Walnuts decrease risk of cardiovascular disease: a summary of efficacy and biologic mechanisms

Molecular Identification of Juglans Regia Endophyte LTL-G3, Its Antifungal Potential and Bioactive Substances

Background

Endophyte is one of the potential biocontrol agents for inhibiting plant pathogens. However, the mechanisms and characteristics involved in the inhibition of different phytopathogenic fungi by endophytes, especially walnut endophytes, are still largely unknown.

Objectives

The present study aimed to identify the walnut endophytic fungus LTL-G3 from a genetic point of view, assess the strain's antifungal activity, and determine the bioactivities of the substances it produces against plant pathogens.

Materials and Methods

The homologous sequence of strain LTL-G3 was examined, and typical strains of the Trichoderma virens group were used to build NJ phylogenetic trees and analyze the taxonomic position of the strain. The biocontrol agent's antagonistic potential for many plant pathogenic fungi. By using silica gel G chromatography, the active components of the strain were separated and purified. The active components were identified using GC-MS and NMR.

Results

The strain LTL-G3 was identified as Trichoderma virens. Its fermentation and secondary metabolite extracts had a broad spectrum and strong inhibitory effect on the spread of six plant pathogens (Botrytis cinerea, Fusarium graminearum, Gloeosporium fructigenum, Phytophthora capsici, Rhizoctonia solani, and Valsa mali) evaluated, of which, its inhibition rate against Valsa mali reached 76.6% (fermentation extract) and 100% (ethyl acetate and n-butanol extracts). On silica gel G chromatography, bioactive compounds were divided into 6 fractions and 7 sub-fractions. Fr.2-2 was the sub-fraction that showed the greatest inhibitory against V. mali, as an inhibition percentage of 89.36% in 1 mg. mL-1. Fifteen key inhibitory chemicals identified using GC-MS. By examining the NMR data, the chemical make-up of the precipitated white solid was identified. The inhibition rate against V. mali increased by over 95% at a dosage of 1 mg. mL-1, indicating a significant linear association between compound A and that rate.

Conclusions

The strain LTL-G3 can be applied as an efficient biological control agent against V. mali, and its highly inhibitive secondary metabolites provide the mechanism for this action.

Nuts and seeds consumption and risk of cardiovascular disease, type 2 diabetes and their risk factors: a systematic review and meta-analysis

Objectives

We aimed to systematically review studies and evaluate the strength of the evidence on nuts/seeds consumption and cardiometabolic diseases and their risk factors among adults.

Methods

A protocol was pre-registered in PROSPERO (CRD42021270554). We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials and Scopus up to September 20, 2021 for prospective cohort studies and ≥12-week randomized controlled trials (RCTs). Main outcomes were cardiovascular disease (CVD), coronary heart disease (CHD), stroke and type 2 diabetes (T2D), secondary total-/low density lipoprotein (LDL)-cholesterol, blood pressure and glycaemic markers. Data extraction and risk of bias (RoB) assessments (using RoB 2.0 and RoB-NObS) were performed in duplicate. Effect sizes were pooled using random-effects meta-analyses and expressed as relative risk (RR) or weighted mean differences with 95% confidence intervals (CI); heterogeneity quantified as I ². One-stage dose-response analyses assessed the linear and non-linear associations with CVD, CHD, stroke and T2D. The strength of evidence was classified per the World Cancer Research Fund criteria.

Results

After screening 23,244 references, we included 42 papers from cohort studies (28 unique cohorts, 1,890,573 participants) and 18 RCTs (2,266 participants). In the cohorts, mainly populations with low consumption, high versus low total nuts/seeds consumption was inversely associated with total CVD (RR 0.81; 95% CI 0.75, 0.86; I ² = 67%), CVD mortality (0.77; 0.72, 0.82; I ² = 59.3%), CHD (0.82; 0.76, 0.89; I ² = 64%), CHD mortality (0.75; 0.65, 0.87; I ² = 66.9%) and non-fatal CHD (0.85; 0.75, 0.96; I ² = 62.2%). According to the non-linear dose-response analyses, consumption of 30 g/day of total nuts/seeds was associated with RRs of similar magnitude. For stroke and T2D the summary RR for high versus low intake was 0.91 (95% CI 0.85, 0.97; I ² = 24.8%) and 0.95 (0.75, 1.21; I ² = 82.2%). Intake of nuts (median ~50 g/day) lowered total (-0.15 mmol/L; -0.22, -0.08; I ² = 31.2%) and LDL-cholesterol (-0.13 mmol/L; -0.21, -0.05; I ² = 68.6%), but not blood pressure. Findings on fasting glucose, HbA1c and insulin resistance were conflicting. The results were robust to sensitivity and subgroup analyses. We rated the associations between nuts/seeds and both CVD and CHD as probable. There was limited but suggestive evidence for no association with stroke. No conclusion could be made for T2D.

Conclusion

There is a probable relationship between consumption of nuts/seeds and lower risk of CVD, mostly driven by CHD, possibly in part through effects on blood lipids. More research on stroke and T2D may affect the conclusions. The evidence of specific nuts should be further investigated.

Dietary Walnuts Preserve Aspects of Health Span and Alter the Hippocampal Lipidome in Aged High-Fat Diet-Fed Mice

Evidence continues to accrue that aging and its diseases can be delayed by pharmacologic and dietary strategies that target the underlying hallmarks of the aging process. However, identifying simple, safe, and effective dietary strategies involving the incorporation of whole foods that may confer some protection against the aging process is also needed. Recent observational studies have suggested that nut consumption can reduce mortality risk in humans. Among these, walnuts are particularly intriguing, given their high content of n-3 fatty acids, fiber, and antioxidant and anti-inflammatory compounds. To this end, 12-month-old male CB6F1 mice were provided either a defined control low-fat diet (LFD), a control high-fat diet (HFD), or an isocaloric HFD containing 7.67% walnuts by weight (HFD + W), and measures of healthspan and related biochemical markers (n = 10-19 per group) as well as survival (n = 20 per group) were monitored. Mice provided the HFD or HFD + W demonstrated marked weight gain, but walnuts lowered baseline glucose (p < 0.05) and tended to temper the effects of HFD on liver weight gain (p < 0.05) and insulin tolerance (p = 0.1). Additional assays suggested a beneficial effect on some indicators of health with walnut supplementation, including preservation of exercise capacity and improved short-term working memory, as determined by Y maze (p = 0.02). However, no effect was observed via any diet on inflammatory markers, antioxidant capacity, or survival (p = 0.2). Ingenuity Pathway Analysis of the hippocampal transcriptome identified two processes predicted to be affected by walnuts and potentially linked to cognitive function, including estrogen signaling and lipid metabolism, with changes in the latter confirmed by lipidomic analysis. In summary, while walnuts did not significantly improve survival on a HFD, they tended to preserve features of healthspan in the context of a metabolic stressor with aging.

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.

The Effect of Walnut Intake on Lipids: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Cardiovascular diseases (CVD) are the leading causes of death worldwide. Dyslipidemia is a cardiometabolic risk factor of CVD, yet it can be modifiable. Walnuts have been suggested as a dietary intervention to improve the lipid profile. Therefore, we reviewed the literature to assess the evidence linking walnut intake to the improvement of blood lipids, including total cholesterol (TC), low-density lipoprotein (LDL-C) cholesterol, high-density lipoprotein (HDL-C) cholesterol, and triglycerides (TG). PubMed and Embase databases were searched from 2010 up to March 2022. We limited our search to randomized controlled trials conducted on humans and published in English during the specified period. Cochrane's risk of bias tool for interventional studies was used. A random-effects model was used for the meta-analysis, and weighted mean differences were obtained (WMD) Thirteen trials from the U.S., Europe, and Asia were included. Walnut intake was associated with significant reductions in TC (WMD: -8.58 mg/dL), LDL-C (WMD: -5.68 mg/dL), and TG (WMD: -10.94 mg/dL). Walnut consumption was not associated with HDL-C. Subgroup analysis showed that overweight/obese and those with comorbidities had more lipid improvement. A longer trial duration did result in further improvements. However, our results may be prone to bias due to extraneous confounding factors. Additionally, levels of heterogeneity were considerable for some outcomes of interest. Results from this meta-analysis provide evidence for the health benefits of walnuts on blood lipids. Walnuts possibly reduce the risk of CVD; thus, they can be successfully added to a dietary pattern to enhance health benefits.

Consumption of walnuts suppresses the conversion of palmitic to palmitoleic acid and enhances omega-3 fatty acid metabolism in the heart of fructose-fed rats

Walnut consumption mostly has a positive implication for cardiovascular health. Walnut diet effects on the cardiac fatty acid (FA) metabolism of healthy rats and those with fructose diet-induced metabolic burden were analysed. Both walnuts and fructose increased CD36 transporter level and the nuclear content of some/all of Lipin 1/PPARα/PGC-1 complex partners, as well as cytosolic and nuclear FOXO1. However, fructose, independently of walnuts, increased the content of palmitic (PA), oleic, and vaccenic acid (VA), while in walnut-fed rats failed to increase palmitoleic acid (POA) level and the POA/PA ratio, as well as total MUFA content. In opposite, walnuts reduced the level of PA and VA and increased alpha-linolenic, eicosapentaenoic and docosapentaenoic acid level, regardless of fructose. In conclusion, both fructose and walnuts stimulated the uptake and oxidation of FA in the heart, but the walnuts, opposite to fructose, favourably altered cardiac FA profile in healthy and metabolically compromised rats.

Impact of walnut consumption on cardio metabolic and anthropometric parameters in metabolic syndrome patients: GRADE-assessed systematic review and dose-response meta-analysis of data from randomized controlled trials

BACKGROUND

In recent years, the effect of walnut consumption on various components of metabolic syndrome (Mets) in different populations has been investigated. However, the findings on the alterations of cardiometabolic and anthropometric indices following walnut consumption in adults with Mets have not been fully conclusive.

METHODS

The current study of eight randomized controlled trials (RCTs) examined the effects of walnut consumption on glucose homeostasis factors (fasting plasma glucose (FPG), insulin, hemoglobin A1C (HbA1c)), lipid profile (triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c)), high sensitivity C-reactive protein (hs-CRP) concentrations and anthropometric indices (body weight (BW), body mass index (BMI), and waist circumference (WC)) in trials of 549 participants. A systematic search was conducted in online databases including MEDLINE, Scopus, and Clarivate Analytics Web of Science uses related keywords to detect eligible studies until December 2021. To calculate the weighted mean difference (WMD) and 95% confidence intervals (CIs), a random-effects model was used.

RESULTS

Results from the pooled analysis showed that serum TG concentration was significantly reduced (WMD, - 0.1 mmol/L; 95%CI (- 0.3 to - 0.02); p = 0.02; I2 = 38.6%; p = 0.10), although other lipid profile components (TC, LDL-c, and HDL-c), glucose homeostasis markers (FPG, insulin, and HbA1c), hs-CRP levels, anthropometric indices (BW, BMI, and WC) and blood pressure (SBP and DBP) were not influenced by walnut consumption. A significant dose-response association was detected between the dose of walnut intake and serum concentrations of FPG (Pnon-linearity < 0.03, Pdose-response < 0.001) and HDL-c (Pnon-linearity = 0.01, Pdose-response = 0.006).

CONCLUSIONS

Walnut consumption reduces serum TG levels in individuals with metabolic syndrome, but it cannot affect other cardiometabolic indices. Future well-designed and large RCTs are required to clarify further beneficial effects of walnut consumption on the cardiometabolic profile.

Perspective: Is it Time to Expand Research on "Nuts" to Include "Seeds"? Justifications and Key Considerations

The health benefits of nuts reported throughout the literature are extensive and well established for reducing the risk of, and managing several chronic conditions such as cardiovascular disease, type 2 diabetes, nonalcoholic fatty liver disease, and cognition. Despite their comparable nutrient profile to nuts, seeds are often not assessed in clinical and epidemiological studies. Interestingly, dietary guidelines and recommendations often refer to "nuts and seeds" collectively, even though they are not consistently examined together in nutrition research when determining associated health benefits. The purpose of this review is to call for future nutrition research to consider combining nuts and seeds. This review provides justification for this proposal by summarizing current definitions for nuts and seeds and highlighting the similarities or dissimilarities in their nutrient compositions. Following this, we summarize current evidence on the health benefits of nuts and seeds, research gaps that should be addressed, and considerations for future research using both epidemiological and interventional study designs.

Is FOP Nutrition Label Nutri-Score Well Understood by Consumers When Comparing the Nutritional Quality of Added Fats, and Does It Negatively Impact the Image of Olive Oil?

It has been suggested that the current ranking of olive oil by Nutri-Score (C) is not in line with its nutritional quality and could have a negative impact on the sales and consumption of olive oil, especially compared to other added fats with lower nutritional qualities One of the objectives of this study is to investigate consumers' understanding of Nutri-Score when comparing the nutritional quality of added fats, and to test whether or not Nutri-Score has a negative impact on the image and the choice of olive oil in a sample of Spanish consumers. A cross-sectional study of 486 Spanish adults (mean age ± SD: 45.8 ± 14.0 years; 48.6% women) was conducted. Subjects were recruited through a web panel provider to participate in an online questionnaire. Almost 80% of participants declared that Nutri-Score was useful for recognizing the differences in nutritional quality between the eight added fats presented in the study; 89.1% rightly identified that olive oil was among the added fats with the best nutritional quality (vs. 4.1% for rapeseed oil (Nutri-Score C), and less than 3% for other added fats (Nutri-Score D or E)). When asked about which added fat they would buy more frequently, 86.2% of participants selected olive oil. Then, after being reminded that among added fats, the Nutri-Score C given to olive oil was the best grade, a majority of participants declared that they would keep consuming olive oil as much as before (71.4%). Finally, almost 78% of participants thought that Nutri-Score should be displayed on olive oil. In conclusion, the results of our study suggest that displaying Nutri-Score on olive oil was well accepted and understood by a large majority of participants who appeared to accept the current ranking of the Nutri-Score for olive oil (Nutri-Score C).

Assessment of Total Fat and Fatty Acids in Walnuts Using Near-Infrared Hyperspectral Imaging

"Persian" walnut (Juglans Regia L.) is one of the most consumed tree nuts in the world. It is rich in several bioactive compounds, with polyunsaturated and monounsaturated fatty acids (PUFA and MUFA) appearing at high concentrations. Walnut consumption protects against cardiovascular, carcinogenic, and neurological disorders. The fatty acid profile has usually been determined by gas chromatography, a reliable and robust tool, but also complex, polluting, and time consuming. In this study, near infrared hyperspectral imaging has been used for the screening of total fat, MUFA, PUFA, saturated, and individual fatty acids in walnuts. Five different walnuts varieties have been considered and modified partial least square (MPLS) regressions have been performed. The SEs of prediction (SEP) in external validation (ranged from 2.12% for PUFA to 13.08% for MUFA) suggest that hyperspectral imaging can be a reliable tool for controlling these parameters in a simple, non-destructive and environmentally friendly way.

Water and alcohol extracts from Diaphragma juglandis on anti-fatigue and antioxidative effects in vitro and vivo

BACKGROUND

To estimate the anti-fatigue and antioxidative effects of water and alcohol extracts from Diaphragma juglandis (DJ), H₂ O₂ -treated HepG2 cells were used as an in vitro model to determine the total antioxidant capacities of these two extracts, and behavioral tests on mice and biochemical assay were performed via in vivo experiments.

RESULTS

The results indicate that both extracts possess remarkable HepG2 protective capacities and were capable of scavenging 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) similar to vitamin C. Furthermore, they could significantly prolong the bar climbing time and force swimming time, as well as decrease the serum urea nitrogen and increase the lactate dehydrogenase level and glycogen content. These extracts could also improve the activities of total antioxidant capacity, malondialdehyde, superoxide dismutase, catalase and glutathione peroxidase.

CONCLUSION

In conclusion, both water and alcohol extracts from DJ showed good performance with respect to anti-fatigue and could be a potential antioxidant additive in the field of functional foods. © 2020 Society of Chemical Industry.

Dietary Sources of Plasma trans Fatty Acids among Adults in the United States: NHANES 2009-2010

BACKGROUND

Intake of trans fatty acids (TFAs) increases LDL cholesterol, decreases HDL cholesterol, and increases the risk of heart disease morbidity and mortality. Many food products potentially contain industrially produced or ruminant TFAs. However, little is known about the dietary sources of plasma TFA concentrations.

OBJECTIVE

The objective of this study was to examine associations between foods consumed and plasma TFA concentrations using 24-h dietary recall data and plasma TFA measures among adults aged ≥20 y who participated in the NHANES 2009-2010 in the United States.

METHODS

Over 4400 food products in the dietary interview data were categorized into 32 food and beverage groups/subgroups. Four major plasma TFAs (palmitelaidic acid, elaidic acid, vaccenic acid, linolelaidic acid) and the sum of the 4 TFAs (sumTFAs) were analyzed using GC-MS. Multivariable linear regression analyses were conducted to identify associations of plasma TFAs with all 32 food and beverage groups/subgroups, controlling for the potential confounding effects of 11 demographic, socioeconomic, behavioral, lifestyle, and health-related variables.

RESULTS

Consumption of the following food groups/subgroups was significantly associated with elevated plasma TFA concentrations: cream substitutes (P < 0.001 for palmitelaidic acid, elaidic acid, vaccenic acid, and sumTFAs); cakes, cookies, pastries, and pies (P < 0.001 for elaidic acid, vaccenic acid, and sumTFAs; P < 0.05 for linolelaidic acid); milk and milk desserts (P < 0.01 for palmitelaidic acid and vaccenic acid; P < 0.05 for linolelaidic acid and sumTFAs); beef/veal, lamb/goat, and venison/deer (P < 0.01 for vaccenic acid; P < 0.05 for sumTFAs); and butters (P < 0.001 for palmitelaidic acid and vaccenic acid; P < 0.05 for sumTFAs).

CONCLUSIONS

The findings suggest that the above 5 food groups/subgroups could be the main dietary sources of plasma TFAs among adults in the United States in 2009-2010.

Fatty Acids and Cardiovascular Risk. Evidence, Lack of Evidence, and Diligence

One of the most controversial areas of nutrition research relates to fats, particularly essential fatty acids, in the context of cardiovascular disease risk. A critical feature of dietary fatty acids is that they incorporate into the plasma membrane, modifying fluidity and key physiological functions. Importantly, they can reshape the bioavailability of eicosanoids and other lipid mediators, which direct cellular responses to external stimuli, such as inflammation and chronic stress conditions. This paper provides an overview of the most recent evidence, as well as historical controversies, linking fat consumption with human health and disease. We underscore current pitfalls in the area of fatty acid research and critically frame fatty acid intake in the larger context of diet and behavior. We conclude that fundamental research on fatty acids and lipids is appropriate in certain areas, but the rigor and reproducibility are lacking in others. The pros and cons are highlighted throughout the review, seeking to guide future research on the important area of nutrition, fat intake, and cardiovascular disease risk.

B. Assis R, Zaini PA, Wilmarth PA, Phinney BS, Moreira LM, Dandekar AM. Proteome Analysis of Walnut Bacterial Blight Disease

The interaction between the plant host, walnut (Juglans regia; Jr), and a deadly pathogen (Xanthomonas arboricola pv. juglandis 417; Xaj) can lead to walnut bacterial blight (WB), which depletes walnut productivity by degrading the nut quality. Here, we dissect this pathosystem using tandem mass tag quantitative proteomics. Walnut hull tissues inoculated with Xaj were compared to mock-inoculated tissues, and 3972 proteins were identified, of which 3296 are from Jr and 676 from Xaj. Proteins with differential abundance include oxidoreductases, proteases, and enzymes involved in energy metabolism and amino acid interconversion pathways. Defense responses and plant hormone biosynthesis were also increased. Xaj proteins detected in infected tissues demonstrate its ability to adapt to the host microenvironment, limiting iron availability, coping with copper toxicity, and maintaining energy and intermediary metabolism. Secreted proteases and extracellular secretion apparatus such as type IV pilus for twitching motility and type III secretion effectors indicate putative factors recognized by the host. Taken together, these results suggest intense degradation processes, oxidative stress, and general arrest of the biosynthetic metabolism in infected nuts. Our results provide insights into molecular mechanisms and highlight potential molecular tools for early detection and disease control strategies.

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.

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.

Association of nut intake with risk factors, cardiovascular disease, and mortality in 16 countries from 5 continents: analysis from the Prospective Urban and Rural Epidemiology (PURE) study

BACKGROUND

The association of nuts with cardiovascular disease and deaths has been investigated mostly in Europe, the USA, and East Asia, with few data available from other regions of the world or from low- and middle-income countries.

OBJECTIVE

To assess the association of nuts with mortality and cardiovascular disease (CVD).

METHODS

The Prospective Urban Rural Epidemiology study is a large multinational prospective cohort study of adults aged 35-70 y from 16 low-, middle-, and high-income countries on 5 continents. Nut intake (tree nuts and ground nuts) was measured at the baseline visit, using country-specific validated FFQs. The primary outcome was a composite of mortality or major cardiovascular event [nonfatal myocardial infarction (MI), stroke, or heart failure].

RESULTS

We followed 124,329 participants (age = 50.7 y, SD = 10.2; 41.5% male) for a median of 9.5 y. We recorded 10,928 composite events [deaths (n = 8,662) or major cardiovascular events (n = 5,979)]. Higher nut intake (>120 g per wk compared with <30 g per mo) was associated with a lower risk of the primary composite outcome of mortality or major cardiovascular event [multivariate HR (mvHR): 0.88; 95% CI: 0.80, 0.96; P-trend = 0.0048]. Significant reductions in total (mvHR: 0.77; 95% CI: 0.69, 0.87; P-trend <0.0001), cardiovascular (mvHR: 0.72; 95% CI: 0.56, 0.92; P-trend = 0.048), and noncardiovascular mortality (mvHR: 0.82; 95% CI: 0.70, 0.96; P-trend = 0.0046) with a trend to reduced cancer mortality (mvHR: 0.81; 95% CI: 0.65, 1.00; P-trend = 0.081) were observed. No significant associations of nuts were seen with major CVD (mvHR: 0.91; 95% CI: 0.81, 1.02; P-trend = 0.14), stroke (mvHR: 0.98; 95% CI: 0.84, 1.14; P-trend = 0.76), or MI (mvHR: 0.86; 95% CI: 0.72, 1.04; P-trend = 0.29).

CONCLUSIONS

Higher nut intake was associated with lower mortality risk from both cardiovascular and noncardiovascular causes in low-, middle-, and high-income countries.

A Pilot Study on the Effects of Nut Consumption on Cardiovascular Biomarkers

BACKGROUND

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality in the United States and changes in lifestyle can minimize the likelihood of succumbing to heart disease. Anti-inflammatory agents are commonly used to reduce the chronic inflammatory state behind the pathogenesis of CVD. Multiple studies have been published correlating nut consumption with a reduction in both heart attacks and strokes. The goal of this study is to determine to what extent the consumption of almonds, hazelnuts, and walnuts have on the blood markers associated with cardiac disease and inflammation.

METHODS

This was a six-week study in which subject's baseline values act as controls. Fasting blood draws occurred at week 0, week 2, and after four weeks of intervention (week 6). All participants had undesirable lipid profiles and no medications related to heart disease.

RESULTS

Total cholesterol (TC): high-density lipoprotein (HDL-C) ratio was lowered a statistically significant amount at the six-week time point (3.89 ± 0.74) compared to both the zero-week (4.93 ± 1.16, p < 0.01) and two-week (4.63 ± 1.20, p < 0.5) timepoints. Low-density lipoprotein (LDL) measurements were lowered a statistically significant amount at the six-week time point (135.6 ± 15.0 mg/dL) compared to the zero-week (159.7 ± 12.3 mg/dL, p < 0.01). Erythrocyte sedimentation rate (ESR) was lowered a statistically significant amount at six-week time point (10.44 ± 5.05 mm/h) compared to the zero-week (14.44 ± 5.12 mm/h, p < 0.01).

CONCLUSIONS

Blood markers associated with CVD specifically and the general marker for inflammation associated with many chronic diseases can be favorably modified with the consumption of specific nuts as demonstrated by this study.

Bioactive Peptides from Walnut Residue Protein

Walnut residue is a kind of high-quality plant protein resource. The bioactive peptide prepared from walnut residue has excellent health care functions such as antioxidation and antihypertensive activity, but at present, walnut residue is often regarded as waste or low value feed, fertilizer and other materials. The uneconomical use of walnut residue has hindered the development of the walnut industry to some extent. Effective utilization of walnut residue protein to develop bioactive peptides and other products is of great significance to realize the comprehensive utilization of walnut residue, improve the added value of by-products, and change the current low utilization rate of walnut residue. In this paper, the preparation, purification and structure identification of walnut protein bioactive peptides are reviewed, and different functional walnut active peptides (WBPs) are introduced. The potential effects of these bioactivities on human health and their different uses in food, medicine and other industries are discussed. The purpose is to provide reference information for the effective utilization of walnut residue resources and the development of walnut industry.

Energy extraction from nuts: walnuts, almonds and pistachios

The bioaccessibility of fat has implications for satiety and postprandial lipidaemia. The prevailing view holds that the integrity of plant cell wall structure is the primary determinant of energy and nutrient extraction from plant cells as they pass through the gastrointestinal (GI) tract. However, comparisons across nuts (walnuts, almonds and pistachios) with varying physical properties do not support this view. In the present study, masticated samples of three nuts from healthy adults were exposed to a static model of gastric digestion followed by simulated intestinal digestion. Primary outcomes were particle size and lipid release at each phase of digestion. Walnuts produced a significantly larger particle size post-mastication compared with almonds. Under gastric and intestinal conditions, the particle size was larger for walnuts compared with pistachios and almonds (P < 0·05). However, the masticated and digesta particle sizes were not related to the integrity of cell walls or lipid release. The total lipid release was comparable between nuts after the in vitro intestinal phase (P > 0·05). Microstructural examination showed ruptured and fissured cell walls that would allow digestion of cellular contents, and this may be governed by internal cellular properties such as oil body state. Furthermore, the cell walls of walnuts tend to rupture rather than separate and as walnut tissue passes through the GI tract, lipids tend to coalesce reducing digestion efficiency.

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.

Effects of Supplementing the Usual Diet with a Daily Dose of Walnuts for Two Years on Metabolic Syndrome and Its Components in an Elderly Cohort

Accumulating evidence links nut consumption with an improved risk of metabolic syndrome (MetS); however, long-term trials are lacking. We examined the effects of a daily dose of walnuts for two years on MetS in a large elderly cohort. A total of 698 healthy elderly participants were randomly assigned to either a walnut supplemented or a control diet. The participants in the walnut group were provided with packaged walnuts (1, 1.5, or 2 oz. or ~15% of energy) and asked to incorporate them into their daily habitual diet. The participants in the control group were asked to continue with their habitual diet and abstain from eating walnuts and other tree nuts. Intake of n-3 fatty acid supplements was not permitted in either group. Fasting blood chemistries, blood pressure, and anthropometric measurements were obtained at baseline and at the end of intervention. A total of 625 participants (67% women, mean age 69.1 y) completed this two-year study (90% retention rate). Triglycerides decreased in both walnut (-0.94 mg/dl) and control (-0.96 mg/dl) groups, with no significant between-group differences. There was a non-significant decrease in systolic and diastolic blood pressure in the walnut group (-1.30 and -0.71 mm Hg, respectively) and no change in the control group. Fasting blood glucose decreased by ~1 point in both the walnut and control groups. There were no significant between-group differences in the development or reversion of MetS. In conclusion, supplementing the diet of older adults with a daily dose of walnuts had no effect on MetS status or any of its components, although the walnut group tended to have lower blood pressure.

Identification of the characteristic components in walnut and anti-inflammatory effect of glansreginin A as an indicator for quality evaluation

Walnut is a nutritious food material, but only a few studies have been conducted on the mechanisms of its functions and the technique for quality evaluation. Therefore, we analyzed the components in aqueous methanol extract of walnut, and characterized 30 components, including three new compounds, glansreginin C, ellagic acid 4-O-(3′-O-galloyl)-β-D-xyloside, and platycaryanin A methyl ester. We analyzed the extracts of other nuts using HPLC and clarified that a characteristic peak corresponding to glansreginin A was mainly observed in walnut. These results suggested that glansreginin A might be an indicator component of the quality of walnut. We then examined whether glansreginin A has neuroprotective effect, using lipopolysaccharide (LPS)-induced inflammatory model mice. The results revealed that oral administration of glansreginin A prevented LPS-induced abnormal behavior and LPS-induced hyper-activation of microglia in the hippocampus. These results suggested that glansreginin A has the ability to exert neuroprotective effect via anti-inflammation in the brain.

Neuroprotective and Memory-Enhancing Effects of Antioxidant Peptide From Walnut (Juglans regia L.) Protein Hydrolysates

Peptides have been reported to possess interesting biological properties. The present study was designed to evaluate neuroprotective and memory-enhancing effects of antioxidant peptide from walnut ( Juglans regia L.) protein hydrolysates. The neuroprotective effect of walnut peptide (WP) against oxidative stress on PC12 cells was evaluated. And zebrafish was used as the model to corroborate the effect. Its effect on learning and memory of mice using the Morris water maze and the step-down passive avoidance tests were performed. Moreover, the acute toxicity of WP was carried out to assess its safety profile. It was found that WP was able to suppress H2O2-induced cell death in PC12 cells. In the zebrafish model, WP had an obvious neuroprotective effect, and the ratio reached 42% at 222 µg/mL. The mechanism study revealed that WP could inhibit the activity of caspases 3/7 and 8, reduce the mRNA expression levels of Bax and glial cell line-derived neurotrophic factor, and improve the mRNA expression level of brain-derived neurotrophic factor significantly. Besides, the treatment of mice with WP shortened the escape latency and exhibited much longer target time and more crossing times significantly, compared with untreated control groups in the Morris water maze test. Similarly, the step-down passive avoidance test showed that WP could ameliorate memory impairments. The administrated dose (20.1 g/kg body weight [BW]) did not produce mortality or treatment-related adverse effects with regard to BW, general behavior, or relative organ weights of the tested male and female mice. The current results indicated that WP could exert neuroprotective effect, and attenuated learning and memory impairments. These ameliorating effects of WP may be useful for treatment of memory impairment in Alzheimer’s and its related diseases.

Sequencing a Juglans regia × J. microcarpa hybrid yields high-quality genome assemblies of parental species

Members of the genus Juglans are monecious wind-pollinated trees in the family Juglandaceae with highly heterozygous genomes, which greatly complicates genome sequence assembly. The genomes of interspecific hybrids are usually comprised of haploid genomes of parental species. We exploited this attribute of interspecific hybrids to avoid heterozygosity and sequenced an interspecific hybrid Juglans microcarpa × J. regia using a novel combination of single-molecule sequencing and optical genome mapping technologies. The resulting assemblies of both genomes were remarkably complete including chromosome termini and centromere regions. Chromosome termini consisted of arrays of telomeric repeats about 8 kb long and heterochromatic subtelomeric regions about 10 kb long. The centromeres consisted of arrays of a centromere-specific Gypsy retrotransposon and most contained genes, many of them transcribed. Juglans genomes evolved by a whole-genome-duplication dating back to the Cretaceous-Paleogene boundary and consist of two subgenomes, which were fractionated by numerous short gene deletions evenly distributed along the length of the chromosomes. Fractionation was shown to be asymmetric with one subgenome exhibiting greater gene loss than the other. The asymmetry of the process is ongoing and mirrors an asymmetry in gene expression between the subgenomes. Given the importance of J. microcarpa × J. regia hybrids as potential walnut rootstocks, we catalogued disease resistance genes in the parental genomes and studied their chromosomal distribution. We also estimated the molecular clock rates for woody perennials and deployed them in estimating divergence times of Juglans genomes and those of other woody perennials.

The clinical utility of the AUSDRISK tool in assessing change in type 2 diabetes risk in overweight/obese volunteers undertaking a healthy lifestyle intervention

The objective of this study was to assess the clinical utility of the AUSDRISK tool for determining risk of Type 2 diabetes mellitus (T2DM). In this secondary analysis from the HealthTrack study, the AUSDRISK tool was applied to data from overweight/obese volunteers completing a lifestyle intervention trial. Participants were volunteer residents of the Illawarra region recruited in 2014–2015. From 377 trial participants (BMI 25–40 kg/m², 25–54 yr), 161 provided data required for measurement of AUSDRISK, collected at 0 and 12 months. They had been randomised to one of two lifestyle interventions (±a healthy food sample, 30 g walnuts/day, I and IW) delivered by dietitians, or a control intervention (C) delivered by nurse practitioners. HbA1c measures were considered for comparison. At baseline the AUSDRISK score indicated n = 83 (51.5%) were at high risk of T2DM within 5 years (≥12 points). After 12 months the proportion scored as high risk significantly decreased in the IW group (51.5% vs 33.3%; p = 0.005), but not I (51.2% vs 39.0%; p = 0.063) or C group (51.9% vs 38.9%; p = 0.065). By comparison, HbA1c measures indicated high risk in n = 24 (17%) of 139 participants at baseline and borderline non-significant changes over time in the randomised groups. In conclusion, the AUSDRISK tool has reasonable clinical utility in identifying T2DM risk in clinical samples of overweight/obese individuals.

Natural Products to Fight Cancer: A Focus on Juglans regia

Even if cancer represents a burden for human society, an exhaustive cure has not been discovered yet. Low therapeutic index and resistance to pharmacotherapy are two of the major limits of antitumour treatments. Natural products represent an excellent library of bioactive molecules. Thus, tapping into the natural world may prove useful in identifying new therapeutic options with favourable pharmaco-toxicological profiles. Juglans regia, or common walnut, is a very resilient tree that has inhabited our planet for thousands of years. Many studies correlate walnut consumption to beneficial effects towards several chronic diseases, such as cancer, mainly due to the bioactive molecules stored in different parts of the plant. Among others, polyphenols, quinones, proteins, and essential fatty acids contribute to its pharmacologic activity. The present review aims to offer a comprehensive perspective about the antitumour potential of the most promising compounds stored in this plant, such as juglanin, juglone, and the ellagitannin-metabolites urolithins or deriving from walnut dietary intake. All molecules and a chronic intake of the fruit provide tangible anticancer effects. However, the scarcity of studies on humans does not allow results to be conclusive.

Effects of walnut consumption on blood lipids and other cardiovascular risk factors: an updated meta-analysis and systematic review of controlled trials

BACKGROUND

Intervention studies suggest that incorporating walnuts into the diet may improve blood lipids without promoting weight gain.

OBJECTIVE

We conducted a systematic review and meta-analysis of controlled trials evaluating the effects of walnut consumption on blood lipids and other cardiovascular risk factors.

Design

We conducted a comprehensive search of PubMed and EMBASE databases (from database inception to January 2018) of clinical trials comparing walnut-enriched diets with control diets. We performed random-effects meta-analyses comparing walnut-enriched and control diets for changes in pre-post intervention in blood lipids (mmol/L), apolipoproteins (mg/dL), body weight (kg), and blood pressure (mm Hg).

RESULTS

Twenty-six clinical trials with a total of 1059 participants were included. The following weighted mean differences (WMDs) in reductions were obtained for walnut-enriched diets compared with control groups: -6.99 mg/dL (95% CI: -9.39, -4.58 mg/dL; P < 0.001) (3.25% greater reduction) for total blood cholesterol (TC) and -5.51 mg/dL (95% CI: -7.72, -3.29 mg/dL; P < 0.001) (3.73% greater reduction) for low-density lipoprotein (LDL) cholesterol. Triglyceride concentrations were also reduced in walnut-enriched diets compared with control [WMD = -4.69 (95% CI: -8.93, -0.45); P = 0.03; 5.52% greater reduction]. More pronounced reductions in blood lipids were observed when walnut interventions were compared with American and Western diets [WMD for TC = -12.30 (95% CI: -23.17, -1.43) and for LDL = -8.28 (95% CI: -13.04, -3.51); P < 0.001]. Apolipoprotein B (mg/dL) was also reduced significantly more on walnut-enriched diets compared with control groups [WMD = -3.74 (95% CI: -6.51, -0.97); P = 0.008] and a trend towards a reduction was observed for apolipoprotein A [WMD = -2.91 (95% CI: -5.98, 0.08); P = 0.057]. Walnut-enriched diets did not lead to significant differences in weight change (kg) compared with control diets [WMD = -0.12 (95% CI: -2.12, 1.88); P = 0.90], systolic blood pressure (mm Hg) [WMD = -0.72 (95% CI: -2.75, 1.30); P = 0.48], or diastolic blood pressure (mm Hg) [WMD = -0.10 (95% CI: -1.49, 1.30); P = 0.88].

Conclusions

Incorporating walnuts into the diet improved blood lipid profile without adversely affecting body weight or blood pressure.

Walnut Consumption Alters the Gastrointestinal Microbiota, Microbially Derived Secondary Bile Acids, and Health Markers in Healthy Adults: A Randomized Controlled Trial

Background

Epidemiologic data suggest that diets rich in nuts have beneficial health effects, including reducing total and cause-specific mortality from cancer and heart disease. Although there is accumulating preclinical evidence that walnuts beneficially affect the gastrointestinal microbiota and gut and metabolic health, these relations have not been investigated in humans.

Objective

We aimed to assess the impact of walnut consumption on the human gastrointestinal microbiota and metabolic markers of health.

Methods

A controlled-feeding, randomized crossover study was undertaken in healthy men and women [n = 18; mean age = 53.1 y; body mass index (kg/m2): 28.8]. Study participants received isocaloric diets containing 0 or 42 g walnuts/d for two 3-wk periods, with a 1-wk washout between diet periods. Fecal and blood samples were collected at baseline and at the end of each period to assess secondary outcomes of the study, including effects of walnut consumption on fecal microbiota and bile acids and metabolic markers of health.

Results

Compared with after the control period, walnut consumption resulted in a 49-160% higher relative abundance of Faecalibacterium, Clostridium, Dialister, and Roseburia and 16-38% lower relative abundances of Ruminococcus, Dorea, Oscillospira, and Bifidobacterium (P < 0.05). Fecal secondary bile acids, deoxycholic acid and lithocholic acid, were 25% and 45% lower, respectively, after the walnut treatment compared with the control treatment (P < 0.05). Serum LDL cholesterol and the noncholesterol sterol campesterol concentrations were 7% and 6% lower, respectively, after walnut consumption compared with after the control treatment (P < 0.01).

Conclusion

Walnut consumption affected the composition and function of the human gastrointestinal microbiota, increasing the relative abundances of Firmicutes species in butyrate-producing Clostridium clusters XIVa and IV, including Faecalibacterium and Roseburia, and reducing microbially derived, proinflammatory secondary bile acids and LDL cholesterol. These results suggest that the gastrointestinal microbiota may contribute to the underlying mechanisms of the beneficial health effects of walnut consumption. This trial was registered at www.clinicaltrials.gov as NCT01832909.

Dietary Walnuts Protect Against Obesity-Driven Intestinal Stem Cell Decline and Tumorigenesis

Obesity can negatively impact intestinal homeostasis, and increase colon cancer risk and related mortality. Thus, given the alarmingly high rates of obesity in the US and globally, it is critical to identify practical strategies that can break the obesity-cancer link. Walnuts have been increasingly recognized to mitigate cancer risk, and contain many bioactive constituents with antioxidant and anti-inflammatory properties that could potentially counteract pathways thought to be initiators of obesity-related cancer. Therefore, the purpose of this study was to determine if walnuts could preserve intestinal homeostasis, and attenuate tumorigenesis and growth in the context of obesity and a high calorie diet. To this end, we studied effects of walnuts on these parameters under different dietary conditions in wildtype mice, two independent Apc models (Apc^1638N/+ and Apc^Δ14), and in MC38 colon cancer cells in vivo, respectively. Walnuts did not alter the metabolic phenotype or intestinal morphology in normal mice fed either a low-fat diet (LFD), LFD with 6% walnuts (LFD+W), high-fat diet (HFD), or HFD with 7.6% walnuts (HFD+W). However, walnuts did lead to a significant reduction in circulating CCL5 and preserved intestinal stem cell (ISC) function under HFD-fed conditions. Furthermore, walnuts reduced tumor multiplicity in Apc^1638N/+ male HFD+W animals, as compared to HFD controls (3.7 ± 0.5 vs. 2.5 ± 0.3; P = 0.015), tended to reduce the number of adenocarcinomas (0.67 ± 0.16 vs. 0.29 ± 0.12; P = 0.07), and preferentially limited tumor growth in Apc^Δ14 male mice (P = 0.019) fed a high-calorie western-style diet. In summary, these data demonstrate that walnuts confer significant protection against intestinal tumorigenesis and growth and preserve ISC function in the context of a high-calorie diet and obesity. Thus, these data add to the accumulating evidence connecting walnuts as a potentially effective dietary strategy to break the obesity-colon cancer link.

Cardiovascular Benefits of Dietary Melatonin: A Myth or a Reality?

The role of the diet as well as the impact of the dietary habits on human health and disease is well established. Apart from its sleep regulatory effect, the indoleamine melatonin is a well-established antioxidant molecule with multiple health benefits. Convincing evidence supports the presence of melatonin in plants and foods with the intake of such foods affecting circulating melatonin levels in humans. While numerous actions of both endogenous melatonin and melatonin supplementation are well described, little is known about the influence of the dietary melatonin intake on human health. In the present review, evidence for the cardiovascular health benefits of melatonin supplementation and dietary melatonin is discussed. Current knowledge on the biological significance as well as the underlying physiological mechanism of action of the dietary melatonin is also summarized. Whether dietary melatonin constitutes an alternative preventive treatment for cardiovascular disease is addressed.

Nutrients and Oxidative Stress: Friend or Foe?

There are different types of nutritionally mediated oxidative stress sources that trigger inflammation. Much information indicates that high intakes of macronutrients can promote oxidative stress and subsequently contribute to inflammation via nuclear factor-kappa B- (NF-κB-) mediated cell signaling pathways. Dietary carbohydrates, animal-based proteins, and fats are important to highlight here because they may contribute to the long-term consequences of nutritionally mediated inflammation. Oxidative stress is a central player of metabolic ailments associated with high-carbohydrate and animal-based protein diets and excessive fat consumption. Obesity has become an epidemic and represents the major risk factor for several chronic diseases, including diabetes, cardiovascular disease (CVD), and cancer. However, the molecular mechanisms of nutritionally mediated oxidative stress are complex and poorly understood. Therefore, this review aimed to explore how dietary choices exacerbate or dampen the oxidative stress and inflammation. We also discussed the implications of oxidative stress in the adipocyte and glucose metabolism and obesity-associated noncommunicable diseases (NCDs). Taken together, a better understanding of the role of oxidative stress in obesity and the development of obesity-related NCDs would provide a useful approach. This is because oxidative stress can be mediated by both extrinsic and intrinsic factors, hence providing a plausible means for the prevention of metabolic disorders.

Walnut Supplementation in the Diet Reduces Oxidative Damage and Improves Antioxidant Status in Transgenic Mouse Model of Alzheimer's Disease

Our previous study has shown beneficial effects of walnuts on memory and learning skills in transgenic mouse model of Alzheimer's disease (AD-tg). To understand underlying mechanism, we studied here whether walnuts can reduce oxidative stress in AD. From 4 months of age, experimental AD-tg mice were fed diets containing 6% (T6) or 9% walnuts (T9) (equivalent to 1 or 1.5 oz, of walnuts per day in humans) for 5, 10, or 15 months. The control groups, i.e., AD-tg (T0) and wild-type (Wt) mice, were fed diets without walnuts. Free radicals, i.e., reactive oxygen species (ROS), lipid peroxidation, protein oxidation, and antioxidant enzymes were assessed in these mice at different ages. AD-tg mice on control diet (T0) showed significant age-dependent increase in ROS levels, lipid peroxidation, and protein oxidation coupled with impaired activities of antioxidant enzymes [superoxide dismutase, catalase, and glutathione peroxidase] compared to Wt mice. Oxidative stress was significantly reduced in AD-tg mice on diets with walnuts (T6, T9), as evidenced by decreased levels of ROS, lipid peroxidation, and protein oxidation, as well as by enhanced activities of antioxidant enzymes compared to T0 mice. Long-term supplementation with walnuts for 10 or 15 months was more effective in reducing oxidative stress in AD-tg mice. Our findings indicate that walnuts can reduce oxidative stress, not only by scavenging free radicals, but also by protecting antioxidant status, thus leading to reduced oxidative damage to lipids and proteins in AD. Therefore, by reducing oxidative stress, a walnut-enriched diet may help reduce the risk or delay the onset and progression of AD.

Almond, hazelnut and walnut, three nuts for neuroprotection in Alzheimer's disease: A neuropharmacological review of their bioactive constituents

An increase in the prevalence of Alzheimer's disease (AD) as a multifactorial neurodegenerative disorder is an almost obvious issue in the world. Researches on natural products for finding effective drugs to prevent the disease are in progress. There is special attention to the three types of nuts including almond, hazelnut and walnut in manuscripts of traditional Persian medicine (PM) as the preventive agents against brainatrophy and memory loss. The purpose of this study is a pharmacological review of their bioactive constituents and introducing the value of these nuts as the effective supplements and natural medicinal foods in AD patients. Databases including PubMed and ScienceDirect were searched in title, abstract and keywords from year 2000 to present for AD-related researches on these tree nuts, their major phytochemicals and their mechanisms of action. As result, almond, hazelnut and walnut provide macronutrients, micronutrients, and phytochemicals which affect several pathways in AD pathogenesis such as amyloidogenesis, tau phosphorylation, oxidative stress, cholinergic pathways, and some non-target mechanisms including cholesterol lowering and anti-inflammatory properties, as well as effect on neurogenesis. These nuts are recommended in PM for their brain-protective activity and particularly reversing brain atrophy in case of hazelnut. The therapeutical statements of PM scholars mentioned in their books are based on their clinical observations with support of a long history of experiences. Beyond the molecular activities attributed to the phytochemicals, the use of these tree nuts could be more considered in scientific researches as the effective nutrients for prevention or even management of AD.

Co-administration of walnut (Juglans regia) prevents systemic hypertension induced by long-term use of dexamethasone: a promising strategy for steroid consumers

CONTEXT

The long-term consumption of glucocorticoids (GCs) may induce serious adverse effects such as hypertension. There is sufficient evidence related to the benefit of walnuts on the cardiovascular system.

OBJECTIVE

This study assesses the effect of methanol extract of walnut [Juglans regia L. (Juglandaceae)] on dexamethasone-induced hypertension and the possible mechanisms in Wistar rats.

MATERIAL AND METHODS

Animals were randomized into control, kernel extract (100 and 200 mg/kg/d, orally), dexamethasone (0.03 mg/kg/d, subcutaneously), dexamethasone + kernel (100 and 200 mg/kg/d, separately), and dexamethasone + captopril (25 mg/kg/d, orally) groups. Animals were treated with water, kernel extract or captopril by gavage 4 d before and during 11 d of saline or dexamethasone treatment. On the 16th day, blood pressure (BP) was recorded and blood samples were collected to measure nitric oxide (NO). Animal hearts were frozen for measurement of malondialdehyde (MDA) and glutathione peroxidase (GPX).

RESULTS

Dexamethasone increased the diastolic BP and MDA/GPX ratio in comparison with control group (128 ± 7 vs. 105 ± 3 mmHg, p < 0.05 and 0.2 ± 0.046 vs. 0.08 ± 0.02, p < 0.05). Combination of dexamethasone and walnut (200 mg/kg) prevented the dexamethasone-induced diastolic hypertension (109 ± 3 vs. 128 ± 7 mmHg; p < 0.05), increased the GPX level (14.8 ± 1.46 vs. 5.1 ± 0.64 unit/mg, p < 0.05), reduced the MDA/GPX ratio (0.16 ± 0.015 vs. 0.2 ± 0.046) and improved serum NO level.

CONCLUSION

Similar to captopril, walnut extract normalized dexamethasone-induced hypertension. A part of this beneficial effect apparently involves maintaining balance of the redox system and NO production.

Nut Consumption and Risk of Cardiovascular Disease

BACKGROUND

The associations between specific types of nuts, specifically peanuts and walnuts, and cardiovascular disease remain unclear.

OBJECTIVES

The authors sought to analyze the associations between the intake of total and specific types of nuts and cardiovascular disease, coronary heart disease, and stroke risk.

METHODS

The authors included 76,364 women from the Nurses' Health Study (1980 to 2012), 92,946 women from the Nurses' Health Study II (1991 to 2013), and 41,526 men from the Health Professionals Follow-Up Study (1986 to 2012) who were free of cancer, heart disease, and stroke at baseline. Nut consumption was assessed using food frequency questionnaires at baseline and was updated every 4 years.

RESULTS

During 5,063,439 person-years of follow-up, the authors documented 14,136 incident cardiovascular disease cases, including 8,390 coronary heart disease cases and 5,910 stroke cases. Total nut consumption was inversely associated with total cardiovascular disease and coronary heart disease after adjustment for cardiovascular risk factors. The pooled multivariable hazard ratios for cardiovascular disease and coronary heart disease among participants who consumed 1 serving of nuts (28 g) 5 or more times per week, compared with the reference category (never or almost never), were 0.86 (95% confidence interval: 0.79 to 0.93; p for trend = 0.0002) and 0.80 (95% confidence interval: 0.72 to 0.89; p for trend <0.001), respectively. Consumption of peanuts and tree nuts (2 or more times/week) and walnuts (1 or more times/week) was associated with a 13% to 19% lower risk of total cardiovascular disease and 15% to 23% lower risk of coronary heart disease.

CONCLUSIONS

In 3 large prospective cohort studies, higher consumption of total and specific types of nuts was inversely associated with total cardiovascular disease and coronary heart disease.

Changes in the gut microbial communities following addition of walnuts to the diet

Walnuts are rich in omega-3 fatty acids, phytochemicals and antioxidants making them unique compared to other foods. Consuming walnuts has been associated with health benefits including a reduced risk of heart disease and cancer. Dysbiosis of the gut microbiome has been linked to several chronic diseases. One potential mechanism by which walnuts may exert their health benefit is through modifying the gut microbiome. This study identified the changes in the gut microbial communities that occur following the inclusion of walnuts in the diet. Male Fischer 344 rats (n=20) were randomly assigned to one of two diets for as long as 10 weeks: (1) walnut (W), and (2) replacement (R) in which the fat, fiber, and protein in walnuts were matched with corn oil, protein casein, and a cellulose fiber source. Intestinal samples were collected from the descending colon, the DNA isolated, and the V3-V4 hypervariable region of 16S rRNA gene deep sequenced on an Illumina MiSeq for characterization of the gut microbiota. Body weight and food intake did not differ significantly between the two diet groups. The diet groups had distinct microbial communities with animals consuming walnuts displaying significantly greater species diversity. Walnuts increased the abundance of Firmicutes and reduced the abundance of Bacteriodetes. Walnuts enriched the microbiota for probiotic-type bacteria including Lactobacillus, Ruminococcaceae, and Roseburia while significantly reducing Bacteroides and Anaerotruncus. The class Alphaproteobacteria was also reduced. Walnut consumption altered the gut microbial community suggesting a new mechanism by which walnuts may confer their beneficial health effects.

A walnut-containing meal had similar effects on early satiety, CCK, and PYY, but attenuated the postprandial GLP-1 and insulin response compared to a nut-free control meal

Regular nut consumption is associated with lower adiposity and reduced weight gain in adulthood. Walnut feeding studies have observed minimal effect on body weight despite potential additional energy intake. Several mechanisms may explain why consuming nuts promotes weight control, including increased early phase satiety, possibly reflected in postprandial response of gastrointestinal and pancreatic peptides hypothesized to affect appetite. The purpose of this study was to compare postprandial insulin, glucagon and gastrointestinal peptide response and satiety following a meal with ∼54% of energy from walnuts or cream cheese, using a within-subject crossover study design in overweight/obese adults (N = 28). Sixty minutes after the walnut-containing meal, glucagon-like peptide-1 was lower than after the reference meal (p=0.0433), and peptide YY, cholecystokinin and ghrelin did not differ after the two meals. Sixty and 120 min after the walnut-containing meal, pancreatic polypeptide (p = 0.0014 and p = 0.0002) and glucose-dependent insulinotropic peptide (p < 0.0001 and p = 0.0079) were lower than after the reference meal, and 120 min after the walnut-containing meal, glucagon was higher (p=0.0069). Insulin and C-peptide increased at 60 min in response to both meals but were lower at 120 min after the walnut-containing meal (p=0.0349 and 0.0237, respectively). Satiety measures were similar after both meals. These findings fail to support the hypothesis that acute postprandial gastrointestinal peptide response to a walnut-containing meal contributes to increased satiety. However, inclusion of walnuts attenuated the postprandial insulin response, which may contribute to the more favorable lipid profile observed in association with regular walnut consumption.

Compositional analysis of walnut lipid extracts and properties as an anti-cancer stem cell regulator via suppression of the self-renewal capacity

Colon cancer is a leading cause of cancer-related deaths worldwide. Effects of walnut (Juglans regia L.) lipid extracts (WLEs) on the self-renewal capacity of cancer stem cells (CSCs) in colon cancer were investigated. The dominant component of WLEs was α-linoleic acid (64.6%), followed by α-linolenic acid (14.6%), and oleic acid (12.6%). A higher concentration of γ-tocopherol (37.1%) was also present than of α-tocopherol (0.6%). CD133⁺CD44⁺CSCs treated with WLEs showed inhibition of colony formation and sphere formation, indicating a decrease in the self-renewal capacity. Treatment with WLEs also resulted in down-regulation of protein levels, including Notch1, phospho-GSK3β (p-GSK3β), and β-catenin, which are associated with CSCs and the self-renewing capacity. WLEs rich in essential fatty acids and γ-tocopherol can exert therapeutic actions on colon cancer via targeting of CSCs.

Effects of Diet Composition and Insulin Resistance Status on Plasma Lipid Levels in a Weight Loss Intervention in Women

BACKGROUND

Optimal macronutrient distribution of weight loss diets has not been established. The distribution of energy from carbohydrate and fat has been observed to promote differential plasma lipid responses in previous weight loss studies, and insulin resistance status may interact with diet composition and affect weight loss and lipid responses.

METHODS AND RESULTS

Overweight and obese women (n=245) were enrolled in a 1-year behavioral weight loss intervention and randomly assigned to 1 of 3 study groups: a lower fat (20% energy), higher carbohydrate (65% energy) diet; a lower carbohydrate (45% energy), higher fat (35% energy) diet; or a walnut-rich, higher fat (35% energy), lower carbohydrate (45% energy) diet. Blood samples and data available from 213 women at baseline and at 6 months were the focus of this analysis. Triglycerides, total cholesterol, and high- and low-density lipoprotein cholesterol were quantified and compared between and within groups. Triglycerides decreased in all study arms at 6 months (P<0.05). The walnut-rich diet increased high-density lipoprotein cholesterol more than either the lower fat or lower carbohydrate diet (P<0.05). The walnut-rich diet also reduced low-density lipoprotein cholesterol in insulin-sensitive women, whereas the lower fat diet reduced both total cholesterol and high-density lipoprotein cholesterol in insulin-sensitive women (P<0.05). Insulin sensitivity and C-reactive protein levels also improved.

CONCLUSIONS

Weight loss was similar across the diet groups, although insulin-sensitive women lost more weight with a lower fat, higher carbohydrate diet versus a higher fat, lower carbohydrate diet. The walnut-rich, higher fat diet resulted in the most favorable changes in lipid levels.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01424007.

Omega-3 Polyunsaturated Fatty Acids Intake to Regulate Helicobacter pylori-Associated Gastric Diseases as Nonantimicrobial Dietary Approach

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), commonly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been acknowledged as essential long-chain fatty acids imposing either optimal health promotion or the rescuing from chronic inflammatory diseases such as atherosclerosis, fatty liver, and various inflammatory gastrointestinal diseases. Recent studies dealing with EPA and DHA have sparked highest interests because detailed molecular mechanisms had been documented with the identification of its receptor, G protein coupled receptor, and GPR120. In this review article, we have described clear evidences showing that n-3 PUFAs could reduce various Helicobacter pylori- (H. pylori-) associated gastric diseases and extended to play even cancer preventive outcomes including H. pylori-associated gastric cancer by influencing multiple targets, including proliferation, survival, angiogenesis, inflammation, and metastasis. Since our previous studies strongly concluded that nonantimicrobial dietary approach for reducing inflammation, for instance, application of phytoceuticals, probiotics, natural products including Korean red ginseng, and walnut plentiful of n-3 PUFAs, might be prerequisite step for preventing H. pylori-associated gastric cancer as well as facilitating the rejuvenation of precancerous atrophic gastritis, these beneficial lipids can restore or modify inflammation-associated lipid distortion and correction of altered lipid rafts to send right signaling to maintain healthy stomach even after chronic H. pylori infection.