucose metabolism, plasma insulin, or concentrations of lipids and lipoproteins. Changes in plasma BCAAs across all diets were negatively correlated with changes in the metabolic clearance rate of insulin (ρ = -0.18, P = 0.03) and positively correlated with changes in the acute insulin response to glucose (ρ = 0.15, P = 0.05).

CONCLUSIONS

These findings suggest that short-term intake of BCAAs can influence insulin dynamics. However, in this group of overweight and obese individuals, neither high protein nor SF intake affected insulin sensitivity or plasma concentrations of lipids and lipoproteins. This trial was registered at clinicaltrials.gov as NCT00508937.

Nut consumption has favorable effects on lipid profiles of Korean women with metabolic syndrome

Nut consumption has been studied for its cardioprotective effects. However, the findings of clinical intervention studies are inconsistent; and no intervention studies have been conducted in the Korean population. We hypothesized that nut supplementation may have favorable influence on metabolic markers. Therefore, this study aimed to investigate the effects of nut consumption on metabolic parameters and biomarkers related to inflammation, oxidative stress, and endothelial function in Korean adults with metabolic syndrome. To this end, we designed a randomized, parallel, controlled dietary intervention study (ClinicalTrials.gov NCT02023749). Subjects with metabolic syndrome and a body mass index of at least 23 kg/m(2) were randomized to the Control group and the Nut group, which received supplementation with 30 g/d of mixed nuts (walnuts, peanuts, and pine nuts) for 6 weeks. Sixty volunteers were included in the final analysis. Metabolic markers were evaluated at baseline and at the end of the study. Total cholesterol and non-high-density lipoprotein cholesterol levels significantly improved in the Nut group compared to those in the Control group (P = .023 and P = .016, respectively) in women. Biomarkers related to inflammation, oxidative stress, and endothelial function did not significantly change from baseline in either group. Thus, supplementing a usual diet with mixed nuts for 6 weeks had favorable effects on several lipid parameters in Korean women with metabolic syndrome. These findings present a possible mechanism for the cardioprotective effects of nut consumption.

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

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

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

BACKGROUND

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

METHODS AND FINDINGS

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

CONCLUSIONS

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

Nuts in the prevention and treatment of metabolic syndrome

Nuts are rich in many bioactive compounds that can exert beneficial effects on cardiovascular health. We reviewed the evidence relating nut consumption and the metabolic syndrome (MetS) and its components. Nuts reduce the postprandial glycemic response; however, long-term trials of nuts on insulin resistance and glycemic control in diabetic individuals are inconsistent. Epidemiologic studies have shown that nuts may lower the risk of diabetes incidence in women. Few studies have assessed the association between nuts and abdominal obesity, although an inverse association with body mass index and general obesity has been observed. Limited evidence suggests that nuts have a protective effect on blood pressure and endothelial function. Nuts have a cholesterol-lowering effect, but the relation between nuts and hypertriglyceridemia and high-density lipoprotein cholesterol is not well established. A recent pooled analysis of clinical trials showed that nuts are inversely related to triglyceride concentrations only in subjects with hypertriglyceridemia. An inverse association was found between the frequency of nut consumption and the prevalence and the incidence of MetS. Several trials evaluated the effect of nuts on subjects with MetS and found that they may have benefits in some components. Compared with a low-fat diet, a Mediterranean diet enriched with nuts could be beneficial for MetS management. The protective effects on metabolism could be explained by the modulation of inflammation and oxidation. Further trials are needed to clarify the role of nuts in MetS prevention and treatment.

Effects of R219K polymorphism of ATP-binding cassette transporter 1 gene on serum lipids ratios induced by a high-carbohydrate and low-fat diet in healthy youth

Background

Diets are the important players in regulating plasma lipid profiles. And the R219K polymorphism at the gene of ATP-binding cassette transporter 1(ABCA1) was reported to be associated with the profiles. However, no efforts have been made to investigate the changes of lipid profiles after a high-carbohydrate and low-fat diet in different subjects with different genotypes of this polymorphism. This study was to evaluate the effects of ABCA1 R219K polymorphism on serum lipid and apolipoprotein (apo) ratios induced by a high-carbohydrate/low-fat (high-CHO) diet. After a washout diet of 54.1% carbohydrate for 7 days, 56 healthy young subjects (22.89 ± 1.80 years old) were given a high-CHO diet of 70.1% carbohydrate for 6 days. Height, weight, waist circumference, hip circumference, glucose (Glu), triglyceride (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), apoA-1 and apoB-100 were measured on the 1^st, 8^th and 14^th days of this study. Body mass index (BMI), waist-to-hip ratios (WHR), log(TG/HDL-C), TC/HDL-C, LDL-C/HDL-C and apoA-1/apoB-100 were calculated. ABCA1 R219K was analyzed by a PCR-RFLP method.

Results

The results indicate that the male subjects of all the genotypes had higher WHR than their female counterparts on the 1^st, 8^th and 14^th days of this study. The male K carriers had higher log(TG/HDL-C) and TC/HDL-C than the female carriers on the 1^st and 14^th days, and higher LDL-C/HDL-C on the 14^th day. When compared with that on the 8^th day, TC/HDL-C was decreased regardless of the genotypes and genders on the 14^th day. Log(TG/HDL-C) was increased in the males with the RR genotype and the female K carriers. Lowered BMI, Glu and LDL-C/HDL-C were found in the male K carriers, but only lowered BMI in the female K carriers and only lowered LDL-C/HDL-C in the females with the RR genotype.

Conclusions

These results suggest that ABCA1 R219K polymorphism is associated differently in males and females with elevated log(TG/HDL-C) and decreased LDL-C/HDL-C induced by the high-CHO diet.

Is Almond Consumption More Effective Than Reduced Dietary Saturated Fat at Decreasing Plasma Total Cholesterol and LDL-c Levels? A Theoretical Approach

Hypercholesterolemia can be a consequence of excessive dietary saturated fatty acid (SFA), while almond-supplemented diets can improve lipid profiles. However, the differential and independent impacts of dietary SFA and almondsupplemented diets on plasma total cholesterol (pTC) and low-density lipoprotein (pLDL-c) concentrations have not been directly compared and are not well described. We reviewed the available data to construct multiple regression analyses to theoretically assess the impact of relative almond intake (RAI) and dietary SFA on reducing pTC and pLDL-c concentrations. Strong, negative correlations between RAI and percent change in mean pTC (R = 0.776; P = 0.005) and RAI and percent change in mean pLDL-c (R = 0.818; P = 0.002) were detected. The relationships between percent change in mean dietary SFA, and percent change in mean pTC and mean pLDL-c were weaker and only significant for pLDL-c. The multiple regression analyses demonstrated modest improvements in the strength of the correlations for both pTC (R = 0.804; P = 0.016) and pLDL-c (R = 0.855; P = 0.005). The models suggest that the increase in RAI contributes to the reduction in pTC and pLDL-c to a greater extent than a reduction in dietary SFA, but a simultaneous decrease in dietary SFA should further improve lipid profiles.

The role of diet and nutrient composition in nonalcoholic Fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the developed world. NAFLD is tightly linked to insulin resistance and considered to be the hepatic manifestation of the metabolic syndrome. The cornerstone of any treatment regimen for patients with NAFLD is lifestyle modification focused on weight loss, exercise, and improving insulin sensitivity. Here we review the literature and discuss the role of diet and nutrient composition in the management of NAFLD. Because there are currently no specific dietary guidelines for NAFLD, this review proposes a dietary framework for patients with NAFLD based on the available evidence and extrapolates from dietary guidelines aimed at reducing insulin resistance and cardiovascular risk.

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.

Effects of adiposity on plasma lipid response to reductions in dietary saturated fatty acids and cholesterol

Dietary SFA and cholesterol are major targets for reducing plasma total and LDL cholesterol as a strategy to decrease cardiovascular disease risk. However, many studies show that excess adiposity attenuates the expected lipid and lipoprotein response to a plasma cholesterol-lowering diet. Diets low in SFA and cholesterol are less effective in improving the lipid profile in obese individuals and in patients with metabolic syndrome. In contrast, lean persons are more responsive to reductions in dietary SFA and cholesterol. Multiple mechanisms likely contribute to the altered plasma lipid responses to dietary changes in individuals with excess adiposity. The greater rate of hepatic cholesterol synthesis in obese individuals suppresses the expression of hepatic LDL receptors (LDLR), thereby reducing hepatic LDL uptake. Insulin resistance develops as a result of adipose-tissue induced inflammation, causing significant changes in enzymes necessary for normal lipid metabolism. In addition, the LDLR-mediated uptake in obesity is attenuated by alterations in neuroendocrine regulation of hormonal secretions (e.g. growth hormone, thyroid hormone, and cortisol) as well as the unique gut microbiota, the latter of which appears to affect lipid absorption. Reducing adipose tissue mass, especially from the abdominal region, is an effective strategy to improve the lipid response to dietary interventions by reducing inflammation, enhancing insulin sensitivity, and improving LDLR binding. Thus, normalizing adipose tissue mass is an important goal for maximizing the diet response to a plasma cholesterol-lowering diet.

Nuts and berries for heart health

Nuts are nutrient-dense foods with complex matrices rich in unsaturated fatty acids and other bioactive compounds, such as L-arginine, fiber, minerals, tocopherols, phytosterols, and polyphenols. By virtue of their unique composition, nuts are likely to beneficially impact heart health. Epidemiologic studies have associated nut consumption with a reduced incidence of coronary heart disease in both genders and diabetes in women. Limited evidence also suggests beneficial effects on hypertension and inflammation. Interventional studies consistently show that nut intake has a cholesterol-lowering effect and there is emerging evidence of beneficial effects on oxidative stress, inflammation, and vascular reactivity. Blood pressure, visceral adiposity, and glycemic control also appear to be positively influenced by frequent nut consumption without evidence of undue weight gain. Berries are another plant food rich in bioactive phytochemicals, particularly flavonoids, for which there is increasing evidence of benefits on cardiometabolic risk that are linked to their potent antioxidant power.

Effects of one serving of mixed nuts on serum lipids, insulin resistance and inflammatory markers in patients with the metabolic syndrome

BACKGROUND AND AIMS

Knowledge of the effect of nut consumption on metabolic syndrome (MetS) components is limited. We assessed the effects of nut intake on adiposity, serum lipids, insulin resistance, and inflammatory biomarkers in patients with MetS.

METHODS AND RESULTS

In a randomized, parallel-group, 12-week feeding trial, 50 patients with MetS were given recommendations for a healthy diet with or without supplementation with 30 g/day of raw nuts (15 g walnuts, 7.5 g almonds and 7.5 g hazelnuts) (Nut and Control diet groups, respectively). Adiposity measures, serum lipids, insulin, Homeostasis Model Assessment (HOMA), interleukin-6 (IL-6) and other inflammatory biomarkers, and 48-h fecal fat were determined basally and at study's completion. Moderate weight loss, decreased adiposity, and lower blood pressure occurred similarly after both diets. The Control, but not the Nut diet, was associated with significant (P<0.05) reduction of LDL-cholesterol, with mean changes of -0.36 versus -0.13 mmol/L, respectively (between-group differences, P=0.154). The Nut diet reduced fasting insulin by 2.60 μU/mL (95% CI, -4.62 to -0.59) and HOMA-insulin resistance by 0.72 (-1.28 to -0.16) (P<0.05 versus Control diet; both). Among inflammatory markers, the Nut diet resulted in changes of median plasma IL-6 of -1.1 ng/L (-2.7 to -0.1; P=0.035 versus Control diet), but adjustment for weight loss attenuated the significance of the association. Stool fat decreased with the Control diet and slightly increased with the Nut diet (P<0.05 for between-group differences).

CONCLUSION

Patients with MetS show decreased lipid responsiveness but improved insulin sensitivity after daily intake of 30 g of mixed nuts.

Dietary monounsaturated fatty acids appear not to provide cardioprotection

Dietary interventions have been consistently proposed as a part of a comprehensive strategy to lower the incidence and severity of coronary heart disease (CHD), in the process providing long-term cardioprotection. Replacement of dietary saturated fatty acids (SFA) with higher intakes of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) has been reported to be inversely associated with risk of CHD. The observed lower incidence of CHD among populations consuming a Mediterranean-type diet, mainly enriched in MUFA from olive oil, has long supported the belief that MUFA are an optimal substitution for SFA. However, both epidemiologic and interventional studies suggest that although substituting MUFA-rich foods for SFA-rich foods in the diet can potentially lower total plasma cholesterol concentrations, this substitution does not lower the extent of coronary artery atherosclerosis. In addition, although recent evidence suggests that the source of MUFA (animal fat vs vegetable oils) may differentially influence the correlation between MUFA intake and CHD mortality, animal studies suggest that neither source is cardioprotective.

Effects of dietary fat modification on insulin sensitivity and on other risk factors of the metabolic syndrome--LIPGENE: a European randomized dietary intervention study

BACKGROUND

Excessive energy intake and obesity lead to the metabolic syndrome (MetS). Dietary saturated fatty acids (SFAs) may be particularly detrimental on insulin sensitivity (SI) and on other components of the MetS.

OBJECTIVE

This study determined the relative efficacy of reducing dietary SFA, by isoenergetic alteration of the quality and quantity of dietary fat, on risk factors associated with MetS.

DESIGN

A free-living, single-blinded dietary intervention study.

SUBJECTS AND METHODS

MetS subjects (n = 417) from eight European countries completed the randomized dietary intervention study with four isoenergetic diets distinct in fat quantity and quality: high-SFA; high-monounsaturated fatty acids and two low-fat, high-complex carbohydrate (LFHCC) diets, supplemented with long chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs) (1.2 g per day) or placebo for 12 weeks. SI estimated from an intravenous glucose tolerance test (IVGTT) was the primary outcome measure. Lipid and inflammatory markers associated with MetS were also determined.

RESULTS

In weight-stable subjects, reducing dietary SFA intake had no effect on SI, total and low-density lipoprotein cholesterol concentration, inflammation or blood pressure in the entire cohort. The LFHCC n-3 PUFA diet reduced plasma triacylglycerol (TAG) and non-esterified fatty acid concentrations (P < 0.01), particularly in men.

CONCLUSION

There was no effect of reducing SFA on SI in weight-stable obese MetS subjects. LC n-3 PUFA supplementation, in association with a low-fat diet, improved TAG-related MetS risk profiles.

A high legume low glycemic index diet improves serum lipid profiles in men

Clinical studies have shown that fiber consumption facilitates weight loss and improves lipid profiles; however, the beneficial effects of high fermentable fiber low glycemic index (GI) diets under conditions of weight maintenance are unclear. In the Legume Inflammation Feeding Experiment, a randomized controlled cross-over feeding study, 64 middle-aged men who had undergone colonoscopies within the previous 2 years received both a healthy American (HA) diet (no legume consumption, fiber consumption = 9 g/1,000 kcal, and GI = 69) and a legume enriched (1.5 servings/1,000 kcal), high fiber (21 g/1,000 kcal), low GI (GI = 38) diet (LG) in random order. Diets were isocaloric and controlled for macronutrients including saturated fat; they were consumed each for 4 weeks with a 2-4 week break separating dietary treatments. Compared to the HA diet, the LG diet led to greater declines in both fasting serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) (P < 0.001 and P < 0.01, respectively). Insulin-resistant (IR) subjects had greater reductions in high density lipoprotein cholesterol (HDL-C; P < 0.01), and triglycerides (TAG)/HDL-C (P = 0.02) after the LG diet, compared to the HA diet. Insulin-sensitive (IS) subjects had greater reductions in TC (P < 0.001), LDL-C (P < 0.01), TC/HDL-C (P < 0.01), and LDL-C/HDL-C (P = 0.02) after the LG diet, compared to the HA diet. In conclusion, a high legume, high fiber, low GI diet improves serum lipid profiles in men, compared to a healthy American diet. However, IR individuals do not achieve the full benefits of the same diet on cardiovascular disease (CVD) lipid risk factors.

Health benefits of nut consumption

Nuts (tree nuts and peanuts) are nutrient dense foods with complex matrices rich in unsaturated fatty and other bioactive compounds: high-quality vegetable protein, fiber, minerals, tocopherols, phytosterols, and phenolic compounds. By virtue of their unique composition, nuts are likely to beneficially impact health outcomes. Epidemiologic studies have associated nut consumption with a reduced incidence of coronary heart disease and gallstones in both genders and diabetes in women. Limited evidence also suggests beneficial effects on hypertension, cancer, and inflammation. Interventional studies consistently show that nut intake has a cholesterol-lowering effect, even in the context of healthy diets, and there is emerging evidence of beneficial effects on oxidative stress, inflammation, and vascular reactivity. Blood pressure, visceral adiposity and the metabolic syndrome also appear to be positively influenced by nut consumption. Thus it is clear that nuts have a beneficial impact on many cardiovascular risk factors. Contrary to expectations, epidemiologic studies and clinical trials suggest that regular nut consumption is unlikely to contribute to obesity and may even help in weight loss. Safety concerns are limited to the infrequent occurrence of nut allergy in children. In conclusion, nuts are nutrient rich foods with wide-ranging cardiovascular and metabolic benefits, which can be readily incorporated into healthy diets.

Health benefits of nut consumption

We investigated the effect of a mixture of long-chain fructo-oligosaccharides, galacto-oligosaccharides and acidic oligosaccharides on the number and consistency of stools and on immune system biomarkers in 104 supplemented and non-supplemented subjects (aged 9-24 months) with acute diarrhea. Interleukin-1 (IL-1), IL-1RA, IL-6, IL-8, IL-10, TNF-α and sIL-2R cytokine levels were determined. The significant decrease in number of stools and increase in stool consistency in the supplemented group was of little clinical relevance. The only significant change in pro- and anti-inflammatory cytokines was decreased TNF-α levels in the supplemented group. Prebiotic supplementation during acute diarrhea episodes did not influence the clinical course.

Saturated fat, carbohydrate, and cardiovascular disease

A focus of dietary recommendations for cardiovascular disease (CVD) prevention and treatment has been a reduction in saturated fat intake, primarily as a means of lowering LDL-cholesterol concentrations. However, the evidence that supports a reduction in saturated fat intake must be evaluated in the context of replacement by other macronutrients. Clinical trials that replaced saturated fat with polyunsaturated fat have generally shown a reduction in CVD events, although several studies showed no effects. An independent association of saturated fat intake with CVD risk has not been consistently shown in prospective epidemiologic studies, although some have provided evidence of an increased risk in young individuals and in women. Replacement of saturated fat by polyunsaturated or monounsaturated fat lowers both LDL and HDL cholesterol. However, replacement with a higher carbohydrate intake, particularly refined carbohydrate, can exacerbate the atherogenic dyslipidemia associated with insulin resistance and obesity that includes increased triglycerides, small LDL particles, and reduced HDL cholesterol. In summary, although substitution of dietary polyunsaturated fat for saturated fat has been shown to lower CVD risk, there are few epidemiologic or clinical trial data to support a benefit of replacing saturated fat with carbohydrate. Furthermore, particularly given the differential effects of dietary saturated fats and carbohydrates on concentrations of larger and smaller LDL particles, respectively, dietary efforts to improve the increasing burden of CVD risk associated with atherogenic dyslipidemia should primarily emphasize the limitation of refined carbohydrate intakes and a reduction in excess adiposity.

TaqIB polymorphism in the CETP gene modulates the impact of HC/LF diet on the HDL profile in healthy Chinese young adults

The aim of this study was to investigate the interactions of genetic variants in the genes of cholesterol ester transfer protein (CETP) and low-density lipoprotein receptor (LDLR) with high carbohydrate and low fat (HC/LF) diet on lipid profiles in a young and healthy Chinese Han population. Fifty-six healthy subjects (22.89±1.80 years) were given washout diets of 31% fat and 54% carbohydrate for 7 days, followed by HC/LF diets of 15% fat and 70% carbohydrate for 6 days, with no total energy restriction. Serum lipid profiles at baseline, after washout and following HC/LF diets, as well as CETP and LDLR polymorphisms were analyzed. Carriers of B2 allele of CETP TaqIB polymorphism had significantly higher levels of high density lipoprotein cholesterol (HDL-C) and apo A-I in the whole study population after the diet intervention. Notably, males with CETP TaqIB B1B1 experienced significantly increased HDL-C and apo A-I after HC/LF diet. Regarding the LDLR Pvu II polymorphism, both P1P1 subjects and P2 carriers experienced decreased total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels after HC/LF diet with no statistically significant differences between the genotypes. Our results demonstrate that the elevated HDL-C levels after HC/LF diet in healthy Chinese Han youth are associated with CETP TaqI B2 allele while males with B1B1 genotype are more susceptible to the influence of HC/LF diet on their HDL-C levels. The decreased TC and LDL-C levels after HC/LF diet are not associated with LDLR Pvu II polymorphism.

Genetic influences on blood lipids and cardiovascular disease risk: tools for primary prevention

Genetic polymorphism in human populations is part of the evolutionary process that results from the interaction between the environment and the human genome. Recent changes in diet have upset this equilibrium, potentially influencing the risk of most common morbidities such as cardiovascular diseases, obesity, diabetes, and cancer. Reduction of these conditions is a major public health concern, and such a reduction could be achieved by improving our ability to detect disease predisposition early in life and by providing more personalized behavioral recommendations for successful primary prevention. In terms of cardiovascular diseases, polymorphisms at multiple genes have been associated with differential effects in terms of lipid metabolism; however, the connection with cardiovascular disease has been more elusive, and considerable heterogeneity exists among studies regarding the predictive value of genetic markers. This may be because of experimental limitations, the intrinsic complexity of the phenotypes, and the aforementioned interactions with environmental factors. The integration of genetic and environmental complexity into current and future research will drive the field toward the implementation of clinical tools aimed at providing dietary advice optimized for the individual's genome. This may imply that dietary changes are implemented early in life to gain maximum benefit. However, it is important to highlight that most reported studies have focused on adult populations and to extrapolate these findings to children and adolescents may not be justified until proper studies have been carried out in these populations and until the ethical and legal issues associated with this new field are adequately addressed.