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Research Area: Diabetes

Long-term associations of nut consumption with body weight and obesity.

Jackson, C.L., F. Hu, 2014. Long-term associations of nut consumption with body weight and obesity. Am J Clin Nutr. 100(suppl):408S-llS.

There is some concern that the high-fat, energy-dense content of nuts may promote weight gain. Nuts, however, are rich in protein and dietary fiber, which are associated with increased satiety. They also contain high amounts of vitamins, minerals, antioxidants, and phytoesterols that may confer health benefits for cardiovascular disease and type 2 diabetes delay and prevention. Therefore, it is important to determine the association between nut consumption and long-term weight change and disease risk to reach scientific consensus and to make evidence-based public health recommendations. Several cross-sectional analyses have shown an inverse association between higher nut consumption and lower body weight. In addition, several independent prospective studies found that increasing nut consumption was associated with lower weight gain over relatively long periods of time. Moreover, high consumption of nuts (especially walnuts) has been associated with lower diabetes risk. Therefore, regular consumption (approximately one handful daily) of nuts over the long term, as a replacement to less healthful foods, can be incorporated as a component of a healthy diet for the prevention of obesity and type 2 diabetes.

Pistachio nut consumption modifies systemic hemodynamics, increases heart rate variability, and reduces ambulatory blood pressure in well‐controlled type 2 diabetes: a randomized trial.

Sauder, K.A., C.E. McCrea, J.S. Ulbrecht, P.M. Kris‐Etherton, S.G. West, 2014. Pistachio nut consumption modifies systemic hemodynamics, increases heart rate variability, and reduces ambulatory blood pressure in well‐controlled type 2 diabetes: a randomized trial. J. Am. Heart Assoc. doi: 10.1161/JAHA.114.000873

Background Managing cardiovascular risk factors is important for reducing vascular complications in type 2 diabetes, even in individuals who have achieved glycemic control. Nut consumption is associated with reduced cardiovascular risk; however, there is mixed evidence about the effect of nuts on blood pressure (BP), and limited research on the underlying hemodynamics. This study assessed the effect of pistachio consumption on BP, systemic hemodynamics, and heart rate variability in adults with well‐controlled type 2 diabetes. Methods and Results We enrolled 30 adults (40 to 74 years) with type 2 diabetes in a randomized, crossover, controlled feeding study. After a 2‐week run‐in period, participants consumed a low‐fat control diet (27% fat) containing low‐fat/high‐carbohydrate snacks and a moderate‐fat diet (33% fat) containing pistachios (20% of total energy) for 4 weeks each, separated by a 2‐week washout. Following each diet period, we assessed BP, systemic hemodynamics, and heart rate variability at rest and during acute mental stress, and, in a subset of participants (n=21), 24‐hour ambulatory BP. BP at rest and during stress did not differ between treatments. The pistachio diet significantly reduced total peripheral resistance (−3.7±2.9%,P=0.004), increased cardiac output (3.1±2.3%, P=0.002), and improved some measures of heart rate variability (all P<0.05). Systolic ambulatory BP was significantly reduced by 3.5±2.2 mm Hg (P=0.046) following the pistachio diet, with the greatest reduction observed during sleep (−5.7±2.6 mm Hg, P=0.052). Conclusions A moderate‐fat diet containing pistachios modestly improves some cardiovascular risk factors in adults with well‐controlled type 2 diabetes.

The effect of almonds on anthropometric measurements and lipid profile in overweight and obese females in a weight reduction program: A randomized controlled clinical trial.

Abazarfard Z., M. Salehi, S. Keshavarzi, 2013. The effect of almonds on anthropometric measurements and lipid profile in overweight and obese females in a weight reduction program: A randomized controlled clinical trial. J Res Med Sci. 19:457-64.

Background: Due to the wholesome benefits of nuts increased consumption of them has been recommended. However, because of nut’s high energy density, the role of them in the treatment of overweight and obesity is vague. This current clinical trial study aims to investigate the effects of a balanced hypo-caloric almond-enriched diet (AED) (almond group) in comparison to a balanced Hypo-caloric nut-free diet (NFD) (nut-free group) on body weight and cardiovascular disease risk factors in women with body mass index (BMI) >25 for 3-month. Materials and Methods: A total of 108 overweight and obese women were assigned in our 3-month randomized controlled trial. The subjects were randomly divided into two groups regarding a balanced hypo-caloric diet with or without almond. The planned reduced calorie diets for both groups were identical except for the almond group who consumed 50 g of almonds daily. Anthropometric and laboratory measurements of the participants who completed the study were made prior to and at the end of the study. Results: A total of 100 subjects completed the study. Weight, BMI, waist circumference, waist to hip circumference ratio, total cholesterol, and triglyceride, total: High density lipoprotein-cholesterol (HDL-C), fasting blood sugar and diastolic blood pressure decreased significantly in the almond group compared to the nut-free group (P > 0.001). Greater reduction in low density lipoprotein-cholesterol (P > 0.002) and systolic blood pressure (P > 0.001) and greater increase in HDL-C (P = 0.001) were found in the nut-free group. Conclusion: The balanced hypo-caloric AED in comparison to the balanced hypo-caloric NFD led to a greater weight-loss and overall better improvements in studied cardiovascular disease risk factors.

Association of nut consumption with total and cause-specific mortality.

Bao, Y., J. Han, F.B. Hu, E.L. Giovannucci, M.J. Stampfer, W.C. Willett, C.S. Fuchs, 2013. Association of nut consumption with total and cause-specific mortality. N Engl J Med. 369:2001-2011.

Background: Increased nut consumption has been associated with a reduced risk of major chronic diseases, including cardiovascular disease and type 2 diabetes mellitus. However, the association between nut consumption and mortality remains unclear. Methods: We examined the association between nut consumption and subsequent total and cause-specific mortality among 76,464 women in the Nurses’ Health Study (1980–2010) and 42,498 men in the Health Professionals Follow-up Study (1986–2010). Participants with a history of cancer, heart disease, or stroke were excluded. Nut consumption was assessed at baseline and updated every 2 to 4 years. Results: During 3,038,853 person-years of follow-up, 16,200 women and 11,229 men died. Nut consumption was inversely associated with total mortality among both women and men, after adjustment for other known or suspected risk factors. The pooled multivariate hazard ratios for death among participants who ate nuts, as compared with those who did not, were 0.93 (95% confidence interval [CI], 0.90 to 0.96) for the consumption of nuts less than once per week, 0.89 (95% CI, 0.86 to 0.93) for once per week, 0.87 (95% CI, 0.83 to 0.90) for two to four times per week, 0.85 (95% CI, 0.79 to 0.91) for five or six times per week, and 0.80 (95% CI, 0.73 to 0.86) for seven or more times per week (P<0.001 for trend). Significant inverse associations were also observed between nut consumption and deaths due to cancer, heart disease, and respiratory disease. Conclusions: In two large, independent cohorts of nurses and other health professionals, the frequency of nut consumption was inversely associated with total and cause-specific mortality, independently of other predictors of death.

Nut consumption and incidence of metabolic syndrome after 6-year follow-up: the SUN (Seguimiento Universidad de Navarra, University of Navarra Follow-up) cohort.

Fernández-Montero A., M. Bes-Rastrollo, J.J. Beunza, M.T. Barrio-Lopez, C. de la Fuente-Arrillaga, L. Moreno-Galarraga, M.A. Martínez-González, 2012. Nut consumption and incidence of metabolic syndrome after 6-year follow-up: the SUN (Seguimiento Universidad de Navarra, University of Navarra Follow-up) cohort.  Public Health Nutr. 23:1-9. [Epub ahead of print]

OBJECTIVE: To assess the long-term relationship between tree nut consumption and the risk of developing metabolic syndrome (MetS). DESIGN:  Nut consumption was collected using a validated 136-item FFQ. The MetS was defined according to the International Diabetes Federation and American Heart Association/National Heart, Lung, and Blood Institute harmonizing definition. The association between nut consumption and MetS was assessed with logistic regression models adjusting for potential confounders. We compared the incidence of MetS between extreme categories of nut intake (≥2 servings/week v. never/almost never) after 6 years of follow-up. SETTING:  The SUN Project (Seguimiento Universidad de Navarra, University of Navarra Follow-up) is a prospective cohort study, formed of Spanish university graduates. Information is gathered by mailed questionnaires collected biennially. Nut consumption and MetS information was collected by self-reported data. SUBJECTS: Participants (n 9887) initially free of MetS or diabetes and followed up for a minimum of 6 years were included. RESULTS:  We observed 567 new cases of MetS during follow-up. Participants who consumed nuts ≥2 servings/week presented a 32 % lower risk of developing MetS than those who never/almost never consumed (adjusted OR = 0·68, 95 % CI 0·50, 0·92). The inverse association was stronger among participants who were health professionals. CONCLUSIONS:  Nut consumption was significantly associated with lower risk of developing MetS after a 6-year follow-up period in a cohort of Spanish graduates

Nuts for diabetes prevention and management.

Kamil, A., C.-Y. O. Chen, 2012. Nuts for diabetes prevention and management. Journal of Food and Drug Analysis. 20(Suppl.1): 323-327.

Type 2 diabetes mellitus is an important preventable disease and a growing public health problem. Epidemiologic and clinical studies suggest that healthy eating, physical activity, and BW control are the main driving forces to reduce diabetes risk. Owing to their low available carbohydrate content, favorable fat and protein profile as well as phytonutrient content, nut consumption has been associated with a reduced risk of development and management of diabetes. Nuts, by virtue of its cardioprotective actions, have also been shown to reduce biomarkers of risk factors for diabetic complications. Although more studies are warranted, the emerging picture is that nut consumption beneficially influences diabetes risk and management beyond blood glucose control.

Healthful dietary patterns and Type 2 diabetes mellitus risk among women with a history of gestational diabetes mellitus.

Tobias, D.K., F.B. Hu, J. Chavarro, B. Rosner, D. Mozaffarian, C. Zhang, 2012. Healthful dietary patterns and Type 2 diabetes mellitus risk among women with a history of gestational diabetes mellitus. Arch Intern Med. doi:10.1001/archinternmed.2012.3747.

 Background: Type 2 diabetes mellitus (T2DM) has reached epidemic proportions. Women with gestational diabetes mellitus (GDM) are at high risk for T2DM after pregnancy. Adherence to healthful dietary patterns has been inversely associated withT2DMin the general population; however, whether these dietary patterns are associated with progression to T2DM among a susceptible population is unknown. Methods: Four thousand four hundred thirteen participants from the Nurses’ Health Study II cohort with prior GDM were followed up from 1991 to 2005. We derived the alternate Mediterranean diet (aMED), Dietary Approaches to Stop Hypertension (DASH), and alternate Healthy Eating Index (aHEI) dietary pattern adherence scores from a post-GDM validated food-frequency questionnaire, with cumulative average updating every 4 years. Multivariable Cox proportional hazards models estimated the relative risk (hazard ratios) and 95% confidence intervals. Results: We observed 491 cases of incident T2DM during 52 743 person-years. All 3 patterns were inversely associated with T2DM risk with adjustment for age, total calorie intake, age at first birth, parity, ethnicity, parental diabetes, oral contraceptive use, menopause, and smoking. When we compared participants with the highest adherence (quartile 4) vs lowest (quartile 1), the aMED pattern was associated with 40% lower risk ofT2DM (hazard ratio, 0.60 [95% CI, 0.44-0.82; P=.002]); the DASH pattern, with 46% lower risk (0.54 [0.39-0.73; P<.001]); and the aHEI pattern, with 57% lower risk (0.43 [0.31-0.59; P<.001]). Adjustment for body mass index moderately attenuated these findings. Conclusions: Adherence to healthful dietary patterns is associated with lower T2DM risk among women with a history of GDM. The inverse associations are partly mediated by body mass index.

Pistachio nuts: composition and potential health benefits.

Dreher, M.L., 2012. Pistachio nuts: composition and potential health benefits. Nutrition Reviews. Vol.70(4):234–240.

The pistachio is a nutrient-dense nut with a heart-healthy fatty-acid profile as well as protein, dietary fiber, potassium, magnesium, vitamin K, γ-tocopherol, and a number of phytochemicals. The pistachio’s unique green and purple kernel color is a result of its lutein and anthocyanin content. Among nuts, pistachios contain the highest levels of potassium, γ-tocopherol, vitamin K, phytosterols, and xanthophyll carotenoids. Five published randomized cardiovascular trials have shown that pistachios promote heart-healthy blood lipid profiles. Exploratory clinical studies suggest that pistachios help maintain healthy antioxidant and anti-inflammatory activity, glycemic control, and endothelial function. When consumed in moderation, pistachios may help control body weight because of their satiety and satiation effects and their reduced net metabolizable energy content. One study with subjects in a weight-loss program demonstrated lower body mass index and triglyceride levels in individuals who consumed pistachios compared with those who consumed an isocaloric pretzel snack. Emerging research suggests that the addition of pistachios to high-glycemic meals may lower the overall postprandial glycemic response. This review examines the nutrients and phytochemicals in pistachios as well as the potential health effects of these nuts.

Effects of pistachios on body weight in Chinese subjects with metabolic syndrome.

Wang, X., Z. Li, Y. Liu, X. Lv, W. Yang, 2012. Effects of pistachios on body weight in Chinese subjects with metabolic syndrome. Nutrition Journal. 11:20.

Background: Studies have shown that pistachios can improve blood lipid profiles in subjects with moderate hypercholesterolemia which could reduce the risk of cardiovascular disease. However, there is also a widely perceived view that eating nuts can lead to body weight gain due to their high fat content. Purpose: To investigate the impact of different dosages of pistachios on body weight, blood pressure, blood lipids, blood glucose and insulin in subjects with metabolic syndrome. Methods: Ninety subjects with metabolic syndrome (consistent with 2005 International Diabetes Federation metabolic syndrome standard without diabetes) were enrolled in three endocrinology outpatient clinics in Beijing. All subjects received dietary counseling according to the guidelines of the American Heart Association Step I diet. After a 4 week run-in, subjects were randomized to consume either the recommended daily serving of 42 g pistachios (RSG), a higher daily serving of 70 g pistachio (HSG) or no pistachios (DCG) for 12 weeks. Results: Subjects in all three groups were matched at baseline for BMI: DCG 28.03 ± 4.3; RSG 28.12 ± 3.22; and HSG 28.01 ± 4.51 kg/m2. There were no significant changes in body weight or BMI in any groups during the study nor any change from baseline at any time point in any group. During the entire study, there were no significant differences in waist-to-hip ratio among the groups or any change from baseline in any group (DCG -0.00 ± 0.03, RSG -0.01 ± 0.02 and HSG 0.01 ± 0.04). There were no significant differences detected among groups in triglycerides, fasting glucose and 2 hour postprandial glucose following a 75 gram glucose challenge. Exploratory analyses demonstrated that glucose values 2 h after a 75 gm glucose challenge were significantly lower at week 12 compared with baseline values in the HSG group (-1.13 ± 2.58 mmol/L, p = 0.02), and a similar trend was noted in the RSG group (-0.77 ± 2.07 mmol/L, p = 0.06), while no significant change was seen in the DCG group (-0.15 ± 2.27 mmol/L, p = 0.530). At the end of study, serum triglyceride levels were significantly lower compared with baseline in the RSG group (-0.38 ± 0.79 mmol/L, p = 0.018), but no significant changes were observed in the HSG or DCG groups. Conclusion: Despite concerns that pistachio nut consumption may promote weight gain, the daily ingestion of either 42 g or 70 g of pistachios for 12 weeks did not lead to weight gain or an increase in waist-to-hip ratio in Chinese subjects with metabolic syndrome. In addition, pistachio consumption may improve the risk factor associated with the metabolic syndrome.

Out-of-hand nut consumption is associated with improved nutrient intake and health risk markers in US children and adults: National Health and Nutrition Examination Survey 1999-2004.

O’Neil, C.E., D.R. Keast, T.A. Nicklas, V.L. Fulgoni, 2012. Out-of-hand nut consumption is associated with improved nutrient intake and health risk markers in US children and adults: National Health and Nutrition Examination Survey 1999-2004. Nutrition Research. 32:185-194.

The purpose of this study was to determine the association of out-of-hand nut (OOHN) consumption with nutrient intake, diet quality, and the prevalence of risk factors for cardiovascular disease and metabolic syndrome. Data from 24-hour recalls from individuals aged 2+ years (n = 24,385) participating in the 1999-2004 National Health and Nutrition Examination Survey were used. The population was divided into children aged 2 to 11, 12 to 18, and adults 19+ years, and each group was dichotomized into OOHN consumers and nonconsumers. Out-of-hand nut consumers were defined as those individuals consuming ¼ oz of nuts or more per d. Means, standard errors, and covariate-adjusted analyses of variance were determined using appropriate sample weights. Diet quality was determined using the Healthy Eating Index-2005. Significance was set at P < .05. The percent of OOHN consumers increased with age: 2.1% ± 0.3%, 2.6% ± 0.3%, 6.5% ± 0.5%, and 9.6% ± 0.5% those aged 2 to 11, 12 to 18, 19 to 50, and 51+ years, respectively. The 2 latter groups were combined into a single group of consumers aged 19+ years for subsequent analyses. Consumers of OOHN from all age groups had higher intakes of energy, monounsaturated and polyunsaturated fatty acids, dietary fiber, copper, and magnesium and lower intakes of carbohydrates, cholesterol, and sodium than did nonconsumers. Diet quality was higher in OOHN consumers of all age groups. In children aged 2 to 11 years, consumers had a higher prevalence of overweight/obesity. In those aged 12 to 18 years, weight and percent overweight were lower in consumers. Adult consumers had higher high-density lipoprotein cholesterol, red blood cell folate, and serum folate levels and lower insulin, glycohemoglobin, and C-reactive protein levels than did nonconsumers. Adult consumers also had a 19% decreased risk of hypertension and a 21% decreased risk of low high-density lipoprotein cholesterol levels. Data suggested that OOHN consumption was associated with improved nutrient intake, diet quality, and, in adults, a lower prevalence of 2 risk factors for metabolic syndrome. Consumption of OOHN, as part of a healthy diet, should be encouraged by health professionals.