Gayathri, R., K. Abirami, N. Kalpana, V.S. Manasa, V. Sudha, S. Shobana, R.G. Jeevan, V. Kavitha, K. Parkavi, R.M. Anjana, R. Unnikrishnan, K. Gokulakrishnan, D.A. Beatrice, K. Krishnaswamy, R. Pradeepa, R.D. Mattes, J. Salas-Salvadó, W. Willett, V. Mohan, 2023. Effect of almond consumption on insulin sensitivity and serum lipids among Asian Indian adults with overweight and obesity- A randomized controlled trial. Front. Nutr. 9: 1055923. https://doi.org/10.3389/fnut.2022.1055923
Background: Asian Indians have an increased susceptibility to type 2 diabetes and premature coronary artery disease. Nuts, like almonds, are rich in unsaturated fat and micronutrients with known health benefits. Objectives: This study aimed to assess the efficacy of almonds for reduction of insulin resistance and improving lipid profile in overweight Asian Indian adults. Methods: This parallel-arm, randomized, controlled trial was conducted in Chennai, India on 400 participants aged 25-65 years with a body mass index ≥ 23 kg/m2. The intervention group received 43 g of almonds/day for 12 weeks, while the control group was advised to consume a customary diet but to avoid nuts. Anthropometric, clinical, and dietary data were assessed at periodic intervals. Glucose tolerance, serum insulin, glycated hemoglobin, C-peptide and lipid profile were assessed at baseline and end of the study. Insulin resistance (homeostasis assessment model-HOMA IR) and oral insulin disposition index (DIo) were calculated. Results: A total of 352 participants completed the study. Significant improvement was seen in DIo [mean (95% CI) = + 0.7 mmol/L (0.1, 1.3); p = 0.03], HOMA IR (-0.4 (-0.7, -0.04; p = 0.03) and total cholesterol (-5.4 mg/dl (-10.2, -0.6); p = 0.03) in the intervention group compared to the control group. Incremental area under the curve (IAUC) and mean amplitude of glycemic excursion (MAGE) assessed using continuous glucose monitoring systems were also significantly lower in the intervention group. Dietary 24-h recalls showed a higher significant reduction in carbohydrate and increase in mono unsaturated fatty acid (MUFA) and polyunsaturated fatty acids (PUFA) intake in the intervention group compared to the control group. Conclusion: Daily consumption of almonds increased the intake of MUFA with decrease in carbohydrate calories and decreases insulin resistance, improves insulin sensitivity and lowers serum cholesterol in Asian Indians with overweight/obesity. These effects in the long run could aid in reducing the risk of diabetes and other cardiometabolic disease.
Gu, X., J.-P. Drouin-Chartier, F.M. Sacks, F.B. Hu, B. Rosner, W.C. Willett, 2023. Red meat intake and risk of type 2 diabetes in a prospective cohort study of United States females and males. Amer J Clin Nutr. doi.org/10.1016/j.ajcnut.2023.08.021
Background: Studies with methodological advancements are warranted to confirm the relation of red meat consumption to the incidence of type 2 diabetes (T2D). Objective: We aimed to assess the relationships of intakes of total, processed, and unprocessed red meat to risk of T2D and to estimate the effects of substituting different protein sources for red meats on T2D risk. Methods: Our study included 216,695 participants (81% females) from the Nurses’ Health Study (NHS), NHS II, and Health Professionals Follow-up Study (HPFS). Red meat intakes were assessed with semiquantitative food frequency questionnaires (FFQs) every 2 to 4 y since the study baselines. We used multivariable-adjusted proportional hazards models to estimate the associations between red meats and T2D. Results: Over 5,483,981 person-years of follow-up, we documented 22,761 T2D cases. Intakes of total, processed, and unprocessed red meat were positively and approximately linearly associated with higher risks of T2D. Comparing the highest to the lowest quintiles, hazard ratios (HR) were 1.62 (95% confidence interval [CI]: 1.53, 1.71) for total red meat, 1.51 (95% CI: 1.44, 1.58) for processed red meat, and 1.40 (95% CI: 1.33, 1.47) for
unprocessed red meat. The percentage lower risk of T2D associated with substituting 1 serving/d of nuts and legumes for total red meat was 30% (HR ¼ 0.70, 95% CI: 0.66, 0.74), for processed red meat was 41% (HR ¼ 0.59, 95% CI: 0.55, 0.64), and for unprocessed red meat was 29% (HR ¼ 0.71, 95% CI: 0.67, 0.75); Substituting 1 serving/d of dairy for total, processed, or unprocessed red meat was also associated with significantly lower risk of T2D. The observed associations became stronger after we calibrated dietary intakes to intakes assessed by weighed diet records. Conclusions: Our study supports current dietary recommendations for limiting consumption of red meat intake and emphasizes the importance of different alternative sources of protein for T2D prevention.
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.
Dorans, K.S., L.A. Bazzano, L. Qi, H. He, J. Chen, L.J. Appel, C.S. Chen, M.H. Hsieh, F.B. Hu, K.T. Mills, B.T. Nguyen, M.J. O’Brien, J.M. Samet, G.I. Uwaifo, J. He, 2022. Effects of a low-carbohydrate dietary intervention on hemoglobin A1c: a randomized clinical trial. JAMA Netw. Open. 5(10), e2238645. https://doi.org/10.1001/jamanetworkopen.2022.38645
Importance: Low-carbohydrate diets decrease hemoglobin A1c (HbA1c) among patients with type 2 diabetes at least as much as low-fat diets. However, evidence on the effects of low-carbohydrate diets on HbA1c among individuals with HbA1c in the range of prediabetes to diabetes not treated by diabetes medications is limited. Objective: To study the effect of a behavioral intervention promoting a low-carbohydrate diet compared with usual diet on 6-month changes in HbA1c among individuals with elevated untreated HbA1c. Design, setting, and participants: This 6-month randomized clinical trial with 2 parallel groups was conducted from September 2018 to June 2021 at an academic medical center in New Orleans, Louisiana. Laboratory analysts were blinded to assignment. Participants were aged 40 to 70 years with untreated HbA1c of 6.0% to 6.9% (42-52 mmol/mol). Data analysis was performed from November 2021 to September 2022. Interventions: Participants were randomized to a low-carbohydrate diet intervention (target <40 net grams of carbohydrates during the first 3 months; <60 net grams for months 3 to 6) or usual diet. The low-carbohydrate diet group received dietary counseling. Main outcomes and measures: Six-month change in HbA1c was the primary outcome. Outcomes were measured at 0, 3, and 6 months. Results: Of 2722 prescreened participants, 962 underwent screening, and 150 were enrolled (mean [SD] age, 58.9 [7.9] years; 108 women [72%]; 88 Black participants [59%]) and randomized to either the low-carbohydrate diet intervention (75 participants) or usual diet (75 participants) group. Six-month data were collected on 142 participants (95%). Mean (SD) HbA1c was 6.16% (0.30%) at baseline. Compared with the usual diet group, the low-carbohydrate diet intervention group had significantly greater 6-month reductions in HbA1c (net difference, -0.23%; 95% CI, -0.32% to -0.14%; P < .001), fasting plasma glucose (-10.3 mg/dL; 95% CI, -15.6 to -4.9 mg/dL; P < .001), and body weight (-5.9 kg; 95% CI, -7.4 to -4.4 kg; P < .001). Conclusions and relevance: In this randomized clinical trial, a low-carbohydrate dietary intervention led to improvements in glycemia in individuals with elevated HbA1c not taking glucose-lowering medication, but the study was unable to evaluate its effects independently of weight loss. This diet, if sustained, might be a useful dietary approach for preventing and treating type 2 diabetes, but more research is needed.
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.
Madan, J., S. Desai, P. Moitra, S. Salis, S. Agashe, R. Battalwar, A. Mehta, R. Kamble, S. Kalita, A.G. Phatak, S.A. Udipi, R.A. Vaidya, A.B. Vaidya, 2021. Effect of almond consumption on metabolic risk factors-glucose metabolism, hyperinsulinemia, selected markers of inflammation: a randomized controlled trial in adolescents and young adults. Front. Nutr. 8:668622. https://doi.org/10.3389/fnut.2021.668622
A large percentage of the Indian population has diabetes or is at risk of pre-diabetes. Almond consumption has shown benefits on cardiometabolic risk factors in adults. This study explored the effect of almond consumption on determinants of metabolic dysfunction-blood glucose, lipids, insulin and selected inflammatory markers in adolescents and young adults aged 16-25 years from Mumbai city. This randomized controlled trial was conducted for a period of 90 days on individuals with impaired levels of fasting glucose levels between 100-125 mg/dL (5.6-6.9 mmol/L) and 2-h post-glucose value 140-199 mg/dL (7.8-11.0 mmol/L) and/or fasting insulin (≥15 mIU/ml)/stimulated insulin (≥80 mIU/ml). Of 1,313 individuals screened, 421 met the inclusion criteria, of which 275 consented to participate and 219 completed the trial. The trial was registered with Clinical Trials Registry India (CTRI) CTRI/2018/02/011927. The almonds group (n = 107) consumed 56 g almonds daily, the control group (n = 112) was provided an iso-caloric cereal-pulse based snack. At baseline and endline, blood glucose, insulin, HbA1c, LDL-c, HDL-c, total and ox-cholesterol, triglycerides, hs-CRP, IL-6, TNF-α, adiponectin, leptin were measured and HOMA-IR and FG:FI ratios were calculated. Dietary intakes were assessed. The anthropometric measurements, biochemical markers as well as macronutrient intakes did not differ significantly between the two groups at baseline. Almond consumption significantly decreased HbA1c, total cholesterol and LDL-c. Stimulated insulin decreased post-intervention in both groups, but the decrease was greater in the almonds group. Fasting glucose was reduced post intervention in the controls with no change in the almonds group. FG:FI ratio decreased in the almonds group. TNF-α and IL-6 decreased in the almonds group, while it increased in the control group. Our results showed that almonds reduced HbA1c, LDL-c and total cholesterol levels in just 12 weeks of consumption in these adolescents and young adults who were at risk for developing diabetes. Almonds can be considered as part of food-based strategies for preventing pre-diabetes. Clinical Trial Registration: ClinicalTrials.gov, identifier: CTRI/2018/02/011927.
Dorans, K.S., L.A. Bazzano, L. Qi, H. Hua, L.J. Appel, J.M. Samet, J. Chen, K.T. Mills, B.T. Nguyen, M.J. O’Brien, I.U. Uwaifo, J. He, 2021. Low-carbohydrate dietary pattern on glycemic outcomes trial (ADEPT) among individuals with elevated hemoglobin A1c: study protocol for a randomized controlled trial. Trials 22, 108. https://doi.org/10.1186/s13063-020-05001-x.
Background: Type 2 diabetes mellitus (T2DM) is a major cause of morbidity and mortality globally. Strong evidence supports the importance of diet and other lifestyle factors in preventing T2DM. Among individuals with T2DM, low carbohydrate diets lead to decreases in hemoglobin A1c (HbA1c). However, research on the effects of low carbohydrate diets on glycemic outcomes among individuals not currently on glucose-lowering medications who have elevated HbA1c is limited. Methods: The objective of this randomized controlled trial is to study the effect of a healthy low-carbohydrate diet achieved through behavioral intervention and key food supplementation compared with usual diet on HbA1c and other metabolic risk factors among individuals with HbA1c from 6.0 to 6.9% who are not on glucose-lowering medications. In this parallel trial, 150 participants will be randomized to the intervention or control group for 6 months. The healthy low-carbohydrate diet target is < 40 g of net carbohydrates during the first 3 months and < 40 to 60 net grams for months 3 to 6. This diet is characterized by abundant unsaturated fat and protein, high-fiber foods such as non-starchy vegetables and nuts, and minimal refined carbohydrates. The primary outcome is the difference in HbA1c change from baseline to 6 months in the intervention compared with usual diet group. Secondary outcomes include differences between groups in 6-month changes in fasting glucose, systolic blood pressure, total-to-high-density lipoprotein (HDL) cholesterol ratio, and body weight. Exploratory outcomes include differences in 6-month changes in fasting insulin, homeostasis model assessment of insulin resistance, diastolic blood pressure, waist circumference, and 10-year cardiovascular disease risk. An intention-to-treat analysis will be used. Discussion: We expect that the results from this study will lead to new approaches for developing and implementing dietary approaches (other than the most commonly used reduced fat diet) that will substantially reduce risk of cardiometabolic disease among adults with or at high risk of T2DM. The study intervention involves behavioral counseling and promotes consumption of dietary components thought to reduce risk of cardiometabolic disease and has expected applicability in clinical practice.
Becerra-Tomás, N., I. Paz-Graniel, P. Hernández-Alonso, D.J.A. Jenkins, C.W.C. Kendall, J.L. Sievenpiper, J. Salas-Salvadó, 2021. Nut consumption and type 2 diabetes risk: a systematic review and meta-analysis of observational studies. Am J Clin Nutr 00:1–12.
Background: Previous meta-analyses, with some methodological controversies, have assessed the relation between nut consumption and type 2 diabetes (T2D) risk and pointed to contradictory results, making desirable the performance of an updated meta-analysis. Objectives: We aimed to systematically review and meta-analyze all the published studies investigating the relations of total nuts and different types of nuts—i.e., walnuts, peanuts, peanut butter, and total tree nuts—with the prevalence and incidence of T2D. Methods: A systematic search was conducted in the PubMed and Cochrane databases through 12 August, 2020. The inverse variance method with fixed-effect models was used to pool data across studies, expressed as risk ratios (RRs) or ORs and 95% CIs for prospective cohort and cross-sectional studies, respectively. The Cochran Q test and I 2 statistics were used to test and quantify heterogeneity, respectively. Dose-response meta-analysis was also conducted. Results: Eight studies (5 prospective and 3 cross-sectional) were included in the quantitative synthesis. Meta-analyses of crosssectional studies and prospective cohort studies, comparing the highest with the lowest categories, revealed a nonsignificant association between total nut consumption and T2D. Meta-analyses of prospective cohort studies showed an inverse association between peanut butter consumption and T2D incidence (RR: 0.87; 95% CI: 0.77, 0.98; I 2 = 50.6%; Pheterogeneity = 0.16), whereas no association was observed between peanuts or tree nuts and T2D. There was no evidence of a linear dose-response or nonlinear dose-response gradient for total nut and peanut consumption in prospective cohort studies. The certainty of the evidence using NutriGrade was very low for all the exposures. Conclusions: Current results do not demonstrate an association of total nut, peanut, or tree nut consumption with T2D. Peanut butter consumption may be inversely associated with this disease. This review protocol was registered at www.crd.york.ac.uk/prospero/ as CRD42020149756.
Neale, E. V. Guan, L. Tapsell, Y. Probst, 2020. Effect of walnut consumption on markers of blood glucose control: A systematic review and meta-analysis. Br J Nutr. 1‐13. doi:10.1017/S0007114520001415
Type 2 diabetes mellitus is a chronic disease increasing in global prevalence. Although habitual consumption of walnuts is associated with reduced risk of CVD, there is inconsistent evidence for the impact of walnut consumption on markers of glycaemic control. This systematic review and meta-analysis aimed to examine the effect of walnut consumption on markers of blood glucose control. A systematic search of Medline, PubMed, CINAHL and Cochrane databases (to 2 March 2019) was conducted. Inclusion criteria were randomised controlled trials conducted with adults which assessed the effect of walnut consumption on fasting blood glucose and insulin, glycated Hb and homeostatic model assessment of insulin resistance. Random effects meta-analyses were conducted to assess the weighted mean differences (WMD) for each outcome. Risk of bias in studies was assessed using the Cochrane Risk of Bias tool 2.0. Sixteen studies providing eighteen effect sizes were included in the review. Consumption of walnuts did not result in significant changes in fasting blood glucose levels (WMD: 0·331 mg/dl; 95 % CI −0·817, 1·479) or other outcome measures. Studies were determined to have either ‘some concerns’ or be at ‘high risk’ of bias. There was no evidence of an effect of walnut consumption on markers of blood glucose control. These findings suggest that the known favourable effects of walnut intake on CVD are not mediated via improvements in glycaemic control. Given the high risk of bias observed in the current evidence base, there is a need for further high-quality randomised controlled trials.
Guasch-Ferré, M., P. Hernández-Alonso, J.P. Drouin-Chartier, M. Ruiz-Canela, C. Razquin, E. Toledo, J. Li, C. Dennis, C. Wittenbecher, D. Corella, R. Estruch, M. Fitó, E. Ros, N. Babio, S.N. Bhupathiraju, C.B. Clish, L. Liang, M.A. Martínez-González, F.B. Hu, J. Salas-Salvadó, 2020. Walnut consumption, plasma metabolomics, and risk of Type 2 diabetes and cardiovascular disease. J Nutr. doi: 10.1093/jn/nxaa374.
Background: Walnut consumption is associated with lower risk of type 2 diabetes (T2D) and cardiovascular disease (CVD). However, it is unknown whether plasma metabolites related to walnut consumption are also associated with lower risk of cardiometabolic diseases. Objectives: The study aimed to identify plasma metabolites associated with walnut consumption and evaluate the prospective associations between the identified profile and risk of T2D and CVD. Methods: The discovery population included 1833 participants at high cardiovascular risk from the PREvención con DIeta MEDiterránea (PREDIMED) study with available metabolomics data at baseline. The study population included 57% women (baseline mean BMI (in kg/m2): 29.9; mean age: 67 y). A total of 1522 participants also had available metabolomics data at year 1 and were used as the internal validation population. Plasma metabolomics analyses were performed using LC-MS. Cross-sectional associations between 385 known metabolites and walnut consumption were assessed using elastic net continuous regression analysis. A 10-cross-validation (CV) procedure was used, and Pearson correlation coefficients were assessed between metabolite weighted models and self-reported walnut consumption in each pair of training–validation data sets within the discovery population. We further estimated the prospective associations between the identified metabolite profile and incident T2D and CVD using multivariable Cox regression models. Results: A total of 19 metabolites were significantly associated with walnut consumption, including lipids, purines, acylcarnitines, and amino acids. Ten-CV Pearson correlation coefficients between self-reported walnut consumption and the plasma metabolite profile were 0.16 (95% CI: 0.11, 0.20) in the discovery population and 0.15 (95% CI: 0.10, 0.20) in the validation population. The metabolite profile was inversely associated with T2D incidence (HR per 1 SD: 0.83; 95% CI: 0.71, 0.97; P = 0.02). For CVD incidence, the HR per 1-SD was 0.71 (95% CI: 0.60, 0.85; P < 0.001). Conclusions: A metabolite profile including 19 metabolites was associated with walnut consumption and with a lower risk of incident T2D and CVD in a Mediterranean population at high cardiovascular risk.
