Replacing Saturated Fat With Walnuts or Vegetable Oils Improves Central Blood Pressure and Serum Lipids in Adults at Risk for Cardiovascular Disease: A Randomized Controlled-Feeding Trial

Can daily consumption of enriched fatty acids diet be effective in improving metabolic syndrome? An attractive paradox for walnut kernel

Imagine consuming a daily diet rich in fatty acids to help treat diseases such as hypertension and obesity. This concept presents an attractive paradox. In particular, consuming walnut kernels is beneficial for treating diseases associated with metabolic syndrome (MetS), including type 2 diabetes, cardiovascular disease, dyslipidemia, and obesity. Different parts of the Juglans regia tree (family Juglandaceae), including its leaves, green husks, bark, and septum, have shown promising effects on pathological conditions related to MetS. The therapeutic advantages of consuming walnut kernels for MetS can be attributed to the presence of polyunsaturated fatty acids and polyphenolic compounds such as juglone and ellagic acid. Diets enriched with walnut kernel have a positive impact on MetS complications by reducing diastolic blood pressure, improving blood lipid profiles, lowering fasting blood sugar levels, and increasing insulin sensitivity. The potential cellular mechanisms responsible for these benefits involve activating the cholesterol hemostasis pathway by inhibiting sterol regulatory element-binding proteins (SREBPs), proprotein convertase subtilisin/kexin type 9 (PCSK9), and cholesteryl ester transfer protein (CETP). Furthermore, other by-products of walnuts, such as leaves and green husks, have also demonstrated effectiveness in managing MetS. These findings highlight the potential of incorporating walnut-based products into our diets as a natural approach to combating MetS and its complications.

Inverse Association between the Global Diet Quality Score and New-Onset Hypertension in Adults: A Nationwide Cohort Study

BACKGROUND

The Global Diet Quality Score (GDQS) is a simple and practical dietary metric associated with a number of chronic diseases. The GDQS included various foods related to blood pressure, especially diverse plant-based foods that have shown to lower blood pressure. However, studies on the role of the GDQS in reducing the risk of new-onset hypertension and whether its performance differs from that of other dietary metrics are lacking.

OBJECTIVE

We aimed to examine the association between the GDQS and new-onset hypertension and to compare its performance with that of other dietary patterns, including the Plant-based Diet Index (PDI), alternate Mediterranean diet (aMED) score, Alternative Healthy Eating Index-2010, and Dietary Approaches to Stop Hypertension (DASH) score in Chinese adults.

METHODS

We included a total of 12,002 participants (5644 males and 6358 females) aged >18 y from the China Health and Nutrition Survey (1997-2015). Dietary intake was estimated using average food intakes from 3 consecutive 24-h dietary recalls. Multivariable relative risks (RRs) were computed for hypertension using modified Poisson regression models.

RESULTS

With ≤18 y of follow-up (mean 8.7± 5.4 y), we ascertained 4232 incident cases of hypertension. Compared with participants with a low GDQS score (<15), the multivariable-adjusted RR of hypertension was 0.72 [95% confidence interval (CI): 0.62, 0.83] among participants with a high score (≥23). A 25% increment in the GDQS was associated with a 30% (RR, 0.70; 95% CI: 0.64, 0.76) lower risk of new-onset hypertension, which was comparable with the RRs of new-onset hypertension associated with every 25% increment in the PDI (RR, 0.84; 95% CI: 0.76, 0.93), DASH score (RR, 0.84; 95% CI: 0.78, 0.91), and aMED score (RR, 0.89; 95% CI: 0.84, 0.93).

CONCLUSION

A higher GDQS was associated with a lower risk of new-onset hypertension, with comparable associations of new-onset hypertension with PDI, DASH, and aMED scores in Chinese adults.

Olive Oil Consumption and Cardiovascular Protection: Mechanism of Action

Cardiovascular diseases (CVDs) are still the leading cause of death and disability worldwide, and they could be prevented by a diet modification and a healthy lifestyle. Dietary modifications include a reduction in the consumption of saturated fatty acids and replacing them with mono or polyunsaturated fatty acids. Olive oil is a monounsaturated fatty acid and its increased consumption has been associated with a significant reduction of CVDs. Its significant cardiovascular benefits have been attributed to its high content of vitamin E, polyphenols, and other ingredients that possess significant anti-inflammatory and antioxidant properties. Several prospective and epidemiological studies have reported an inverse association between olive oil consumption and the incidence of CVD, hypertension, and type 2 diabetes mellitus. Also, a seminal study demonstrated that the use of a Mediterranean diet, which is rich in olive oil, fruits, vegetables, and fish, and low in red meat, was associated with significant reductions in CVD and mortality. However, despite its proven cardiovascular benefits, olive oil is scarcely used in the United States and other Western countries. To determine the current use of olive oil in the United States and other Western countries, a Medline search of the English literature between 2012 and January 2022 was conducted, and 36 pertinent articles were selected. The data from these articles, together with collateral literature, will be discussed in this concise review.

Can different types of tree nuts and peanuts induce varied effects on specific blood lipid parameters? A systematic review and network meta-analysis

Tree nuts and peanuts have shown cardioprotective effects through the modulation of blood lipid levels. Despite the abundance of scientific evidence available, it remains uncertain whether the type of nut consumed influences these changes. The objective of this study was to evaluate and rank the effects of six types of nuts on total cholesterol (total-c), low-density lipoprotein (LDL-c), triglyceride (TG) and high-density lipoprotein (HDL-c) levels through a systematic search of randomized controlled trials (RCTs), a frequentist network meta-analysis (NMA), and the estimation of SUCRA values. A total of 76 RCTs were ultimately analyzed. The total c for pistachios, almond, and walnuts; LDL-c for cashews, walnuts, and almond; and TG for hazelnuts and walnuts significantly decreased, while only peanuts exhibited a significant increase in HDL-c levels. According to the rankings, the most effective type of nut for reducing total cholesterol was pistachio, cashew for LDL-c, hazelnut for TG, and peanut for increasing HDL-c levels. It should be noted that every type of nut analyzed exhibited a significant positive impact on some parameters, and specific types demonstrated enhanced advantages for particular blood lipids. These results endorse the use of personalized nutritional strategies to address and prevent dyslipidemia.Registration: PROSPERO database CRD42021270779.

High dietary intake of unsaturated fatty acids is associated with improved insulin resistance - a cross-sectional study based on the NHANES database

BACKGROUND

A moderate intake of unsaturated fatty acids (UFA) is associated positively with improved insulin resistance. The aim of this study was to investigate the relationship between the dietary intake of unsaturated fatty acids/total fats (UFA/TF) and insulin resistance.

METHODS

15,560 participants were selected from the National Health and Nutrition Examination Survey (NHANES) database enrolled between March 2017 and 2020, and excluded those under 20 years of age, pregnant, or with missing data for key research items. Finally, 7,630 participants were included in the study. R software was used for data analysis that included: (1) general descriptive statistics; (2) comparison of differences in baseline information of three UFA/TF groups, namely low, medium, and high ratios; (3) calculation of the correlation between the UFA/TF ratio and markers of insulin resistance: triglyceride-glucose index (TyG) and homeostatic model assessment for insulin resistance (HOMA-IR); (4) stratification of the study subjects into two groups, with or without insulin resistance, using a cut-off value of HOMA-IR ≥ 2, followed by logistic regression analysis to examine the relationship between UFA/TF and insulin resistance status in the two groups; and (5) further stratification of the subjects according to age, gender, body mass index (BMI), race, total energy intake, total protein, total carbohydrate, total sugars, total dietary fiber, total fat, alcohol consumption, diabetes, hypercholesterolemia to analyze the impact of UFA/TF on insulin resistance status in different subgroups.

RESULTS

(1) A high UFA/TF level was associated with a low TyG index and HOMA-IR [β (vs. TyG index) = -0.559, 95% CI: (-0.821~-0.297), P < 0.001; β (vs. HOMA-IR) = -0.742, 95% CI: (-1.083~-0.402), P < 0.001]. This negative relationship became more pronounced when UFA/TF exceeded 57.9% (i.e., the higher group). (2) Logistic regression analysis showed that a higher UFA/TF level was associated with a lower risk of developing insulin resistance [Q3 vs. Q1: 0.838 (95%CI: 0.709 ~ 0.991); P for trend = 0.038]. After adjusting for covariates such as gender, age, and BMI, this protective effect remained significant (P value < 0.05). (3) Analysis also showed that increased UFA/TF intake reduced the risk of developing insulin resistance (OR = 0.266, 95% CI: (0.075 ~ 0.946), P = 0.041). Subgroup analysis showed that although elevated UFA/TF intake showed no statistically significant difference in its effect in most subgroups, the large study population in this study provides valuable insights on potential changes. Increased UFA/TF intake may confer relatively greater benefits within specific subgroups, particularly among the elderly [Q3 age group, OR = 0.114, 95%CI: (0.012 ~ 1.078), P = 0.058], females [OR = 0.234, 95%CI: (0.041 ~ 1.333), P = 0.102], those with a BMI ≤ 25 kg/m²[OR = 0.191, 95%CI: (0.016 ~ 2.344), P = 0.196], and individuals without hypercholesterolemia [OR = 0.207, 95%CI: (0.042 ~ 1.013), P = 0.0519]. The impact of high UFA/TF levels within subgroups based on the presence or absence of coronary heart disease and stroke displayed contrasting trends. In those without coronary heart disease, there was a significant protective effect against insulin resistance [OR = 0.254, 95% CI: (0.07 ~ 0.929), P = 0.0384], while in the stroke subgroup, a significantly protective effect against insulin resistance was observed [OR = 0.002, 95%CI: (0 ~ 0.695), P = 0.0376].

CONCLUSION

A high dietary intake of UFA relative to total fat consumption could be a protective factor against the risk of developing insulin resistance.

Prevention of Alzheimer's disease through diet: An exploratory review

Introduction

This exploratory review article describes about the genetic factors behind Alzheimer's disease (AD), their association with foods, and their relationships with cognitive impairment. It explores the dietary patterns and economic challenges in AD prevention.

Methods

Scopus, PubMed and Google Scholar were searched for articles that examined the relationships between Diets, Alzheimer's Disease (AD), and Socioeconomic conditions in preventative Alzheimer's disease studies. Graphs and Network analysis data were taken from Scopus under the MeSH search method, including words, Alzheimer's, APoE4, Tau protein, APP, Amyloid precursor protein, Beta-Amyloid, Aβ, Mediterranean Diet, MD, DASH diet, MIND diet, SES, Socioeconomic, Developed country, Underdeveloped country, Preventions. The network analysis was done through VOS viewer.

Results

Mediterranean diet (MD) accurately lowers AD (Alzheimer's Disease) risk to 53% and 35% for people who follow it moderately. MIND scores had a statistically significant reduction in AD rate compared to those in the lowest tertial (53% and 35% reduction, respectively). Subjects with the highest adherence to the MD and DASH had a 54% and 39% lower risk of developing AD, respectively, compared to those in the lowest tertial. Omega-6, PUFA, found in nuts and fish, can play most roles in the clearance of Aβ. Vitamin D inhibits induced fibrillar Aβ apoptosis. However, the high cost of these diet components rise doubt about the effectiveness of AD prevention through healthy diets.

Conclusion

The finding of this study revealed an association between diet and the effects of the chemical components of foods on AD biomarkers. More research is required to see if nutrition is a risk or a protective factor for Alzheimer's disease to encourage research to be translated into therapeutic practice and to clarify nutritional advice.

Functional characterization of the MSP-C6 promoter as a potential tool for mesocarp-preferential expression of transgenes

Modification of lipid composition in the mesocarp tissue of oil palm involves genetic manipulation of multiple genes. More than one mesocarp-preferential promoter is necessary for the expression of individual transgenes in the same plant to obviate transcriptional gene silencing. This study aimed to identify genes that are preferentially expressed in the mesocarp tissue and characterize selected candidate mesocarp-preferential promoters. Ten transcripts that were preferentially expressed in the mesocarp tissue were identified from the analysis of 82 transcriptome datasets of 12 different oil palm tissues. The expression of two candidate genes, MSP-C1 and MSP-C6, was verified to be preferentially expressed in the mesocarp tissues and shown to have a low expression level in non-mesocarp tissues by reverse transcription quantitative real-time PCR (RT-qPCR). MSP-C6 promoter fragments of different lengths were transformed into tomato plants for further characterization. Both unripe and ripe fruits of transgenic tomato plants transformed with a construct harboring the MSP-C6-F1 (2014 bp) promoter were shown to have high beta-glucuronidase (GUS) activities. The findings of this study suggest the potential applications of the MSP-C6 promoter as a molecular tool for genetic engineering of novel traits in fruit crops.

Comprehensive quality evaluation of plant-based cheese analogues

BACKGROUND

In recent years, there has been an increasing demand for plant-based cheese analogues, however, the protein content of plant-based cheeses currently on the market is generally low and cannot meet the nutritional needs of consumers.

RESULTS

Based on the ideal value similarity method (TOPSIS) analysis the best recipe for plant-based cheese was 15% tapioca starch, 20% soy protein isolate, 7% gelatine as a quality enhancer and 15% coconut oil. The protein content of this plant-based cheese was170.1 g kg-1 , which was close to commercial dairy-based cheese and significantly higher than commercial plant-based cheese, The fat content was 114.7 g kg-1 , lower than that of commercial dairy-based cheese. The rheology properties show that the viscoelasticity of the plant-based cheese is higher than that of dairy-based cheese and commercial plant-based. The microstructure results show that the type and content of protein has a significant impact on its microstructure. The Fourier-transform infrared (FTIR) spectrum of the microstructure shows a characteristic value at 1700 cm-1 , because the starch was heated and leached to form a complex with lauric acid under the action of hydrogen bond. It can be inferred that in the interaction between plant-based cheese raw materials, fatty acids serve as a bridge between starch and protein.

COUCLUSION

This study described the formula of plant-based cheese and the interaction mechanism between the ingredients, providing a basis for the development of subsequent plant-based cheese related products. © 2023 Society of Chemical Industry.

Perspective: Challenges and Future Directions in Clinical Research with Nuts and Berries

Consumption of nuts and berries are considered part of a healthy eating pattern. Nuts and berries contain a complex nutrient profile consisting of essential vitamins and minerals, fiber, polyunsaturated fatty acids, and phenolics in quantities that improve physiological outcomes. The spectrum of health outcomes that may be impacted by the consumptions of nuts and berries includes cardiovascular, gut microbiome, and cognitive, among others. Recently, new insights regarding the bioactive compounds found in both nuts and berries have reinforced their role for use in precision nutrition efforts. However, challenges exist that can affect the generalizability of outcomes from clinical studies, including inconsistency in study designs, homogeneity of test populations, variability in test products and control foods, and assessing realistic portion sizes. Future research centered on precision nutrition and multi-omics technologies will yield new insights. These and other topics such as funding streams and perceived risk-of-bias were explored at an international nutrition conference focused on the role of nuts and berries in clinical nutrition. Successes, challenges, and future directions with these foods are presented here.

Tree Nut and Peanut Consumption and Risk of Cardiovascular Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Cardiovascular disease (CVD) is the leading cause of death globally. Habitual consumption of tree nuts and peanuts is associated with cardioprotective benefits. Food-based dietary guidelines globally recommend nuts as a key component of a healthy diet. This systematic review and meta-analysis were conducted to examine the relationship between tree nut and peanut consumption and risk factors for CVD in randomized controlled trials (RCTs) (PROSPERO: CRD42022309156). MEDLINE, PubMed, CINAHL, and Cochrane Central databases were searched up to 26 September, 2021. All RCT studies that assessed the effects of tree nut or peanut consumption of any dose on CVD risk factors were included. Review Manager software was used to conduct a random effect meta-analysis for CVD outcomes from RCTs. Forest plots were generated for each outcome, between-study heterogeneity was estimated using the I2 test statistic and funnel plots and Egger's test for outcomes with ≥10 strata. The quality assessment used the Health Canada Quality Appraisal Tool, and the certainty of the evidence was assessed using grading of recommendations assessment, development, and evaluation (GRADE). A total of 153 articles describing 139 studies (81 parallel design and 58 cross-over design) were included in the systematic review, with 129 studies in the meta-analysis. The meta-analysis showed a significant decrease for low-density lipoprotein (LDL) cholesterol, total cholesterol (TC), triglycerides (TG), TC:high-density lipoprotein (HDL) cholesterol, LDL cholesterol:HDL cholesterol, and apolipoprotein B (apoB) following nut consumption. However, the quality of evidence was "low" for only 18 intervention studies. The certainty of the body of evidence for TC:HDL cholesterol, LDL cholesterol:HDL cholesterol, and apoB were "moderate" because of inconsistency, for TG were "low," and for LDL cholesterol and TC were "very low" because of inconsistency and the likelihood of publication bias. The findings of this review provide evidence of a combined effect of tree nuts and peanuts on a range of biomarkers to create an overall CVD risk reduction.

Mechanisms linking hypertriglyceridemia to acute pancreatitis

Hypertriglyceridemia (HTG) is a metabolic disorder, defined when serum or plasma triglyceride concentration (seTG) is >1.7 mM. HTG can be categorized as mild to very severe groups based on the seTG value. The risk of acute pancreatitis (AP), a serious disease with high mortality and without specific therapy, increases with the degree of HTG. Furthermore, even mild or moderate HTG aggravates AP initiated by other important etiological factors, including alcohol or bile stone. This review briefly summarizes the pathophysiology of HTG, the epidemiology of HTG-induced AP and the clinically observed effects of HTG on the outcomes of AP. Our main focus is to discuss the pathophysiological mechanisms linking HTG to AP. HTG is accompanied by an increased serum fatty acid (FA) concentration, and experimental results have demonstrated that these FAs have the most prominent role in causing the consequences of HTG during AP. FAs inhibit mitochondrial complexes in pancreatic acinar cells, induce pathological elevation of intracellular Ca²⁺ concentration, cytokine release and tissue injury, and reduce the function of pancreatic ducts. Furthermore, high FA concentrations can induce respiratory, kidney, and cardiovascular failure in AP. All these effects may contribute to the observed increased AP severity and frequent organ failure in patients. Importantly, experimental results suggest that the reduction of FA production by lipase inhibitors can open up new therapeutic options of AP. Overall, investigating the pathophysiology of HTG-induced AP or AP in the presence of HTG and determining possible treatments are needed.

Walnut inclusion in a palm oil-based atherogenic diet promotes traits predicting stable atheroma plaque in Apoe-deficient mice

Introduction

The lower rates of cardiovascular disease in Southern Europe could be partially explained by the low prevalence of lipid-rich atheroma plaques. Consumption of certain foods affects the progression and severity of atherosclerosis. We investigated whether the isocaloric inclusion of walnuts within an atherogenic diet prevents phenotypes predicting unstable atheroma plaque in a mouse model of accelerated atherosclerosis.

Methods

Apolipoprotein E-deficient male mice (10-week-old) were randomized to receive a control diet (9.6% of energy as fat, n = 14), a palm oil-based high-fat diet (43% of energy as fat, n = 15), or an isocaloric diet in which part of palm oil was replaced by walnuts in a dose equivalent to 30 g/day in humans (n = 14). All diets contained 0.2% cholesterol.

Results

After 15 weeks of intervention, there were no differences in size and extension in aortic atherosclerosis among groups. Compared to control diet, palm oil-diet induced features predicting unstable atheroma plaque (higher lipid content, necrosis, and calcification), and more advanced lesions (Stary score). Walnut inclusion attenuated these features. Palm oil-based diet also boosted inflammatory aortic storm (increased expression of chemokines, cytokines, inflammasome components, and M1 macrophage phenotype markers) and promoted defective efferocytosis. Such response was not observed in the walnut group. The walnut group's differential activation of nuclear factor kappa B (NF-κB; downregulated) and Nrf2 (upregulated) in the atherosclerotic lesion could explain these findings.

Conclusion

The isocaloric inclusion of walnuts in an unhealthy high-fat diet promotes traits predicting stable advanced atheroma plaque in mid-life mice. This contributes novel evidence for the benefits of walnuts, even in an unhealthy dietary environment.

Preferences for dietary oils and fats in cooking and food preparation methods: a cross-sectional analysis of Australian adults

Dietary oils and fats contain different fatty acid compositions that are associated with cardiometabolic disease risk. Despite their influence on disease outcomes, the types of dietary oils and fats predominately used in Australian households remain unknown. The aim of this study was to investigate the use of dietary oils and fats in cooking and food preparation in Australia. Adults living in Australia completed a cross-sectional online survey outlining their current household oil and fat use from July to December 2021. The survey was disseminated via social media platforms and included questions about the types of dietary oils and fats used for different cooking methods and the perceived motivators for choosing the main household oil. A total of 1248 participants responded to the survey. Participants were mostly female (91·6 %) aged between 25 and 44 years (56·7 %). The majority of participants (84·5 %) reported using some form of olive oil as their main source of oil for cooking and food preparation. Almost two-thirds of the sample (65·4 %) reported using extra virgin olive oil (EVOO), mainly in raw food preparation (71·5 %) or savoury baking and roasting (58 %). Fewer households reported using rice bran oil (4·6 %), canola oil (4·3 %) and vegetable oil (1·8 %). Almost half of all participants (49·6 %) identified perceived health benefits as the primary motivating factor for their main choice of oil, followed by sensory preference (46·7 %), versatility (10·2 %) and convenience (8·8 %). Australian adults frequently use olive oil, specifically EVOO, as the main oil for cooking and food preparation in the household.

Mixture Effects of Tryptophan Intestinal Microbial Metabolites on Aryl Hydrocarbon Receptor Activity

Aryl hydrocarbon receptor (AHR) plays pivotal roles in intestinal physiology and pathophysiology. Intestinal AHR is activated by numerous dietary, endogenous, and microbial ligands. Whereas the effects of individual compounds on AHR are mostly known, the effects of real physiological mixtures occurring in the intestine have not been studied. Using reporter gene assays and RT-PCR, we evaluated the combinatorial effects (3520 combinations) of 11 microbial catabolites of tryptophan (MICTs) on AHR. We robustly (n = 30) determined the potencies and relative efficacies of single MICTs. Synergistic effects of MICT binary mixtures were observed between low- or medium-efficacy agonists, in particular for combinations of indole-3-propionate and indole-3-lactate. Combinations comprising highly efficacious agonists such as indole-3-pyruvate displayed rather antagonist effects, caused by saturation of the assay response. These synergistic effects were confirmed by RT-PCR as CYP1A1 mRNA expression. We also tested mimic multicomponent and binary mixtures of MICTs, prepared based on the metabolomic analyses of human feces and colonoscopy aspirates, respectively. In this case, AHR responsiveness did not correlate with type of diet or health status, and the indole concentrations in the mixtures were determinative of gross AHR activity. Future systematic research on the synergistic activation of AHR by microbial metabolites and other ligands is needed.

Walnut consumption and health outcomes with public health relevance-a systematic review of cohort studies and randomized controlled trials published from 2017 to present

CONTEXT

Considering the accumulation of recent studies investigating the health effects of walnut consumption, both including and beyond cardiovascular health effects, a systematic review of this literature to investigate the strength of the evidence is warranted.

OBJECTIVE

To investigate associations between walnut consumption and outcomes with public health relevance (specifically all-cause mortality, type 2 diabetes, CVD, metabolic syndrome, obesity, cancer, neurological and mental health, musculoskeletal, gastrointestinal, and maternal disorders) and the effect on associated disease risk markers, reported in studies published from 2017 to present.

DATA SOURCES

MEDLINE, FSTA, CENTRAL, and Scopus were searched from 1 January 2017 to 5 May 2021.

DATA EXTRACTION

Human studies (cohort studies and RCTs) ≥3 weeks in duration comparing consumption of walnuts (whole, pieces, or 100% butter) to a control and measuring associations with relevant public health outcomes and disease risk markers were assessed. Key study characteristics were extracted independently by 2 investigators using a standardized table. The quality of the studies was assessed using the Cochrane Risk-of-Bias tool 2.0 and the Newcastle-Ottawa Scale.

DATA ANALYSIS

Only 1 RCT was considered to be at low risk of bias for any of its outcomes. The cohort studies were considered to be of moderate or high quality. The results were synthesized using vote counting, based on the direction of effect. Thirty-three articles, 23 describing RCTs (walnut dose ∼10-99 g/day, 1,948 subjects) and 10 describing cohort studies (∼675,928 subjects), were included. Vote counting could be performed for the blood lipids, cardiovascular function, inflammation- and hemostatic-related factors, markers of glucose metabolism, and body weight and composition outcome groupings. The results are presented in effect direction plots. With respect to blood lipids, results from 8/8 RCTs favoured walnuts, in accordance with associations with a reduced risk of CVD suggested by cohort studies; results from 6/6 RCTs favoured control with respect to body weight and composition, although most of these effects were small. This was contrary to cohort study results suggesting small benefits of walnut consumption on body weight. There was no overall consistent direction of effect for cardiovascular function, markers of glucose metabolism, or inflammation- and hemostatic-related factors.

CONCLUSIONS

Evidence published since 2017 is consistent with previous research suggesting that walnut consumption improves lipid profiles and is associated with reduced CVD risk. Evidence is accumulating in other areas, such as cognitive health, although more research is needed to draw firm conclusions.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD4202122.

Dietary Acid Load but Not Mediterranean Diet Adherence Score Is Associated With Metabolic and Cardiovascular Health State: A Population Observational Study From Northern Italy

Diet plays a pivotal role in shaping the trajectory of chronic diseases. In this regard, the Mediterranean diet has been widely shown to exert beneficial effects on cardiometabolic health. On the contrary, the Western diet, which has also been reported to be an acidogenic dietary pattern, elicits detrimental effects on both metabolic and cardiovascular (CV) health. However, the role of dietary acid load (DAL) as a predictor of cardiometabolic prognosis remains to be elucidated. Thus, this study aims to compare Mediterranean diet adherence (MDA) and DAL focusing on their relationship with metabolic and CV prognosis. A total of 448 individuals aged 55–80 years were grouped depending on their MDA, assessed using food frequency questionnaires, or DAL, evaluated using potential renal load acid (PRAL) and net-endogenous acid production (NEAP). Study participants underwent anthropometric and biochemical measurements. The metabolic syndrome (MetS) prevalence was evaluated according to the National Cholesterol Education Program-Adult Treatment Panel III. Finally, the CV risk was evaluated using three independent algorithms: atherosclerotic cardiovascular disease (ASCVD), European Systematic COronary Risk Evaluation (SCORE), and Cuore risk scores. Mediterranean diet adherence was negatively associated with PRAL and NEAP. Individuals in the higher MDA tertile group had higher HDL cholesterol as well as lower homeostasis model assessment index (HOMA-IR) and fat mass relative to the lowest MDA tertile. However, in the high-MDA tertile group, there was neither a significantly lower MetS prevalence nor CV risk. Instead, both the MetS prevalence and CV risk were higher in individuals in the higher acid PRAL quartile relative to the lower alkaline PRAL quartile. Dietary acid load, especially assessed using PRAL but not MDA, was associated with indices of metabolic and CV prognosis. Thus, DAL assessed by 24-h dietary recalls may represent a better predictor of cardiometabolic health if compared to MDA evaluated using food frequency questionnaires.

Changes in body weight in response to pecan-enriched diets with and without substitution instructions: a randomised, controlled trial

Substantial evidence suggests that regular tree nut consumption does not lead to changes in body weight (BW). However, these studies used a variety of dietary substitution instructions which may confound the interpretation of prior BW outcomes. The purpose of the present study was to examine the impact of daily pecan consumption, with or without isocaloric substitution instructions, on BW and composition. This was an 8-week randomised, controlled trial with three treatments: a nut-free control group (n 32) and two pecan groups. ADD (n 30) consumed pecans (68 g/d) as part of a free-living diet, and SUB (n 31) substituted the pecans (68 g/d) for isocaloric foods from their habitual diet. BW and total body fat percentage (BF) were measured, and theoretical changes in these outcomes if pecans were consumed without compensation were determined. BW increased in all groups across the intervention, and there was a trend (P = 0⋅09) for an increase in ADD (1⋅1 ± 0⋅2 kg) and SUB (0⋅9 ± 0⋅3 kg) compared to control (0⋅3 ± 0⋅2 kg). In addition, there was increased BF in SUB (1⋅0 ± 0⋅3 %; P = 0⋅005) but not ADD (0⋅1 ± 0⋅2 %) or control (−0⋅2 ± 0⋅3 %) There was a large difference in the actual v. theoretical change in BW regardless of pecan treatment (actual: 1⋅1 ± 0⋅2 and 0⋅9 ± 0⋅3 v. theoretical: 3⋅3 ± 0⋅0 and 3⋅2 ± 0⋅0 kg in ADD and SUB, respectively; P < 0⋅001). Furthermore, there was a difference in actual v. theoretical change in BF in ADD (0⋅1 ± 0⋅2 v. 1⋅2 ± 0⋅1 %; P = 0⋅002) but not SUB or control. In conclusion, daily pecan consumption for 8 weeks did not result in significant weight gain, regardless of dietary substitution instructions.

The Effect of Dietary Interventions on Hypertriglyceridemia: From Public Health to Molecular Nutrition Evidence

Approximately 25–50% of the population worldwide exhibits serum triglycerides (TG) (≥150 mg/dL) which are associated with an increased level of highly atherogenic remnant-like particles, non-alcoholic fatty liver disease, and pancreatitis risk. High serum TG levels could be related to cardiovascular disease, which is the most prevalent cause of mortality in Western countries. The etiology of hypertriglyceridemia (HTG) is multifactorial and can be classified as primary and secondary causes. Among the primary causes are genetic disorders. On the other hand, secondary causes of HTG comprise lifestyle factors, medical conditions, and drugs. Among lifestyle changes, adequate diets and nutrition are the initial steps to treat and prevent serum lipid alterations. Dietary intervention for HTG is recommended in order to modify the amount of macronutrients. Macronutrient distribution changes such as fat or protein, low-carbohydrate diets, and caloric restriction seem to be effective strategies in reducing TG levels. Particularly, the Mediterranean diet is the dietary pattern with the most consistent evidence for efficacy in HTG while the use of omega-3 supplements consumption is the dietary component with the highest number of randomized clinical trials (RCT) carried out with effective results on reducing TG. The aim of this review was to provide a better comprehension between human nutrition and lipid metabolism.

Tree nut consumption and prevalence of carotid artery plaques: The National Heart, Lung, and Blood Institute Family Heart Study

PURPOSE

While tree nut consumption has been shown to be cardioprotective, a few studies have examined the relationship between tree nut consumption and carotid atherosclerosis. We tested the hypothesis that tree nut consumption would be inversely related with carotid atherosclerosis in adults.

METHODS

We cross-sectionally analyzed data from 4536 participants of the National Heart, Lung, and Blood Institute (NHLBI) Family Heart Study conducted in the United States. Dietary patterns among participants were variable, tree nut consumption was self-reported using the Food Frequency Questionnaire (FFQ), and B-mode ultrasound of the carotid arteries was used to assess for the presence of carotid artery plaques (primary outcome) and carotid intima media thickness (cIMT). Multivariable logistic regression was used to estimate odds ratio (95% confidence interval) of prevalent carotid artery plaques and linear regression was used to estimate adjusted mean cIMT across categories of nut consumption.

RESULTS

The mean age was 52.3 years (SD = 13.6), 95.6% of the participants were white, and 54% were female. The median tree nut intake was 1-3 servings/month. Odds ratios (95% CI) for prevalent carotid artery plaques were 1.0 (reference), 1.03 [0.86, 1.4], 0.89 [0.70, 1.13], and 0.96 [0.73, 1.26] for tree nut consumption of almost never, 1-3 times/month, 1/week, and 2+/week, respectively, adjusting for age, sex, race, field center, BMI, smoking status, alcohol consumption, creatinine, energy intake, fruit and vegetable consumption, exercise, and education. In secondary analysis, there was a suggestive inverse association of tree nut consumption with cIMT in the internal carotid artery, but not the common carotid or bifurcation.

CONCLUSION

Our data showed no association between tree nut consumption and prevalence of carotid artery plaques in adults.

Protective Effects of Appropriate Amount of Nuts Intake on Childhood Blood Pressure Level: A Cross-Sectional Study

OBJECTIVE

Increased blood pressure (BP) is a major risk factor for cardiovascular disease (CVD) in adults. Regular consumption of nuts may improve some BP in adults whereas evidence in children is relatively lacking. This study aimed to determine the efficacy of nuts intake on BP in children.

METHODS

Stratified cluster sampling was performed to include a total of 15,268 primary school children aged 6-12 years in urban and rural areas in Southwest China. The daily nuts intake dosage was collected by questionnaires, and generalized linear model (GLM) and logistic regression were used to analyze the relationship between nuts intake and BP.

RESULTS

For the total subjects, 11,130 (72.9%) participants consumed <35 g/day of nuts, 1,145 (7.5%) participants consumed 35 g/day ≤ nut <50 g/day of nuts, 2,053 (13.4%) participants consumed 50~100 g/day of nuts, and 940 (6.2%) participants consumed over 100 g/day of nut. For sex subgroup, 1,074 (13.53%) boys and 979 (13.35%) girls consumed 50~100 g/day of nuts. Compared with the 50~100 g/day of nuts intake group, systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were significantly different in <35 g/day, 35g/day ≤ nut <50 g/day, and >100 g/day nuts intake groups (all p < 0.001). The logistic regression showed that compared with the 50~100 g/day group, the other three groups are more likely associated with childhood hypertension (all p < 0.001). Therefore, a U-shaped relationship between nuts intake and BP level was identified.

CONCLUSIONS

The finding suggests that intake of 50~100 g/day nuts is the recommended dose of nuts intake to control childhood hypertension, as well as for cardioprotection purposes.

Walnut intake, cognitive outcomes and risk factors: a systematic review and meta-analysis

BACKGROUND

Walnuts contain nutrients that are associated with improved cognitive health. To our knowledge, no review has systematically examined the effects of walnuts on cognitive function and risk for cognitive decline.

OBJECTIVE

To conduct a systematic review and meta-analysis evaluating the effects of walnut intake on cognition-related outcomes and risk-factors for cognitive decline in adults.

METHODS

Medline®, Commonwealth Agricultural Bureau, and Cochrane Central Register of Controlled Trials were searched for randomized controlled trials (RCTs) and observational studies published until April 2020 on walnut intake, cognition (e.g. cognitive function, stroke, and mood), and selected risk factors for cognitive decline (e.g. glucose homeostasis and inflammation). Risk-of-bias and strength-of-evidence assessments were conducted using standard validated tools. Random-effects meta-analyses were conducted when ≥3 studies reported quantitative data for each outcome.

RESULTS

32 RCT and 7 observational study publications were included. Meta-analysis of cognition-related outcomes could not be conducted due to heterogeneity of tests. None of the 5 cognition RCTs found significant effects of walnuts on overall cognition, although 3 studies found improvements on subdomains and/or subgroups. All 7 observational studies found significant associations and a dose-response relationship between walnut intake and cognition-related outcomes. Meta-analyses of 27 RCTs reporting glucose homeostasis and inflammation outcomes, selected risk factors for cognitive decline, did not show significant effects of walnut intake.

CONCLUSIONS

Due to the non-uniformity of tests for cognition-related outcomes, definitive conclusions regarding the effect of walnut consumption on cognition could not be reached. Additionally, evidence does not show associations between walnut intake and glucose homeostasis or inflammation, cognitive decline risk-factors. High-quality studies with standardized measures are needed to clarify the role of walnuts in cognitive health.KEY MESSAGESThis is a systematic review and meta-analysis of 5 randomized clinical trials and 7 observational study articles of the impact of walnut intake on cognition decline and 27 randomized clinical trials of the effect of walnut intake on risk factors for cognitive decline including glucose homeostasis and inflammation.The non-uniformity of tests performed to measure cognitive function in the various studies did not allow for a meta-analysis of these studies. A definitive conclusion could therefore not be reached regarding the effect of walnut intake on cognitive decline.The evidence available does not show an association between walnut intake and glucose homeostasis or inflammation.

Are fatty nuts a weighty concern? A systematic review and meta-analysis and dose-response meta-regression of prospective cohorts and randomized controlled trials

Nuts are recommended for cardiovascular health, yet concerns remain that nuts may contribute to weight gain due to their high energy density. A systematic review and meta-analysis of prospective cohorts and randomized controlled trials (RCTs) was conducted to update the evidence, provide a dose-response analysis, and assess differences in nut type, comparator and more in subgroup analyses. MEDLINE, EMBASE, and Cochrane were searched, along with manual searches. Data from eligible studies were pooled using meta-analysis methods. Interstudy heterogeneity was assessed (Cochran Q statistic) and quantified (I² statistic). Certainty of the evidence was assessed by Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Six prospective cohort studies (7 unique cohorts, n = 569,910) and 86 RCTs (114 comparisons, n = 5873) met eligibility criteria. Nuts were associated with lower incidence of overweight/obesity (RR 0.93 [95% CI 0.88 to 0.98] P < 0.001, "moderate" certainty of evidence) in prospective cohorts. RCTs presented no adverse effect of nuts on body weight (MD 0.09 kg, [95% CI -0.09 to 0.27 kg] P < 0.001, "high" certainty of evidence). Meta-regression showed that higher nut intake was associated with reductions in body weight and body fat. Current evidence demonstrates the concern that nut consumption contributes to increased adiposity appears unwarranted.

Pecan-Enriched Diets Alter Cholesterol Profiles and Triglycerides in Adults at Risk for Cardiovascular Disease in a Randomized, Controlled Trial

BACKGROUND

Research indicates that tree nuts are cardioprotective, but studies on pecans are limited.

OBJECTIVES

We examined the impact of daily pecan consumption on blood lipids and glycemia in adults at-risk for cardiovascular disease (CVD).

METHODS

This was a randomized, controlled trial where 56 adults (BMI ≥28 kg/m2 or hypercholesterolemia) were randomly allocated into a control group (n = 18) or 1 of 2 pecan groups. The ADD group (n = 16) consumed pecans (68 g) as part of a free-living diet. The SUB group (n = 18) substituted the pecans (68 g) for isocaloric foods from their diet. At baseline and 8 wk, a high-fat meal was consumed with 4-h postprandial blood draws to determine changes in blood lipids and glycemia.

RESULTS

There was a significant reduction from baseline to 8 wk in fasting total cholesterol (TC) (204 ± 8.76 to 195 ± 8.12; 205 ± 8.06 to 195 ± 6.94 mg/dL), LDL cholesterol (143 ± 8.09 to 129 ± 7.71; 144 ± 6.60 to 135 ± 6.16 mg/dL), triglycerides (TGs) (139 ± 12.1 to 125 ± 14.6; 133 ± 10.7 to 120 ± 10.3 mg/dL), TC/HDL cholesterol ratio (3.92 ± 0.206 to 3.58 ± 0.175; 4.08 ± 0.167 to 3.79 ± 0.151), non-HDL cholesterol (151 ± 8.24 to 140 ± 7.95; 155 ± 6.87 to 143 ± 6.00 mg/dL), and apolipoprotein B (99.1 ± 5.96 to 93.0 ± 5.35; 104 ± 3.43 to 97.1 ± 3.11 mg/dL) in the ADD and SUB groups, respectively (P ≤ 0.05 for all), with no changes in control. There was a reduction in postprandial TGs (P ≤ 0.01) in ADD, and a reduction in postprandial glucose (P < 0.05) in SUB.

CONCLUSIONS

Pecan consumption improves fasting and postprandial blood lipids in CVD at-risk adults. This trial was registered at clinicaltrials.gov as NCT04376632.

Cardio-Metabolic Benefits of Walnuts in Type 2 Diabetes Mellitus: A Literature Review

Diabetes and its complications are main causes of morbidity and mortality among adults in the USA. An increase in the number of individuals with diabetes is primarily attributed to changes in dietary patterns including increased consumption of obesogenic foods and beverages. Many individuals who are overweight and obese show signs of insulin resistance and are at increased risk of Type 2 diabetes mellitus (T2DM) and cardiovascular disease. Lifestyle interventions (i.e., physical activity and nutrition) are the cornerstone of T2DM management and prevention. Prior research attests to the health benefits of consuming nuts, which have a substantial amount of mono- and polyunsaturated fatty acids, for individuals at risk for or with T2DM, and walnuts appear to be particularly promising. Walnuts are rich in nutrients, minerals, antioxidants, and vitamins that can contribute to improved cardio-metabolic risk factors in individuals at risk for or with T2DM. This review assesses the cardio-metabolic benefits of walnuts in T2DM. The authors’ review indicates that the reported effects of walnuts on glycaemic control have been inconclusive, with several studies showing association with improved glycaemic control while others show no effect. Despite their high energy density and potential to contribute to weight gain, the authors’ review suggests that walnuts can contribute to satiety without association with weight gain. This review also suggests that walnut consumption has been associated with improved low-density lipoprotein cholesterol levels and endothelial function but has not been associated with blood pressure improvement. Meta-analyses are warranted to quantitatively assess impact of walnut consumption on these cardio-metabolic risk factors in T2DM.

Improvements in the methodology for fatty acids analysis in meat products: One-stage transmethylation and fast-GC method

The quantification of fatty acids (FA) in meat products is frequently carried out by two-stage methylation procedures followed by long gas chromatography (GC) runs. This work aimed to simplify this methodology by means of a one-stage transmethylation method and a fast GC run, evaluating the influence of sample preparation, reagents and type of heating on the amount of FA in different meat products and optimizing a fast GC-FID (flame ionization detector) run. This allowed to establish the optimum combination of parameters (methanol + chlorotrimethylsilane, lyophilized samples and oven heating) to achieve the quantification of the highest possible amount of FA and to reduce the time of GC run from 60 to 10 min. The quality evaluation of this method obtained satisfactory results. Thus, the quantification of FA in meat products was achieved in a straightforwardly and quickly way by using a one-stage transmethylation procedure followed by a fast GC-FID run.

The Relationship of Tree Nuts and Peanuts with Adiposity Parameters: A Systematic Review and Network Meta-Analysis

The network meta-analysis and systematic review conducted aim to comparatively assess the effects of tree nuts and peanuts on body weight (BW), body mass index (BMI), waist circumference (WC), and body fat percentage (BF%). A systematic search up to 31 December 2020 was performed. A random-effects network meta-analysis was conducted following the PRISMA-NMA statement. A total of 105 randomized controlled trials (RCTs) with measures of BW (n = 6768 participants), BMI (n = 2918), WC (n = 5045), and BF% (n = 1226) were included. The transitivity assumption was met based on baseline characteristics. In the comparisons of nut consumption versus a control diet, there was no significant increase observed in any of the adiposity-related measures examined except for hazelnut-enriched diets, which raised WC. Moreover, almond-enriched diets significantly reduced WC compared to the control diet and to the pistachio-, mixed nuts-, and hazelnut-enriched diets. In subgroup analyses with only RCTs, designed to assess whether nut consumption affected weight loss, almonds were associated with reduced BMI and walnuts with reduced %BF. The evidence supports that: (1) tree nut and peanut consumption do not influence adiposity, and (2) compared to a control diet, the consumption of almond-enriched diets was associated with a reduced waist circumference.

Solid Fat Replacement with Canola Oil-Carnauba Wax Oleogels for Dairy-Free Imitation Cheese Low in Saturated Fat

Canola oil was structured into oleogels with different amounts of carnauba wax, and their processing performances were assessed as an alternative to solid fat for imitation cheese low in saturated fat. The contents of solid fat in the oleogels were less vulnerable to the change in temperature than the palm oil. The replacement of palm oil with oleogels produced cheese samples with harder and more cohesive/chewy textures. Dynamic and transient viscoelastic measurements demonstrated that the use of oleogels was effective in increasing the elastic nature of the cheeses. Two distinct components with different proton mobilities were observed in the imitation cheeses, and longer T₂ relaxation times were detected in the oleogel samples. The meltability of the cheese with palm oil was not significantly different from those with 3% and 6% oleogels. The saturated fat level of the oleogel cheese was significantly reduced from 45.70 to 5.20%. The application of canola oil-carnauba wax oleogels could successfully produce imitation cheese high in unsaturated fat and low in saturated fat. This study thus demonstrated that the health-functional properties of imitation cheese could be enhanced by using oleogels.

Walnut consumption and cardiac phenotypes: The Coronary Artery Risk Development in Young Adults (CARDIA) study

BACKGROUND AND AIMS

Observational studies and clinical trials have shown cardiovascular benefits of nut consumption, including walnuts. However, the relations of walnut consumption with systolic and diastolic function, risk factors for heart failure, are unknown. We examined the associations of walnut consumption with cardiac structure and function parameters in black and white adults enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study.

METHODS AND RESULTS

After exclusions, the study population included 3341 participants. Dietary intake was assessed using the CARDIA Diet History questionnaire at baseline, year 7 and year 20 exams. Cardiac structure and function were measured by echocardiography at year 25. Multivariable linear regression evaluated the associations of walnut consumption with blood pressure (BP), heart rate, and cardiac phenotypes, adjusting for age, sex, race, lifestyle habits, and clinical characteristics. We found the majority of walnut consumers compared to non-consumers were females, whites, and more highly educated, and had lower waist circumference, diastolic BP, and heart rate, and higher diet quality score. Even though cardiac structure and function measures were generally within normal ranges among participants, walnut consumers had significantly better values for diastolic function parameters A wave, E/A ratio, septal and lateral e' than non-consumers. Further adjustment for body mass index and diabetes status did not materially change the significance between walnut consumer groups. Systolic function parameters did not differ by walnut group.

CONCLUSION

Compared to non-consumers, walnut consumption is associated with better diastolic dysfunction in young to middle-aged adults.

Perspective: Design and Conduct of Human Nutrition Randomized Controlled Trials

In the field of human nutrition, randomized controlled trials (RCTs) are considered the gold standard for establishing causal relations between exposure to nutrients, foods, or dietary patterns and prespecified outcome measures, such as body composition, biomarkers, or event rates. Evidence-based dietary guidance is frequently derived from systematic reviews and meta-analyses of these RCTs. Each decision made during the design and conduct of human nutrition RCTs will affect the utility and generalizability of the study results. Within the context of limited resources, the goal is to maximize the generalizability of the findings while producing the highest quality data and maintaining the highest levels of ethics and scientific integrity. The aim of this document is to discuss critical aspects of conducting human nutrition RCTs, including considerations for study design (parallel, crossover, factorial, cluster), institutional ethics approval (institutional review boards), recruitment and screening, intervention implementation, adherence and retention assessment, and statistical analyses considerations. Additional topics include distinguishing between efficacy and effectiveness, defining the research question(s), monitoring biomarker and outcome measures, and collecting and archiving data. Addressed are specific aspects of planning and conducting human nutrition RCTs, including types of interventions, inclusion/exclusion criteria, participant burden, randomization and blinding, trial initiation and monitoring, and the analysis plan.

Intestinal microbiota-derived tryptophan metabolites are predictive of Ah receptor activity

Commensal microbiota-dependent tryptophan catabolism within the gastrointestinal tract is known to exert profound effects upon host physiology, including the maintenance of epithelial barrier and immune function. A number of abundant microbiota-derived tryptophan metabolites exhibit activation potential for the aryl hydrocarbon receptor (AHR). Gene expression facilitated by AHR activation through the presence of dietary or microbiota-generated metabolites can influence gastrointestinal homeostasis and confer protection from intestinal challenges. Utilizing untargeted mass spectrometry-based metabolomics profiling, combined with AHR activity screening assays, we identify four previously unrecognized tryptophan metabolites, present in mouse cecal contents and human stool, with the capacity to activate AHR. Using GC/MS and LC/MS platforms, quantification of these novel AHR activators, along with previously established AHR-activating tryptophan metabolites, was achieved, providing a relative order of abundance. Using physiologically relevant concentrations and quantitative gene expression analyses, the relative efficacy of these tryptophan metabolites with regard to mouse or human AHR activation potential is examined. These data reveal indole, 2-oxindole, indole-3-acetic acid and kynurenic acid as the dominant AHR activators in mouse cecal contents and human stool from participants on a controlled diet. Here we provide the first documentation of the relative abundance and AHR activation potential of a panel of microbiota-derived tryptophan metabolites. Furthermore, these data reveal the human AHR to be more sensitive, at physiologically relevant concentrations, to tryptophan metabolite activation than mouse AHR. Additionally, correlation analyses indicate a relationship linking major tryptophan metabolite abundance with AHR activity, suggesting these cecal/fecal metabolites represent biomarkers of intestinal AHR activity.

Walnut Consumption Induces Tissue-Specific Omega-6/Omega-3 Decrease in High-Fructose-Fed Wistar Rats

Increased dietary, blood, and tissue n-6/n-3 fatty acid ratios are associated with obesity and metabolic syndrome. Due to Westernized dietary patterns, the increasing n-6/n-3 ratio is of growing concern worldwide, and dietary strategies aimed at its lowering are of public health importance. Walnuts are rich in dietary fats, and their consumption promotes cardiometabolic health. This study aimed to examine the effect of 6-week walnut consumption on tissue-specific n-6/n-3 ratio and fatty acid metabolic conversion in fructose-fed rats with a cluster of metabolic disorders. Male Wistar rats were fed a standard diet with or without 10% fructose in drinking water for 9 weeks. Diets of half of the animals were then supplemented with walnuts (2.4 g/day) for 6 weeks, upon which fatty acid profiles were determined in plasma, liver, adipose tissue, and kidney total lipids. Results showed that walnuts induced significant decreases in the n-6/n-3 content of total lipid pool in plasma and examined tissues, irrespective of metabolic burden. Walnut intervention decreased plasma and liver palmitoleic/palmitic, arachidonic/linoleic, and docosahexaenoic/α-linolenic acid ratios. It also modulated individual fatty acid levels by reducing arachidonic and palmitic acid and increasing α-linolenic, eicosapentaenoic, and docosapentaenoic acid in plasma and most tissues. Our study demonstrated that 6-week consumption of walnuts favorably modulated n-6/n-3 plasma and tissue ratio in male Wistar rats regardless of high-fructose feeding, underscoring the promising potential of walnuts in both prevention and treatment of the metabolic syndrome.

Diet Quality, Saturated Fat and Metabolic Syndrome

Indices reflecting overall diet quality are used globally in research to predict the risk of various diseases and metabolic disorders such as metabolic syndrome (MetS). Such indices are built to measure adherence to current dietary guidelines or to best assess the diet-disease relationship. Although mostly food-based, dietary guidelines often include recommendations to limit saturated fatty acid (SFA) intake in order to prevent cardiovascular diseases. However, not all diet quality indices consider SFA in their definition of diet quality. Additionally, the relationship between SFA consumption and the development of MetS remains unclear. The purpose of this short review was to explore the association between MetS and various diet quality indices and dietary patterns, with a focus on how SFA contributes to these associations.

Prevalent Seasoning and Cooking Fats, Arterial Stiffness and Blood Lipid Pattern in a Rural Population Sample: Data from the Brisighella Heart Study

Background: Dietary fats have been variably associated with the risk of cardiovascular disease. The aim of our study was to evaluate the association between everyday mainly used dietary fats in cooking and as seasoning and hemodynamic and lipid parameters. Methods: For this study, we selected from the Brisighella Heart Study cohort subjects who were not treated with antihypertensive drugs and report with certainty their daily mean intake of dietary fats in cooking and as seasoning. Depending on the main source of dietary fat, the involved subjects were classified as prevalent extra-virgin olive oil (EVO) users, prevalent corn oil users, prevalent users of different vegetable oils and prevalent animal fat users, and we compared their characteristics. Results: Everyday consumption of EVO as a main seasoning and cooking fat source was significantly associated to lower body mass index, visceral adiposity index, blood pressure, arterial stiffness, and cholesterolemia, when compared with predominantly animal fat users. Corn oil users also had lower blood pressure, arterial stiffness, and cholesterolemia, when compared with predominantly animal fat users, as well. In particular, in an age and systolic blood pressure adjusted model, the predictors of carotid-femoral pulse wave velocity were the prevalent use of EVO (RR = 0.84, 95% CI 0.67–0.94 vs. other prevalent fat sources), LDL-Cholesterol (RR = 1.12, 95% CI 1.02–1.42), serum uric acid (RR = 1.21, 95% CI 1.09–1.54) and estimated GFR (RR = 0.77, 95% CI 0.59–0.99). Conclusions: According to our findings, the choice of everyday seasoning and cooking fat is associated with a different metabolic and haemodynamic pattern.

How strong is the evidence that gut microbiota composition can be influenced by lifestyle interventions in a cardio-protective way?

Alterations in composition and function of the gut microbiota have been demonstrated in diseases involving the cardiovascular system, particularly coronary heart disease and atherosclerosis. The data are still limited but the typical altered genera include Roseburia and Faecalibacterium. Plausible mechanisms by which microbiota may mediate cardio-protective effects have been postulated, including the production of metabolites like trimethylamine (TMA), as well as immunomodulatory functions. This raises the question of whether it is possible to modify the gut microbiota by lifestyle interventions and thereby improve cardiovascular health. Nevertheless, lifestyle intervention studies that have involved modifications of dietary intake and/or physical activity, as well as investigating changes in the gut microbiota and subsequent modifications of the cardioprotective markers, are still scarce, and the results have been inconclusive. Current evidence points to benefits of consuming high-fibre foods, nuts and an overall healthy dietary pattern to achieve beneficial effects on both gut microbiota and serum cardiovascular markers, primarily lipids. The relationship between physical exercise and gut microbiota is probably complex and may be dependent on the intensity of exercise. In this article, we review the available evidence on lifestyle, specifically diet, physical activity and smoking as modifiers of the gut microbiota, and subsequently as modifiers of serum cardiovascular health markers. We have attempted to elucidate the plausible mechanisms and further critically appraise the caveats and gaps in the research.

Replacing Saturated Fat With Walnuts or Vegetable Oils Improves Central Blood Pressure and Serum Lipids in Adults at Risk for Cardiovascular Disease: A Randomized Controlled-Feeding Trial

Background Walnuts have beneficial effects on cardiovascular risk factors, but it is unclear whether these effects are attributable to the fatty acid ( FA ) content, including α-linolenic acid ( ALA ), and/or bioactives. Methods and Results A randomized, controlled, 3-period, crossover, feeding trial was conducted in individuals at risk for cardiovascular disease (n=45). Following a 2-week standard Western diet run-in (12% saturated FAs [ SFA ], 7% polyunsaturated FAs, 12% monounsaturated FAs), participants consumed 3 isocaloric weight-maintenance diets for 6 weeks each: a walnut diet ( WD ; 7% SFA , 16% polyunsaturated FAs, 3% ALA , 9% monounsaturated FAs); a walnut FA -matched diet; and an oleic acid-replaced- ALA diet (7% SFA , 14% polyunsaturated FAs, 0.5% ALA , 12% monounsaturated FAs), which substituted the amount of ALA from walnuts in the WD with oleic acid. This design enabled evaluation of the effects of whole walnuts versus constituent components. The primary end point, central systolic blood pressure, was unchanged, and there were no significant changes in arterial stiffness. There was a treatment effect ( P=0.04) for central diastolic blood pressure; there was a greater change following the WD versus the oleic acid-replaced-ALA diet (-1.78±1.0 versus 0.15±0.7 mm Hg, P=0.04). There were no differences between the WD and the walnut fatty acid-matched diet (-0.22±0.8 mm Hg, P=0.20) or the walnut FA-matched and oleic acid-replaced-ALA diets ( P=0.74). The WD significantly lowered brachial and central mean arterial pressure. All diets lowered total cholesterol, LDL (low-density lipoprotein) cholesterol, HDL (high-density lipoprotein) cholesterol, and non- HDL cholesterol. Conclusions Cardiovascular benefits occurred with all moderate-fat, high-unsaturated-fat diets. As part of a low- SFA diet, the greater improvement in central diastolic blood pressure following the WD versus the oleic acid-replaced-ALA diet indicates benefits of walnuts as a whole-food replacement for SFA . Clinical Trial Registration URL : https://www.clinicaltrials.gov . Unique identifier: NCT02210767.

Walnut intake may increase circulating adiponectin and leptin levels but does not improve glycemic biomarkers: A systematic review and meta-analysis of randomized clinical trials

BACKGROUND & OBJECTIVE

Walnut intake is considered a healthy dietary approach worldwide, particularly as a nutritional tool for the management of obesity and cardiometabolic disorders. Among these lines, leptin and adiponectin, as well as glycemic biomarkers, deserve further attention. We aimed to examine the impact of walnut intake on circulation levels of leptin and adiponectin through a systematic review and meta-analysis of randomized clinical trials (RCTs); secondarily, assessing the glycemic profile as well.

METHODS

The literature search was implemented in four following databases: Web of Science, Scopus, PubMed/Medline, and Google Scholar, thus, determining studies that measured the effects of walnut consumption on adiponectin, leptin, and glycemic biomarkers levels from 2004 up to December 2019.

RESULTS

Fourteen trials were include in the meta-analysis, with an intervention period ranging from 5 weeks to 12 months.Walnut intake increased leptin (weighted mean difference (WMD): 2.502 ng/mL; 95 % CI: 2.147-2.856, p < 0.001) and adiponectin (WMD: 0.440 ng/mL; 95 % CI: 0.323 to 0.557, p < 0.001) levels. Pertaining to glycemic biomarkers, neither overall analyses nor sub-analyses corroborated with changes in fasting blood glucose (WMD: 0.500 mg/dL, 95 % CI: -0.596, 1.596, p = 0.371), insulin (WMD: -0.21 mg/dL, 95 % CI: -0.67, 0.24, p = 0.367), and glycated hemoglobin (WMD: 0.004 mg/dL, 95 % CI: -0.041, 0.049, p = 0.870) concentrations.

CONCLUSION

Walnut intake may increase leptin and adiponectin levels but does not improve glycemic biomarkers.

Effects of walnut intake on blood pressure: A systematic review and meta-analysis of randomized controlled trials

The impact of walnuts on blood pressure (BP) is not a well-established fact. Although several studies have assessed the effects of walnut consumption on BP, results are conflicting. Thus, we examined the effects of walnut doses and length of supplementation on BP. Biomedical databases were searched for published trials that compared walnut-enhanced diet to control diet. Eighteen trials met eligibility criteria (n = 1,799). Overall, walnut consumption neither did alter SBP (weighted mean difference [WMD]: 0.08 mmHg; 95% CI: -0.69, 0.85) nor DBP (WMD: 0.08 CI: -0.26, 0.42). In subgroup analyses, walnut ingestion ≤40 g was statistically correlated with reduction in SBP (WMD: -0.53 mmHg, 95% CI: -0.79, -0.26) and DBP (WMD: -0.191 mmHg, 95% CI: -0.384, -0.034). Moreover, the length of intervention ≥8 weeks was linked to a significant reduction in SBP (WMD: -1.18 mmHg, 95% CI: -1.30, -1.06). Following dose-response evaluation, walnut intake significantly changed SBP (p = .015) and DBP (p = .026) through a nonlinear fashion at walnut dose up to 40 g/d. Nevertheless, these statistical results cannot be translated into clinical practice, once the changes expressed as WMD are slight taking into consideration the absolute values of BP categories. In conclusion, this meta-analysis does not support walnut consumption as a BP-lowering strategy.

Olive Oil Consumption and Cardiovascular Risk in U.S. Adults

BACKGROUND

Olive oil intake has been associated with lower risk of cardiovascular disease (CVD) in Mediterranean populations, but little is known about these associations in the U.S population.

OBJECTIVES

This study sought to examine whether olive oil intake is associated with total CVD, coronary heart disease (CHD), and stroke risk.

METHODS

This study included 61,181 women from the Nurses' Health Study (1990 to 2014) and 31,797 men from the Health Professionals Follow-up Study (1990 to 2014) who were free of cancer, heart disease, and stroke at baseline. Diet was assessed using food frequency questionnaires at baseline and then every 4 years. Cox proportional hazards regressions were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

During 24 years of follow-up, this study documented 9,797 incident cases of CVD, including 6,034 CHD cases and 3,802 stroke cases. After adjusting for major diet and lifestyle factors, compared with nonconsumers, those with higher olive oil intake (>0.5 tablespoon/day or >7 g/day) had 14% lower risk of CVD (pooled HR: 0.86; 95% CI: 0.79 to 0.94) and 18% lower risk of CHD (pooled HR: 0.82; 95% CI: 0.73 to 0.91). No significant associations were observed for total or ischemic stroke. Replacing 5 g/day of margarine, butter, mayonnaise, or dairy fat with the equivalent amount of olive oil was associated with 5% to 7% lower risk of total CVD and CHD. No significant associations were observed when olive oil was compared with other plant oils combined. In a subset of participants, higher olive oil intake was associated with lower levels of circulating inflammatory biomarkers and a better lipid profile.

CONCLUSIONS

Higher olive oil intake was associated with lower risk of CHD and total CVD in 2 large prospective cohorts of U.S. men and women. The substitution of margarine, butter, mayonnaise, and dairy fat with olive oil could lead to lower risk of CHD and CVD.

Effects of walnut intake on anthropometric characteristics: A systematic review and dose-response meta-analysis of randomized controlled trials

BACKGROUND & OBJECTIVE

Effects of walnut intake on anthropometric measurements have been inconsistent among clinical studies. Thus, we conducted a meta-analysis of randomized clinical trials (RCTs) to evaluate and quantify the effects of walnut intake on anthropometric characteristics.

METHODS

We carried out a systematic search of all available RCTs up to June 2019 in the following electronic databases: PubMed, Scopus, Web of Science and Google Scholar. Pooled weight mean difference (WMD) of the included studies was estimated using random-effects model.

RESULTS

A total of 27 articles were included in this meta-analysis, with walnuts dosage ranging from 15 to 108 g/d for 2 wk to 2 y. Overall, interventions with walnut intake did not alter waist circumference (WC) (WMD: -0.193 cm, 95 % CI: -1.03, 0.64, p = 0.651), body weight (BW) (0.083 kg, 95 % CI: -0.032, 0.198, p = 0.159), body mass index (BMI) (WMD: -0.40 kg/m,²95 % CI: -0.244, 0.164, p = 0.703), and fat mass (FM) (WMD: 0.28 %, 95 % CI: -0.49, 1.06, p = 0.476). Following dose-response evaluation, reduced BW (Coef.= -1.62, p = 0.001), BMI (Coef.= -1.24, p = 0.041) and WC (Coef.= -5.39, p = 0.038) were significantly observed through walnut intake up to 35 g/day. However, the number of studies can be limited as to the individual analysis of the measures through the dose-response fashion.

CONCLUSIONS

Overall, results from this meta-analysis suggest that interventions with walnut intake does not alter BW, BMI, FM, and WC. To date, there is no discernible evidence to support walnut intake for improving anthropometric indicators of weight loss.

Replacing Saturated Fats with Unsaturated Fats from Walnuts or Vegetable Oils Lowers Atherogenic Lipoprotein Classes Without Increasing Lipoprotein(a)

BACKGROUND

Walnuts have established lipid-/lipoprotein-lowering properties; however, their effect on lipoprotein subclasses has not been investigated. Furthermore, the mechanisms by which walnuts improve lipid/lipoprotein concentrations are incompletely understood.

OBJECTIVES

We aimed to examine, as exploratory outcomes of this trial, the effect of replacing SFAs with unsaturated fats from walnuts or vegetable oils on lipoprotein subclasses, cholesterol efflux, and proprotein convertase subtilisin/kexin type 9 (PCSK9).

METHODS

A randomized, crossover, controlled-feeding study was conducted in individuals at risk of cardiovascular disease (CVD) (n = 34; 62% men; mean ± SD age 44 ± 10 y; BMI: 30.1 ± 4.9 kg/m2). After a 2-wk run-in diet (12% SFAs, 7% PUFAs, 12% MUFAs), subjects consumed the following diets, in randomized order, for 6 wk: 1) walnut diet (WD) [57-99 g/d walnuts, 7% SFAs, 16% PUFAs [2.7% α-linolenic acid (ALA)], 9% MUFAs]; 2) walnut fatty acid-matched diet [7% SFAs, 16% PUFAs (2.6% ALA), 9% MUFAs]; and 3) oleic acid replaces ALA diet (ORAD) [7% SFAs, 14% PUFAs (0.4% ALA); 12% MUFAs] (all percentages listed are of total kilocalories ). Serum collected after the run-in (baseline) and each diet period was analyzed for lipoprotein classes and subclasses (vertical auto profile), cholesterol efflux, and PCSK9. Linear mixed models were used for data analysis.

RESULTS

Compared with the ORAD, total cholesterol (mean ± SEM -8.9± 2.3 mg/dL; -5.1%; P < 0.001), non-HDL cholesterol (-7.4 ± 2.0 mg/dL; -5.4%; P = 0.001), and LDL cholesterol (-6.9 ± 1.9 mg/dL; -6.5%; P = 0.001) were lower after the WD; no other pairwise differences existed. There were no between-diet differences for HDL-cholesterol or LDL-cholesterol subclasses. Lipoprotein(a) [Lp(a)], cholesterol efflux, and PCSK9 were unchanged after the diets.

CONCLUSIONS

In individuals at risk of CVD, replacement of SFAs with unsaturated fats from walnuts or vegetable oils improved lipid/lipoprotein classes, including LDL-cholesterol, non-HDL cholesterol, and total cholesterol, without an increase in Lp(a). These improvements were not explained by changes in cholesterol efflux capacity or PCSK9. This trial was registered at clinicaltrials.gov as NCT01235832.

Walnuts and Vegetable Oils Containing Oleic Acid Differentially Affect the Gut Microbiota and Associations with Cardiovascular Risk Factors: Follow-up of a Randomized, Controlled, Feeding Trial in Adults at Risk for Cardiovascular Disease

BACKGROUND

It is unclear whether the favorable effects of walnuts on the gut microbiota are attributable to the fatty acids, including α-linolenic acid (ALA), and/or the bioactive compounds and fiber.

OBJECTIVE

This study examined between-diet gut bacterial differences in individuals at increased cardiovascular risk following diets that replace SFAs with walnuts or vegetable oils.

METHODS

Forty-two adults at cardiovascular risk were included in a randomized, crossover, controlled-feeding trial that provided a 2-wk standard Western diet (SWD) run-in and three 6-wk isocaloric study diets: a diet containing whole walnuts (WD; 57-99 g/d walnuts; 2.7% ALA), a fatty acid-matched diet devoid of walnuts (walnut fatty acid-matched diet; WFMD; 2.6% ALA), and a diet replacing ALA with oleic acid without walnuts (oleic acid replaces ALA diet; ORAD; 0.4% ALA). Fecal samples were collected following the run-in and study diets to assess gut microbiota with 16S rRNA sequencing and Qiime2 for amplicon sequence variant picking.

RESULTS

Subjects had elevated BMI (30 ± 1 kg/m2), blood pressure (121 ± 2/77 ± 1 mmHg), and LDL cholesterol (120 ± 5 mg/dL). Following the WD, Roseburia [relative abundance (RA) = 4.2%, linear discriminant analysis (LDA) = 4], Eubacterium eligensgroup (RA = 1.4%, LDA = 4), LachnospiraceaeUCG001 (RA = 1.2%, LDA = 3.2), Lachnospiraceae UCG004 (RA = 1.0%, LDA = 3), and Leuconostocaceae (RA = 0.03%, LDA = 2.8) were most abundant relative to taxa in the SWD (P ≤ 0.05 for all). The WD was also enriched in Gordonibacter relative to the WFMD. Roseburia (3.6%, LDA = 4) and Eubacterium eligensgroup (RA = 1.5%, LDA = 3.4) were abundant following the WFMD, and Clostridialesvadin BB60group (RA = 0.3%, LDA = 2) and gutmetagenome (RA = 0.2%, LDA = 2) were most abundant following the ORAD relative to the SWD (P ≤ 0.05 for all). Lachnospiraceae were inversely correlated with blood pressure and lipid/lipoprotein measurements following the WD.

CONCLUSIONS

The results indicate similar enrichment of Roseburia following the WD and WFMD, which could be explained by the fatty acid composition. Gordonibacter enrichment and the inverse association between Lachnospiraceae and cardiovascular risk factors following the WD suggest that the gut microbiota may contribute to the health benefits of walnut consumption in adults at cardiovascular risk. This trial was registered at clinicaltrials.gov as NCT02210767.

Beneficial Effects of Walnuts on Cognition and Brain Health

Oxidative stress and neuroinflammation have important roles in the aging process, mild cognitive impairment (MCI), Alzheimer’s disease (AD), and other brain disorders. Amyloid beta protein (Aβ) is the main component of amyloid plaques in the brains of people with AD. Several studies suggest that Aβ increases the generation of free radicals in neurons, which leads to oxidative damage and cell death. Aβ can also induce neuroinflammation by increasing pro-inflammatory cytokines and enzymes. Walnuts contain several components that have antioxidant and anti-inflammatory effects. Animal and human studies from our and other groups suggest that supplementation with walnuts in the diet may improve cognition and reduce the risk and/or progression of MCI and AD. In the transgenic AD mouse model (AD-tg), we have reported the beneficial effects of a diet with walnuts on memory, learning, motor coordination, anxiety, and locomotor activity. Human clinical trials have also suggested an association of walnut consumption with better cognitive performance and improvement in memory when compared to baseline in adults. Our recent study in AD-tg mice has shown that a walnut-enriched diet significantly improves antioxidant defense and decreases free radicals’ levels, lipid peroxidation, and protein oxidation when compared to a control diet without walnuts. These findings suggest that a diet with walnuts can reduce oxidative stress by decreasing the generation of free radicals and by boosting antioxidant defense, thus resulting in decreased oxidative damage to lipids and proteins. An in vitro study with synthetic Aβ showed that walnut extract can inhibit Aβ fibrillization and solubilize the preformed Aβ fibrils, suggesting an anti-amyloidogenic property of walnuts. Because it takes many years for cognitive impairment and dementia to develop, we suggest that early and long-term dietary supplementation with walnuts may help to maintain cognitive functions and may reduce the risk of developing, or delay the onset and/or slow the progression of, MCI and dementia by decreasing Aβ fibrillization, reducing oxidative damage, increasing antioxidant defense, and decreasing neuroinflammation. Furthermore, several animal and human studies have suggested that walnuts may also decrease the risk or progression of other brain disorders such as Parkinson’s disease, stroke, and depression, as well as of cardiovascular disease and type 2 diabetes. Together, these reports suggest the benefits of a walnut-enriched diet in brain disorders and in other chronic diseases, due to the additive or synergistic effects of walnut components for protection against oxidative stress and inflammation in these diseases.

An overview of phytochemicals and potential health-promoting properties of black walnut

Black walnut contains a diverse mixture of bioactive compounds, including phenolics, phytosterols, unsaturated fatty acids, and tocopherols potentially important to human health.

Health Benefits of Nut Consumption in Middle-Aged and Elderly Population

Aging is considered the major risk factor for most chronic disorders. Oxidative stress and chronic inflammation are two major contributors for cellular senescence, downregulation of stress response pathways with a decrease of protective cellular activity and accumulation of cellular damage, leading in time to age-related diseases. This review investigated the most recent clinical trials and cohort studies published in the last ten years, which presented the influence of tree nut and peanut antioxidant diets in preventing or delaying age-related diseases in middle-aged and elderly subjects (≥55 years old). Tree nut and peanut ingestion has the possibility to influence blood lipid count, biochemical and anthropometric parameters, endothelial function and inflammatory biomarkers, thereby positively affecting cardiometabolic morbidity and mortality, cancers, and cognitive disorders, mainly through the nuts’ healthy lipid profile and antioxidant and anti-inflammatory mechanisms of actions. Clinical evidence and scientific findings demonstrate the importance of diets characterized by a high intake of nuts and emphasize their potential in preventing age-related diseases, validating the addition of tree nuts and peanuts in the diet of older adults. Therefore, increased consumption of bioactive antioxidant compounds from nuts clearly impacts many risk factors related to aging and can extend health span and lifespan.