Delgadillo-Puga, C., I. Torre-Villalvazo, L.G. Noriega, L.A. Rodríguez-López, G. Alemán, E.A. Torre-Anaya, Y.Y. Cariño-Cervantes, B. Palacios-Gonzalez, J. Furuzawa-Carballeda, A.R. Tovar, L. Cisneros-Zevallos, 2023. 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. Nutrients. 15(11):2591. https://doi.org/10.3390/nu15112591
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.
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.
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.
Guarneiri, L.L., C.M. Paton, J.A. Cooper, 2022. Appetite responses to pecan-enriched diets. Appetite. 173:106003. https://doi.org/10.1016/j.appet.2022.106003
Research suggests that tree nuts improve satiety during an acute meal, but the effects of daily consumption are less clear. The purpose of this study was to examine the impact of daily pecan consumption on markers of appetite in adults at-risk for cardiovascular disease (CVD). This was an 8-week, randomized, controlled trial with three treatments: two pecan groups and a nut-free control group (n = 16). The ADD group (n = 15) consumed pecans (68 g) as part of a free-living diet, and the SUB group (n = 16) substituted the pecans (68 g) for isocaloric foods from their diet. At pre- and post-intervention, a high-fat meal was consumed with 3.5 h postprandial blood draws and visual appetite scales (VAS) to determine changes in cholecystokinin (CCK), peptide YY (PYY), ghrelin, and subjective appetite. Participants also completed VAS questionnaires once/h for the next 5 h and recorded dietary intake. Although no differences between groups (p > 0.05), there was an increase in postprandial CCK and PYY and suppression of postprandial ghrelin within ADD (p ≤ 0.05) from pre-to post-intervention. Across the entire day, the decreases in prospective consumption and desire to eat were greater in ADD vs SUB (-79 ± 41 vs 11 ± 26 mm/9 h; p = 0.05) and ADD vs control (-64 ± 39 vs 23 ± 29 mm/9 h; p = 0.05), respectively. There was also a non-significant tendency for a greater decrease in overall appetite in ADD vs control (-67 ± 46 vs 20 ± 27 mm/9 h; p = 0.06). Within ADD, overall appetite, prospective consumption, and desire to eat decreased, and fullness increased from pre-to post-intervention (p ≤ 0.05 for all). There were no changes in self-reported energy intake on test days or other changes within or between groups. In conclusion, adding pecans to the daily diet improves subjective and physiological markers of postprandial appetite in adults that are at-risk for CVD.
