Effect of nut consumption on vascular endothelial function: A systematic review and meta-analysis of randomized controlled trials

Effect of walnut consumption on markers of endothelial function in adults: A systematic review and meta-analysis of randomized controlled trials

Findings on the effect of walnut consumption on endothelial function are conflicting. Therefore, the present systematic review and meta-analysis summarized available trials in this regard. A systematic search was performed in online databases including PubMed-Medline, Scopus, and ISI Web of Science up to October 2023. Articles that reported the effect of walnut intake on flow-mediated dilation (FMD), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and stimulus-adjusted response measure (SARM) were included. Random effects models for a weighted mean difference (WMD) or standardized mean difference (SMD) were used to test for the overall effect. Six eligible trials were analyzed (250 participants). Walnut intake significantly increased FMD (WMD: 0.94%, 95% CI: 0.12 to 1.75; p = 0.02). However, meta-analysis could not show any beneficial effect of walnut intake on ICAM-1 (SMD: -0.23, 95% CI: -0.68 to 0.22; p = 0.31), VCAM-1 (SMD: -0.02, 95% CI: -1.38 to 1.34; p = 0.97), and SARM (WMD: 0.01%, 95% CI: -0.01 to 0.04; p = 0.28). In conclusion, the present meta-analysis suggests that walnuts may reduce cardiovascular disease risk by improving FMD. However, further studies should be performed on adults to determine the effect of walnut intake on endothelial function.

Nuts and seeds - a scoping review for Nordic Nutrition Recommendations 2023

Background

Nuts and seeds have been part of diets in most of the world for millenniums, and they have also been consumed in the Nordic and Baltic countries for centuries. Consumption of nuts and seeds is linked with various health outcomes. Therefore, when updating the Nordic Nutrition Recommendations (NNR), summarizing the best evidence on key health outcomes from the consumption of nuts and seeds is essential.

Objectives

This study aims to evaluate the updated evidence on the consumption of nuts and seeds and health outcomes regarded relevant for the Nordic and Baltic countries, as well as their dose-response relationship presented in updated systematic reviews and meta-analyses.

Method

The scoping review is built on a de novo systematic review and an umbrella review published in 2022 on the consumption of nuts and seeds and its various health outcomes, including cardiovascular disease and diabetes.

Results

Intake of nuts and seeds is associated with a lower risk of cardiovascular diseases, with evidence assessed as probable. This conclusion is mirrored by evidence from trials on biomarkers for chronic diseases. An intake of a serving of nuts of 28-30 g/day compared to not eating nuts is estimated to translate into approximately 20% relative reduction in the risks of cardiovascular disease and premature deaths. For cancers, consumption of a serving of nuts is inversely associated with cancer mortality. However, for type 2 diabetes, there are mixed and inconclusive results. Additionally, there are inverse associations between nut consumption and respiratory and infectious disease mortality. Allergies for nuts are seen among 1-2% of the population.

Conclusion

Overall, the current evidence supports dietary recommendations to increase nut consumption to a serving of nuts and seeds per day for people without allergies to these foods.

A Dietary Model of Partial Meat Replacement with Walnuts Demonstrates Changes in the Nutrient Profile and Quality of the United States Population's Diet

The purpose of the study is to assess the impact of partial meat replacement with walnuts using a dose-escalation approach on nutrient intake and diet quality in the usual US diet. Food modeling was implemented using the nationally representative 2015-2018 National Health and Examination Survey (NHANES), with a focus on non-nut consumers, which included 2707 children and adolescents and 5190 adults. Walnuts replaced meat in a dose-escalating manner (0.5, 1, 1.5, and 2 oz walnuts per day replaced 1, 2, 3, and 4 oz meat, respectively). Diet quality was estimated using the population ratio method of the 2015 Healthy Eating Index. The usual intake of nutrients was estimated using the National Cancer Institute method. Significant differences were determined using non-overlapping 95% confidence intervals. The partial replacement of meat with walnuts demonstrated significant increases in the mean intake of fiber, magnesium, and omega-3 fatty acids and significant decreases in cholesterol and vitamin B12 in the modeled diets for children, adolescents, and adults. Additionally, the partial replacement of meat with walnuts improved overall diet quality. Walnut consumption at 1-2 oz as a replacement for some meat may improve nutrient intake and diet quality across age groups.

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.

Adding Walnuts to the Usual Diet Can Improve Diet Quality in the United States: Diet Modeling Study Based on NHANES 2015-2018

BACKGROUND

The under-consumption of calcium, potassium, fiber, and vitamin D is considered a U.S. public health concern. Shifts in eating patterns that increase the consumption of vegetables, fruits, whole grains, nuts/seeds, and dairy products can help achieve the recommended intakes of these nutrients, leading to healthier diets.

OBJECTIVE

We assessed the impact of adding 1 ounce (28.35 g) of walnuts to usual diets on diet quality and nutrients of concern, including magnesium, fiber, and potassium.

METHODS

We utilized 24 h dietary recalls obtained from the What We Eat in America, National Health and Nutrition Examination Survey (NHANES) and modeled the addition of 1 ounce (28.35 g) of walnuts to the usual diets of no-nut consumers. No-nut consumers aged ≥4 years (n = 7757) from the 2015-2018 NHANES study were included. Population percentages with intakes below the estimated average requirement (EAR) values for calcium, magnesium, folate, and vitamin E and above the adequate intake (AI) values for potassium and fiber were examined. Diet quality was assessed using the Healthy Eating Index-2015 (HEI-2015). The National Cancer Institute method was used to estimate the usual and modeled intakes. Significant differences between usual (current) and modeled intakes were determined using non-overlapping 95% confidence intervals. All analyses included sample weights to account for the NHANES survey design.

RESULTS

Adding 1 ounce (28.35 g) of walnuts to the usual diet resulted in significant reductions in the percentages of adults with intakes below the EAR for magnesium and folate (69.6% vs. 52.0%; 49.2% vs. 40.6%, respectively), and increased the percentage of adults above the AI for potassium (22.8% vs. 26.5%). A similar trend was observed among children (4-18 years). HEI scores improved significantly from 49.1 (95% CI: 48.0-50.4) to 58.5 (95% CI: 57.5-59.6) in children and from 52.4 (95% CI: 51.0-53.8) to 59.2 (95% CI: 58.0-60.5) in adults.

CONCLUSIONS

Adding 1 ounce (28.35 g) of walnuts to the usual diet of no-nut consumers improved the diet quality and adequacy of some under-consumed nutrients.

Mediterranean Diet and its Effect on Endothelial Function: A Meta-analysis and Systematic Review

BACKGROUND

Endothelial dysfunction serves as an early marker for the risk of cardiovascular disease (CVD); therefore, it is a site of therapeutic interventions to reduce the risk of CVD.

AIMS

To examine the effect of the Mediterranean diet (MedDiet), as an intervention, on structural and functional parameters of endothelial function, and how it may reduce the risk of CVD and associated mortality.

METHODS

Medline database was searched for randomized controlled trials. Random-effects meta-analysis was conducted on 21 independent datasets. Meta-regression and subgroup analysis were performed to assess whether the effect of MedDiet was modified by health status (healthy subjects or with increased CVD risk), type of MedDiet intervention (alone or combined), type of parameter (functional or structural), study design (cross-over or parallel), BMI, age, and study duration. Our study used sample size, mean, and standard deviation of endothelial function measurements for both MedDiet intervention and control in the analyses.

RESULTS

Inverse relationship between endothelial function and intake of MedDiet was observed (SMD: 0.34; 95% CI: 0.16, 0.52; P = 0.0001). Overall, MedDiet increased FMD by 1.39% (95% CI: 0.47, 2.19; P < 0.001). There was a significant improvement in endothelial function in both healthy patients and in those with an increased risk of CVD. No significant variation was observed in the effects of MedDiet on endothelial function, due to study design or type of intervention.

CONCLUSIONS

These findings support that MedDiet can reduce the risk of CVD by improving endothelial function.

Consumption of Nuts and Seeds and Health Outcomes Including Cardiovascular Disease, Diabetes and Metabolic Disease, Cancer, and Mortality: An Umbrella Review

Consumption of nuts and seeds is associated with a range of health outcomes. Summarizing the best evidence on essential health outcomes from the consumption of nuts is essential to provide optimal recommendations. Our objective is to comprehensively assess health outcome associations related to the consumption of nuts and seeds, using a culinary definition including tree nuts and peanuts (registered in PROSPERO: CRD42021258300). Health outcomes of interest include cardiovascular disease, cancer, diabetes, obesity, respiratory disease, mortality, and their disease biomarkers. We present associations for high compared with low consumption, per serving, and dose-response relations. MEDLINE, Embase, Cochrane, and Epistemonikos were searched and screened for systematic reviews and meta-analyses. Evidence was extracted from 89 articles on the consumption of nuts and relevant health outcomes, including 23 articles with meta-analysis on disease and mortality, 66 articles on biomarkers for disease, and 9 articles on allergy/adverse outcomes. Intake of nuts was associated with reduced risk of cardiovascular diseases and related risk factors, with moderate quality of evidence. An intake of 28 g/d nuts compared with not eating nuts was associated with a 21% RR reduction of cardiovascular disease (including coronary heart disease incidence and mortality, atrial fibrillation, and stroke mortality), an 11% risk reduction of cancer deaths, and 22% reduction in all-cause mortality. Nut consumption was also inversely associated with mortality from respiratory diseases, infectious diseases, and diabetes; however, associations between nut consumption and diabetes incidence were mixed. Meta-analyses of trials on biomarkers for disease generally mirrored meta-analyses from observational studies on cardiovascular disease, cancers, and diabetes. Allergy and related adverse reactions to nuts were observed in 1-2% of adult populations, with substantial heterogeneity between studies. Overall, the current evidence supports dietary recommendations to consume a handful of nuts and seeds per day for people without allergies to these foods.

The effect of walnut consumption on cardiometabolic profiles of individuals with abnormal glucose homoeostasis: a systematic review and meta-analysis of clinical trials

Findings on the effect of walnut consumption on cardiometabolic profiles in individuals with abnormal glucose homoeostasis are conflicting. We summarised earlier data in this regard. A systematic literature search of relevant reports published in Medline/PubMed, ISI web of Science, EMBASE, SCOPUS and Google Scholar up to October 2020 was conducted. Randomised trials that enrolled individuals with abnormal glucose homoeostasis in which the main intervention was walnut consumption were included. Abnormal glucose homoeostasis was defined as a spectrum of impaired glucose tolerance or pre-diabetic status that is associated with insulin resistance. Twelve studies were included in systematic review and eight in meta-analysis. No significant effect of walnut consumption on anthropometric measures, including weighted mean difference (WMD: -0·13; 95 % CI -0·64, 0·39 kg), BMI (-0·08; 95 % CI -0·47, 0·32 kg/m²) and waist circumference (0·01; 95 % CI -0·50, 0·52 cm) was observed. Although walnut intake did not influence on lipid profiles (including TAG, total- and HDL-cholesterol levels), individuals in the intervention group tended to have lower levels of LDL-cholesterol than those in the control group (-0·10; 95 % CI -0·20, 0·01 mmol/l; P = 0·06). Other cardiometabolic factors including markers of glycaemic control (fasting blood glucose and HbA1C levels), blood pressure and stimulus-adjusted response measure (a parameter of endothelial function) were not significantly affected. However, walnut consumption resulted in a significant increase in flow-mediated dilation (FMD) (0·93 %; 95 % CI 0·16, 1·71 %). Summarising earlier evidence, we found that walnut consumption might influence FMD and LDL-cholesterol levels in individuals with abnormal glucose homoeostasis. It did not affect other cardiometabolic profiles in these individuals.

The phytochemical components of walnuts and their application for geographical origin based on chemical markers

Place of origin has an important influence on walnut quality and commercial value, which results in the requirement of rapid geographical traceability method. Thus, a method for geographical origin identification of walnuts on the basis of nutritional quality of walnut from China was conducted. The concentrations of 43 phytochemical components were analyzed in walnut samples from five different walnut-producing regions of China. Based on 14 chemical markers selected by the Random Forest method from these phytochemical components, a new discriminant model for geographical origin was built, with the corresponding correct classification rate of 99.3%. In addition, the quantitative quality differences of walnuts from five regions were analyzed, with the values of 0.17-1.43. Moreover, the top three chemical markers for the geographical origin discriminant analysis were Mo, V and stearic acid, with the contribution rates of 26.8%, 18.9% and 10.9%. This study provides a potentially viable method for application in the food authentication.

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.

Effects of Hazelnut Consumption on Cardiometabolic Risk Factors and Acceptance: A Systematic Review

Despite being rich sources of monounsaturated fat and a number of vitamins, minerals, and phytonutrients, hazelnuts have received less attention than some other nut types. A qualitative systematic review was carried out to determine the effects of hazelnut consumption on acceptance and markers of cardiometabolic health, including blood lipids and lipoproteins, apolipoproteins A1 and B100, body weight and composition, blood pressure, glycemia, antioxidant status, oxidative stress, inflammation, and endothelial function. In total, 22 intervention studies (25 publications) met our inclusion criteria. The findings indicate some improvements in cardiometabolic risk factors; however, limitations in study design mean interpretation is problematic. The inclusion of hazelnuts in the diet did not adversely affect body weight and composition. Acceptance of hazelnuts remained stable over time confirming nut consumption guidelines are feasible and sustainable. Future studies using more robust study designs in a variety of populations are required to draw more definitive conclusions on the health benefits of hazelnut consumption.

Brazil and cashew nuts intake improve body composition and endothelial health in women at cardiometabolic risk (Brazilian Nuts Study): a randomized controlled trial

Several mechanisms have been proposed for the beneficial effect of nuts on health. However, Brazil and cashew nuts remain the least studied. We aim to evaluate the effect of these nuts within an energy-restricted diet on body weight, body composition, cardiometabolic markers, and endothelial function in cardiometabolic risk women. Brazilian nuts study is a randomized controlled parallel 8-week dietary intervention trial. Forty women were randomly allocated to 1) Control group: Energy-restricted diet without nuts, n= 19 or, 2) Brazil and cashew nuts group (BN-Group): Energy-restricted diet containing daily 45 g of nuts (15 g of Brazil nuts + 30g of cashew nuts), n= 21. At the beginning and final intervention, anthropometry, body composition, and blood pressure were measured. Fasting blood sampling was obtained to evaluate lipid profile, glucose homeostasis, and endothelial function markers. After 8-week, plasma selenium concentration increased in BN-group (∆ = + 31.5 ± 7.8 μg/L; p= 0.001). Brazil and cashew nuts intake reduced total body fat (-1.3 ± 0.4 %) parallel to improvement of lean mass percentage in BN-group compared to the control. Besides, the soluble adhesion molecule VCAM-1 decreased (24.03 ± 15.7 pg/mL vs. -22.2 ± 10.3 pg/mL; p= 0.019) after Brazil and cashew nuts intake compared to the control. However, lipid and glucose profile markers, apolipoproteins, and blood pressure remained unchanged after the intervention. Thus, the addition of Brazil and cashew nuts to an energy-restricted diet can be a healthy strategy to improve body composition, selenium status, and endothelial inflammation in cardiometabolic risk women.

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.

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.

Nuts: Natural Pleiotropic Nutraceuticals

Common nuts (tree nuts and peanuts) are energy-dense foods that nature has gifted with a complex matrix of beneficial nutrients and bioactives, including monounsaturated and polyunsaturated fatty acids, high-quality protein, fiber, non-sodium minerals, tocopherols, phytosterols, and antioxidant phenolics. These nut components synergize to favorably influence metabolic and vascular physiology pathways, ameliorate cardiovascular risk factors and improve cardiovascular prognosis. There is increasing evidence that nuts positively impact myriad other health outcomes as well. Nut consumption is correlated with lower cancer incidence and cancer mortality, and decreased all-cause mortality. Favorable effects on cognitive function and depression have also been reported. Randomized controlled trials consistently show nuts have a cholesterol-lowering effect. Nut consumption also confers modest improvements on glycemic control, blood pressure (BP), endothelial function, and inflammation. Although nuts are energy-dense foods, they do not predispose to obesity, and in fact may even help in weight loss. Tree nuts and peanuts, but not peanut butter, generally produce similar positive effects on outcomes. First level evidence from the PREDIMED trial shows that, in the context of a Mediterranean diet, consumption of 30 g/d of nuts (walnuts, almonds, and hazelnuts) significantly lowered the risk of a composite endpoint of major adverse cardiovascular events (myocardial infarction, stroke, and death from cardiovascular disease) by ≈30% after intervention for 5 y. Impressively, the nut-supplemented diet reduced stroke risk by 45%. As they are rich in salutary bioactive compounds and beneficially impact various health outcomes, nuts can be considered natural pleiotropic nutraceuticals.

Association of Walnut Consumption with Total and Cause-Specific Mortality and Life Expectancy in U.S. Adults

Walnut consumption is associated with health benefits. We aimed to (1) examine the association between walnut consumption and mortality and (2) estimate life expectancy in relation to walnut consumption in U.S. adults. We included 67,014 women of the Nurses' Health Study (1998-2018) and 26,326 men of the Health Professionals Follow-up Study (1998-2018) who were free of cancer, heart disease, and stroke at baseline. We used Cox regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). During up to 20 years of follow-up, we documented 30,263 deaths. The hazard ratios for total mortality across categories of walnut intake (servings/week), as compared to non-consumers, were 0.95 (95% confidence interval (CI), 0.91, 0.98) for <1 serving/week, 0.94 (95% CI, 0.89, 0.99) for 1 serving/week, 0.87 (95% CI, 0.82, 0.93) for 2-4 servings/week, and 0.86 (95% CI, 0.79, 0.93) for >=5 servings/week (p for trend <0.0001). A greater life expectancy at age 60 (1.30 years in women and 1.26 years in men) was observed among those who consumed walnuts more than 5 servings/week compared to non-consumers. Higher walnut consumption was associated with a lower risk of total and CVD mortality and a greater gained life expectancy among U.S. elder adults.

Health Benefits Related to Tree Nut Consumption and Their Bioactive Compounds

Long-term studies with regular tree nut consumption have indicated positive outcomes for multiple health benefits. Here, we review the beneficial effects of tree nuts, highlighting the impact on glucose modulation, body weight management, cardiovascular risk, inflammation, oxidative stress, cognitive performance, and gut microbiota. Nuts are important sources of nutrients and phytochemicals, which, together with a healthy lipid profile, could help prevent certain chronic diseases, protect against oxidative stress and inflammation, and improve cognitive performance, thus reducing the impact of aging and neurodegeneration.

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.

Identifying Usual Food Choice Combinations With Walnuts: Analysis of a 2005-2015 Clinical Trial Cohort of Overweight and Obese Adults

Consumption of nuts has been associated with a range of favorable health outcomes. Evidence is now emerging to suggest that walnuts may also play an important role in supporting the consumption of a healthy dietary pattern. However, limited studies have explored how walnuts are eaten at different meal occasions. The aim of this study was to explore the food choices in relation to walnuts at meal occasions as reported by a sample of overweight and obese adult participants of weight loss clinical trials. Baseline usual food intake data were retrospectively pooled from four food-based clinical trials (n = 758). A nut-specific food composition database was applied to determine walnut consumption within the food intake data. The a priori algorithm of association rules was used to identify food choices associated with walnuts at different meal occasions using a nested hierarchical food group classification system. The proportion of participants who were consuming walnuts was 14.5% (n = 110). The median walnut intake was 5.14 (interquartile range, 1.10–11.45) g/d. A total of 128 food items containing walnuts were identified for walnut consumers. The proportion of participants who reported consuming unsalted raw walnut was 80.5% (n = 103). There were no identified patterns to food choices in relation to walnut at the breakfast, lunch, or dinner meal occasions. A total of 24 clusters of food choices related to walnuts were identified at others (meals). By applying a novel food composition database, the present study was able to map the precise combinations of foods associated with walnuts intakes at mealtimes using data mining. This study offers insights into the role of walnuts for the food choices of overweight adults and may support guidance and dietary behavior change strategies.

Effects of tree nut and groundnut consumption compared with those of l-arginine supplementation on fasting and postprandial flow-mediated vasodilation: Meta-analysis of human randomized controlled trials

INTRODUCTION

l-arginine supplementation may improve vascular endothelial function. As tree nuts and groundnuts are a source of the amino acid l-arginine, we performed a meta-analysis of human randomized controlled trials (RCTs) to compare effects of tree nut and groundnut consumption with those of l-arginine supplementation on fasting and postprandial endothelial function as assessed by flow-mediated vasodilation of the brachial artery (FMD).

METHODS

Summary estimates of weighted mean differences (WMDs) in FMD and 95% confidence intervals (CIs) were calculated using random-effect meta-analyses.

RESULTS

A total of thirteen RCTs focusing on tree nut and groundnut consumption and nineteen RCTs investigating effects of l-arginine supplementation were included. Longer-term consumption of tree nuts and groundnuts increased fasting FMD by 1.09 %-point (PP) (95% CI: 0.49, 1.69, P < 0.001; I²: 76.7%, P < 0.001), while l-arginine supplementation (daily range: 3-21 g) increased fasting FMD by 0.53 PP (95% CI: 0.12, 0.93; P = 0.012; I²: 91.6%, P < 0.001). Effects between treatments were not statistically different (P = 0.31). Tree nut and groundnut consumption did not affect postprandial FMD responses (1.25 PP, 95% CI: -0.31, 2.81, P = 0.12; I²: 91.4%, P < 0.001), whereas l-arginine supplementation (range: 3-15 g) improved FMD during the postprandial phase by 2.02 PP (95% CI: 0.92, 3.13, P < 0.001; I²: 99.1%, P < 0.001). However, treatment effects did not differ significantly (P = 0.60). Overall, these results derive from high-quality evidence.

CONCLUSION

Longer-term consumption of tree nuts and groundnuts, as well as l-arginine supplementation did improve fasting endothelial function, as assessed by FMD. However, the positive effects of tree nuts and groundnuts could not be fully explained by the amount of l-arginine in these nuts. Only l-arginine supplementation did improve postprandial FMD, but effects were not different from those of tree nuts and groundnuts. Future studies should focus on the identifications of the bioactive nutrients in tree nuts and groundnuts and mechanistic pathways behind differences in postprandial and longer-term fasting changes in FMD.

Beneficial effect of walnuts on vascular tone is associated with Akt signalling, voltage-dependent calcium channel LTCC and ATP-sensitive potassium channel Kv1.2

Consumption of walnuts is beneficial for cardiovascular health. To study walnut effects on proteins involved in vascular tone regulation, control and fructose-fed rats were subjected to walnut diet for 6 weeks. In contrast with increased energy intake and body mass gain, aortic protein level of L-type calcium channel alpha subunit was decreased and the level of SUR2B subunit of ATP-sensitive K + channel was increased in healthy rats subjected to walnuts, together with improved Akt phosphorylation. Upon the walnut diet in rats subjected to fructose overload, the rise in energy intake and body mass gain, was followed by an increase in blood insulin. Although SUR2B level was elevated, the level of sodium-calcium exchanger NCX1 and inducible nitric oxide synthase were reduced and increased, respectively. In summary, walnut consumption was accompanied with moderate beneficial vascular effect in healthy rats, while an effect of walnut in rats with metabolic disturbances was rather controversial.

Snacking on whole almonds for 6 weeks improves endothelial function and lowers LDL cholesterol but does not affect liver fat and other cardiometabolic risk factors in healthy adults: the ATTIS study, a randomized controlled trial

BACKGROUND

There is convincing evidence that daily whole almond consumption lowers blood LDL cholesterol concentrations, but effects on other cardiometabolic risk factors such as endothelial function and liver fat are still to be determined.

OBJECTIVES

We aimed to investigate whether isoenergetic substitution of whole almonds for control snacks with the macronutrient profile of average snack intakes, had any impact on markers of cardiometabolic health in adults aged 30-70 y at above-average risk of cardiovascular disease (CVD).

METHODS

The study was a 6-wk randomized controlled, parallel-arm trial. Following a 2-wk run-in period consuming control snacks (mini-muffins), participants consumed either whole roasted almonds (n = 51) or control snacks (n = 56), providing 20% of daily estimated energy requirements. Endothelial function (flow-mediated dilation), liver fat (MRI/magnetic resonance spectroscopy), and secondary outcomes as markers of cardiometabolic disease risk were assessed at baseline and end point.

RESULTS

Almonds, compared with control, increased endothelium-dependent vasodilation (mean difference 4.1%-units of measurement; 95% CI: 2.2, 5.9), but there were no differences in liver fat between groups. Plasma LDL cholesterol concentrations decreased in the almond group relative to control (mean difference -0.25 mmol/L; 95% CI: -0.45, -0.04), but there were no group differences in triglycerides, HDL cholesterol, glucose, insulin, insulin resistance, leptin, adiponectin, resistin, liver function enzymes, fetuin-A, body composition, pancreatic fat, intramyocellular lipids, fecal SCFAs, blood pressure, or 24-h heart rate variability. However, the long-phase heart rate variability parameter, very-low-frequency power, was increased during nighttime following the almond treatment compared with control (mean difference 337 ms2; 95% CI: 12, 661), indicating greater parasympathetic regulation.

CONCLUSIONS

Whole almonds consumed as snacks markedly improve endothelial function, in addition to lowering LDL cholesterol, in adults with above-average risk of CVD.This trial was registered at clinicaltrials.gov as NCT02907684.

Mediterranean Diet Increases Endothelial Function in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

The endothelium plays a key role in the maintenance of vascular health and represents a potential physiological target for dietary and other lifestyle interventions designed to reduce the risk of cardiovascular diseases (CVD) including stroke or coronary heart disease.

OBJECTIVE

To conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) investigating the effects of the Mediterranean dietary pattern (MedDiet) on endothelial function.

METHODS

Medline, Embase, and Scopus databases were searched from inception until January 2019 for studies that met the following criteria: 1) RCTs including adult participants, 2) interventions promoting the MedDiet, 3) inclusion of a control group, and 4) measurements of endothelial function. A random-effects meta-analysis was conducted. Metaregression and subgroup analyses were performed to identify whether effects were modified by health status (i.e., healthy participants versus participants with existing comorbidities), type of intervention (i.e., MedDiet alone or with a cointervention), study duration, study design (i.e., parallel or crossover), BMI, and age of participants.

RESULTS

Fourteen articles reporting data for 1930 participants were included in the meta-analysis. Study duration ranged from 4 wk to 2.3 y. We observed a beneficial effect of the MedDiet on endothelial function [standardized mean difference (SMD): 0.35; 95% CI: 0.17, 0.53; P <0.001; I2 = 73.68%]. MedDiet interventions improved flow-mediated dilation (FMD)-the reference method for noninvasive, clinical measurement of endothelial function-by 1.66% (absolute change; 95% CI: 1.15, 2.17; P <0.001; I2 = 0%). Effects of the MedDiet on endothelial function were not modified by health status, type of intervention, study duration, study design, BMI, or age of participants (P >0.05).

CONCLUSIONS

MedDiet interventions improve endothelial function in adults, suggesting that the protective effects of the MedDiet are evident at early stages of the atherosclerotic process with important implications for the early prevention of CVD. This study has the PROSPERO registration number: CRD42018106188.

Changes in Nut Consumption and Subsequent Cardiovascular Disease Risk Among US Men and Women: 3 Large Prospective Cohort Studies

Background We aim to evaluate the association of within-individual changes in consumption of total and specific types of nuts and the subsequent risk of incident cardiovascular disease (CVD) in US men and women. Methods and Results We included 34 103 men from the HPFS (Health Professionals Follow-Up Study) (1986-2012), 77 815 women from the NHS (Nurses' Health Study) (1986-2012), and 80 737 women from the NHS II (1991-2013). We assessed nut consumption every 4 years using validated food frequency questionnaires. We used multivariable Cox proportional hazards regression models to examine the association between 4-year changes in nut consumption and risk of confirmed CVD end points in the subsequent 4 years. Per 0.5 serving/day increase in total nut consumption was associated with lower risk of CVD (relative risk [RR], 0.92; 95% CI, 0.86-0.98), coronary heart disease (RR, 0.94; 95% CI, 0.89-0.99), and stroke (RR, 0.89; 95% CI, 0.83-0.95). Compared with individuals who remained nonconsumers in a 4-year interval, those who had higher consumption of total nuts (≥0.5 servings/day) had a lower risk of CVD (RR, 0.75; 95% CI, 0.67-0.84), coronary heart disease (RR, 0.80; 95% CI, 0.69-0.93), and stroke (RR, 0.68; 95% CI, 0.57-0.82) in next 4 years. Individuals who decreased nut consumption by ≥0.50 servings/day had a higher risk of developing CVD (RR, 1.14; 95% CI, 0.99-1.32), coronary heart disease (RR, 1.06; 95% CI, 0.88-1.28), and stroke (RR, 1.28; 95% CI, 1.02-1.60) when compared with those who maintained their nut consumption. Conclusions Increasing total consumption of nuts and intake of individual types of nuts (eg, walnuts, other tree nuts, and peanuts) was associated with a subsequent lower risk of CVD. These data support the role of nut intake in the primary prevention of CVD. Registration URL: http://www.clini​caltr​ials.gov. Unique identifiers: NCT00005152 and NCT00005182.

Effect of a Walnut Diet on Office and 24-Hour Ambulatory Blood Pressure in Elderly Individuals

Supplemental Digital Content is available in the text.

Nut consumption lowers blood cholesterol and is associated with reduced cardiovascular disease, but effects on blood pressure (BP) are inconsistent. We assessed the 2-year effects of a walnut diet versus a control diet on office BP and 24-hours ambulatory BP in free-living elders participating in the Walnuts and Healthy Aging study, a randomized trial testing the effects of walnuts at ≈15% energy on age-related disorders. In a prespecified analysis, we enrolled 305 participants, of whom 236 (75%) completed the study (65% women; age, 69 years; 60% with mild hypertension). Walnuts were well tolerated, and compliance was >98%. Mean baseline office BP was 128/79 mm Hg. Adjusted changes from baseline in mean office systolic BP were −4.61 mm Hg (95% CI, −7.43 to −1.79 mm Hg) in the walnut group and −0.59 mm Hg (−3.38 to 2.21 mm Hg) in controls (P=0.051). Respective changes in mean systolic 24-hour ambulatory BP were −3.86 mm Hg (CI, −5.45 to −2.26 mm Hg) and −2.00 mm Hg (CI, −3.58 to −0.42 mm Hg; P=0.111). No changes in diastolic BP were observed. In participants in the upper tertile of baseline 24-hour ambulatory systolic BP (>125 mm Hg), mean 2-year systolic 24-hour BP was −8.5 mm Hg (CI, −12 to −5.0 mm Hg) in the walnut group and −2.5 mm Hg (CI, −6.3 to 1.3 mm Hg) in controls (P=0.034). During the trial, participants in the walnut group required less uptitration of antihypertensive medication and had better overall BP regulation than controls. Walnut consumption reduces systolic BP in elderly subjects, particularly in those with mild hypertension.

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.

The Associations between Meat Group Consumption and Acute Myocardial Infarction Risks in an Iranian Population: a Case-Control Study

Acute myocardial infraction (AMI) is a highly frequent cause of mortality and disability around the world. The aim of the present study was to evaluate the associations between meat group intake levels and AMI risks in an adult Iranian population. This case-control study was conducted on 200 first AMI cases and 200 healthy individuals matched by age, sex, and body mass index. A Food Frequency Questionnaire validated for Iranian populations was used to assess usual dietary intake levels over the previous year. Data was extracted regarding the meat group-including meat (red and processed), fish, poultry, eggs, nuts, and legumes. The associations between meat group items and AMI were calculated by multivariable logistic regression. Red meat consumption was significantly positively associated with increased risk of AMI. After adjustment for potential confounders, a positive association was found between higher frequency of processed and red meat intake, and increased risk of AMI (processed meat consumption: odds ratio [OR], 1.71; 95% confidence interval [CI], 1.31-2.23 and red meat consumption: OR, 2.51; 95% CI, 1.84-5.11). In addition, the results indicated an inverse association between the frequency of nuts consumption and AMI (OR, 0.52; 95% CI, 0.31-0.92). There were no associations seen between poultry, fish, eggs and beans intake levels, and the odds of AMI. The current study suggested a direct association between the frequency of processed/red meat consumption and increased AMI risks. In addition, an inverse relation was observed between frequency of nuts consumption and the risks of AMI.

The Effects of Nut Consumption on Vascular Function

Vascular stiffness can be measured using numerous techniques including assessments of central haemodynamics, aortic arterial stiffness, and indices of aortic wave reflection and endothelial dilatation. Impaired vascular function is associated with increased risk of cardiovascular disease (CVD). Epidemiological studies indicate that regular nut consumption reduces CVD risk, with one of the proposed mechanisms being via improvements in vascular function. This narrative review summarizes the evidence from a systematic search of the literature of the effects of tree nut and peanut consumption on measures of vascular function excluding flow mediated dilatation. A total of 16 studies were identified, with a mix of acute controlled studies (n = 3), an uncontrolled pre/post chronic study (n = 1), chronic crossover (n = 7) and parallel studies (n = 5). Nut types tested included almonds, peanuts, pine nuts, pistachios and walnuts, with dose and length of supplementation varying greatly across studies. Most studies (n = 13) included individuals at risk for CVD, according to various criteria. Findings were inconsistent, with ten studies reporting no significant changes in vascular function and six studies (one acute and five chronic studies) reporting improvements in at least one measure of vascular function. In summary, nuts have the potential to improve vascular function and future studies should consider the population, dose and length of nut supplementation as well as suitability of the different vascular function techniques.

A Prospective Association of Nut Consumption with Cognitive Function in Chinese Adults aged 55+ _ China Health and Nutrition Survey

OBJECTIVES

We aimed to investigate the association of nut intake with cognitive function in Chinese adults aged 55 and over.

DESIGN

This was a prospective open cohort study with repeated measurements of diet and cognition scores. Participants/settings: 4822 adults aged 55 and over participating in the China Health Nutrition Survey during 1991-2006.

MEASUREMENTS

Global cognitive function measured repeatedly in 1997, 2001, 2004, and 2006 using a subset of modified Telephone Interview for Cognitive Status; poor cognitive function was defined as cognition score<7. Nut consumption was collected using 3-day 24 recall method in 1991, 1993, and at surveys of cognition assessment.

STATISTICAL ANALYSES PERFORMED

Multilevel mixed effect linear regression and logistic regression analysis were conducted to assess the association with cognitive function.

RESULTS

The unadjusted cognitive score decreased by 0.29 (95% CI 0.22-0.28) with one-year aging during 1997-2006. Nut intake of more than 10g/d was associated with higher cognition score by 0.63 points (95% CI 0.15-1.12) or 40% less likely to have poor cognitive function (OR 0.60, 95% CI 0.43-0.84) after adjusted for demographic, lifestyle behavioural, BMI, and energy intake.

CONCLUSIONS

Nut consumption was inversely associated with cognition decline.

Nuts and Cardio-Metabolic Disease: A Review of Meta-Analyses

OBJECTIVES

Accumulating epidemiological and intervention evidence suggest that nut consumption is associated with reduced incidence of some cardiometabolic diseases. However, to date no review of meta-analyses of epidemiological and intervention studies has evaluated the effects of nut consumption on cardiometabolic disease. Design/Results: Electronic searches for meta-analyses of epidemiological and intervention studies were undertaken in PubMed®/MEDLINE®. Meta-analyses of prospective studies show that nut consumption appears to be associated with reduced all-cause mortality by 19⁻20% (n = 6), cardiovascular disease (CVD) incidence (19%; n = 3) and mortality (25%; n = 3), coronary heart disease (CHD) incidence (20⁻34%; n = 2) and mortality (27⁻30%; n = 2) and stroke incidence (10⁻11%; n = 7) and mortality (18%; n = 2). No association between nut consumption and the risk of type 2 diabetes mellitus (T2DM) was observed in meta-analyses of prospective studies, whereas a decrease in fasting blood glucose ranging from 0.08 to 0.15 mmol/L was observed in 3 meta-analyses of intervention studies. In the interventions, nut consumption also had favorable effects on total cholesterol (0.021 to 0.28 mmol/L reduction from 8 meta-analyses of interventions) and low-density lipoprotein cholesterol (0.017 to 0.26 mmol/L reduction from 8 meta-analyses of interventions) and endothelial function (0.79 to 1.03% increase in flow-mediated dilation from 4 meta-analyses of interventions). Nut consumption did not significantly affect body weight. Nut consumption had no effect on inflammatory markers in intervention studies. The effect on blood pressure was inconsistent. A higher nut consumption was associated with a lower incidence of hypertension in prospective studies, while nut consumption did not improve blood pressure in intervention studies.

CONCLUSIONS

Nut consumption appeared to be associated with lower all-cause mortality and CVD and CHD mortality. There was no association between nut consumption and the incidence of T2DM although fasting blood glucose is decreased in intervention studies. In intervention studies nuts lower total cholesterol and low-density lipoprotein cholesterol (LDL-C).

Beneficial effects of walnut consumption on human health: role of micronutrients

PURPOSE OF REVIEW

Nuts in general and walnuts in particular are in the limelight for the association of their consumption with improved health outcomes. Walnuts have an optimal composition in bioactive nutrients and recent clinical and experimental studies have uncovered a number of beneficial effects of walnut micronutrients, working in isolation or in concert, on metabolic pathways and clinical outcomes that make this review timely and relevant.

RECENT FINDINGS

Alpha-linolenic acid, a critical walnut component, is metabolized into bioactive oxylipins, has been shown to protect microglial cells from inflammation, and is associated with lower fatal myocardial infarction rates through a putative antiarrhythmic effect. Phytosterols relate to the cholesterol-lowering effect of nut consumption. Nonsodium minerals are associated with better cardiometabolic health. Walnut phytomelatonin has anticancer effects that are shared by the main walnut polyphenols and their metabolites, ellagitannins and urolithins, respectively.

SUMMARY

This review highlights new evidence on the health-promoting properties of walnuts and their main micronutrient components. The conclusion is that walnuts are optimal healthful foods.

Nut consumption and incidence of seven cardiovascular diseases

BACKGROUND

Nut consumption has been found to be inversely associated with cardiovascular disease mortality, but the association between nut consumption and incidence of specific cardiovascular diseases is unclear. We examined the association between nut consumption and incidence of seven cardiovascular diseases.

METHODS

This prospective study included 61 364 Swedish adults who had completed a Food Frequency Questionnaire and were followed up for 17 years through linkage with the Swedish National Patient and Death Registers.

RESULTS

Nut consumption was inversely associated with risk of myocardial infarction, heart failure, atrial fibrillation and abdominal aortic aneurysm in the age-adjusted and sex-adjusted analysis. However, adjustment for multiple risk factors attenuated these associations and only a linear, dose-response, association with atrial fibrillation (ptrend=0.004) and a non-linear association (pnon-linearity=0.003) with heart failure remained. Compared with no consumption of nuts, the multivariable HRs (95% CI) of atrial fibrillation across categories of nut consumption were 0.97 (0.93 to 1.02) for 1-3 times/month, 0.88 (0.79 to 0.99) for 1-2 times/week and 0.82 (0.68 to 0.99) for ≥3 times/week. For heart failure, the corresponding HRs (95% CI) were 0.87 (0.80 to 0.94), 0.80 (0.67 to 0.97) and 0.98 (0.76 to 1.27). Nut consumption was not associated with risk of aortic valve stenosis, ischaemic stroke or intracerebral haemorrhage.

CONCLUSIONS

These findings suggest that nut consumption or factors associated with this nutritional behaviour may play a role in reducing the risk of atrial fibrillation and possibly heart failure.

TRIAL REGISTRATION NUMBER

NCT01127711 and NCT01127698;Results.

Nuts and Cardiovascular Disease Prevention

PURPOSE OF REVIEW

We review recent epidemiological and clinical studies investigating the consumption of tree nuts and peanuts and cardiovascular disease (CVD) mortality as well as CVD risk factors.

RECENT FINDINGS

A greater consumption of tree nuts and peanuts is associated with a reduced risk of CVD mortality, as well as lower CVD events. Furthermore, risk factors associated with the development of CVD such as dyslipidemia, impaired vascular function, and hypertension are improved with regular tree nut and peanut consumption through a range of mechanism associated with their nutrient-rich profiles. There is weak inconsistent evidence for an effect of nut consumption on inflammation. There is emerging evidence that consuming tree nuts reduces the incidence of non-alcoholic fatty liver disease (NAFLD) and promotes diversity of gut microbiota, which in turn may improve CVD outcomes. Evidence for CVD prevention is strong for some varieties of tree nuts, particularly walnuts, and length of supplementation and dose are important factors for consideration with recommendations.

Recent Science and Clinical Application of Nutrition to Coronary Heart Disease

One of the greatest threats to mortality in industrialized societies continues to be coronary heart disease (CHD). Moreover, the ability to decrease the incidence of CHD has reached a limit utilizing traditional diagnostic evaluations and prevention and treatment strategies for the top five cardiovascular risk factors (hypertension, diabetes mellitus, dyslipidemia, obesity, and smoking). It is well known that about 80% of CHD can be prevented with optimal nutrition, coupled with exercise, weight management, mild alcohol intake, and smoking cessation. Among all of these factors, optimal nutrition provides the basic foundation for prevention and treatment of CHD. Numerous prospective nutrition clinical trials have shown dramatic reductions in the incidence of CHD. As nutritional science and nutrigenomics research continues, our ability to adjust the best nutrition with an individualized approach is emerging. This article reviews the role of nutrition in the prevention and treatment of CHD and myocardial infarction (MI).

Prospective Study of Nut Consumption and Incidence of Metabolic Syndrome: Tehran Lipid and Glucose Study

This study aimed to assess the association of various types of nut per se, and total nut consumption with the incidence of metabolic syndrome (MetS). A 6.2 ± 0.7-year population-based prospective study was conducted among 1265 adults, aged 19–74 years, participants of the Tehran Lipid and Glucose Study. A 168-item semi-quantitative food frequency questionnaire was used to collect information on nut consumption. MetS was defined according to the Joint Interim Statement guidelines and 276 new cases of MetS were identified. Median ± interquartile range of nut consumption was 2.08 (0.88–5.68) servings/week. After adjusting for family history of diabetes, age, gender, smoking, physical activity, fasting serum glucose at baseline, serum high density lipoprotein cholesterol (HDL-C) at baseline, energy intake, fiber, macronutrients, cholesterol intake, fruit, vegetables, dairy products and body mass index (BMI), a statistically significant decrease was observed in MetS in the third (≥5 servings/week) tertile of nuts (odds ratio: 0.68, 95% CI: 0.44–0.91, p trend: 0.03) compared with the lowest (≤1 serving/week). Walnut consumption showed a significant, inverse association with MetS risk; associations for other nut varieties were not significant. For each additional serving/week of walnuts consumed, incidence of MetS decreased by 3% (ORs: 0.97 CI: 0.93–0.99), after adjusting for confounding factors. Total nut consumption, especially walnuts, reduces the risk of MetS.

Metabolic and Blood Pressure Effects of Walnut Supplementation in a Mouse Model of the Metabolic Syndrome

There is extensive evidence that walnut consumption is protective against cardiovascular disease and diabetes in the healthy population, but the beneficial effects of walnut consumption in individuals with the metabolic syndrome (MetS) remain uncertain. We compared a range of cardio-metabolic traits and related tissue gene expression associated with 21 weeks of dietary walnut supplementation in a mouse model of MetS (MetS-Tg) and wild-type (WT) mice (n = 10 per genotype per diet, equal males and females). Compared to standard diet, walnuts did not significantly alter food consumption or body weight trajectory of either MetS-Tg or WT mice. In MetS-Tg mice, walnuts were associated with reductions in oral glucose area under the curve (gAUC, standard diet 1455 ± 54, walnut 1146 ± 91, p = 0.006) and mean arterial blood pressure (MAP, standard diet 100.6 ± 1.9, walnut 73.2 ± 1.8 mmHg, p < 0.001), with neutral effects on gAUC and MAP in WT mice. However, in MetS-Tg mice, walnuts were also associated with trends for higher plasma cholesterol (standard diet 4.73 ± 0.18, walnut 7.03 ± 1.99 mmol/L, p = 0.140) and triglyceride levels (standard diet 2.4 ± 0.5, walnut 5.4 ± 1.6 mmol/L, p = 0.061), despite lowering cholesterol and having no effect on triglycerides in WT mice. Moreover, in both MetS-Tg and WT mice, walnuts were associated with significantly increased liver expression of genes associated with metabolism (Fabp1, Insr), cell stress (Atf6, Ddit3, Eif2ak3), fibrosis (Hgf, Sp1, Timp1) and inflammation (Tnf, Ptpn22, Pparg). In conclusion, dietary walnuts were associated with modest favourable effects in WT mice, but a combination of beneficial and adverse effects in MetS-Tg mice, and up-regulation of hepatic pro-fibrotic and pro-inflammatory genes in both mouse strains.