Effects Of Walnut Consumption Research Articles

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.

Effect of walnut consumption on neuropsychological development in healthy adolescents: a multi-school randomised controlled trial

Omega-3 fatty acids are critical for neuropsychological functioning. Adolescence is increasingly believed to entail brain vulnerability to dietary intake. The potential benefit on adolescent neurodevelopment of consuming walnuts, a source of omega-3 alpha-linolenic acid (ALA), remains unclear. We conducted a 6-month multi-school-based randomised controlled nutrition intervention trial to assess whether walnut consumption has beneficial effects on the neuropsychological and behavioural development of adolescents. The study took place between 04/01/2016 and 06/30/2017 in twelve different high schools in Barcelona, Spain (ClinicalTrials.gov Identifier: NCT02590848). A total of 771 healthy teenagers aged 11-16 years were randomised into two equal groups (intervention or control). The intervention group received 30g/day of raw walnut kernels to be incorporated into their diet for 6 months. Multiple primary endpoints concerning neuropsychological (working memory, attention, fluid intelligence, and executive function) and behavioural (socio-emotional and attention deficit hyperactivity disorder [ADHD] symptoms) development were assessed at baseline and after intervention. Red blood cell (RBC) ALA status was determined at baseline and 6 months as a measure of compliance. Main analyses were based on intention-to-treat using a linear mixed-effects model. A per-protocol effect of the intervention was analysed using inverse-probability weighting to account for post-randomisation prognostic factors (including adherence) using generalised estimating equations. In intention-to-treat analyses, at 6 months there were no statistically significant changes between the intervention and control groups for all primary endpoints. RBC ALA (%) significantly increased only in the intervention group, coefficient=0.04 (95% Confidence Interval (CI)=0.03, 0.06; p<0.0001). The per-protocol (adherence-adjusted) effect on improvement in attention score (hit reaction time variability) was-11.26ms (95% CI=-19.92,-2.60; p=0.011) for the intervention group as compared to the control group, improvement in fluid intelligence score was 1.78 (95% CI=0.90, 2.67; p<0.0001), and reduction of ADHD symptom score was-2.18 (95% CI=-3.70,-0.67; p=0.0050). Our study suggested that being prescribed eating walnuts for 6 months did not improve the neuropsychological function of healthy adolescents. However, improved sustained attention, fluid intelligence, and ADHD symptoms were observed in participants who better complied with the walnut intervention. This study provides a foundation for further clinical and epidemiological research on the effect of walnuts and ALA on neurodevelopment in adolescents. This study was supported by Instituto de Salud Carlos III through the projects 'CP14/00108, PI16/00261, PI21/00266' (co-funded by European Union Regional Development Fund 'A way to make Europe'). The California Walnut Commission (CWC) has given support by supplying the walnuts for free for the Walnuts Smart Snack Dietary Intervention Trial.

Abstract 1703: Effects of Walnut Consumption on Gut Microbiota Function and Composition

Abstract 1703: Effects of Walnut Consumption on Gut Microbiota Function and Composition

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.

A Walnut-Enriched Diet Affects Gut Microbiome in Healthy Caucasian Subjects: A Randomized, Controlled Trial.

Regular walnut consumption is associated with better health. We have previously shown that eight weeks of walnut consumption (43 g/day) significantly improves lipids in healthy subjects. In the same study, gut microbiome was evaluated. We included 194 healthy subjects (134 females, 63 ± 7 years, BMI 25.1 ± 4.0 kg/m2) in a randomized, controlled, prospective, cross-over study. Following a nut-free run-in period, subjects were randomized to two diet phases (eight weeks each); 96 subjects first followed a walnut-enriched diet (43 g/day) and then switched to a nut-free diet, while 98 subjects followed the diets in reverse order. While consuming the walnut-enriched diet, subjects were advised to either reduce fat or carbohydrates or both to account for the additional calories. Fecal samples were collected from 135 subjects at the end of the walnut-diet and the control-diet period for microbiome analyses. The 16S rRNA gene sequencing data was clustered with a 97% similarity into Operational Taxonomic Units (OTUs). UniFrac distances were used to determine diversity between groups. Differential abundance was evaluated using the Kruskal–Wallis rank sum test. All analyses were performed using Rhea. Generalized UniFrac distance shows that walnut consumption significantly affects microbiome composition and diversity. Multidimensional scaling (metric and non-metric) indicates dissimilarities of approximately 5% between walnut and control (p = 0.02). The abundance of Ruminococcaceae and Bifidobacteria increased significantly (p < 0.02) while Clostridium sp. cluster XIVa species (Blautia; Anaerostipes) decreased significantly (p < 0.05) during walnut consumption. The effect of walnut consumption on the microbiome only marginally depended on whether subjects replaced fat, carbohydrates or both while on walnuts. Daily intake of 43 g walnuts over eight weeks significantly affects the gut microbiome by enhancing probiotic- and butyric acid-producing species in healthy individuals. Further evaluation is required to establish whether these changes are preserved during longer walnut consumption and how these are linked to the observed changes in lipid metabolism.

SUN-P105: Effects of Walnut Consumption on Blood Lipids and Lipoproteins in Hyperlipidemic Individuals

SUN-P105: Effects of Walnut Consumption on Blood Lipids and Lipoproteins in Hyperlipidemic Individuals

Effects of Walnut Consumption on Colon Carcinogenesis and Microbial Community Structure.

Walnuts are composed of a complex array of biologically active constituents with individual cancer-protective properties. Here, we assessed the potential benefit of whole walnut consumption in a mouse tumor bioassay using azoxymethane. In study 1, a modest reduction (1.3-fold) in tumor numbers was observed in mice fed a standard diet (AIN-76A) containing 9.4% walnuts (15% of total fat). In study 2, the effects of walnut supplementation was tested in the Total Western Diet (TWD). There was a significant reduction (2.3-fold; P < 0.02) in tumor numbers in male mice fed TWD containing 7% walnuts (10.5% of total fat). Higher concentrations of walnuts lacked inhibitory effects, particularly in female mice, indicating there may be optimal levels of dietary walnut intake for cancer prevention. Since components of the Mediterranean diet have been shown to affect the gut microbiome, the effects of walnuts were therefore tested in fecal samples using 16S rRNA gene sequencing. Carcinogen treatment reduced the diversity and richness of the gut microbiome, especially in male mice, which exhibited lower variability and greater sensitivity to environmental changes. Analysis of individual operational taxonomic units (OTU) identified specific groups of bacteria associated with carcinogen exposure, walnut consumption, and/or both variables. Correlation analysis also identified specific OTU clades that were strongly associated with the presence and number of tumors. Taken together, our results indicate that walnuts afford partial protection to the colon against a potent carcinogenic insult, and this may be due, in part, to walnut-induced changes to the gut microbiome. Cancer Prev Res; 9(8); 692-703. ©2016 AACR.

Effects of Walnut Consumption on Endothelial Function in People with Type 2 Diabetes: a Randomized Pilot Trial

The aim of this study was to obtain preliminary data to test the hypothesis that (1) a 12-week intervention with 28 g/day of walnuts improves endothelial function in people with type 2 diabetes mellitus (DM) and (2) intake of walnuts improves plasma adipokines after 12 weeks of intervention. In this pilot randomized, single-blinded, controlled trial of 26 adult subjects with prevalent DM, each subject was randomized to a usual diet with 28 g of walnuts per day or usual diet without walnuts (control group). Reactive hyperemia index (RHI), a measure of endothelial function, was measured non-invasively at baseline and after 12 weeks using Endo-PAT2000. We used linear regression to examine the effects of the intervention on RHI. The mean age at baseline was 64.8 ± 11.6 years; 61.5 % of participants were female, and 15.4 % had coronary artery disease. The standard error of RHI was 0.19. The difference in change in RHI during the intervention between the two groups was −0.029 (95 % confidence interval (CI) −0.52, 0.46, p = 0.23). Walnut intervention led to a suggestive increase in adiponectin, albeit non-statistically significant (difference 0.50 μg/ml (95 % CI −0.10, 1.09), p = 0.65). We demonstrated the feasibility of the proposed randomized trial and obtained needed standard deviations to calculate the required sample size to test proposed hypotheses in an efficacy trial.

Effects of Walnut Consumption on Mood in Young Adults

Walnuts contain a number of potentially neuroprotective compounds like vitamin E, folate, melatonin, several antioxidative polyphenols and significant amounts of omega‐3 fatty acids. The present study sought to determine the effect of walnuts on mood. Sixty‐four college students were randomly assigned to two treatment sequences in a cross‐over fashion: walnut‐placebo or placebo‐walnut. Baseline data was assessed using Profiles of Mood States (POMS). Data was collected again after eight weeks of intervention. After six‐weeks of washout the intervention groups followed the diets in reverse order. Data was collected once more at the end of the eight‐week intervention period. No significant change in mood was observed in analysis that included both genders on the walnut supplemented diet. However, in gender specific analysis significant improvement was observed in males in the anger/hostility domain (p=0.013) and in the Total Mood Disturbance score (p=0.043). In young males, walnuts seem to have the ability improve some mood domains. The study was in part supported by the California Walnut Commision. The funders had no role in the implementation, data collection, management, analysis, or interpretation of the study or preparation of this publication.

The effect of walnut consumption on lipid profiles of the first-degree relatives of type two diabetes mellitus patients (T2DM) with prediabetes

Background and Objective: Prevalence of Diabetes mellitus as a group of metabolic diseases is increasing. Abnormal lipid profile in diabetic patients is major risk factor for cardiovascular disease. According to studies, polyunsaturated fatty acid (PUFA) effect on lipid profile. We evaluated the association between walnut consumption as a source of PUFA and high-density lipoprotein cholesterol (HDL-C) in prediabetic patients. Methodology: Four hundred eleven (411) first-degree relatives of T2DM male and female 35 to 55 year of age were included in the present study. Dietary intake was assessed with three days record and record’s contents were changed to grams. Biochemical assessments were done according to the standard protocol. Results: Findings show positive associations between walnut consumption and HDL –C level (p=0.01). No other significant associations were observed between other blood lipid components, glycemic control parameters and walnut consumption. Conclusions: Walnut consumption may improve HDL-C in prediabetes patients who were the first-degree relatives of type two diabetic patients.

Effects of walnut consumption on cognitive performance in young adults

Walnuts contain a number of potentially neuroprotective compounds like vitamin E, folate, melatonin, several antioxidative polyphenols and significant amounts of n-3 α-linolenic fatty acid. The present study sought to determine the effect of walnuts on verbal and non-verbal reasoning, memory and mood. A total of sixty-four college students were randomly assigned to two treatment sequences in a crossover fashion: walnuts-placebo or placebo-walnuts. Baseline data were collected for non-verbal reasoning, verbal reasoning, memory and mood states. Data were collected again after 8 weeks of intervention. After 6 weeks of washout, the intervention groups followed the diets in reverse order. Data were collected once more at the end of the 8-week intervention period. No significant increases were detected for mood, non-verbal reasoning or memory on the walnut-supplemented diet. However, inferential verbal reasoning increased significantly by 11.2 %, indicating a medium effect size (P = 0.009; d = 0.567). In young, healthy, normal adults, walnuts do not appear to improve memory, mood or non-verbal reasoning abilities. However, walnuts may have the ability to increase inferential reasoning.

Effects of Walnut Consumption on Endothelial Function in Type 2 Diabetic Subjects

OBJECTIVETo determine the effects of daily walnut consumption on endothelial function, cardiovascular biomarkers, and anthropometric measures in type 2 diabetic individuals.RESEARCH DESIGN AND METHODSThis study was a randomized, controlled, single-blind, crossover trial. Twenty-four participants with type 2 diabetes (mean age 58 years; 14 women and 10 men) were randomly assigned to one of the two possible sequence permutations to receive an ad libitum diet enriched with 56 g (366 kcal) walnuts/day and an ad libitum diet without walnuts for 8 weeks. Subjects underwent endothelial function testing (measured as flow-mediated dilatation [FMD]) and assessment of cardiovascular biomarkers before and after each 8-week treatment phase. The primary outcome measure was the change in FMD after 8 weeks. Secondary outcome measures included changes in plasma lipids, A1C, fasting glucose, insulin sensitivity, and anthropometric measures.RESULTSEndothelial function significantly improved after consumption of a walnut-enriched ad libitum diet compared with that after consumption of an ad libitum diet without walnuts (2.2 ± 1.7 vs. 1.2 ± 1.6%; P = 0.04). The walnut-enriched diet increased fasting serum glucose and lowered serum total cholesterol and LDL cholesterol from baseline (10.0 ± 20.5 mg/dl, P = 0.04; −9.7 ± 14.5 mg/dl, P < 0.01; and −7.7 ± 10 mg/dl, P < 0.01, respectively), although these changes were not significant compared with those for an ad libitum diet without walnuts. There were no significant changes in anthropometric measures, plasma A1C, and insulin sensitivity.CONCLUSIONSA walnut-enriched ad libitum diet improves endothelium-dependent vasodilatation in type 2 diabetic individuals, suggesting a potential reduction in overall cardiac risk.

Effects of walnut consumption as part of heart healthy diet on atherogenic lipoprotein subclasses

Effects of walnut consumption as part of heart healthy diet on atherogenic lipoprotein subclasses

Effects Of Walnut Consumption As Part Of Heart Healthy Diet On Atherogenic Lipoprotein Subclasses

Nutritional therapy is fundamental in the treatment ofcardiovascular disease. Studies that utilized a low-fat dietsupplemented with 64 grams/day of walnuts have showna significant reduction in serum levels of total and LDLcholesterol, and triglycerides. This study was designed tosee if lipoprotein subclasses varied in patients eating alow-fat walnut supplemented diet.

Effects of walnut consumption on plasma fatty acids and lipoproteins in combined hyperlipidemia

Epidemiologic studies show an inverse relation between nut consumption and coronary heart disease. We determined the effects of walnut intake on plasma fatty acids, lipoproteins, and lipoprotein subclasses in patients with combined hyperlipidemia. Participants sequentially adhered to the following diets: 1) a habitual diet (HD), 2) a habitual diet plus walnuts (HD+W), 3) a low-fat diet (LFD), and 4) a low-fat diet plus walnuts (LFD+W). In 13 postmenopausal women and 5 men ( +/- SD age 60 +/- 8 y), walnut supplementation did not increase body weight despite increased energy intake and the LFD caused weight loss (1.3 +/- 0.5 kg; P < 0.01). When comparing the HD with the HD+W, linoleic acid concentrations increased from 29.94 +/- 1.14% to 36.85 +/- 1.13% and alpha-linolenic acid concentrations increased from 0.78 +/- 0.04% to 1.56 +/- 0.11%. During the LFD+W, plasma total cholesterol concentrations decreased by 0.58 +/- 0.16 mmol/L when compared with the HD and by 0.46 +/- 0.14 mmol/L when compared with the LFD. LDL-cholesterol concentrations decreased by 0.46 +/- 0.15 mmol/L when compared with the LFD. Measurements of lipoprotein subclasses and particle size suggested that walnut supplementation lowered cholesterol preferentially in small LDL (46.1 +/- 1.9% compared with 33.4 +/- 4.3%, HD compared with HD+W, respectively; P < 0.01). HDL-cholesterol concentrations decreased from 1.27 +/- 0.07 mmol/L during the HD to 1.14 +/- 0.07 mmol/L during the HD+W and to 1.11 +/- 0.08 mmol/L during the LFD. The decrease was seen primarily in the large HDL particles. Walnut supplementation may beneficially alter lipid distribution among various lipoprotein subclasses even when total plasma lipids do not change. This may be an additional mechanism underlying the antiatherogenic properties of nut intake.