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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 The data presented here are from a paper that was retracted at the authors’ request ( https://doi.org/10.2337/dc16-rt02) owing to lack of adjustment for repeated measures in the same individual.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.