Mandalari, G., T. Gervasi, D.W. Rosenberg, K.G. Lapsley, D.J. Baer, 2023. Effect of nuts on gastrointestinal health. Nutrients. 15(7):1733. https://doi.org/10.3390/nu15071733
Nuts are high nutrient-dense foods containing healthy lipids, dietary fiber, and bioactive phytochemicals, including vitamins and minerals. Although the beneficial effect of nut consumption on different chronic diseases has been well documented, especially in relation to their cardiometabolic benefits, less scientific evidence is available on their possible beneficial effects on gastrointestinal health. In this narrative review, we summarize the most important findings and new research perspectives in relation to the importance of nut consumption on gastrointestinal health. The integrity of the cell wall structure, cell size and particle size after mastication are known to play a crucial role in energy, nutrient and bioactive release from nuts during digestion, therefore affecting bioaccessibility. Other mechanisms, such as cell wall composition, thickness and porosity, as well as stability of the membranes surrounding the oil bodies within the cell, are also important for energy extraction. As the undigested nutrients and phytochemicals are delivered to the colon, effects on gut microbiota composition are predicted. Although the overall effect of nut consumption on microbial alpha- and beta-diversity has been inconsistent, some scientific evidence suggests an increase in fecal butyrate after almond consumption, and a beneficial role of walnuts on the prevention of ulcerative colitis and protection against the development of gastric mucosal lesions.
Gulati, S., A. Misra, R. Tiwari, M. Sharma, R.M. Pandey, A.D. Upadhyay, H.C. Sati, 2023. Beneficial effects of premeal almond load on glucose profile on oral glucose tolerance and continuous glucose monitoring: randomized crossover trials in Asian Indians with prediabetes. European journal of clinical nutrition. 77(5):586–595. https://doi.org/10.1038/s41430-023-01263-1
Background: Rapid conversion from prediabetes to diabetes and frequent postprandial hyperglycemia (PPHG) is seen in Asian Indians. These should be the target of dietary strategies. Objectives: We hypothesized that dietary intervention of preloading major meals with almonds in participants with prediabetes will decrease overall glycemia and PPHG. Design: The study included two phases: (1) an oral glucose tolerance test (OGTT)-based crossover randomized control study, the effect of a single premeal almond load (20 g) given before OGTT was evaluated (n = 60, 30 each period). (2) The continuous glucose monitoring system (CGMS)-based study for 3 days including premeal almond load before three major meals was a free-living, open-labeled, crossover randomized control trial, where control and premeal almond load diets were compared for glycaemic control (n = 60, 30 in each period). The study was registered at clinicaltrials.gov (registration no. NCT04769726). Results: In the OGTT-based study phase, the overall AUC for blood glucose, serum insulin, C-peptide, and plasma glucagon post-75 g oral glucose load was significantly lower for treatment vs. control diet (p < 0.001). Specifically, with the former diet, PPHG was significantly lower (18.05% in AUC on OGTT, 24.8% at 1-h, 28.9% at 2-h post OGTT, and 10.07% during CGMS). The CGMS data showed that premeal almond load significantly improved 24-glucose variability; SD of mean glucose concentration and mean of daily differences. Daily glycaemic control improved significantly as per the following: mean 24-h blood glucose concentration (M), time spent above 7.8 mmol/L of blood glucose, together with the corresponding AUC values. Premeal almond load significantly decreased following: overall hyperglycemia (glucose AUC), PPHG, peak 24-h glycaemia, and minimum glucose level during night. Conclusion: Incorporation of 20 g of almonds, 30 min before each major meal led to a significant decrease in PPHG (as revealed in OGTT-based study phase) and also improved insulin, C-peptide, glucagon levels, and improved glucose variability and glycemic parameters on CGMS in participants with prediabetes.
Carter, S., A.M. Hill, L.C. Mead, H.Y. Wong, C. Yandell, J.D. Buckley, S.Y. Tan, G.B. Rogers, F. Fraysse, A.M. Coates, 2023. Almonds vs. carbohydrate snacks in an energy-restricted diet: Weight and cardiometabolic outcomes from a randomized trial. Obesity (Silver Spring). 31(10):2467-2481. https://doi.org/10.1002/oby.23860
Objective: This study evaluated weight and cardiometabolic outcomes after a 3-month energy-restricted diet (−30%) containing almonds (almond-enriched diet [AED]) or containing carbohydrate-rich snacks (nut-free control diet [NFD]) (Phase 1), followed by 6 months of weight maintenance (Phase 2). Methods: Participants (25–65 years old) with overweight or obesity (BMI 27.5–34.9 kg/m2) were randomly allocated to AED (n = 68) or NFD (n = 72). Results: Both groups lost weight during Phase 1 (p < 0.001) (mean [SE], −7.0 [0.5] kg AED vs. −7.0 [0.5] kg NFD, p = 0.858) and Phase 2 (p = 0.009) (−1.1 [0.5] kg AED vs. −1.3 [0.6] NFD, p = 0.756), with improvements in percentage lean mass after Phase 2 (4.8% [0.3%], p < 0.001). Reductions occurred in fasting glucose (−0.2 [0.07] mmol/L, p = 0.003), insulin (−8.1 [4.0] pmol/L, p = 0.036), blood pressure (−4.9 [0.8] mm Hg systolic, −5.0 [0.5] mm Hg diastolic, p < 0.001), total cholesterol (−0.3 [0.1] mmol/L), low-density lipoprotein (LDL) (−0.2 [0.1] mmol/L), very low density lipoprotein (−0.1 [0.03] mmol/L), and triglycerides (−0.3 [0.06] mmol/L) (all p < 0.001), and high-density lipoprotein increased (0.1 [0.02] mmol/L, p = 0.011) by the end of Phase 2 in both groups. There were group by time interactions for lipoprotein particle concentrations: very small triglyceride-rich (−31.0 [7.7] nmol/L AED vs. −4.8 [7.9] nmol/L NFD, p = 0.007), small LDL (−109.3 [40.5] nmol/L AED vs. −20.7 [41.6] nmol/L NFD, p = 0.017), and medium LDL (−24.4 [43.4] nmol/L AED vs. −130.5 [44.4] nmol/L NFD, p = 0.045). Conclusions: An energy-restricted AED resulted in weight loss and weight loss maintenance comparable to an energy-restricted NFD, and both diets supported cardiometabolic health. The AED resulted in greater improvements in some lipoprotein subfractions, which may enhance reductions in cardiovascular risk.
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.
