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Research Nut: Pecans

Upcycling commercial nut byproducts for food, nutraceutical, and pharmaceutical applications: A comprehensive review.

Alasalvar, C., G. Huang, B.W. Bolling, P.A. Jantip, R.B. Pegg, X.K. Wong, S.K. Chang, E. Pelvan, A.C. de Camargo, G. Mandalari, A. Hossain, F. Shahidi, 2025. Upcycling commercial nut byproducts for food, nutraceutical, and pharmaceutical applications: A comprehensive review. Food Chem. 467:142222. https://doi.org/10.1016/j.foodchem.2024.142222

This article presents a comprehensive overview of upcycling commercial nut byproducts (such as almond, Brazil nut, cashew, hazelnut, macadamia, peanut (also known as a legume), pecan, pine nut, pistachio, and walnut) for food, nutraceutical, and pharmaceutical applications. Upcycling nut byproducts, namely husk/hull, hard shell, brown skin, defatted flour/meal/cake, pine cone, cashew nut shell liquid, cashew apple, walnut septum, and dreg/okara, has great potential, not only to reduce/minimise waste, but also to fit within the circular economy concept. Each byproduct has its own unique functional properties, which can bring significant value. These byproducts can be used as value-added ingredients to promote better health and well-being, due to their rich sources of diverse bioactive components/phytochemicals, polysaccharides, fibre, lignin, prebiotics, oils, proteins, bioactive peptides, minerals, and vitamins, among other components. This comprehensive review provides a basis for future research and development of product applications for nut byproducts. More studies are needed on novel product development to valorise nut byproducts.

Consumption of tree nuts as snacks stimulates changes in plasma fatty acid profiles and adipose tissue gene expression in young adults at risk for metabolic syndrome

Widmer, A., K. Lillegard, K. Wood, M. Robles, R. Fan, F. Ye, J.R. Koethe, H.J. Silver, 2025. Consumption of tree nuts as snacks stimulates changes in plasma fatty acid profiles and adipose tissue gene expression in young adults at risk for metabolic syndrome. Clinical Nutrition. (48)25 – 34. https://doi.org/10.1016/j.clnu.2025.03.002.

Background and aims: The prevalence of metabolic syndrome has been increasing in young adults, concomitant with the occurrence of increased abdominal adiposity. We previously reported that consuming tree nuts, as replacement for typical high-carbohydrate snacks, reduces visceral fat and waist circumference in young adults who have one or more metabolic syndrome risk factors. We aimed to investigate the effects of tree nuts snack consumption on plasma and adipose tissue fatty acid profiles along with changes in the expression of adipose tissue genes involved in thermogenesis, glycemia, adipocyte signaling, lipolysis, and immunity. Methods: A randomized parallel-arm 16-week intervention trial was conducted in 84 adults aged 22-36 years. Participants in both groups were provided with caloric goals for weight maintenance, daily menus, and pre-portioned snacks at every other week visits with study registered dietitians. Changes in dietary fatty acid intakes, plasma and abdominal subcutaneous adipose tissue (SAT) triglycerides fatty acid profiles using gas-liquid chromatography, and the expression of 241 genes in abdominal SAT were evaluated. Results: Consuming tree nuts snacks increased mono- and polyunsaturated fatty acid intakes yielding a 9-fold greater dietary unsaturated to saturated fat ratio. The tree nuts snack group also had significantly greater improvements in plasma 16:1/16:0 ratio; plasma phospholipids oleic and gamma linolenic acid content; plasma diglycerides, triglycerides, and cholesterol esters oleic acid content; and total plasma monounsaturated fatty acids. While abdominal SAT only showed trends for increased oleic acid content and unsaturated to saturated fat ratio, the tree nuts snacks participants had altered expression of 13 genes in abdominal SAT that have roles in nutrient sensing, energy homeostasis, and vulnerability to obesity. Conclusions: Replacing typical high-carbohydrate snacks with tree nuts results in more favorable dietary, plasma, and adipose tissue fatty acid profiles that could aid in preventing the development of excess adiposity and cardiometabolic disease states including metabolic syndrome.

Consuming pecans as a snack improves lipids/lipoproteins and diet quality compared with usual diet in adults at increased risk of cardiometabolic diseases: a randomized controlled trial.

Hart, T.L., P.M. Kris-Etherton, K.S. Petersen, 2025. Consuming pecans as a snack improves lipids/lipoproteins and diet quality compared with usual diet in adults at increased risk of cardiometabolic diseases: a randomized controlled trial. Amer J Clin Nutr. ISSN 0002-9165,doi.org/10.1016/j.ajcnut.2025.01.024.

Background: The vascular and cardiometabolic effects of pecans are relatively understudied. Objectives: The aim was to examine how substitution of usual snack foods with 57g/d of pecans affects vascular health, risk factors for cardiometabolic diseases, and diet quality, compared with continuing usual intake in individuals at risk of cardiometabolic diseases. Methods: A 12-wk single-blinded, parallel, randomized controlled trial was conducted. Adults with ≥1 criterion for metabolic syndrome who were free from cardiovascular disease and type 2 diabetes were included. Participants were provided with 57g/d of pecans and instructed to replace the snacks usually consumed with the provided pecans. The control group was instructed to continue consuming their usual diet. Flow-mediated dilation (FMD),primary outcome, along with blood pressure, carotid-femoral pulse wave velocity (cf-PWV), lipids/lipoproteins, and glycemic control were measured at baseline and following the intervention. Participants completed 3 24-h recalls at 3 time points (baseline, week 6, and week 12) during the study (9 recalls in total). The Healthy Eating Index-2020 (HEI-2020) was calculated to assess diet quality. Results: In total, 138 participants (mean ± SD; 46 ± 13 y, 29.8 ± 3.7 kg/m2) were randomly assigned (69 per group). No between-group differences in FMD, cf-PWV, or blood pressure were observed. Compared with the usual diet group, pecan intake reduced total cholesterol (− 8.1 mg/dL; 95% confidence interval [CI]: −14.5, −1.7), LDL cholesterol ( −7.2 mg/dL; 95% CI −12.3, −2.1), non-HDL-cholesterol (− 9.5 mg/dL; 95% CI −15.3, −3.7), and triglycerides concentrations ( −16.4 mg/dL; 95% CI −30.0, −2.9). Weight tended to increase in the pecan group compared with the usual diet group (0.7 kg; 95% CI −0.1, 1.4). The HEI-2020 increased by 9.4 points (95% CI 5.0, 13.7) in the pecan group compared with the usual diet group. Conclusions: Replacing usual snacks with 57 g/d of pecans for 12-wk improves lipids/lipoproteins and diet quality but does not affect vascular health in adults at risk of cardiometabolic disease.

Current options in the management of tree nut allergy: A systematic review and narrative synthesis.

Pasioti, M., P. Xepapadaki, A.G. Mathioudakis, J. Lakoumentas, E. Efstathiou, N.G. Papadopoulos, 2024. Current options in the management of tree nut allergy: A systematic review and narrative synthesis. Pediatr Allergy Immunol. 35(5):e14132. doi: 10.1111/pai.14132.

Tree nut allergy is a lifelong and potentially life-threatening condition. The standard of care is strictly avoiding the culprit nut and treating accidental reactions symptomatically. To evaluate potential therapeutic options for desensitizing patients with IgE-mediated tree nut allergy, we systematically searched three bibliographic databases for studies published until January 2024. We looked for active treatments of IgE-mediated allergy to tree nuts (walnut, hazelnut, pistachio, cashew, almond, pecan, macadamia nut, and brazil nut). We focused on allergen-specific immunotherapy (AIT) using oral (OIT), sublingual (SLIT), epicutaneous (EPIT), or subcutaneous (SCIT) delivery, or other disease-modifying treatments. We found 19 studies that met our criteria: 3 studies investigated sublingual immunotherapy, 5 studied oral immunotherapy to a single tree nut, and 6 used multi-food oral immunotherapy with or without omalizumab. The remaining studies investigated the effectiveness of monoclonal antibodies or IgE-immunoadsorption in multi-food allergic patients, including patients with tree nut allergy. The heterogeneity of the studies prevented pooling and meta-analysis. Oral immunotherapy, single or multi-nut, with or without omalizumab, was the most studied approach and appears effective in conferring protection from accidental exposures. Omalizumab monotherapy is the only approved alternative management for reducing allergic reactions that may occur with accidental exposure.

Consumption of tree nuts as snacks reduces metabolic syndrome risk in young adults: a randomized trial.

Sumislawski, K., A. Widmer, R.R. Suro, M.E. Robles, K. Lillegard, D. Olson, J.R. Koethe, H.J. Silver, 2023. Consumption of tree nuts as snacks reduces metabolic syndrome risk in young adults: a randomized trial. Nutrients. 15(24):5051. doi: 10.3390/nu15245051.

Metabolic syndrome (MetSx) and its chronic disease consequences are major public health concerns worldwide. Between-meal snacking may be a modifiable risk factor. We hypothesized that consuming tree nuts as snacks, versus typical carbohydrate snacks, would reduce risk for MetSx in young adults. A prospective, randomized, 16-week parallel-group diet intervention trial was conducted in 84 adults aged 22-36 with BMI 24.5 to 34.9 kg/m2 and ≥1 MetSx clinical risk factor. Tree nuts snacks (TNsnack) were matched to carbohydrate snacks (CHOsnack) for energy (kcal), protein, fiber, and sodium content as part of a 7-day eucaloric menu. Difference in change between groups was tested by analysis of covariance using general linear models. Multivariable linear regression modeling assessed main effects of TNsnack treatment and interactions between TNsnack and sex on MetSx score. Age, BMI, and year of study enrollment were included variables. There was a main effect of TNsnack on reducing waist circumference in females (mean difference: -2.20 ± 0.73 cm, p = 0.004) and a trend toward reduced visceral fat (-5.27 ± 13.05 cm2, p = 0.06). TNsnack decreased blood insulin levels in males (-1.14 ± 1.41 mIU/L, p = 0.05) and multivariable modeling showed a main effect of TNsnack on insulin. Main effects of TNsnack on triglycerides and TG/HDL ratio were observed (p = 0.04 for both) with TG/HDL ratio reduced ~11%. A main effect of TNsnack (p = 0.04) and an interaction effect between TNsnack and sex (p < 0.001) on total MetSx score yielded 67% reduced MetSx score in TNsnack females and 42% reduced MetSx score in TNsnack males. To our knowledge, this is the first randomized parallel-arm study to investigate cardiometabolic responses to TNsnacks versus typical CHOsnacks among young adults at risk of MetSx. Our study suggests daily tree nut consumption reduces MetSx risk by improving waist circumference, lipid biomarkers, and/or insulin sensitivity-without requiring caloric restriction.

Association of tree nut consumption with cardiovascular disease and cardiometabolic risk factors and health outcomes in US adults: NHANES 2011-2018.

Lopez-Neyman, S. M., N. Zohoori, K.S. Broughton, D.C. Miketinas, 2023. Association of tree nut consumption with cardiovascular disease and cardiometabolic risk factors and health outcomes in US adults: NHANES 2011-2018. Curr. Dev. Nutr. 7(10):102007. https://doi.org/10.1016/j.cdnut.2023.102007

Background: Tree nuts are nutrient dense, and their consumption has been associated with improvements in health outcomes. Objective: To estimate the usual tree nut intake and examine the association between tree nut consumption and cardiometabolic (CM) health outcomes in a nationally representative sample of US adults. Methods: Cross-sectional data were analyzed from a sample of 18,150 adults aged ≥ 20y who provided at least one reliable 24-h dietary recall and had complete data for the variables of interest in the NHANES 2011-2018. Tree nut consumers were defined as those consuming ≥ ¼ ounce/d (7.09 g). The National Cancer Institute Method was used to estimate the usual tree nut intake among consumers. Measurement error calibrated regression models were used to assess the association between tree nut consumption and each health outcome of interest. Results: Approximately 8% of all participants (n = 1238) consumed tree nuts and had a mean ± SE usual intake of 39.5 ± 1.8 g/d. Tree nut consumers were less likely to have obesity (31% vs. 40%, P < 0.001) and low high-density lipoprotein cholesterol (22% vs. 30%, P < 0.001) compared with nonconsumers. Moreover, tree nut consumers had a lower mean waist circumference (WC) (97.1 ± 0.7 vs. 100.5 ± 0.3 cm, P < 0.001) and apolipoprotein B (87.5 ± 1.2 vs. 91.8 ± 0.5 mg/dL, P = 0.004) than nonconsumers. After adjusting models for demographics and lifestyle covariates, the difference in WC between average intake (33.7 g/d) and low threshold intake (7.09/g) of tree nuts was -1.42 ± 0.58 cm (P = 0.005). Conclusions: Most US adults do not consume tree nuts, yet modest consumption was associated with decreased prevalence of cardiovascular disease and CM risk factors and improvement for some health outcome measures.

Nuts, Energy Balance and Body Weight.

Baer, D.J., M. Dalton, J. Blundell, G. Finlayson, F.B. Hu, 2023. Nuts, Energy Balance and Body Weight. Nutrients. 15(5):1162. doi: 10.3390/nu15051162.

Over several decades, the health benefits of consuming nuts have been investigated, resulting in a large body of evidence that nuts can reduce the risk of chronic diseases. The consumption of nuts, being a higher-fat plant food, is restricted by some in order to minimize weight gain. In this review, we discuss several factors related to energy intake from nuts, including food matrix and its impact on digestibility, and the role of nuts in regulating appetite. We review the data from randomized controlled trials and observational studies conducted to examine the relationship between nut intake and body weight or body mass index. Consistently, the evidence from RCTs and observational cohorts indicates that higher nut consumption does not cause greater weight gain; rather, nuts may be beneficial for weight control and prevention of long-term weight gain. Multiple mechanisms likely contribute to these findings, including aspects of nut composition which affect nutrient and energy availability as well as satiety signaling.

Mixed nuts as healthy snacks: effect on tryptophan metabolism and cardiovascular risk factors.

Yang, J., R. Lee, Z. Schulz, A. Hsu, J. Pai, S. Yang, S.M. Henning, J. Huang, J.P. Jacobs, D. Heber, Z. Li., 2023. Mixed nuts as healthy snacks: effect on tryptophan metabolism and cardiovascular risk factors. Nutrients. 15, 569; https://doi.org/10.3390/nu15030569.

We recently demonstrated that the consumption of mixed tree nuts (MTNs) during caloric restriction decreased cardiovascular risk factors and increased satiety. Tryptophan (Trp) metabolism has been indicated as a factor in cardiovascular disease. Here, we investigated the effect of MTNs on Trp metabolism and the link to cardiovascular risk markers. Plasma and stool were collected from 95 overweight individuals who consumed either MTNs (or pretzels) daily as part of a hypocaloric weight loss diet for 12 weeks followed by an isocaloric weight maintenance program for an additional 12 weeks. Plasma and fecal samples were evaluated for Trp metabolites by LC–MS and for gut microbiota by 16S rRNA sequencing. Trp–kynurenine metabolism was reduced only in the MTNs group during weight loss (baseline vs. week 12). Changes in Trp–serotonin (week 24) and Trp–indole (week 12) metabolism from baseline were increased in the MTNs group compared to the pretzel group. Intergroup analysis between MTN and pretzel groups does not identify significant microbial changes as indicated by alpha diversity and beta diversity. Changes in the relative abundance of genus Paludicola during intervention are statistically different between the MTNs and pretzel group with p < 0.001 (q = 0.07). Our findings suggest that consumption of MTNs affects Trp host and microbial metabolism in overweight and obese subjects.

Nut consumption in association with overall mortality and recurrence/disease-specific mortality among long-term breast cancer survivors.

Cong, W., K. Gu, F. Wang, H. Cai, W. Zheng, P. Bao, X.-O. Shu, 2022. Nut consumption in association with overall mortality and recurrence/disease-specific mortality among long-term breast cancer survivors. International Journal of Cancer.doi.org/10.1002/ijc.33824.

High nut consumption is associated with reduced total and certain cause-specific mortality in general populations. However, its association with cancer outcomes among long-term breast cancer survivors remains unknown. We examined the associations of nut consumption (including peanuts and tree nuts), assessed at 5-year postdiagnosis, with overall survival (OS) and disease-free survival (DFS) among 3449 long-term breast cancer survivors from the Shanghai Breast Cancer Survival Study, applying Cox regression analysis. During a median follow-up of 8.27 years post dietary assessment, there were 374 deaths, including 252 breast cancer deaths. Among 3274 survivors without previous recurrence at the dietary assessment, 209 developed breast cancer-specific events, that is, recurrence, metastasis or breast cancer mortality. At 5-year post dietary assessment (ie, 10-year postdiagnosis), regular nut consumers had higher OS (93.7% vs 89.0%) and DFS (94.1% vs 86.2%) rates. After multivariable adjustment, nut consumption was positively associated with OS (Ptrend = .022) and DFS (Ptrend = .003) following a dose-response pattern, with hazard ratios (95% confidence interval) of 0.72 (0.52-1.05) for OS and 0.48 (0.31-0.73) for DFS, for participants with greater than median nut intake compared with nonconsumers. The associations did not vary by nut type. Stratified analyses showed that the associations were more evident among participants with a higher total energy intake for OS (Pinteraction = .02) and among participants with early stage (I-II) breast cancers for DFS (Pinteraction = .04). The nut-DFS associations were not modified by estrogen receptor/progesterone receptor status or other known prognostic factors. In conclusion, nut consumption was associated with better survival, particularly DFS, among long-term breast cancer survivors.

The effects of peanuts and tree nuts on lipid profile in type 2 diabetic patients: A systematic review and meta-analysis of randomized, controlled-feeding clinical studies.

Xia, J.Y., J.H. Yu, D.F. Xu, C. Yang, H. Xia, G.J. Sun, 2021. The effects of peanuts and tree nuts on lipid profile in Type 2 diabetic patients: A systematic review and meta-analysis of randomized, controlled-feeding clinical studies. Front. Nutr. https://doi.org/10.3389/fnut.2021.765571

Background: Type 2 diabetes mellitus was found to be associated with metabolic disorders, particularly abnormal glucose and lipid metabolism. Dietary food choices may have profound effects on blood lipids. The primary objective of this study was to examine the effects of peanuts and tree nuts intake on lipid profile in patients with type 2 diabetes. Methods: According to preferred reporting items for systematic reviews and meta-analysis guidelines, we performed a systematic search of randomized controlled clinical trials and systematic reviews published in PubMed, Web of Science, Embase, Scopus, and Cochrane library, from inception through June 2021. Studies in populations with type 2 diabetes, which compare nuts or peanuts to a controlled-diet group were included. We used the mean difference with 95% CIs to present estimates for continuous outcomes from individual studies. In addition, we used the GRADEpro tool to evaluate the overall quality of evidence. Results: Sixteen studies involving 1,041 participants were eligible for this review. The results showed that peanuts and tree nuts supplementation did not induce significant changes in low-density lipoprotein-cholesterol (LDL-C) (mean difference = −0.11; 95%CI: −0.25 – 0.03, p = 0.117) and high-density lipoprotein-cholesterol (HDL-C) (mean difference = 0.01; 95%CI: −0.01 – 0.04, p = 0.400) in patients with type 2 diabetics. In addition, we found that peanuts and tree nuts intake may cause a significantly reduction in total cholesterol (TC) (mean difference = −0.14; 95%CI: −0.26 – −0.02, p = 0.024) and triglyceride (TG) (mean difference = −0.10; 95%CI: −0.17 – −0.02, p = 0.010). In the subgroup analysis, a significantly greater reduction in TC was observed in studies which duration was <12 weeks (mean difference = −0.22; 95%CI: −0.37 – −0.08, p = 0.002). The quality of the body of evidence was “moderate” for TC and TG, the quality of evidence for LDL-C and HDL-C were “low.” Conclusion: Our findings suggest that consuming peanuts and tree nuts might be beneficial to lower TC concentration and TG concentration in type 2 diabetics subjects. Furthermore, peanuts and tree nuts supplementation could be considered as a part of a healthy lifestyle in the management of blood lipids in patients with type 2 diabetes. Given some limits observed in the current studies, more well-designed trials are still needed.