A Pecan-Rich Diet Improves Cardiometabolic Risk Factors in Overweight and Obese Adults: A Randomized Controlled Trial

Effect of nuts on lipid profile and inflammatory biomarkers in atherosclerotic cardiovascular disease: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Nut-enriched diets are related to improve lipid and inflammatory biomarkers in meta-analyses in the context of primary cardiovascular prevention. However, primary studies on secondary cardiovascular prevention are scarce and controversial. This systematic review and meta-analysis aimed to evaluate the effect of nut supplementation on lipid and inflammatory profiles in individuals with atherosclerotic cardiovascular disease, and the frequency of adverse events.

METHODS

Six databases were used for research: PubMed, EMBASE, BVS, Cochrane Library, Web of Science, and ClinicalTrials.gov, until February 2023, with no language restrictions. We performed random-effects meta-analyses to compare nut-enriched diets vs. control diets for pre-post intervention changes. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) system assessed the evidence's certainty.

RESULTS

From the 5187 records identified, eight publications containing data referring to five randomized clinical trials involving 439 participants were included in the final analyses. The nuts evaluated were almonds, pecans, Brazil nuts, and mixed nuts, with doses ranging between 5 g and 85 g (median: 30 g/day). The intervention time varied between 6 and 12 weeks. Compared to nut-free diets, nut intake did not have a statistically significant effect on lipid profile biomarkers, except on the atherogenic index (MD: -0.32 [95% CI -0.58 to -0.06], I2 = 0% - moderate certainty of the evidence). Similarly, there was no effect of nuts on inflammatory profile biomarkers. It was not possible to aggregate data on adverse events.

CONCLUSIONS

Nut supplementation did not change lipid and inflammatory profiles in the secondary cardiovascular prevention setting.

Do polyphenols affect body fat and/or glucose metabolism?

Background

Obesity is reaching epidemic proportions with 51% of the population expected to be obese by 2030. Recently, polyphenols have been highlighted as an effective approach to managing obesity and associated risks. Polyphenols are a large class of bioactive plant compounds classified into two major categories: flavonoids which are distinguished by the fundamental C6-C3-C6 skeleton and non-flavonoids.

Objective

This systematic review evaluated the effect of different polyphenol sources in overweight and obese people with and without type 2 diabetes. The primary outcome was lipid profile and the secondary outcomes were blood glucose, HbA1c (%), HOMA-IR, weight, and body mass index.

Method

A search was undertaken in PubMed, Web of Science, Medline, and Wiley for randomized control trials that assessed different sources of polyphenols in overweight and obese people with or without type 2 diabetes. The quality of the included studies was assessed using the National Heart, Lung, and Blood Institute Quality Assessment Tool.

Result

The search yielded 935 studies, of which six randomized control trials met the inclusion criteria. Five studies found no significant difference in lipid profile between the control and intervention groups in triglycerides, total cholesterol, LDL cholesterol, and HDL cholesterol. However, one study showed significant differences in triglycerides (p = 0.04) and HDL cholesterol (p = 0.05) between the two groups with no significant difference in total cholesterol and LDL cholesterol. There were no significant changes in blood glucose observed in the included studies, with only two studies reporting a significant difference in A1c between the groups. Four studies found no difference in HOMA-IR, while one study showed a significant decrease in HOMA-IR in the intervention group compared to the control group. Three studies reported no difference in BMI or weight between the two groups.

Conclusion

The data associated with the specific health benefits of polyphenols and their sources in people with overweight, obese, and type 2 diabetes are still limited, so further research is required to support their use and prove their benefits.

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

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

A 4-Week Pecan-Enriched Diet Improves Postprandial Lipid Peroxidation in Aging Adults

Pecans are rich in bioactive compounds known to reduce oxidative stress and provide glucoregulatory benefits. Few studies assessing the effect of a pecan-enriched diet on such health outcomes suggest potential improvements to cardiometabolic health; however, this has not been studied in an older adult population. Thus, we aimed to examine the effect of daily pecan consumption for 4-weeks on fasting and postmeal antioxidant status, oxidative stress, and markers of glycemia in healthy aging adults. In this randomized, parallel, controlled trial, 41 healthy adults (50-75 years) either consumed 68 g of pecans/day (pecan; n = 21) or avoided all nuts (control; n = 20). At pre- (V1) and postintervention visits (V2), blood samples were obtained at fasting, and 30, 60, and 120 min following a high saturated fat meal to assess changes in malondialdehyde, which is a measure of lipid peroxidation, total antioxidant capacity (TAC), glucose, and insulin. Across the intervention, there were no differences in fasting or postprandial TAC, glucose, or insulin for pecan versus control. There was a trend for a difference in fasting lipid peroxidation from V1 to V2 by treatment (P = .06) driven by a slight reduction for pecan versus control (Δpecan: -2.0 ± 1.1 vs. Δcontrol: +0.6 ± 0.8 μM). In addition, postprandial lipid peroxidation was suppressed at V2 for pecan, and this was different from control (pecan areas under the curve (AUC): 10.6 ± 1.3 μM/h to 9.1 ± 1.2 μM/h vs. control AUC: 8.9 ± 1.3 μM/h to 9.2 ± 1.1 μM/h; P = .03). These findings suggest that a 1 month, pecan-enriched diet is protective against postmeal oxidative stress. Longer interventions or a diabetic population may be needed to observe glucoregulatory benefits. Clinical Trial Registration: NCT04385537.

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

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

A pecan-enriched diet reduced postprandial appetite intensity and enhanced peptide YY secretion: A randomized control trial

BACKGROUND & AIMS

Tree nuts have been shown to have satiating qualities; however, little is known concerning the effect of pecans on measures of appetite. The purpose of this study was to examine the impact of a pecan-enriched diet on subjective, physiological, and direct measures of appetite in older adults.

METHODS

This was a randomized, controlled trial in which healthy older adults (50-75 y) were randomized to either consume 68 g of pecans/day (pecan; n = 21) or avoid all nuts (control; n = 23) for 4 weeks. At pre- (V1) and post-diet (V2) visits body weight (BW) and body fat percentage (BF) were assessed and actual change in these outcomes for pecan were compared to theoretical changes if pecans were consumed without compensation. Subjective appetite was measured using visual analog scale (VAS), and blood was collected to assess changes in physiological appetite before and every 30 min for 4 h following a high-fat meal. Energy intake (EI) at a buffet meal was then assessed in the laboratory ("in-lab"). VAS assessments continued hourly for the next 7 h and EI ("at-home") was self-reported.

RESULTS

BW and BF did not change for pecan or control across the intervention and theoretical change in BW (theoretical: 2.2 ± 0.1 vs. actual: 0.4 ± 0.2 kg; p < 0.0001) and BF (theoretical: 0.4 ± 0.04 vs. actual: 0.2 ± 0.2%; p < 0.0001) was significantly greater than actual change for pecan. From V1 to V2, there was an increase in fasting (pecan: 77.0 ± 4.6 to 93.5 ± 6.1 vs control: 76.0 ± 5.0 to 72.5 ± 5.0 pg/mL; p = 0.01) and postprandial peptide YY for pecan vs. control (p = 0.04); however, fasting and postprandial cholecystokinin and ghrelin did not differ (p > 0.05). There were no differences in the change in subjective appetite ratings at fasting, following the high-fat meal (in-lab), at-home, or across the full day between groups (p > 0.05 for all). However, there was a significant suppression of peak desire to eat ratings for pecan vs. control (pecan: 67.9 ± 4.6 to 57.1 ± 5.2 vs. control: 61.9 ± 4.2 to 60.6 ± 4.3 mm; p = 0.04). Combined, buffet meal, and at-home EI did not differ significantly within pecan and control; however, there was a trend (p = 0.11) for a between group difference in buffet meal EI driven by increased EI for control (+137 ± 86 kcal) vs. decreased EI for pecan (-45 ± 77 kcal).

CONCLUSION

A 4-week pecan-enriched diet led to enhanced satietogenic metrics compared to a diet void of all nuts. As weight remained stable during the intervention, adding pecans to the daily diet may be beneficial to appetite control and weight maintenance in a healthy older population.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov: NCT04385537.

Pecans and Its Polyphenols Prevent Obesity, Hepatic Steatosis and Diabetes by Reducing Dysbiosis, Inflammation, and Increasing Energy Expenditure in Mice Fed a High-Fat Diet

Pecans (Carya illinoinensis) are considered a functional food due to the high content of polyunsaturated fatty acids, dietary fiber and polyphenols. To determine the effect of whole pecans (WP) or a pecan polyphenol (PP) extract on the development of metabolic abnormalities in mice fed a high-fat (HF) diet, we fed C57BL/6 mice with a Control diet (7% fat), HF diet (23% fat), HF containing 30% WP or an HF diet supplemented with 3.6 or 6 mg/g of PP for 18 weeks. Supplementation of an HF diet with WP or PP reduced fat mass, serum cholesterol, insulin and HOMA-IR by 44, 40, 74 and 91%, respectively, compared to the HF diet. They also enhanced glucose tolerance by 37%, prevented pancreatic islet hypertrophy, and increased oxygen consumption by 27% compared to the HF diet. These beneficial effects were associated with increased thermogenic activity in brown adipose tissue, mitochondrial activity and AMPK activation in skeletal muscle, reduced hypertrophy and macrophage infiltration of subcutaneous and visceral adipocytes, reduced hepatic lipid content and enhanced metabolic signaling. Moreover, the microbial diversity of mice fed WP or PP was higher than those fed HF, and associated with lower circulating lipopolysaccharides (~83-95%). Additionally, a 4-week intervention study with the HF 6PP diet reduced the metabolic abnormalities of obese mice. The present study demonstrates that WP or a PP extract prevented obesity, liver steatosis and diabetes by reducing dysbiosis, inflammation, and increasing mitochondrial content and energy expenditure. Pecan polyphenols were mainly condensed tannin and ellagic acid derivatives including ellagitannins as determined by LC-MS. Herein we also propose a model for the progression of the HF diet-mediated metabolic disorder based on early and late events, and the possible molecular targets of WP and PP extract in preventive and intervention strategies. The body surface area normalization equation gave a conversion equivalent to a daily human intake dose of 2101-3502 mg phenolics that can be obtained from 110-183 g pecan kernels/day (22-38 whole pecans) or 21.6-36 g defatted pecan flour/day for an average person of 60 kg. This work lays the groundwork for future clinical studies.

Role of flavonoids in controlling obesity: molecular targets and mechanisms

Obesity presents a major health challenge that increases the risk of several non-communicable illnesses, such as but not limited to diabetes, hypertension, cardiovascular diseases, musculoskeletal and neurological disorders, sleep disorders, and cancers. Accounting for nearly 8% of global deaths (4.7 million) in 2017, obesity leads to diminishing quality of life and a higher premature mortality rate among affected individuals. Although essentially dubbed as a modifiable and preventable health concern, prevention, and treatment strategies against obesity, such as calorie intake restriction and increasing calorie burning, have gained little long-term success. In this manuscript, we detail the pathophysiology of obesity as a multifactorial, oxidative stress-dependent inflammatory disease. Current anti-obesity treatment strategies, and the effect of flavonoid-based therapeutic interventions on digestion and absorption, macronutrient metabolism, inflammation and oxidative stress and gut microbiota has been evaluated. The use of several naturally occurring flavonoids to prevent and treat obesity with a long-term efficacy, is also described.

Pecan-enriched diet improves cholesterol profiles and enhances postprandial microvascular reactivity in older adults

Pecan-enriched diets have been linked to improved lipid metabolism; however, the impact of pecans on vascular health has yet to be examined. We hypothesized that 4 weeks of a pecan-enriched diet would improve fasting and postprandial blood lipids and vascular function compared with a nut-free diet. In this randomized control study, 44 older adults (59 ± 6 years) consumed 68 g of pecans/d (pecan; n = 21) or avoided all nuts (control; n = 23) for 4 weeks. At pre- and post-diet visits, fasting and postprandial blood lipids, macrovascular (by flow-mediated dilation), and microvascular (tissue saturation index reactive hyperemia [RH] kinetics by continuous-wave near-infrared spectroscopy) function were assessed. From the pre- to post-diet visit, there were greater reductions in fasting total cholesterol (pecan: -14 ± 4.0 vs control: -0.2 ± 5.4 mg/dL; P = .04), low-density lipoprotein (LDL) cholesterol (pecan: -15 ± 3.7 vs control: +1.9 ± 4.4 mg/dL; P = .01), non-high-density lipoprotein cholesterol (pecan: -15 ± 3.6 vs control: -0.5 ± 4.8 mg/dL; P = .02), LDL particle number (pecan: -126 ± 51 vs control: +43 ± 42 nmol/L; P = .01), and LDL medium (pecan: -34 ± 13 vs control: +16 ± 11 nmol/L; P < .01), for pecan vs control. Further, postprandial triglyceride was suppressed for pecan (P = .01) compared with control (P = .78). Postprandial RH slope (P = .04) and RH time to half (P = .004) was different by group, driven by improvements in pecan vs control. However, fasting macro- and microvascular function was unaffected. Daily pecan consumption for 4 weeks improved fasting and postprandial blood lipids and microvascular reactivity in older adults. Because changes in microvascular function typically precipitate macrovascular changes, long-term pecan consumption may improve vascular health and reduce risk for cardiovascular events. This trial was registered at clinicaltrials.gov (NCT04385537).

Proteomic Analysis of Pecan (Carya illinoinensis) Nut Development

Pecan (Carya illinoinensis) nuts are an economically valuable crop native to the United States and Mexico. A proteomic summary from two pecan cultivars at multiple time points was used to compare protein accumulation during pecan kernel development. Patterns of soluble protein accumulation were elucidated using qualitative gel-free and label-free mass-spectrometric proteomic analyses and quantitative (label-free) 2-D gel electrophoresis. Two-dimensional (2-D) gel electrophoresis distinguished a total of 1267 protein spots and shotgun proteomics identified 556 proteins. Rapid overall protein accumulation occurred in mid-September during the transition to the dough stage as the cotyledons enlarge within the kernel. Pecan allergens Car i 1 and Car i 2 were first observed to accumulate during the dough stage in late September. While overall protein accumulation increased, the presence of histones diminished during development. Twelve protein spots accumulated differentially based on 2-D gel analysis in the weeklong interval between the dough stage and the transition into a mature kernel, while eleven protein spots were differentially accumulated between the two cultivars. These results provide a foundation for more focused proteomic analyses of pecans that may be used in the future to identify proteins that are important for desirable traits, such as reduced allergen content, improved polyphenol or lipid content, increased tolerance to salinity, biotic stress, seed hardiness, and seed viability.

Identifying myoglobin as a mediator of diabetic kidney disease: a machine learning-based cross-sectional study

In view of the alarming increase in the burden of diabetes mellitus (DM) today, a rising number of patients with diabetic kidney disease (DKD) is forecasted. Current DKD predictive models often lack reliable biomarkers and perform poorly. In this regard, serum myoglobin (Mb) identified by machine learning (ML) may become a potential DKD indicator. We aimed to elucidate the significance of serum Mb in the pathogenesis of DKD. Electronic health record data from a total of 728 hospitalized patients with DM (286 DKD vs. 442 non-DKD) were used. We developed DKD ML models incorporating serum Mb and metabolic syndrome (MetS) components (insulin resistance and β-cell function, glucose, lipid) while using SHapley Additive exPlanation (SHAP) to interpret features. Restricted cubic spline (RCS) models were applied to evaluate the relationship between serum Mb and DKD. Serum Mb-mediated renal function impairment induced by MetS components was verified by causal mediation effect analysis. The area under the receiver operating characteristic curve of the DKD machine learning models incorporating serum Mb and MetS components reached 0.85. Feature importance analysis and SHAP showed that serum Mb and MetS components were important features. Further RCS models of DKD showed that the odds ratio was greater than 1 when serum Mb was > 80. Serum Mb showed a significant indirect effect in renal function impairment when using MetS components such as HOMA-IR, HGI and HDL-C/TC as a reason. Moderately elevated serum Mb is associated with the risk of DKD. Serum Mb may mediate MetS component-caused renal function impairment.

Effect of nuts on components of metabolic syndrome in healthy adults with overweight/obesity: A systematic review and meta-analysis

AIMS

Randomized controlled trials evaluating the effects of nut consumption on the metabolic profile of healthy adults with overweight/obesity have yielded conflicting results. This systematic review and meta-analysis aimed to summarize the effects of incorporating nuts into the diet on serum lipid profile, glycemic markers, and blood pressure in healthy adults with overweight/obesity.

DATA SYNTHESIS

PubMed, Embase, Scopus, Web of Science, and Cochrane Library were searched up to April 2021. The random-effects model was used to determine the pooled effect sizes expressed as weighted mean difference (WMD) with % 95 confidence intervals (CIs). Ten eligible RCTs (with 12 arms) were included in the meta-analysis. The meta-analysis revealed that nut intake significantly decreased serum triglycerides (TG) (WMD: -13.19 mg/dL, 95% CI: - 25.90, - 0.48). Furthermore, subgroup analysis showed a significant reduction in serum LDL-cholesterol (LDL-C) following adherence to normocaloric, nut-enriched diets (WMD: - 4.56 mg/dL, 95% CI: - 8.24, - 0.88). However, nuts did not affect serum total cholesterol, high-density lipoprotein cholesterol, glycemic markers, and blood pressure.

CONCLUSIONS

Overall, incorporating nuts into the diet of healthy adults with overweight/obesity have favorable effects on serum TG and LDL-C. Thus, nuts might exert protective effects against dyslipidemia in this population.

REGISTRY NUMBER

PROPSPERO CRD42021250662.

Modelling the effects of pecan nut [Carya illinoinensis (Wangenh.) K.Koch], roselle (Hibiscus sabdariffa L.), and salt on the quality characteristics of beef patties

The meat industry has become increasingly interested in developing products containing new ingredients oriented to consumers’ health. Health benefits are gained from frequent consumption of pecan nut and roselle, which can therefore be used as ingredients in meat product formulations. However, incorporating novel ingredients or reducing the content of traditional ingredients might affect meat product quality, thus needs to be evaluated and optimised for the development of functional foods. The objective of the present work was to assess how pecan nut (0 to 10%), roselle (0 to 2%), and salt (0 to 2%) affect the physicochemical properties, antioxidant, and sensory characteristics of beef patties, and use response surface methodology to optimise the content of these ingredients in a meat product formulation. Regression models were developed to predict quality properties. All models were significant (p < 0.05) with an R2 > 0.85 and a nonsignificant lack of fit (p > 0.05), thus indicating that these models could adequately predict response variables. The optimised formulation was 7.97% pecan nut, 1.59% roselle, and 1.08% salt. The predicted physicochemical properties were L* = 42.88, a* = 12.29, b* = 8.51, pH = 5.10, and cooking loss = 24.66%; the antioxidant properties were DPPH = 0.53 mg TE/g fp, ABTS = 0.65 mg TE/g fp, and total phenolic content = 0.46 mg GA/g fp; and the sensory properties were flavour = 7.03, tenderness = 6.98, and juiciness = 7.01. Pecan nut and roselle are promising natural ingredients that can be used to prepare low-salt beef patties.

"Planeterranea": An attempt to broaden the beneficial effects of the Mediterranean diet worldwide

Non-communicable diseases (NCDs) lead to a dramatic burden on morbidity and mortality worldwide. Diet is a modifiable risk factor for NCDs, with Mediterranean Diet (MD) being one of the most effective dietary strategies to reduce diabetes, cardiovascular diseases, and cancer. Nevertheless, MD transferability to non-Mediterranean is challenging and requires a shared path between the scientific community and stakeholders. Therefore, the UNESCO Chair on Health Education and Sustainable Development is fostering a research project-"Planeterranea"-aiming to identify a healthy dietary pattern based on food products available in the different areas of the world with the nutritional properties of MD. This review aimed to collect information about eating habits and native crops in 5 macro-areas (North America, Latin America, Africa, Asia, and Australia). The information was used to develop specific "nutritional pyramids" based on the foods available in the macro-areas presenting the same nutritional properties and health benefits of MD.

Influence of Cultivar on Nutritional Composition and Nutraceutical Potential of Pecan Growing in Uruguay

Composition and antioxidant properties of sixteen pecan [Carya illinoinensis (Wangenh) K. Koch] cultivars grown simultaneously in a single experimental orchard in Uruguay were evaluated to characterize their nutritional properties and nutraceutical potential. The percentage of oil, moisture, ash, minerals, and proteins were determined and also the fatty acid profile. Total phenolic compounds [18–41 mg gallic acid equivalents (GAEs)/g], condensed tannin [2–12 mg catechin equivalents (CEs)/g], and tocopherols (110–163 μg/g) contents were estimated in nut kernels. Total phenolic compounds (32–117 mg GAE/g), condensed tannins (130–357 mg CE/g), and total anthocyanins (1–3 mg 3-glucoside cyanidin/g) were also determined for pecan shells. The antioxidant activity in shells [57.15–578.88 μmol Trolox equivalents (TEs)/g] was 5 times higher compared with the kernels (23.15–156.60 μmol TEs/g) measured with hydrophilic ORAC. Bioactive compounds concentrations present statistically significant genetic variability between cultivars studied (p < 0.05). The presence of phenolic compounds was related with high-antioxidant capacity in kernels and shells, and a strong correlation between content of total phenolic compounds and condensed tannins in pecan shells was found. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) show association between cultivars and the observed variables. The nutritional profile in the different cultivars showed the trends described in other countries, but this work shows some significant differences that could be attributed to the specific edaphoclimatic conditions of cultivation in Uruguay.

Polyphenol Supplementation Did Not Affect Insulin Sensitivity and Fat Deposition During One-Month Overfeeding in Randomized Placebo-Controlled Trials in Men and in Women

Two randomized placebo-controlled double-blind paralleled trials (42 men in Lyon, 19 women in Lausanne) were designed to test 2 g/day of a grape polyphenol extract during 31 days of high calorie-high fructose overfeeding. Hyperinsulinemic-euglycemic clamps and test meals with [1,1,1-¹³C₃]-triolein were performed before and at the end of the intervention. Changes in body composition were assessed by dual-energy X-ray absorptiometry (DEXA). Fat volumes of the abdominal region and liver fat content were determined in men only, using 3D-magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) at 3T. Adipocyte's size was measured in subcutaneous fat biopsies. Bodyweight and fat mass increased during overfeeding, in men and in women. While whole body insulin sensitivity did not change, homeostasis model assessment of insulin resistance (HOMA-IR) and the hepatic insulin resistance index (HIR) increased during overfeeding. Liver fat increased in men. However, grape polyphenol supplementation did not modify the metabolic and anthropometric parameters or counteract the changes during overfeeding, neither in men nor in women. Polyphenol intake was associated with a reduction in adipocyte size in women femoral fat. Grape polyphenol supplementation did not counteract the moderated metabolic alterations induced by one month of high calorie-high fructose overfeeding in men and women. The clinical trials are registered under the numbers NCT02145780 and NCT02225457 at ClinicalTrials.gov and available at https://clinicaltrials.gov/ct2/show/NCT02145780 and https://clinicaltrials.gov/ct2/show/NCT02225457.

Nuts as a Part of Dietary Strategy to Improve Metabolic Biomarkers: A Narrative Review

Background

Nuts are in the spotlight because of their association with improved health outcomes. We aimed to summarize the findings of previous studies to evaluate the impact of nuts consumption on glycaemic and lipid profile, inflammation, and oxidative stress.

Methods

Electronic searches for observational and intervention studies were undertaken in PubMed, Embase, Web of Science, and Science Direct until 2022 for searching the studies aiming the application of different types of nuts and the beneficial effects of nuts in improving glycemia, dyslipidemia, inflammation, and oxidative stress.

Results

Results from 56 interventional, 9 narrative and 3 systematic reviews, and 12 meta-analysis studies, aiming at the evaluating beneficial effects of different types of nuts on metabolic markers, showed that nut consumption could improve metabolic markers, including glycaemic factors, lipid profile, and inflammatory and oxidative stress parameters in both healthy and individuals with metabolic disorders in a type-, dose- and duration-dependent manner. According to their unique nutrient components, nuts can be known as a part of a healthy diet, resulting in improved metabolic biomarkers.

Conclusion

Considering the efficacy of nuts in improving metabolic markers, incorporation of, incorporating nuts the effectiveness of nuts in improving metabolic markers, incorporating nuts in the diet may prevent the incidence or aggravation of chronic metabolic diseases. Considering the health benefits of the nuts' components, including essential micronutrients, if consumed in the appropriate dose and duration to provide the necessary amount of effective micronutrients to improve health, we will see an improvement in metabolic factors. At the same time, more research is required to determine the optimal type, dose, and duration of nut intervention with regards to metabolic control and reducing the risk of developing metabolic disorders.

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

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

Nutraceuticals in the Management of Cardiovascular Risk Factors: Where is the Evidence?

Cardiovascular disease continues to rise at an alarming rate, and research focuses on possible therapies to reduce the risk and slow down its progression. Several epidemiological studies have indicated that dietary modifications, such as increased consumption of fruits and vegetables play an important role in reducing cardiovascular disease risk factors. Food sources rich in antioxidants, anti-inflammatory, hypolipidemic, and hypoglycemic properties are thought to ameliorate the progression of cardiovascular disease and serve as a potential treatment mode. Many in vivo and in vitro studies using turmeric, cinnamon, mango, blueberries, red wine, chocolate, and extra virgin olive oil have demonstrated significant improvements in cholesterol profiles, toxic reactive oxygen species, inflammation, obesity, and hypertension. In this review, we summarize recent evidence on the cardioprotective effect of different food groups, outline their potential mechanisms involved in slowing down the progression of cardiovascular disease, and highlight the beneficial effects associated with increased consumption.

Effect of pecan nuts and extra-virgin olive oil on glycemic profile and nontraditional anthropometric indexes in patients with coronary artery disease: a randomized clinical trial

BACKGROUND/OBJECTIVES

The influence of cardioprotective foods on nontraditional indexes related to dysglycemia and body fat distribution is unknown in individuals with coronary artery disease (CAD). This study aimed to evaluate the effect of a healthy diet supplemented with pecan nuts or extra-virgin olive oil on glycemic profile and adipose tissue dysfunction assessed by anthropometric indexes in patients with stable CAD.

SUBJECTS/METHODS

In a randomized, pragmatic, parallel clinical trial lasting 12 weeks, 204 individuals were allocated to three interventions: a healthy diet (control group [CG], n = 67), a healthy diet plus 30 g/day of pecan nuts (pecan nut group [PNG], n = 68), or a healthy diet plus 30 mL/day of extra-virgin olive oil (olive oil group [OOG], n = 69). Triglyceride-glucose (TyG) index (primary outcome) and other markers of glycemic profile were evaluated, and nontraditional anthropometric indexes as well. Diet quality was assessed according to the Alternate Healthy Eating Index (mAHEI).

RESULTS

After adjustment for baseline values, use of antidiabetic drugs and insulin, there were no differences in both glycemic and anthropometric profiles according to groups at the end of the study. PNG improved the quality of the diet in comparison to other groups (final mAHEI scores: CG: 19 ± 7.5; PNG: 26 ± 8; OOG: 18.9 ± 6; P < 0.001).

CONCLUSIONS

There was no difference regarding glycemic and anthropometric parameters according to interventions in patients with stable CAD. However, adding pecan nuts to a healthy diet may improve its quality. Further studies must be conducted considering dietary interventions on secondary cardiovascular prevention setting.

CLINICAL TRIALS IDENTIFIER NUMBER

NCT02202265. First Posted: July 2014; Last Update: September 2020.

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

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

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Effects of extra virgin olive oil and pecans on plasma fatty acids in patients with stable coronary artery disease

OBJECTIVE

The aim of this study was to determine the effects of a healthy diet supplemented with extra virgin olive oil or pecans on plasma fatty acids (PFAs) in patients with stable coronary artery disease (CAD).

METHODS

Patients 40 to 80 y of age were randomized to one of three dietary interventions (allocation ratio 1: 1: 1): healthy diet based on guidelines (control group [CG]), healthy diet supplemented with 30 g/d of pecans (PNG), or a healthy diet supplemented with 30 mL/d of extra virgin olive oil (OOG). PFAs were identified at baseline and at the end of follow-up (12 wk), and correlations between dietary fatty acids intake, PFAs, and clinical biomarkers of the lipid profile were also assessed before and after the interventions.

RESULTS

Among 149 participants included in the analysis (43 CG; 51 PNG; and 55 OOG), correlations were observed between food intake, PFAs, and lipid profile before and after interventions independent of statins used, but all were considered weak. At the end of the study, the OOG showed increased concentrations of oleic fatty acid independently of the type of statin in use (1.49%; 95% confidence interval, 0.08-2.89; P = 0.029); however, there were no significant differences between the groups regarding the final mean values of oleic fatty acid or in the other PFAs.

CONCLUSIONS

In patients with stable CAD, there were no significant differences in PFAs after 12 wk according to dietary interventions evaluated.

Dietary Flavonoids and Insulin Signaling in Diabetes and Obesity

Type 2 diabetes (T2D) and obesity are relevant worldwide chronic diseases. A common complication in both pathologies is the dysregulation of the insulin-signaling pathway that is crucial to maintain an accurate glucose homeostasis. Flavonoids are naturally occurring phenolic compounds abundant in fruits, vegetables and seeds. Rising evidence supports a role for the flavonoids against T2D and obesity, and at present, these compounds are considered as important potential chemopreventive agents. This review summarizes in vitro and in vivo studies providing data related to the effects of flavonoids and flavonoid-rich foods on the modulation of the insulin route during T2D and obesity. Notably, few human studies have evaluated the regulatory effect of these phenolic compounds at molecular level on the insulin pathway. In this context, it is also important to note that the mechanism of action for the flavonoids is not fully characterized and that a proper dosage to obtain a beneficial effect on health has not been defined yet. Further investigations will contribute to solve all these critical challenges and will enable the use of flavonoids to prevent, delay or support the treatment of T2D and obesity.

Effects of supplementing a healthy diet with pecan nuts or extra-virgin olive oil on inflammatory profile of patients with stable coronary artery disease: a randomised clinical trial

The consumption of nuts and extra-virgin olive oil has been associated with suppression of inflammatory pathways that contribute to atherosclerosis, but its role on the modulation of the inflammatory profile in patients with established coronary artery disease (CAD) is unclear. The aim of this study was to evaluate the effects of adding pecan nuts or extra-virgin olive oil to a healthy diet on inflammatory markers in patients with stable CAD. In this randomised clinical trial, 204 patients were enrolled to three study groups: sixty seven to control group (CG: healthy diet), sixty eight to pecan nuts group (PNG: 30 g/d of pecans + healthy diet) and sixty nine to extra-virgin olive oil group (OOG: 30 ml/d of extra-virgin olive oil + healthy diet). High-sensitivity C-reactive protein (hs-CRP, in mg/l), fibrinogen (mg/dl), IL 2, 4, 6, 10 (pg/ml) and interferon-γ (IFN-γ, in pg/ml), IL-6/IL-10, IL-2/IL-4 and IFN-/γIL-4 ratios were evaluated at baseline and after the follow-up (12 weeks). As main results, after adjustment for sex, statin used and relative body weight variation, there were no differences between groups regarding inflammatory markers at the end of the study. IL-6 levels (primary outcome) were reduced in 12 weeks when compared with baseline in all study groups (CG: difference: -0·593 (se = 0·159) pg/dL; PNG: difference: -0·335 (se = 0·143) pg/dl; OOG: IL-6 difference: -0·325 (se = 0·143) pg/dl). In conclusion, there was no significant effect of including pecan nuts or extra virgin olive oil to a healthy diet on inflammatory markers in individuals with CAD.

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.

Effects of Polyphenols on Insulin Resistance

Insulin resistance (IR) is apparent when tissues responsible for clearing glucose from the blood, such as adipose and muscle, do not respond properly to appropriate signals. IR is estimated based on fasting blood glucose and insulin, but some measures also incorporate an oral glucose challenge. Certain (poly)phenols, as supplements or in foods, can improve insulin resistance by several mechanisms including lowering postprandial glucose, modulating glucose transport, affecting insulin signalling pathways, and by protecting against damage to insulin-secreting pancreatic β-cells. As shown by intervention studies on volunteers, the most promising candidates for improving insulin resistance are (-)-epicatechin, (-)-epicatechin-containing foods and anthocyanins. It is possible that quercetin and phenolic acids may also be active, but data from intervention studies are mixed. Longer term and especially dose-response studies on mildly insulin resistant participants are required to establish the extent to which (poly)phenols and (poly)phenol-rich foods may improve insulin resistance in compromised groups.

Effects of a healthy diet enriched or not with pecan nuts or extra-virgin olive oil on the lipid profile of patients with stable coronary artery disease: a randomised clinical trial

BACKGROUND

The present study aimed to assess the effect of a healthy diet, enriched or not with pecan nuts or extra-virgin olive oil, on the lipid profile of patients with stable coronary artery disease (CAD).

METHODS

This was a randomised clinical trial conducted for 12 weeks with patients aged between 40 and 80 years with stable CAD for more than 60 days. Individuals were randomised into groups [control group (CG) with 67 patients, pecan nut group (PNG) with 68 patients and olive oil group (OOG) with 69 patients]. The CG was prescribed a healthy diet according to the nutritional guidelines; the PNG was prescribed the same healthy diet plus 30 g day^-1 of pecan nuts; and the OOG was prescribed a healthy diet plus 30 mL day^-1 of extra-virgin olive oil.

RESULTS

In total, 204 subjects were submitted to an intention-to-treat analysis. After adjustment for baseline values and type of statin used, there was no difference regarding low-density lipoprotein (LDL)-cholesterol (primary outcome), high-density lipoprotein (HDL)-cholesterol, LDL-cholesterol/HDL-cholesterol ratio and HDL-cholesterol/triglycerides ratio according to groups. However, the PNG exhibited a significant reduction in non-HDL-cholesterol levels [PNG: 114.9 (31) mg dL^-1 ; CG: 127 (33.6) mg dL^-1 ; OOG: 126.6 (37.4) mg dL^-1 ; P = 0.033] and in the total cholesterol/HDL-cholesterol ratio [PNG: 3.7 (0.7); CG: 4.0 (0.8); OOG: 4.0 (0.8); P = 0.044] compared to the CG and OOG.

CONCLUSIONS

Supplementing a healthy diet with 30 g day^-1 of pecan nuts for 12 weeks did not improve LDL-cholesterol levels but may improve other lipid profile markers in patients with stable CAD.

Does Nut Consumption Reduce Mortality and/or Risk of Cardiometabolic Disease? An Updated Review Based on Meta-Analyses

Aim We aimed to determine if nut consumption decreases mortality and/or the risk of cardiometabolic diseases based on updated meta-analyses of epidemiological and intervention studies. Methods. An updated electronic search was conducted in PubMed/MEDLINE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and the Cochrane Library databases for original meta-analyses to investigate the effects of nut consumption on cardiometabolic disease in humans. Results. Seven new meta-analyses were included in this updated review. Findings similar to our previous review were observed, showing that nut consumption significantly decreased cardiovascular disease (CVD) mortality (−19% to −25%; n = 4), coronary heart disease (CHD) mortality (−24% to −30%; n = 3), stroke mortality (−17% to −18%; n = 3), CVD incidence (−15% to −19 %; n = 4), CHD [or coronary artery disease (CAD)] incidence (−17% to −34%; n = 8), and stroke incidence (−10% to −11%; n = 6) comparing high with low categories of nut consumption. Fasting glucose levels (0.08 to 0.15 mmol/L; n = 6), total cholesterol (TC; 0.021 to 0.30 mmol/L; n = 10), and low-density lipoprotein cholesterol (LDL-C; 0.017 to 0.26 mmol/L; n = 10) were significantly decreased with nut consumption compared with control diets. Body weight and blood pressure were not significantly affected by nut consumption. Conclusion. Nut consumption appears to exert a protective effect on cardiometabolic disease, possibly through improved concentrations of fasting glucose, total cholesterol, and LDL-C.

Effects of Moisture, Temperature, and Salt Content on the Dielectric Properties of Pecan Kernels During Microwave and Radio Frequency Drying Processes

Dielectric properties of materials influence the interaction of electromagnetic fields with and are therefore important in designing effective dielectric heating processes. We investigated the dielectric properties (DPs) of pecan kernels between 10 and 3000 MHz using a Novocontrol broadband dielectric spectrometer in a temperature range of 5–65 °C and a moisture content range of 10–30% wet basis (wb) at three salt levels. The dielectric constant (ε′) and loss factor (ε″) of the pecan kernels decreased significantly with increasing frequency in the radio frequency (RF) band, but gradually in the measured microwave (MW) band. The moisture content and temperature increase greatly contributed to the increase in the ε′ and ε″ of samples, and ε″ increased sharply with increasing salt strength. Quadratic polynomial models were established to simulate DPs as functions of temperature and moisture content at four frequencies (27, 40, 915, and 2450 MHz), with R² > 0.94. The average penetration depth of pecan kernels in the RF band was greater than that in the MW band (238.17 ± 21.78 cm vs. 15.23 ± 7.36 cm; p < 0.01). Based on the measured DP data, the simulated and experimental temperature-time histories of pecan kernels at five moisture contents were compared within the 5 min RF heating period.

Effect of whole foods and dietary patterns on markers of subclinical inflammation in weight-stable overweight and obese adults: a systematic review

Context

Reduction of subclinical inflammation is a potential target for chronic disease management. Adiposity is a known modifier of meta-inflammation; however, the influence of dietary factors is less clear.

Objective

This review examines evidence from human trials evaluating effects of whole foods or dietary patterns on circulating inflammatory markers in weight-stable overweight and obese adults. It is the first review to investigate effects of diet on inflammation, independent of changes in adiposity.

Data Sources

The Ovid MEDLINE, EMBASE, CINAHL, and Cochrane databases were searched.

Data Extraction

Data extraction was conducted using the Cochrane Collaboration Handbook for Systematic Reviews of Interventions.

Data Analysis

Study quality was evaluated using the Cochrane Collaboration Risk of Bias Assessment tool. Thirty-three studies were included assessing effects of 17 foods and dietary patterns on 39 inflammatory markers.

Conclusions

Overall, foods and dietary patterns were not found to have significant effects on inflammatory markers in weight-stable individuals. Inconsistencies among studies were largely due to methodological limitations. Future research should invest in longer intervention periods and standardization of inflammatory marker panels paired with novel technologies, while ensuring anthropometric measures are monitored and adequately controls are used.

Systematic Review Registration

Prospero registration number CRD42017067765.

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

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

The effect of nuts on markers of glycemic control: a systematic review and meta-analysis of randomized controlled trials

Background

Observational evidence suggests higher nut consumption is associated with better glycemic control; however, it is unclear if this association is causal.

Objectives

We aimed to conduct a systematic review and meta-analysis of randomized controlled trials to examine the effect of tree nuts and peanuts on markers of glycemic control in adults.

Methods

A systematic review and meta-analysis of randomized controlled trials was conducted. A total of 1063 potentially eligible articles were screened in duplicate. From these articles, 40 were eligible for inclusion and data from these articles were extracted in duplicate. The weighted mean difference (WMD) between the nut intervention and control arms was determined for fasting glucose, fasting insulin, glycated hemoglobin (HbA1c), and homeostasis model assessment of insulin resistance (HOMA-IR) using the DerSimonian and Laird random-effects method. For outcomes where a limited number of studies were published, a qualitative synthesis was presented.

Results

A total of 40 randomized controlled trials including 2832 unique participants, with a median duration of 3 mo (range: 1-12 mo), were included. Overall consumption of tree nuts or peanuts had a favorable effect on HOMA-IR (WMD: -0.23; 95% CI: -0.40, -0.06; I2 = 51.7%) and fasting insulin (WMD: -0.40 μIU/mL; 95% CI: -0.73, -0.07 μIU/mL; I2 = 49.4%). There was no significant effect of nut consumption on fasting blood glucose (WMD: -0.52 mg/dL; 95% CI: -1.43, 0.38 mg/dL; I2 = 53.4%) or HbA1c (WMD: 0.02%; 95% CI: -0.01%, 0.04%; I2 = 51.0%).

Conclusions

Consumption of peanuts or tree nuts significantly decreased HOMA-IR and fasting insulin; there was no effect of nut consumption on HbA1c or fasting glucose. The results suggest that nut consumption may improve insulin sensitivity. In the future, well-designed clinical trials are required to elucidate the mechanisms that account for these observed effects.

Nuts and Cardiovascular Disease Prevention

PURPOSE OF REVIEW

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

RECENT FINDINGS

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