Cohen, A.E., C.S. Johnston, 2011. Almond ingestion at mealtime reduces postprandial glycemia and chronic ingestion reduces hemoglobin A1c in individuals with well-controlled type 2 diabetes mellitus. Metabolism Clinical and Experimental. 60:1312–1317.
Cohort studies are equivocal regarding a relationship between regular nut consumption and reduced risk of type 2 diabetes mellitus. Although acute trials show reductions in postprandial glycemia in healthy individuals ingesting 60 to 90 g almonds, trials have not been conducted using a single serving of almonds (28 g) in individuals with type 2 diabetes mellitus. This randomized crossover trial examined the impact of one serving of almonds at mealtime on postprandial glycemia, insulinemia, and plasma glucagon-like peptide–1 in healthy individuals and individuals with type 2 diabetes mellitus. On 2 occasions separated by at least 1 week, 19 adults (including 7 adults with type 2 diabetes mellitus) consumed a standardized evening meal and fasted overnight before ingesting the test meal (bagel, juice, and butter) with or without almonds. A small pilot study (6-7 subjects per group) was also conducted to observe whether chronic almond ingestion (1 serving 5 d/wk for 12 weeks) lowered hemoglobin A1c in individuals with type 2 diabetes mellitus. A standard serving of almonds reduced postprandial glycemia significantly in participants with diabetes (−30%, P = .043) but did not influence glycemia in participants without diabetes (−7%, P = .638). Insulinemia and glucagon-like peptide–1 at 30 minutes postmeal were not impacted by almond ingestion for either group. In the pilot study, regular almond ingestion for 12 weeks reduced hemoglobin A1c by 4% (P = .045 for interaction) but did not influence fasting glucose concentrations. These data show that modest almond consumption favorably improves both short-term and long-term markers of glucose control in individuals with uncomplicated type 2 diabetes mellitus.
Kendall, C.W., A.R. Josse, A. Esfahani, D.J. Jenkins, 2011. The impact of pistachio intake alone or in combination with high-carbohydrate foods on post-prandial glycemia. Eur J Clin Nutr. 65(6):696-702.
Background/Objectives: Dietary strategies that reduce post-prandial glycemia are important in the prevention and treatment of diabetes and coronary heart disease (CHD). This may be achieved by addition of high-quality protein and fat contained in pistachio nuts, to carbohydrate-containing foods or meals. Subjects/Methods: A total of 10 healthy volunteers (3 males, 7 females); aged 48.3±6.4 years; Body mass index (BMI) 28.0±4.8 kg/m(2) participated in two studies. Study 1 assessed the dose-response effect of 28, 56 and 84 g pistachios consumed alone or co-ingested with white bread (50 g available carbohydrate); Study 2 assessed the effective dose (56 g) of pistachios on post-prandial glycemia consumed with different commonly consumed carbohydrate foods (50 g available carbohydrate). Relative glycemic responses (RGRs) of study meals compared with white bread, were assessed over the 2 h post-prandial period. Results:The RGRs of pistachios consumed alone expressed as a percentage of white bread (100%) were: 28 g (5.7±1.8%); 56 g (3.8±1.8%); 84 g (9.3±3.2%), P<0.001. Adding pistachios to white bread resulted in a dose-dependent reduction in the RGR of the composite meal; 28 g (89.1±6.0, P=0.100); 56 g (67.3±9.8, P=0.009); 84 g (51.5±7.5, P<0.001). Addition of 56 g pistachios to carbohydrate foods significantly reduced the RGR: parboiled rice (72.5±6.0) versus rice and pistachios (58.7±5.1) (P=0.031); pasta (94.8±11.4) versus pasta and pistachios (56.4±5.0) (P=0.025); whereas for mashed potatoes (109.0±6.6) versus potatoes and pistachios, (87.4±8.0) (P=0.063) the results approached significance. Conclusions: Pistachios consumed alone had a minimal effect on post-prandial glycemia and when taken with a carbohydrate meal attenuated the RGR. The beneficial effects of pistachios on post-prandial glycemia could, therefore, be part of the mechanism by which nuts reduce the risk of diabetes and CHD.
Salas-Salvadó, J., M. Bulló, N. Babio, M.Á. Martínez-González, N. Ibarrola-Jurado, J. Basora, R. Estruch, M.I. Covas, D. Corella, F. Arós, V. Ruiz-Gutiérrez, E. Ros, and for the PREDIMED Study Investigators, 2011. Reduction in the incidence of type 2 diabetes with the Mediterranean diet results of the PREDIMED-Reus nutrition intervention randomized trial. Diabetes Care. 34:14–19.
OBJECTIVE: To test the effects of two Mediterranean diet (MedDiet) interventions versus a low-fat diet on incidence of diabetes. RESEARCH DESIGN AND METHODS: This was a three-arm randomized trial in 418 nondiabetic subjects aged 55–80 years recruited in one center (PREDIMED-Reus, northeastern Spain) of the Prevención con Dieta Mediterránea [PREDIMED] study, a large nutrition intervention trial for primary cardiovascular prevention in individuals at high cardiovascular risk. Participants were randomly assigned to education on a low-fat diet (control group) or to one of two MedDiets, supplemented with either free virgin olive oil (1 liter/week) or nuts (30 g/day). Diets were ad libitum, and no advice on physical activity was given. The main outcome was diabetes incidence diagnosed by the 2009 American Diabetes Association criteria. RESULTS: After a median follow-up of 4.0 years, diabetes incidence was 10.1% (95% CI 5.1–15.1), 11.0% (5.9–16.1), and 17.9% (11.4–24.4) in the MedDiet with olive oil group, the MedDiet with nuts group, and the control group, respectively. Multivariable adjusted hazard ratios of diabetes were 0.49 (0.25–0.97) and 0.48 (0.24–0.96) in the MedDiet supplemented with olive oil and nuts groups, respectively, compared with the control group. When the two MedDiet groups were pooled and compared with the control group, diabetes incidence was reduced by 52% (27–86). In all study arms, increased adherence to the MedDiet was inversely associated with diabetes incidence. Diabetes risk reduction occurred in the absence of significant changes in body weight or physical activity. CONCLUSIONS: MedDiets without calorie restriction seem to be effective in the prevention of diabetes in subjects at high cardiovascular risk.
Jenkins, D.J.A., C.W.C. Kendall, M.S. Banach, K. Srichaikul, E. Vidgen, S. Mitchell, T. Parker, S. Nishi, B. Bashyam, R. de Souza, C. Ireland, R.G. Josse, 2011. Nuts as a replacement for carbohydrates in the diabetic diet. Diabetes Care. 34(8):1706-11.
OBJECTIVE: Fat intake, especially monounsaturated fatty acid (MUFA), has been liberalized in diabetic diets to preserve HDL cholesterol and improve glycemic control, yet the exact sources have not been clearly defined. Therefore, we assessed the effect of mixed nut consumption as a source of vegetable fat on serum lipids and HbA1c in type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 117 type 2 diabetic subjects were randomized to one of three treatments for 3 months. Supplements were provided at 475 kcal per 2,000-kcal diet as mixed nuts (75 g/day), muffins, or half portions of both. The primary outcome was change in HbA1c. RESULTS: The relative increase in MUFAs was 8.7% energy on the full-nut dose compared with muffins. Using an intention-to-treat analysis (n = 117), full-nut dose (mean intake 73 g/day) reduced HbA1c (−0.21% absolute HbA1c units, 95% CI −0.30 to −0.11, P < 0.001) with no change after half-nut dose or muffin. Full-nut dose was significantly different from half-nut dose (P = 0.004) and muffin (P = 0.001), but no difference was seen between half-nut dose and muffins. LDL cholesterol also decreased significantly after full-nut dose compared with muffin. The LDL cholesterol reduction after half-nut dose was intermediate and not significantly different from the other treatments. Apolipoprotein (apo) B and the apoB:apoA1 ratio behaved similarly. Nut intake related negatively to changes in HbA1c (r = −0.20, P = 0.033) and LDL cholesterol (r = −0.24, P = 0.011). CONCLUSIONS: Two ounces of nuts daily as a replacement for carbohydrate foods improved both glycemic control and serum lipids in type 2 diabetes.
Kendall C.W., A. Esfahani, A.R. Josse, L.S. Augustin, E. Vidgen, D.J. Jenkins, 2011. The glycemic effect of nut-enriched meals in healthy and diabetic subjects. Nutr. Metab. Cardiovasc. Dis. 21(Suppl 1):S34-9.
BACKGROUND AND AIMS: The intake of nuts has been linked to a reduced risk of cardiovascular disease (CVD) and diabetes in large cohort studies. One potential contributing mechanism may be the ability of nuts to improve post-meal glycemic response. We, therefore, examined the effect of nuts alone and in combination with white bread on postprandial glycemia. METHODS AND RESULTS: 30, 60 and 90 g (approximately 1, 2 and 3 ounces) of mixed nuts were consumed with and without 50 g available carbohydrate from white bread by 10-14 normoglycemic and 5-10 type 2 diabetic subjects. Glycemic response (GR) was assessed by calculating the incremental area under the 2 h blood glucose curve. All three doses of mixed nuts, when fed alone, significantly reduced the glycemic response in both normoglycemic and diabetic patients. Furthermore, in the normoglycemic subjects, adding nuts to white bread progressively reduced the GR of the meal by 11.2 ± 11.6%, 29.7 ± 12.2% and 53.5 ± 8.5% for the 30, 60, and 90 g doses (P = 0.354, P = 0.031 and P < 0.001, respectively), while in subjects with type 2 diabetes, the effect was half of that seen in the non-diabetic subjects (P = 0.474, P = 0.113 and P = 0.015, respectively). CONCLUSION: Nuts alone have little effect on post-meal blood glucose response. Furthermore, when taken with bread, nuts progressively reduce the glycemic response in a dose-dependent manner. While these findings support a short-term benefit for nuts in postprandial glucose response, more studies are required to determine whether these acute benefits result in long-term improvements in glycemic control.
Mori, A.M., R.V. Considine, R.D. Mattes, 2011. Acute and second-meal effects of almond form in impaired glucose tolerant adults: a randomized crossover trial. Nutrition & Metabolism. 8(1):6.
Background: Nut consumption may reduce the risk of developing type 2 diabetes. The aim of the current study was to measure the acute and second-meal effects of morning almond consumption and determine the contribution of different nut fractions. Methods: Fourteen impaired glucose tolerant (IGT) adults participated in a randomized, 5-arm, crossover design study where whole almonds (WA), almond butter (AB), defatted almond flour (AF), almond oil (AO) or no almonds (vehicle – V) were incorporated into a 75 g available carbohydrate-matched breakfast meal. Postprandial concentrations of blood glucose, insulin, non-esterified free fatty acids (NEFA), glucagon-like peptide-1 (GLP-1) and appetitive sensations were assessed after treatment breakfasts and a standard lunch. Results: WA significantly attenuated second-meal and daylong blood glucose incremental area under the curve (AUCI) and provided the greatest daylong feeling of fullness. AB and AO decreased blood glucose AUCI in the morning period and daylong blood glucose AUCI was attenuated with AO. WA and AO elicited a greater secondmeal insulin response, particularly in the early postprandial phase, and concurrently suppressed the second-meal NEFA response. GLP-1 concentrations did not vary significantly between treatments. Conclusions: Inclusion of almonds in the breakfast meal decreased blood glucose concentrations and increased satiety both acutely and after a second-meal in adults with IGT. The lipid component of almonds is likely responsible for the immediate post-ingestive response, although it cannot explain the differential second-meal response to AB versus WA and AO.
Wien, M., D. Bleich, M. Raghuwanshi, S. Gould-Forgerite, J. Gomes, L. Monahan-Couch, K. Oda, 2010. Almond consumption and cardiovascular risk factors in adults with prediabetes. Journal of the American College of Nutrition. 29(3):189–197.
Objective: The authors tested the hypothesis that in adults with prediabetes, an almond-enriched American Diabetes Association (ADA) diet improves measures of insulin sensitivity and other cardiovascular risk factors compared with an ADA nut-free diet. Methods: Design: Randomized parallel-group trial. Setting: Outpatient dietary counseling and blood analysis. Subjects: Sixty-five adult participants with prediabetes. Intervention: Sixteen weeks of dietary modification featuring an ADA diet containing 20% of energy from almonds (approximately 2 oz per day). Measures of Outcome: Outcomes included fasting glucose, insulin, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides, TC:HDL-C, and HbA1c, which were measured at weeks 0, 8, and 16. Body weight, body mass index (BMI), waist circumference, blood pressure, and nutrient intake were measured at weeks 0, 4, 8, 12, and 16. Results: The almond-enriched intervention group exhibited greater reductions in insulin (-1.78 µU/ml vs. +1.47 µU/ml, P = 0.002), homeostasis model analysis for insulin resistance (-0.48 vs. +0.30, P = 0.007), and homeostasis model analysis for beta-cell function (-13.2 vs. +22.3, P = 0.001) compared with the nut-free control group. Clinically significant declines in LDL-C were found in the almond-enriched intervention group (-12.4 mg/dl vs. -0.4 mg/dl) as compared with the nut-free control group. No changes were observed in BMI (-0.4 vs. -0.7 kg/m2, P = 0.191), systolic blood pressure (-4.4 mm Hg vs. -3.5 mm Hg, P = 0.773), or for the other measured cardiovascular risk factors. Conclusions: An ADA diet consisting of 20% of calories as almonds over a 16-week period is effective in improving markers of insulin sensitivity and yields clinically significant improvements in LDL-C in adults with prediabetes.
Kochar, J., J.M. Gaziano, L. Djousse, 2010. Nut consumption and risk of type II diabetes in the Physicians’ Health Study. European Journal of Clinical Nutrition. 64:75–79.
Background/Objectives: While type II diabetes (DM) is a major cause of morbidity in the United States, limited data are available on the association between nut intake and incident DM. We sought to examine the association between nut consumption and the risk of DM. Subjects/Methods: Prospective cohort of 20 224 male participants of the Physicians’ Health Study I. Nut consumption was estimated using a 19-item brief food frequency questionnaire, and incident DM was ascertained through yearly follow-up questionnaires. Cox regression was used to estimate relative risks of DM. Results: The average age of the study participants was 54.4±9.4 years (range: 40.7–87.1). During a mean follow-up of 19.2 years, 1828 cases of DM occurred. The crude incidence rates of DM were 4.82, 4.85, 4.92, 4.16, 4.29 and 3.32 cases per 1000 person-years for individuals reporting nut consumption of rarely/never, <1, 1, 2–4, 5–6 and 7+ servings per week, respectively. While nut consumption was associated with a lower risk of DM in a model adjusted for age (P for tend 0.017), such relation was attenuated on additional control for other confounders (multivariable adjusted hazard ratios (95% confidence interval) for DM were 1.0 (reference), 1.06 (0.93–1.20), 1.10 (0.95–1.26), 0.97 (0.82–1.14), 0.99 (0.76–1.30) and 0.87 (0.61–1.24) from the lowest to the highest category of nut consumption, respectively (P for trend 0.99). No statistically significant association between nut consumption and DM was found in either lean or overweight/obese participants. Conclusions: Our data do not show an association between nut consumption and incident DM in US male physicians.
Kendall, C.W.C., A.R. Josse, A. Esfahani, D. J. A. Jenkins, 2010. Nuts, metabolic syndrome and diabetes. British Journal of Nutrition. 104(4): 465-473.
The ability of nuts to improve the blood lipid profile and reduce the risk of CHD is now well established. The interest that health effects of nuts have gained recently has brought the possible benefits of consuming nuts, such as improvement in the conditions of the metabolic syndrome, and their potential to prevent and control diabetes into focus. Results from cohort studies have associated nut consumption with a reduced risk of developing diabetes and CVD. However, few randomised controlled trials have assessed the effect of nuts on diabetes control, and those that have been undertaken have shown improvements in blood lipids but not in the glycaemic control. Diabetes agencies are increasingly recognising the importance of controlling postprandial glycaemia fluctuations. Acute feeding studies indicate that nuts have minimal effects on rising postprandial blood glucose levels when eaten alone, and diminish the postprandial glycaemic response when consumed with high-glycaemic index carbohydrate foods in both normoglycaemic and type 2 diabetic individuals. Nuts have a healthy nutritional profile, high in MUFA and PUFA, are a good source of vegetable protein and are rich in fibre, vitamins and minerals. Incorporation of nuts in the diet may therefore improve the overall nutritional quality of the diet. While more research is required to establish the ability of nuts to improve glycaemic control in the long run, early data indicate that the inclusion of nuts in the diets of individuals with diabetes and the metabolic syndrome is warranted, in view of their potential to reduce CHD risk.
Ma, Y., V.Y. Njike, J. Millet, S. Dutta, K. Doughty, J.A. Treu, D.L. Katz, 2010. Effects of walnut consumption on endothelial function in type 2 diabetics: a randomized, controlled, cross-over trial. Diabetes Care. 33(2):227-32.
Objective: To determine the effects of daily walnut consumption on endothelial function, cardiovascular biomarkers, and anthropometric measures in type 2 diabetics. Methods: This study was a randomized, controlled, single-blind, cross-over trial. Twenty-four participants with type 2 diabetes (mean age 58 years; 14 women, 10 men) were randomly assigned to one of the two possible sequence permutations to receive an ad libitum diet enriched with 56 g (366 kcal) of walnuts per day and an ad libitum diet without walnuts for 8 weeks. Subjects underwent endothelial function testing (measured as flow-mediated dilatation or FMD) and assessment of cardiovascular biomarkers before and after each 8-week treatment phase. The primary outcome measure was the change in FMD after 8 weeks. Secondary outcome measures included changes in plasma lipids, HbA1c, fasting glucose, insulin sensitivity, and anthropometric measures. Results: Endothelial function significantly improved after consumption of a walnut-enriched ad libitum diet compared to an ad libitum diet without walnuts (2.2 ± 1.7 % vs. 1.2 ± 1.6 %; p=0.04). The walnut-enriched diet increased fasting serum glucose, lowered serum total cholesterol and low-density lipoprotein cholesterol from baseline (10.0 ± 20.5 mg/dL; p=0.04, -9.7 ± 14.5 mg/dL; p<0.01; and -7.7 ± 10 mg/dL; p<0.01 respectively), though these changes were not significant when compared to an ad libitum diet without walnuts. There were no significant changes in anthropometric measures, plasma HbA1c, and insulin sensitivity. Conclusions: A walnut-enriched ad libitum diet improves endothelium-dependent vasodilatation in type 2 diabetics, suggesting a potential reduction in overall cardiac ris
