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Research Area: Diabetes

Nuts as a replacement for carbohydrates in the diabetic diet: a reanalysis of a randomised controlled trial.

Jenkins, D.J.A., C.W.C. Kendall, B. Lamarche, M.S. Banach, K. Srichaikul, E. Vidgen, S. Mitchell, T. Parker, S. Nishi, B. Bashyam, R.J. de Souza, C. Ireland, S.C. Pichika, J. Beyene, J.L. Sievenpiper, R.G. Josse, 2018. Nuts as a replacement for carbohydrates in the diabetic diet: a reanalysis of a randomised controlled trial. Diabetologia. 61: 1734. https://doi.org/10.1007/s00125-018-4628-9

Aims/hypothesis: In line with current advice, we assessed the effect of replacing carbohydrate consumption with mixed nut consumption, as a source of unsaturated fat, on cardiovascular risk factors and HbA1c in type 2 diabetes. The data presented here are from a paper that was retracted at the authors’ request ( https://doi.org/10.2337/dc16-rt02) owing to lack of adjustment for repeated measures in the same individual. Our aim, therefore, was to fix the error and add new complementary data of interest, including information on clotting factors and LDL particle size. Methods: A total of 117 men and postmenopausal women with type 2 diabetes who were taking oral glucose-lowering agents and with HbA1c between 47.5 and 63.9 mmol/mol (6.5–8.0%) were randomised after stratification by sex and baseline HbA1c in a parallel design to one of three diets for 3 months: (1) ‘full-dose nut diet’ (n = 40): a diet with 2.0 MJ (477 kcal) per 8.4 MJ (2000 kcal) energy provided as mixed nuts (75 g/day); (2) ‘full-dose muffin diet’ (n = 39): a diet with 1.97 MJ (471 kcal) per 8.4 MJ (2000 kcal) energy provided as three whole-wheat muffins (188 g/day), with a similar protein content to the nuts, and the same carbohydrate-derived energy content as the monounsaturated fatty acid-derived energy content in the nuts; or (3) ‘half-dose nut diet’ (n = 38): a diet with 1.98 MJ (474 kcal) per 8.4 MJ (2000 kcal) energy provided as half portions of both the nuts and muffins. The primary outcome was change in HbA1c. The study was carried out in a hospital clinical research centre and concluded in 2008. Only the statistician, study physicians and analytical technicians could be blinded to the group assessment. Results: A total of 108 participants had post-intervention data available for analysis (full-dose nut group, n = 40; full-dose muffin group, n = 35; half-dose nut group, n = 33). Compared with the full-dose muffin diet, the full-dose nut diet provided 9.2% (95% CI 7.1, 11.3) greater total energy intake from monounsaturated fat. The full-dose nut diet (median intake, 75 g/day) also reduced HbA1c compared with the full-dose muffin diet by −2.0 mmol/mol (95% CI −3.8, −0.3 mmol/mol) (−0.19% [95% CI −0.35%, −0.02%]), (p = 0.026). Estimated cholesterol levels in LDL particles with a diameter <255 ångström [LDL-c<255Å]) and apolipoprotein B were also significantly decreased after the full-dose nut diet compared with the full-dose muffin diet. According to the dose response, the full-dose nut diet is predicted to reduce HbA1c (−2.0 mmol/mol [−0.18%]; p = 0.044), cholesterol (−0.25 mmol/l; p = 0.022), LDL-cholesterol (−0.23 mmol/l; p = 0.019), non-HDL-cholesterol (−0.26 mmol/l; p = 0.020), apolipoprotein B (−0.06 g/l, p = 0.013) and LDL-c<255Å (−0.42 mmol/l; p < 0.001). No serious study-related adverse events occurred, but one participant on the half-dose nut diet was hospitalised for atrial fibrillation after shovelling snow. Conclusions/interpretation: Nut intake as a replacement for carbohydrate consumption improves glycaemic control and lipid risk factors in individuals with type 2 diabetes.

The antioxidant activity of pistachios reduces cardiac tissue injury of acute ischemia/reperfusion (I/R) in diabetic Streptozotocin (STZ)-induced hyperglycaemic rats.

Di Paola, R., R. Fusco, E. Gugliandolo, R. D’Amico, M. Campolo, S. Latteri, A. Carughi, G. Mandalari, S. Cuzzocrea, 2018. The antioxidant activity of pistachios reduces cardiac tissue injury of acute ischemia/reperfusion (I/R) in diabetic Streptozotocin (STZ)-induced hyperglycaemic rats. Front Pharmacol. 9:51. doi: 10.3389/fphar.2018.00051. eCollection 2018.

Diabetes mellitus is an important risk factor for the development of heart pathology. Myocardial infarction is the cause of death occurring after prolonged ischemia of the coronary arteries. Restoration of blood flow is the first intervention against heart attack, although the process of restoring blood flow to the ischemic myocardium could cause additional injury. This phenomenon, termed myocardial ischemia-reperfusion (MI-R) injury, is characterized by the formation of oxygen radicals. Pistachios have significant glucose- and insulin-lowering effects and can improve the inflammatory contest by downregulating both the expression and the circulating levels of several metabolic risk markers. The monocyte/macrophage cell line J774 was used to assess the extent of protection by natural raw (NP) and roasted salted (RP) pistachios against lipopolysaccharide (LPS)-induced inflammation. Moreover, antioxidant activity of NP and RP was assessed in an in vivo model of paw edema in rats induced by carrageenan (CAR) injection in the paw. This study evaluates the antioxidant properties of pistachios on the inflammatory process associated with myocardial ischemia/reperfusion injury (I/R) in diabetic rats. Rats were pre-treated with either NP or RP pistachios (30 mg/kg) 18 h prior to the experimental procedure. Results: Here, we demonstrated that treatment with NP reduced myocardial tissue injury, neutrophil infiltration, adhesion molecules (ICAM-1, P-selectin) expression, proinflammatory cytokines (TNF-α, IL-1β) production, nitrotyrosine and PAR formation, NF-κB expression and apoptosis (Bax, Bcl-2) activation. This data clearly shows modulation of the inflammatory process, associated with MI-R injury, following administration of pistachios.

Glucoregulatory and cardiometabolic profiles of almond vs. cracker snacking for 8 weeks in young adults: A randomized controlled trial.

Dhillon, J., M. Thorwald, N. De La Cruz, E. Vu, S.A. Asghar, Q. Kuse, L.K. Diaz Rios, R.M. Ortiz, 2018. Glucoregulatory and cardiometabolic profiles of almond vs. cracker snacking for 8 weeks in young adults: A randomized controlled trial. Nutrients. 10, 960; doi:10.3390/nu10080960

The transition to nutritional independence makes new college students vulnerable to alterations in eating patterns, which can increase the risk of cardiometabolic disorders. The aim of the study was to examine the potential benefits of almond vs. cracker snacking in improving glucoregulatory and cardiometabolic profiles in new college students. A randomized controlled, parallel-arm, 8-week intervention of 73 college students (BMI: 18–41 kg/m2) with no cardiometabolic disorders was conducted. Participants were randomized into either an almond snack group (56.7 g/day; 364 kcal; n = 38) or Graham cracker control group (77.5 g/day; 338 kcal/d; n = 35). Chronic, static changes were assessed from fasting serum/plasma samples at baseline, and after 4 and 8 weeks. Acute, dynamic effects were assessed during a 2-h oral glucose tolerance test (OGTT) at 8 weeks. Almond snacking resulted in a smaller decline in HDL cholesterol over 8 weeks (13.5% vs. 24.5%, p < 0.05), 13% lower 2-h glucose area under the curve (AUC), 34% lower insulin resistance index (IRI) and 82% higher Matsuda index (p < 0.05) during the OGTT, despite similar body mass gains over 8 weeks compared with the cracker group. In general, both almond and cracker snacking reduced fasting glucose, and LDL cholesterol. Conclusions: Incorporating a morning snack in the dietary regimen of predominantly breakfast-skipping, first-year college students had some beneficial effects on glucoregulatory and cardiometabolic health. Almond consumption has the potential to benefit postprandial glucoregulation in this cohort. These responses may be influenced by cardiometabolic risk factor status.

Daily walnut consumption favourably changed lipid profiles among Korean subjects with higher waist circumference.

Song, E.K., Y. Liu, H.S. Kim, H. Park, 2018. Daily walnut consumption favourably changed lipid profiles among Korean subjects with higher waist circumference. Acta Scientific Nutritional Health. 2.5:21-26.

Even though many studies have shown that walnuts have beneficial effects on lipid profiles in various populations, there have been limited data on the effects of walnuts in Korean populations. We examined not only the effects of walnut intake on lipid profiles among Korean adults but also focused on the sub-classification by waist circumference (WC). 89 subjects out of 119 completed trial with daily consumption of 45 g of walnuts for 16 weeks. Blood lipid profiles including triglycerides (TG), non-HDL cholesterol (non-HDL-C), LDL cholesterol (LDL-C), total cholesterol (TC), and HDL cholesterol (HDL-C), apolipoprotein B, anthropometric measurements (WC, weight, body mass index (BMI) and blood pressure) and glucose metabolism parameters including fasting blood sugar and insulin levels were assessed. Whose WC was greater than 85 cm for female and 90 cm for male were classified as higher WC group (n=48) and others were classified as normal WC group (n=41). Blood levels of non-HDL-C, LDL-C, TC and apolipoprotein B were improved after daily consumption of 45 g of walnuts (P=0.003, P=0.011, P=0.002, and P=0.012, respectively) compared to baseline levels. Systolic blood pressure, TG, non-HDL-C, LDL-C and TC were significantly decreased in the higher WC groups (P=0.048, P=0.002, P=0.002 and P=0.001, respectively) compared to normal WC group. The results suggest that consuming 45 g of walnuts daily for 16 weeks had beneficial effects on lipid profiles in general, and these results were even much stronger among the subjects with abdominal obesity as waist circumference compared to those with non-abdominal obesity.

The resulting variation in nutrient intake with the inclusion of walnuts in the diets of adults at risk for type 2 diabetes: A randomized, controlled, crossover trial.

Njike, V.Y., V.C. Costales, P. Petraro, A. Annam, N. Yarandi, D.L. Katz, 2018. The resulting variation in nutrient intake with the inclusion of walnuts in the diets of adults at risk for type 2 diabetes: A randomized, controlled, crossover trial. Am J Health Promot. Aug 1:890117118791120. doi: 10.1177/0890117118791120. [Epub ahead of print]

PURPOSE: We previously demonstrated that including walnuts in the diets of adults at risk for type 2 diabetes mellitus (T2DM) led to improved overall diet quality. This report examines the specific changes in their nutrient intake. DESIGN: This was a randomized, controlled, modified Latin square parallel design trial with 2 treatment arms. Participants were randomized to walnut intake with, or without, dietary advice to regulate caloric intake. Within each treatment arm, they were further randomized to one of 2 sequence permutations (walnut-included/walnut-excluded or walnut-excluded/walnut-included diet), with a 3-month washout between treatment phases. SETTING: Community hospital in Lower Naugatuck Valley in Connecticut. PARTICIPANTS: Cohort of 112 participants (31 men and 81 women) at risk for T2DM. INTERVENTION: Participants included 56 g (366 kcal) of walnuts in their daily diets for 6 months. MEASURES: Nutrient intake was assessed using web-based Automated Self-Administered 24-Hour Dietary Assessment. ANALYSIS: Data were analyzed using generalized linear models. RESULTS: Walnut inclusion led to increased intake of total fat, calcium, magnesium, thiamin, total saturated fatty acids, and monounsaturated and polyunsaturated fatty acids (379.0 ± 90.3 g vs -136.5 ± 92.7 g, P < .01; 230.7 ± 114.2 mg vs -95.2 ± 117.4 mg, P = .05; 111.0 ± 33.9 mg vs -32.3 ± 34.9 mg, P < .01; 0.28 ± 0.2 mg vs -0.47 ± 0.2 mg, P = .02; 8.6 ± 3.4 g vs -1.1 ± 3.5 g, P =.05; 6.3 ± 3.9 g vs -6.3 ± 4.0 g, P = .03; and 25.4 ± 4.0 vs -6.6 ± 4.2 g, P < .01, respectively). Vitamin C intake decreased (-65.3 ± 55.3 mg vs 98.9 ± 56.8 mg, P = .04). Protein intake increased from baseline with the inclusion of walnuts (20.0 ± 8.8 g, P < .05). Walnut inclusion led to an increase in total calories consumed when caloric intake is not regulated. CONCLUSION: Including walnuts in the diets of these adults led to increased dietary intake of some nutrients associated with lower risk of developing T2DM and other cardiometabolic risk factors.

Walnut consumption increases activation of the insula to highly desirable food cues: A randomized, double-blind, placebo-controlled, cross-over fMRI study.

Farr, O.M., D. Tuccinardi, J. Upadhyay, S.M. Oussaada, C.S. Mantzoros, 2018. Walnut consumption increases activation of the insula to highly desirable food cues: A randomized, double-blind, placebo-controlled, cross-over fMRI study. Diabetes Obes Metab. 20(1):173-177. doi: 10.1111/dom.13060.

AIMS: The use of walnuts is recommended for obesity and type 2 diabetes, although the mechanisms through which walnuts may improve appetite and/or glycemic control remain largely unknown. MATERIALS AND METHODS: To determine whether short-term walnut consumption could alter the neural control of appetite using functional magnetic resonance imaging, we performed a randomized, placebo-controlled, double-blind, cross-over trial of 10 patients who received, while living in the controlled environment of a clinical research center, either walnuts or placebo (using a validated smoothie delivery system) for 5 days each, separated by a wash-out period of one month. RESULTS: Walnut consumption decreased feelings of hunger and appetite assessed using visual analog scales and increased the activation of the right insula to highly desirable food cues. CONCLUSIONS: These findings suggest that walnut consumption may increase salience and cognitive control processing of highly desirable food cues, leading to the beneficial metabolic effects observed.

Insulin resistance improves more in women than in men in association with a weight loss intervention.

Badri, N.W., S.W. Flatt, H.S. Barkai, B. Pakiz, D.D. Heath, C.L. Rock, 2018. Insulin resistance improves more in women than in men in association with a weight loss intervention. J Obes Weight Loss Ther. 8(1). pii: 365. doi: 10.4172/2165-7904.1000365.

Background: Fasting glucose and homeostatic model assessment-insulin resistance (HOMA-IR) are important measures of the risk for metabolic syndrome and diabetes. Weight loss interventions are considered part of the first line of therapy for those who develop disease states associated with insulin resistance, such as pre-diabetes, diabetes, or metabolic syndrome. Sex differences in insulin resistance have been extensively reported, but sex differences in the ability to improve insulin sensitivity are not well-established. This study sought to identify factors that predict change in HOMA-IR in response to weight loss. Methods: Non-diabetic subjects who were overweight/obese (n=100) were randomly assigned to a walnut-enriched reduced-energy diet or a standard reduced-energy-density diet in a 6-month weight loss intervention. There were no significant differences in weight change, glucose, insulin, or HOMA-IR between the two diet groups. These subjects were combined into a single cohort and analyzed with multivariate analysis. Results: The combined groups lost an average of 8.7 kg (p<0.0001), decreased serum glucose by an average 0.2 mmol/L (p<0.001), and decreased HOMA-IR by an average of 1.4 (p<0.0001). Change in HOMA-IR (R2=0.69) was positively associated with weight change (p<0.0001) and male sex (p<0.01), and negatively associated with baseline HOMA-IR (p<0.0001). Conclusion: Findings from this study suggest that men may have a more difficult time improving insulin sensitivity as compared with women with an equivalent weight loss and baseline HOMA-IR. One hypothesis to explain the differences across sexes may be due to sex differences in visceral adipose fat (VAT). This may mean that insulin resistant men require more aggressive intervention than women to prevent progression to metabolic syndrome or diabetes.

Association between walnut consumption and diabetes risk in NHANES.

Arab, L., S.K. Dhaliwal, C.J. Martin, A.D. Larios, N.J. Jackson, D. Elashoff , 2018. Association between walnut consumption and diabetes risk in NHANES. Diabetes Metab Res Rev. Oct; 34(7):e3031. doi: 10.1002/dmrr.3031. Epub 2018 Jul 11.

BACKGROUND: Dietary interventions and cohort studies relating tree nut consumption to blood glucose levels suggest a possible effect of walnuts. OBJECTIVE: To examine the associations between walnut consumption and diabetes risk using data from the National Health and Nutrition Examination Survey (NHANES). METHODS: NHANES survey data on adults conducting 24-hour dietary recall was pooled across the years 1999 through 2014. Diabetes status or risk was based on self-report, medication use, fasting plasma (FPG) glucose levels and hemoglobin A1c (HbA1c) levels. Individuals were characterized based on reported consumption of walnuts, mixed-nuts, or no nuts. RESULTS: After adjustment for covariates, walnut consumers showed lower risk for diabetes compared to non-nut consumers based on self-report (odds ratio of 0.47 95% confidence interval 0.31-0.72) as well as fasting blood glucose (RRR 0.32 CI 0.17-0.58) and HbA1c (RRR 0.51 CI 0.27-0.99). For each standard deviation of increase in walnut intake, prevalence of diabetes dropped 47%. The gender by walnut interaction suggests the effect may be more potent among women than men (dose response p=0.061). CONCLUSIONS: Both among individuals with known diabetes and those diagnosed based on elevated diabetes blood markers, the prevalence of individuals with diabetes was significantly lower among the walnut consumers. A possible gender specific effect invites further attention.

Effect of almond supplementation on glycemia and cardiovascular risk factors in Asian Indians in north India with type 2 diabetes mellitus: A 24-week study.

Gulati, S., A. Misra, R.M. Pandey, 2017. Effect of almond supplementation on glycemia and cardiovascular risk factors in Asian Indians in north India with type 2 diabetes mellitus: A 24-week study. Metabolic Syndrome and Related Disorders. doi:10.1089/met.2016.0066.

Background: Type 2 diabetes (T2D) statistics have reached menacing proportions in India. Appropriate dietary intervention, as part of healthy lifestyle, is imperative to curb further spread of this disease. Objectives: This pre–post intervention study was conducted in New Delhi, India, to investigate the effects of daily consumption of almonds for 24 weeks in T2D subjects, specifically on measures of glycemia and cardiovascular disease (CVD) risk factors. Methods and Study Design: In this study, the 24-week intervention period was preceded by a control diet and exercise run-in period of 3 weeks. Raw almonds (20% of energy intake) were provided to the patients for consumption along with diet and physical activity counseling. Patients were assessed for anthropometry, blood pressure, measures of glycemia (fasting blood glucose, glycosylated hemoglobin), lipids [total cholesterol (TC), triglycerides, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, lipoprotein(a)], surrogate marker of atherosclerosis (Pulse wave velocity), and marker of inflammation (high sensitivity C-reactive protein [hs-CRP]) at baseline and after the intervention period. Results: Statistically significant improvement in mean values for various parameters post intervention was as follows: waist circumference (P<0.03), waist-to-height ratio (P<0.005), TC (P<0.002), serum triglycerides (P<0.004), low-density lipoprotein cholesterol (P<0.01), glycosylated hemoglobin (P<0.04), and hs-CRP (P<0.01). A trend toward improvement in pulse wave velocity (P<0.06) was also observed. Conclusion: The study findings illustrate that incorporation of almonds in a well-balanced healthy diet leads to multiple beneficial effects on glycemic and CVDs risk factors in Asian Indian patients with T2D.

Inclusion of walnut in the diets of adults at risk for type 2 diabetes and their dietary pattern changes: a randomized, controlled, cross-over trial.

Njike VY, Yarandi N, Petraro P, Ayettey RG, Treu JA, Katz DL, 2016. Inclusion of walnut in the diets of adults at risk for type 2 diabetes and their dietary pattern changes: a randomized, controlled, cross-over trial. BMJ Open Diabetes Res Care. 4(1):e000293.

Abstract: Background: In our recently published study, including walnuts in the diets of adults with prediabetes led to overall improvement in diet quality. This report adds to those study findings by examining the food groups displaced during walnut inclusion in the diets of those adults with prediabetes. Methods: Randomized, controlled, modified Latin square parallel design with 2 treatment arms. The 112 participants (31 men, 81 women) were randomly assigned to a diet with or without dietary counseling to regulate calorie intake in a 1:1 ratio. Within each treatment arm, participants were further randomized to 1 of 2 sequence permutations to receive a walnut included diet with 56 g (366 kcal) of walnuts per day and a walnut-excluded diet. Participants in the calorie regulated arm received advice from a dietitian to preserve an isocaloric condition while including walnuts. We analyzed the 12 components of the 2010 Healthy Eating Index to examine dietary pattern changes of study participants. Results: Seafood and plant protein foods intake significantly increased with walnut inclusion, compared with their exclusion (2.14±2.06 vs −0.49±2.33; p=0.003). The ingestion of healthful fatty acids also significantly increased with walnut inclusion, compared with their exclusion (1.43±4.53 vs −1.76±4.80; p=0.02). Dairy ingestion increased with walnut inclusion in the calorie-regulated phase, compared with walnut inclusion without calorie regulation (1.06±4.42 vs −2.15±3.64; p=0.02). Conclusions: Our data suggest that walnut inclusion in the diets of adults at risk for diabetes led to an increase in intake of other healthful foods.