Maternal diet supplemented with African walnuts enhances cortico-hippocampal gene expression and histomorphology in rat offspring.

BACKGROUND: The brain is built up during pregnancy. How it functions afterwards depends on how the expectant mother's diet nourishes it. Walnuts contain significant quantities of polyunsaturated fatty acids (PUFAs) and bioactive phytochemicals, which enhance brain health and function even with advancing age. This study examined the effects of a walnut-enriched diet (WED) on corticohippocampal histoarchitecture and gene expression in rat offspring. MATERIALS AND METHODS: Twenty-eight female adult Wistar rats (n= 7) averaging about 185 g in weight were used for this study. After mating, pregnant dams were split randomly into four groups: A (standard rat chow/control), B (WED from GD 0 - PND 21), C (WED from GD 0 - PND 1), D (WED from PND 1 - PND 21). Offspring of dams were sacrificed at adolescence (PND 35), with brain tissues of interest harvested for subsequent analyses. RESULTS: We observed no significant correlates in litter size, body, and brain weights across the experimental groups. Histomorphology revealed no distortion in cellular layering and delineation of cells in the PFC and dentate gyrus of both control and WED groups. Nissl staining intensity was enhanced in the offspring of dams exposed to WED versus the control, indicating improved proteostasis. Upregulated mRNA expression of DNMT3a, H2Ax, OPA1, and BDNF was observed in cortical and hippocampal tissues of WEDexposed offspring compared with the control group. CONCLUSION: A diet enriched with African walnuts during early development induced changes predictive of cognitive improvements and enhanced stress-response signalling, plasticity, and neural resilience in rat offspring.

Effectiveness of Green Cupric Oxide Nanoparticles for Walnut Storage Pest Management.

Walnut yield and quality are often affected by beetle infestations, particularly those caused by Carpophilus truncatus (Murray) (Nitidulidae) and Oryzaephilus mercator (L.) (Silvanidae). Beetle damage exposes walnuts to microbial food spoilers such as Fusarium species. Insecticides currently used for beetle control are environmentally unfriendly. This work explored a green synthesis approach for copper oxide nanoparticles (CuO-NPs) in a basic medium at 30°C by hydrolates, aqueous extracts obtained from Lippia integrifolia and Pimpinella anisum, denoted as CuO-I and CuO-A, respectively. Characterization through XRD, FT-IR, Raman, UV-visible absorbance, and AFM techniques indicated that CuO-A and CuO-I have a size ranging from 2-10 nm in height. The antifungal assay showed that both have a similar efficacy (MID = 320 µg), 3-fold stronger than CuO- NPs obtained in absence of hydrolates (denoted CuO-W) (MID = 960 µg), with the broadest inhibitory halos (ID = 126-128 mm) observed for CuO-A. Insecticidal activity of CuO-NPs showed a concentration-dependent behavior, with CuO-I showing an effect comparable to that of diatomaceous earth. SEM images confirmed the adhesion of nanoparticles to insect surfaces, which could induce oxygen deprivation and disruption of metabolic processes. Both CuO-A and CuO-I are promising for their use in integrated pest control in walnut storage.

Elemental Profiling for the Detection of Food Mixtures: A Proof of Principle Study on the Detection of Mixed Walnut Origins Using Measured and Calculated Data.

Element profiling is a powerful tool for detecting fraud related to claims of geographical origin. However, these methods must be continuously developed, as mixtures of different origins in particular offer great potential for adulteration. This study is a proof of principle to determine whether elemental profiling is suitable for detecting mixtures of the same food but from different origins and whether calculated data from walnut mixtures could help to reduce the measurement burden. The calculated data used in this study were generated based on measurements of authentic, unadulterated samples. Five different classification models and three regression models were applied in five different evaluation approaches to detect adulteration or even distinguish between adulteration levels (10% to 90%). To validate the method, 270 mixtures of walnuts from different origins were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Depending on the evaluation approach, different characteristics were observed in mixtures when comparing the calculated and measured data. Based on the measured data, it was possible to detect admixtures with an accuracy of 100%, even at low levels of adulteration (20%), depending on the country. However, calculated data can only contribute to the detection of adulterated walnut samples in exceptional cases.

Dead-End Hybridization in Walnut Trees Revealed by Large-Scale Genomic Sequence Data.

Although hybridization plays a large role in speciation, some unknown fraction of hybrid individuals never reproduces, instead remaining as genetic dead-ends. We investigated a morphologically distinct and culturally important Chinese walnut, Juglans hopeiensis, suspected to have arisen from hybridization of Persian walnut (J. regia) with Asian butternuts (J. cathayensis, J. mandshurica, and hybrids between J. cathayensis and J. mandshurica). Based on 151 whole-genome sequences of the relevant taxa, we discovered that all J. hopeiensis individuals are first-generation hybrids, with the time for the onset of gene flow estimated as 370,000 years, implying both strong postzygotic barriers and the presence of J. regia in China by that time. Six inversion regions enriched for genes associated with pollen germination and pollen tube growth may be involved in the postzygotic barriers that prevent sexual reproduction in the hybrids. Despite its long-recurrent origination and distinct traits, J. hopeiensis does not appear on the way to speciation.

The effect of nuts consumption on circulating oxidized low-density lipoproteins: A systematic review and meta-analysis of randomized controlled trials.

This systematic review and meta-analysis evaluated the effect of nuts in decreasing circulating levels of oxidized low-density lipoproteins (ox-LDL). A literature search was performed of major electronic databases (MEDLINE/PubMed, Scopus, and ISI Web of Science) from inception up to November 15th, 2021 to find randomized controlled trials (RCTs) evaluating the effect of different nuts on circulating levels of ox-LDL. The effect size was determined using standardized mean difference (SMD) and corresponding 95% confidence intervals (CI). Evaluation of funnel plot, Begg's rank correlation, and Egger's weighted regression tests were used to assess the presence of publication bias in the meta-analysis. This systematic review and meta-analysis included 15 RCTs involving 997 subjects. Meta-analysis showed that nuts significantly decreased serum levels of ox-LDL. Besides, meta-regression results of the association between confounders such as duration of nuts consumption or delta LDL-cholesterol and levels of ox-LDL, were not significant. The correlation between nuts type and ox-LDL levels was significant in subgroup analyses suggesting the most significant effect of pistachios consumption on reducing the circulating concentrations of ox-LDL. To conclude, nuts consumption decreases the circulating concentrations of ox-LDL which might be beneficial for the prevention and/or progression of ASCVD.

Research Progress on the Preparation and Function of Antioxidant Peptides from Walnuts.

Food-derived peptides have good antioxidant activity and are highly safe for humans; consequently, there has been continuous growth in research on antioxidants, with potential applications in food, medicine, cosmetics, and other fields. Among food-derived peptides, walnut-derived peptides have attracted increasing attention as food-derived peptides rich in eight essential amino acids. This review summarizes the progress made in the development and identification of antioxidant peptides in walnut proteins. This article mainly describes the interaction between reactive oxygen species and cellular antioxidant products, modulation of enzyme content and activity, and regulation of the redox signaling pathways and analyzes the mechanisms of reduction in oxidative stress. Finally, the complex structure-activity relationships of walnut-derived peptides are analyzed based on their amino acid composition and secondary structure of the polypeptides. This review provides a theoretical basis for the production of walnut-derived antioxidant peptides and could help promote the development of the walnut industry.

Nut consumption is associated with a shift of the NMR lipoprotein subfraction profile to a less atherogenic pattern among older individuals at high CVD risk.

BACKGROUND: Scientific evidence has accumulated on the beneficial effects of nut consumption on cardiovascular risk and cholesterol reduction, but few studies have examined the effects of nuts on advanced measures of lipoprotein atherogenicity determined by nuclear magnetic resonance (NMR) spectroscopy. We analyzed associations between the amount and type of of nuts consumed and advanced measures of lipoprotein atherogenity and insulin resistance in older individuals at high cardiovascular risk. METHODS: The present observational study was carried out within the framework of the Prevención con Dieta Mediterránea (PREDIMED) trial. Cross-sectional and longitudinal analyses after 1-year of follow-up were conducted in 196 men and women recruited in the PREDIMED-Reus (Spain) center. Dietary intake was assessed using a validated semi-quantitative food questionnaire. Baseline and 1-year fasting plasma lipoprotein and metabolite profiling were performed in plasma using NMR spectra Vantera® Clinical Analyzer. Associations by tertiles of nut consumption between baseline and 1-year changes and advanced measures of lipoprotein atherogenicity, branched chain amminoacids, and measures of insulin resistance were tested by multivariable-adjusted ANCOVA models. RESULTS: Compared to paticipants in the bottom tertile, those in the top tertile of total nut consumption showed higher levels of large HDL particles and HDL-cholesterol, lower levels of branched-chain amino acids (BCAA) and GlycA, and reduced lipoprotein insulin resistance and diabetes risk index. Participants in the top tertile of walnut consumption disclosed lower levels of very large VLDL, total LDL particles, LDL-cholesterol, and GlycA. Participants in the top tertile of non-walnut nut consumption displayed higher levels of total HDL particles, HDL-cholesterol and apoliporotein A1, lower BCAA and GlycA, and reduced lipoprotein insulin resistance. Participants in the top tertile of 1-year changes in walnut consumption showed increases in medium-sized HDL particles in comparison to the bottom tertile. CONCLUSIONS: In older individuals at high cardiovascular risk, increasing nut consumption was associated with a shift of the NMR lipoprotein subfraction profile to a less atherogenic pattern, as well as lower circulating concentrations of BCAA and decreased insulin resistance. These results provide novel mechanistic insight into the cardiovascular benefit of nut consumption. Trial registration ISRCTN35739639; registration date: 05/10/2005; recruitment start date 01/10/2003.

Exploration of walnut components and their association with health effects.

Traditionally, walnuts have occupied an imperative position in the functional food market with consistently recognized nutritious and functional properties. In the past years, the lipid profile of walnuts has brought much scientific attention via linking a cascade of biological attributes and health-promoting effects. Over time, researchers have focused on diversified composition (polyphenols and vitamins) of different parts of walnut (flower, pellicle, and kernel) and emphasized their physiological significance. Consequently, a plethora of reports has emerged on the potential role of walnut consumption against a series of diseases including cancer, gut dysbiosis, cardiovascular, and neurodegenerative diseases. Therefore, we accumulated the updated data on composition and classification, extraction methods, and utilization of different parts of walnuts as well as associated beneficial effects under in vivo and clinical studies. Altogether, this review summarized the ameliorative effects of a walnut-enriched diet in chronic diseases which can be designated to the synergistic or individual effects of walnut components mainly through anti-oxidative and anti-inflammatory role.

n-3 index is associated with cardiometabolic risk factors but is not improved by walnut intake in free-living elderly: a single-blind, randomised controlled trial.

n-3 index, the erythrocyte proportion of the EPA + DHA fatty acids is a clinical marker of age-related disease risk. It is unclear whether regular intake of α-linolenic acid (ALA), a plant-derived n-3 polyunsaturated fatty acid, raises n-3 index in older adults. Of the 356 participants at the Loma Linda, CA centre from the original study, a randomly selected subset (n 192) was included for this secondary analysis (mostly Caucasian women, mean age 69 years). Participants were assigned to either the walnut (15 % of daily energy from walnuts) or the control group (usual diet, no walnuts) for 2 years. Erythrocyte fatty acids were determined at baseline and 1-year following intervention. No differences were observed for erythrocyte EPA, but erythrocyte DHA decreased albeit modestly in the walnut group (-0·125 %) and slightly improved in the control group (0·17 %). The change in n-3 index between the walnut and control groups was significantly different only among fish consumers (those who ate fish ≥ once/month). Longitudinal analyses combining both groups showed significant inverse association between the 1-year changes of the n-3 index and fasting plasma TAG (ß = -10), total cholesterol (ß = -5·59) and plasma glucose (ß = -0·27). Consuming ALA-rich walnuts failed to improve n-3 index in elders. A direct source of EPA/DHA may be needed to achieve desirable n-3 index, as it is inversely associated with cardiometabolic risk. Nevertheless, incorporating walnuts as part of heart healthy diets is still encouraged.

Association of nut consumption with CVD risk factors in young to middle-aged adults: The Coronary Artery Risk Development in Young Adults (CARDIA) study.

BACKGROUND AND AIMS: Few studies have examined long-term associations of walnut, other nut, and no nut consumption with cardiovascular disease (CVD) risk factors. Results from prospective studies with long-term follow-up can provide further evidence for dietary guideline messaging to consume nuts. Therefore, we examined the associations of walnut, other nut, and no nut consumption with diet quality and CVD risk factors over 30 years of follow-up. METHODS AND RESULTS: Data were analyzed from 3092 young adults enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Dietary intake, including walnuts and other nuts, was assessed 3 times over 20 years. CVD risk factors were measured at multiple exams. General linear regression evaluated the associations of walnut, other nut, and no nut consumption with CVD risk factors over 30 years (Y30) of follow-up. The 20-year cumulative mean intake of walnuts (0.74 oz/d), other nuts (1.6 oz/d), or no nut consumption was differentially associated with HEI-2015 and CVD risk factors by Y30. Generally, walnut consumers had significantly higher HEI-2015, lower body mass index, waist circumference, blood pressure, and triglyceride concentration, and gained less weight since baseline than other nut consumers (p ≤ 0.05 for all). Further, walnut consumers had lower fasting blood glucose than no nut consumers (p ≤ 0.05). CONCLUSION: Study findings that walnut and other nut consumption was associated with better CVD risk factors and diet quality aligns with the 2020-2025 US. Dietary Guidelines for Americans recommendation to consume nuts, such as walnuts, within the context of a healthy diet.

[Management of severe nut allergy in adults]. / Management einer schweren Nussallergie im Erwachsenenalter.

We present a case of walnut allergy in a 24-year-old man. The allergy work up revealed sensitization to walnut including a positive skin prick test and a high value of walnut-specific IgEs. The patient showed an anaphylactic reaction during the double blind placebo-controlled food challenge, to a cumulative dose of 3.723 g of walnut protein. The oral food challenge resulted in counseling regarding strict walnut avoidance and optimization of the emergency management. At follow-up the patient reported that having adhered to the recommended dietary measures resulted in no further allergic reactions.

Walnut Consumption, Plasma Metabolomics, and Risk of Type 2 Diabetes and Cardiovascular Disease.

BACKGROUND: Walnut consumption is associated with lower risk of type 2 diabetes (T2D) and cardiovascular disease (CVD). However, it is unknown whether plasma metabolites related to walnut consumption are also associated with lower risk of cardiometabolic diseases. OBJECTIVES: The study aimed to identify plasma metabolites associated with walnut consumption and evaluate the prospective associations between the identified profile and risk of T2D and CVD. METHODS: The discovery population included 1833 participants at high cardiovascular risk from the PREvención con DIeta MEDiterránea (PREDIMED) study with available metabolomics data at baseline. The study population included 57% women (baseline mean BMI (in kg/m2): 29.9; mean age: 67 y). A total of 1522 participants also had available metabolomics data at year 1 and were used as the internal validation population. Plasma metabolomics analyses were performed using LC-MS. Cross-sectional associations between 385 known metabolites and walnut consumption were assessed using elastic net continuous regression analysis. A 10-cross-validation (CV) procedure was used, and Pearson correlation coefficients were assessed between metabolite weighted models and self-reported walnut consumption in each pair of training-validation data sets within the discovery population. We further estimated the prospective associations between the identified metabolite profile and incident T2D and CVD using multivariable Cox regression models. RESULTS: A total of 19 metabolites were significantly associated with walnut consumption, including lipids, purines, acylcarnitines, and amino acids. Ten-CV Pearson correlation coefficients between self-reported walnut consumption and the plasma metabolite profile were 0.16 (95% CI: 0.11, 0.20) in the discovery population and 0.15 (95% CI: 0.10, 0.20) in the validation population. The metabolite profile was inversely associated with T2D incidence (HR per 1 SD: 0.83; 95% CI: 0.71, 0.97; P = 0.02). For CVD incidence, the HR per 1-SD was 0.71 (95% CI: 0.60, 0.85; P < 0.001). CONCLUSIONS: A metabolite profile including 19 metabolites was associated with walnut consumption and with a lower risk of incident T2D and CVD in a Mediterranean population at high cardiovascular risk.

One-year dietary supplementation with walnuts modifies exosomal miRNA in elderly subjects.

PURPOSE: Epidemiological studies and clinical trials support the association of nut consumption with a lower risk of prevalent non-communicable diseases, particularly cardiovascular disease. However, the molecular mechanisms underlying nut benefits remain to be fully described. MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression and play a pivotal role in health and disease. Exosomes are extracellular vesicles released from cells and mediate intercellular communication. Whether nut consumption modulates circulating miRNAs (c-miRNAs) transported in exosomes is poorly described. METHODS: Cognitively healthy elderly subjects were randomized to either control (n = 110, abstaining from walnuts) or daily supplementation with walnuts (15% of their total energy, ≈30-60 g/day, n = 101) for 1-year. C-miRNAs were screened in exosomes isolated from 10 samples, before and after supplementation, and identified c-miRNA candidates were validated in the whole cohort. In addition, nanoparticle tracking analysis and lipidomics were assessed in pooled exosomes from the whole cohort. RESULTS: Exosomal hsa-miR-32-5p and hsa-miR-29b-3p were consistently induced by walnut consumption. No major changes in exosomal lipids, nanoparticle concentration or size were found. CONCLUSION: Our results provide novel evidence that certain c-miRNAs transported in exosomes are modulated by walnut consumption. The extent to which this finding contributes to the benefits of walnuts deserves further research.

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

BACKGROUND AND AIMS: Observational studies and clinical trials have shown cardiovascular benefits of nut consumption, including walnuts. However, the relations of walnut consumption with systolic and diastolic function, risk factors for heart failure, are unknown. We examined the associations of walnut consumption with cardiac structure and function parameters in black and white adults enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study. METHODS AND RESULTS: After exclusions, the study population included 3341 participants. Dietary intake was assessed using the CARDIA Diet History questionnaire at baseline, year 7 and year 20 exams. Cardiac structure and function were measured by echocardiography at year 25. Multivariable linear regression evaluated the associations of walnut consumption with blood pressure (BP), heart rate, and cardiac phenotypes, adjusting for age, sex, race, lifestyle habits, and clinical characteristics. We found the majority of walnut consumers compared to non-consumers were females, whites, and more highly educated, and had lower waist circumference, diastolic BP, and heart rate, and higher diet quality score. Even though cardiac structure and function measures were generally within normal ranges among participants, walnut consumers had significantly better values for diastolic function parameters A wave, E/A ratio, septal and lateral e' than non-consumers. Further adjustment for body mass index and diabetes status did not materially change the significance between walnut consumer groups. Systolic function parameters did not differ by walnut group. CONCLUSION: Compared to non-consumers, walnut consumption is associated with better diastolic dysfunction in young to middle-aged adults.

A green molecular imprinted solid-phase extraction protocol for bisphenol A monitoring with HPLC-UV to guarantee the quality and safety of walnuts under different storage conditions.

Monitoring the residual toxicant concentrations in foods is the key step for minimizing potential hazards. The huge interest about food contamination and exposure to endocrine disruptors such as bisphenol A has emerged the development of sensitive analytical methodologies to guarantee the safety and quality of foods. In this work, a green molecularly imprinted solid-phase extraction protocol coupled with high-performance liquid chromatography with UV detection was optimized following the principles of green analytical chemistry. An imprinted sol-gel silica-based hybrid inorganic-organic polymeric sorbent was used to monitor the leaching of bisphenol A from different packaging materials (glass vessels, cans, and polypropylene containers) in walnuts stored within a period of 6 months at 25 and 4°C. Extraction parameters including loading time (5-20 min), solvent type (acetonitrile, ethanol, methanol, acetone, acetonitrile:methanol, 50:50, v/v), and elution flow rate (0.2-1 mL/min) were optimized with one-factor-at-a-time method. The selected extraction optimum parameters incorporated elution with acetonitrile at 0.2 mL/min flow rate, for 10 min sample holding time. The imprinting factor was equal to 4.55 ± 0.26 (n = 3). The optimized method presented high recovery (94.3 ± 4.2%, n = 3), good linearity (>0.999), intra-assay repeatability (90.2-95.6%, n = 3), and interassay precision (86.7-93.1%, n = 3).

Investigating walnut consumption and cognitive trajectories in a representative sample of older US adults.

OBJECTIVE: Existing research suggests walnut intake may be associated with better cognitive function in older adults, yet few studies utilise longitudinal data from observational studies of ageing populations. Our objective was to estimate the association between whole walnut intake and cognitive change in a representative sample of older Americans. DESIGN: Secondary analysis of the Health and Retirement Study and Health Care and Nutrition Study. Walnut consumption was defined as a categorical measure (none, low intake (0·01-0·08 1 oz. servings per day) and moderate intake (>0·08 1 oz. servings per day)) and cognitive function was measured using the Telephone Interview for Cognitive Status. Latent growth modelling estimated the association between walnut consumption and trajectories of cognitive status over a 4-year observational period. Sensitivity analyses assessing non-random dropout and Monte Carlo power analyses were conducted to contextualise results. SETTING: The USA. PARTICIPANTS: A sample of 3632 US adults aged 65 years and older. RESULTS: Those reporting any walnut consumption had greater cognitive scores at baseline than those not consuming walnuts (low walnut consumption, b = 1·53, se = 0·21, P < 0·001; moderate walnut consumption, b = 2·22, se = 0·27, P < 0·001), but walnut consumption was not associated with cognitive change. Walnut consumption was positively associated with socioeconomic status and health behaviours as well as intake of nutrients identified to have neuroprotective benefits. CONCLUSIONS: We identified an association between walnut consumption and cognitive function in older adults, although we did not find that walnut consumption was protective against age-related cognitive decline.

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.

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.

Effect of walnut consumption on markers of blood glucose control: a systematic review and meta-analysis.

Type 2 diabetes mellitus is a chronic disease increasing in global prevalence. Although habitual consumption of walnuts is associated with reduced risk of CVD, there is inconsistent evidence for the impact of walnut consumption on markers of glycaemic control. This systematic review and meta-analysis aimed to examine the effect of walnut consumption on markers of blood glucose control. A systematic search of Medline, PubMed, CINAHL and Cochrane databases (to 2 March 2019) was conducted. Inclusion criteria were randomised controlled trials conducted with adults which assessed the effect of walnut consumption on fasting blood glucose and insulin, glycated Hb and homeostatic model assessment of insulin resistance. Random effects meta-analyses were conducted to assess the weighted mean differences (WMD) for each outcome. Risk of bias in studies was assessed using the Cochrane Risk of Bias tool 2.0. Sixteen studies providing eighteen effect sizes were included in the review. Consumption of walnuts did not result in significant changes in fasting blood glucose levels (WMD: 0·331 mg/dl; 95 % CI -0·817, 1·479) or other outcome measures. Studies were determined to have either 'some concerns' or be at 'high risk' of bias. There was no evidence of an effect of walnut consumption on markers of blood glucose control. These findings suggest that the known favourable effects of walnut intake on CVD are not mediated via improvements in glycaemic control. Given the high risk of bias observed in the current evidence base, there is a need for further high-quality randomised controlled trials.

HS-SPME GC-MS characterization of volatiles in processed walnuts and their oxidative stability.

Processed walnuts including hot air-dried and roasted walnuts were prepared. Volatiles in raw and processed walnuts were analyzed using head-space solid phase microextraction combined with gas chromatography and mass spectrometry. Oxidative stability of hot air-dried walnuts in different antioxidants, with or without vacuum package was studied to find a proper package for oxidation stability of hot air-dried walnuts. The results showed that there were 14 volatiles in raw walnuts, 28 in hot air-dried walnuts and 38 in roasted walnuts. The changes of oil quality indices, total phenols, malondialdehyde and free radical scavenging activities during storage at 60 °C showed that the oil oxidation increased with storage time. The addition of antioxidants and vacuum package could slow down the oxidation. Vacuum aluminum foil package (14 × 20 cm) can delay the oil oxidation and extend the shelf life to ~ 230 days of hot air-dried walnuts at 20 °C. With added antioxidant this was extended to ~ 257 days.