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Research Nut: Mixed Nuts

Trends in dietary carbohydrate, protein, and fat intake and diet quality among US adults, 1999-2016.

Shan, Z., C.D. Rehm, G. Rogers, M. Ruan, D.D.Wang, F.B. Hu, D. Mozaffarian, F.F. Zhang, S.N. Bhupathiraju, 2019. Trends in dietary carbohydrate, protein, and fat intake and diet quality among US adults, 1999-2016. JAMA. 322(12):1178-1187.

IMPORTANCE: Changes in the economy, nutrition policies, and food processing methods can affect dietary macronutrient intake and diet quality. It is essential to evaluate trends in dietary intake, food sources, and diet quality to inform policy makers. OBJECTIVE: To investigate trends in dietary macronutrient intake, food sources, and diet quality among US adults. DESIGN, SETTING, AND PARTICIPANTS: Serial cross-sectional analysis of the US nationally representative 24-hour dietary recall data from 9 National Health and Nutrition Examination Survey cycles (1999-2016) among adults aged 20 years or older. EXPOSURE: Survey cycle. MAIN OUTCOMES AND MEASURES: Dietary intake of macronutrients and their subtypes, food sources, and the Healthy Eating Index 2015 (range, 0-100; higher scores indicate better diet quality; a minimal clinically important difference has not been defined). RESULTS: There were 43,996 respondents (weighted mean age, 46.9 years; 51.9% women). From 1999 to 2016, the estimated energy from total carbohydrates declined from 52.5% to 50.5% (difference, −2.02%; 95% CI, −2.41% to −1.63%), whereas that of total protein and total fat increased from 15.5%to 16.4% (difference, 0.82%; 95% CI, 0.67%-0.97%) and from 32.0%to 33.2%(difference, 1.20%; 95% CI, 0.84%-1.55%), respectively (all P < .001 for trend). Estimated energy from low-quality carbohydrates decreased by 3.25% (95% CI, 2.74%-3.75%; P < .001 for trend) from 45.1%to 41.8%. Increases were observed in estimated energy from high-quality carbohydrates (by 1.23% [95% CI, 0.84%-1.61%] from 7.42% to 8.65%), plant protein (by 0.38% [95%CI, 0.28%-0.49%] from 5.38%to 5.76%), saturated fatty acids (by 0.36% [95% CI, 0.20%-0.51%] from 11.5% to 11.9%), and polyunsaturated fatty acids (by 0.65% [95% CI, 0.56%-0.74%] from 7.58%to 8.23%) (all P < .001 for trend). The estimated overall Healthy Eating Index 2015 increased from 55.7 to 57.7 (difference, 2.01; 95% CI, 0.86-3.16; P < .001 for trend). Trends in high- and low-quality carbohydrates primarily reflected higher estimated energy from whole grains (0.65%) and reduced estimated energy from added sugars (−2.00%), respectively. Trends in plant protein were predominantly due to higher estimated intake of whole grains (0.12%) and nuts (0.09%). CONCLUSIONS AND RELEVANCE: From 1999 to 2016, US adults experienced a significant decrease in percentage of energy intake from low-quality carbohydrates and significant increases in percentage of energy intake from high-quality carbohydrates, plant protein, and polyunsaturated fat. Despite improvements in macronutrient composition and diet quality, continued high intake of low-quality carbohydrates and saturated fat remained.

Does nut consumption reduce mortality and/or risk of cardiometabolic disease? An updated review based on meta-analyses.

Kim, Y., J.B. Keogh, P.M. Clifton, 2019. Does nut consumption reduce mortality and/or risk of cardiometabolic disease? An updated review based on meta-analyses. Int. J. Environ. Res. Public Health. 16, 4957; doi:10.3390/ijerph16244957.

Aim. We aimed to determine if nut consumption decreases mortality and/or the risk of cardiometabolic diseases based on updated meta-analyses of epidemiological and intervention studies. Methods. An updated electronic search was conducted in PubMed/MEDLINE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and the Cochrane Library databases for original meta-analyses to investigate the effects of nut consumption on cardiometabolic disease in humans. Results. Seven new meta-analyses were included in this updated review. Findings similar to our previous review were observed, showing that nut consumption significantly decreased cardiovascular disease (CVD) mortality (-19% to -25%; n = 4), coronary heart disease (CHD) mortality (-24% to -30%; n = 3), stroke mortality (-17% to -18%; n = 3), CVD incidence (-15% to -19 %; n = 4), CHD [or coronary artery disease (CAD)] incidence (-17% to -34%; n = 8), and stroke incidence (-10% to -11%; n = 6) comparing high with low categories of nut consumption. Fasting glucose levels (0.08 to 0.15 mmol/L; n = 6), total cholesterol (TC; 0.021 to 0.30 mmol/L; n = 10), and low-density lipoprotein cholesterol (LDL-C; 0.017 to 0.26 mmol/L; n = 10) were significantly decreased with nut consumption compared with control diets. Body weight and blood pressure were not significantly affected by nut consumption. Conclusion. Nut consumption appears to exert a protective effect on cardiometabolic disease, possibly through improved concentrations of fasting glucose, total cholesterol, and LDL-C.

Nut consumption in relation to cardiovascular disease incidence and mortality among patients with diabetes mellitus.

Liu, G., M. Guasch-Ferre, Y. Hu, Y. Li, F.B. Hu, E.B. Rimm, J.E. Manson, K. Rexrode, Q. Sun, 2019. Nut consumption in relation to cardiovascular disease incidence and mortality among patients with diabetes mellitus. Circulation Research. doi.org/10.1161/CIRCRESAHA.118.314316

Rationale: The evidence regarding the potential health benefits of nut consumption among individuals with type 2 diabetes is limited. Objective: To examine intake of total and specific types of nuts, including tree nuts and peanuts, in relation to subsequent risk of cardiovascular disease (CVD), including coronary heart disease (CHD) and stroke, and all-cause and cause-specific mortality among individuals with diabetes. Methods and Results: This prospective analysis included 16,217 men and women with diabetes at baseline or diagnosed during follow-up (Nurses’ Health Study: 1980-2014, Health Professionals Follow-Up Study: 1986-2014). Nut consumption was assessed using a validated food frequency questionnaire and updated every 2-4 years. During 223,682 and 254,923 person-years of follow-up, there were 3,336 incident CVD cases and 5,682 deaths. Higher total nut consumption was associated with a lower risk of CVD incidence and mortality. The multivariate-adjusted hazard ratios (95% confidence intervals) for participants who consumed 5 or more servings of total nuts per week (1 serving=28g), compared with those who consumed less than 1 serving per month, were 0.83 (0.71-0.98; P trend=0.01) for total CVD incidence, 0.80 (0.67-0.96; P trend=0.005) for CHD incidence, 0.66 (0.52-0.84; P trend<0.001) for CVD mortality, and 0.69 (0.61-0.77; P trend<0.001) for all-cause mortality. Total nut consumption was not significantly associated with risk of stroke incidence or cancer mortality. For specific types of nuts, higher tree nut consumption was associated with lower risk of total CVD, CHD incidence, and mortality due to CVD, cancer, and all causes, while peanut consumption was associated with lower all-cause mortality only (all P trend<0.001). In addition, compared with participants who did not change the consumption of total nuts from pre- to post-diabetes diagnosis, participants who increased consumption of total nuts after diabetes diagnosis had an 11% lower risk of CVD, a 15% lower CHD risk, a 25% lower CVD mortality, and a 27% lower all-cause mortality. The associations persisted in subgroup analyses stratified by sex/cohort, body mass index at diabetes diagnosis, smoking status, diabetes duration, nut consumption before diabetes diagnosis, or diet quality. Conclusions: Higher consumption of nuts, especially tree nuts, is associated with lower CVD incidence and mortality among participants with diabetes. These data provide novel evidence that supports the recommendation of incorporating nuts into healthy dietary patterns for the prevention of CVD complications and premature deaths among individuals with diabetes.

The effect of nuts on markers of glycemic control: a systematic review and meta-analysis of randomized controlled trials.

Tindall, A.M., E.A. Johnston, P.M. Kris-Etherton, K.S. Petersen, 2019. The effect of nuts on markers of glycemic control: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 109:297–314.

Background: Observational evidence suggests higher nut consumption is associated with better glycemic control; however, it is unclear if this association is causal. Objectives: We aimed to conduct a systematic review and meta-analysis of randomized controlled trials to examine the effect of tree nuts and peanuts on markers of glycemic control in adults. Methods: A systematic review and meta-analysis of randomized controlled trials was conducted. A total of 1063 potentially eligible articles were screened in duplicate. From these articles, 40 were eligible for inclusion and data from these articles were extracted in duplicate. The weighted mean difference (WMD) between the nut intervention and control arms was determined for fasting glucose, fasting insulin, glycated hemoglobin (HbA1c), and homeostasis model assessment of insulin resistance (HOMA-IR) using the DerSimonian and Laird random-effects method. For outcomes where a limited number of studies were published, a qualitative synthesis was presented. Results: A total of 40 randomized controlled trials including 2832 unique participants, with a median duration of 3 mo (range: 1–12 mo), were included. Overall consumption of tree nuts or peanuts had a favorable effect on HOMA-IR (WMD: −0.23; 95% CI: −0.40, −0.06; I2=51.7%) and fasting insulin (WMD: −0.40μIU/mL;95% CI: −0.73, −0.07μ IU/mL; I2 = 49.4%). There was no significant effect of nut consumption on fasting blood glucose (WMD: −0.52 mg/dL;95% CI: −1.43,0.38mg/dL; I2 =53.4%) o rHbA1c (WMD: 0.02%; 95% CI: −0.01%, 0.04%; I2 =51.0%). Conclusions: Consumption of peanuts or tree nuts significantly decreased HOMA-IR and fasting insulin; there was no effect of nut consumption on HbA1c or fasting glucose. The results suggest that nut consumption may improve insulin sensitivity. In the future, well-designed clinical trials are required to elucidate the mechanisms that account for these observed effects.

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.

Nut Consumption and Survival in Patients With Stage III Colon Cancer: Results From CALGB 89803 (Alliance).

Fadelu, T., S. Zhang, D. Niedzwiecki, X. Ye, L.B. Saltz, R.J. Mayer, R.B. Mowat, R. Whittom, A. Hantel, A.B. Benson, D.M. Atienza, M. Messino, H.L. Kindler, A. Venook, S. Ogino, K. Ng, K. Wu, W. Willett, E. Giovannucci, J. Meyerhardt, Y. Bao, C.S. Fuchs, 2018. Nut Consumption and Survival in Patients With Stage III Colon Cancer: Results From CALGB 89803 (Alliance). J Clin Oncol. 36(11):1112-1120.

Purpose: Observational studies have reported increased colon cancer recurrence and mortality in patients with states of hyperinsulinemia, including type 2 diabetes, obesity, sedentary lifestyle, and high glycemic load diet. Nut intake has been associated with a lower risk of type 2 diabetes, metabolic syndrome, and insulin resistance. However, the effect of nut intake on colon cancer recurrence and survival is not known. Patients and Methods: We conducted a prospective, observational study of 826 eligible patients with stage III colon cancer who reported dietary intake on food frequency questionnaires while enrolled onto a randomized adjuvant chemotherapy trial. Using Cox proportional hazards regression, we assessed associations of nut intake with cancer recurrence and mortality. Results: After a median follow-up of 6.5 years, compared with patients who abstained from nuts, individuals who consumed two or more servings of nuts per week experienced an adjusted hazard ratio (HR) for disease-free survival of 0.58 (95% CI, 0.37 to 0.92; Ptrend = .03) and an HR for overall survival of 0.43 (95% CI, 0.25 to 0.74; Ptrend = .01). In subgroup analysis, the apparent benefit was confined to tree nut intake (HR for disease-free survival, 0.54; 95% CI, 0.34 to 0.85; Ptrend = .04; and HR for overall survival, 0.47; 95% CI, 0.27 to 0.82; Ptrend = .04). The association of total nut intake with improved outcomes was maintained across other known or suspected risk factors for cancer recurrence and mortality. Conclusion: Diets with a higher consumption of nuts may be associated with a significantly reduced incidence of cancer recurrence and death in patients with stage III colon cancer.

Tree nut allergens.

Geiselhart, S., K. Hoffmann-Sommergruber, M. Bublin, 2018. Tree nut allergens. Mol Immunol. 100:71-81.

Tree nuts are considered as part of a healthy diet due to their high nutritional quality. However, they are also a potent source of allergenic proteins inducing IgE mediated hypersensitivity often causing serious, life-threatening reactions. The reported prevalence of tree nut allergy is up to 4.9% worldwide. The general term “tree nuts” comprises a number of nuts, seeds, and drupes, derived from trees from different botanical families. For hazelnut and walnut several allergens have been identified which are already partly applied in component resolved diagnosis, while for other tree nuts such as macadamia, coconut, and Brazil nut only individual allergens were identified and data on additional allergenic proteins are missing. This review summarizes the current knowledge on tree nut allergens and describes their physicochemical and immunological characterization and clinical relevance.

Effect of nut consumption on semen quality and functionality in healthy men consuming a Western-style diet: a randomized controlled trial.

Salas-Huetos, A., R. Moraleda, S. Giardina, E. Anton, J. Blanco, J. Salas-Salvadó, M. Bulló, 2018. Effect of nut consumption on semen quality and functionality in healthy men consuming a Western-style diet: a randomized controlled trial. Am J Clin Nutr. 108:953–962.

Background: Human semen quality has declined in industrialized countries. Pollution, smoking, and the consumption of a Western style diet are all hypothesized as potential causes. Objective: We evaluated the effect of chronic consumption of nuts on changes in conventional semen parameters and the potential mechanisms implicated. Design: The FERTINUTS study was a 14-wk randomized, controlled, parallel trial. A total of 119 healthy men, aged 18–35 y, were allocated to 1 of 2 intervention groups: one group was fed the usual Western-style diet enriched with 60 g of a mixture of nuts/d (nut group), and the other was fed the usual Western-style diet avoiding nuts (control group). Semen and blood samples were collected at baseline and at the end of the intervention. Dietary information was recorded throughout the trial. Changes in conventional semen parameters (pH, volume, sperm count and concentration, motility, and morphology) were determined as primary outcomes. The effect of nut consumption on sperm DNA fragmentation (SDF), reactive oxygen species (ROS) production, chromosome anomalies (X, Y, and 18), total DNA methylation, and microRNA expression were measured in sperm samples as potential causes of the changes in the seminogram. Results: Compared with the control group, improvements in total sperm count (P = 0.002) and vitality (P = 0.003), total motility (P = 0.006), progressive motility (P = 0.036), and morphology of sperm (P = 0.008) were observed in the nut group. Participants in the nut group showed an increase in the consumption of total fat, monounsaturated fatty acids, polyunsaturated fatty acids, magnesium, vitamin E, α-linolenic acid, total omega-3 (n–3) and ω-3: ω-6 ratio intake during the intervention. Participants in the nut group showed a significant reduction in SDF (P < 0.001) and in the expression of hsa-miR-34b-3p (P = 0.036). No significant changes in ROS, sperm chromosome anomalies, or DNA methylation were observed between groups. Conclusions: The inclusion of nuts in a Western-style diet significantly improves the total sperm count and the vitality, motility, and morphology of the sperm. These findings could be partly explained by a reduction in the sperm DNA fragmentation. This trial was registered at ISRCTN as ISRCTN12857940.

Effect of nut consumption on vascular endothelial function: A systematic review and meta-analysis of randomized controlled trials.

Xiao, Y., W. Huang, C. Peng, J. Zhang, C. Wong, J.H. Kim, E.-K. Yeoh, 2017. Effect of nut consumption on vascular endothelial function: A systematic review and meta-analysis of randomized controlled trials. Clinical Nutrition. http://dx.doi.org/10.1016/j.clnu.2017.04.011

Objective: Nut consumption has consistently been found to be associated with a reduced risk of cardiovascular diseases (CVD) and mortality in prospective studies. However, its effect on endothelial function, a prognostic marker of CVD, is still controversial in clinical trials. This meta-analysis of randomized controlled trials (RCTs) aimed to quantitatively assess the effect of nuts on vascular endothelial function. Methods: Major electronic databases were searched for published RCTs that reported the effect of nuts on flow mediated dilation (FMD) as a measurement of endothelial function in the adult population (age eighteen years or over). We calculated the pooled estimates of weighted mean differences (WMDs) and their 95% confidence intervals (CIs) by using random-effects models. Results: A total of nine papers (10 trials) involving 374 participants were included. The pooled estimates found that nut consumption significantly improved FMD (WMD: 0.41%; 95% CI: 0.18%, 0.63%; P = 0.001). Moderate and marginally significant heterogeneity was observed among the studies (I2 = 39.5%, P = 0.094). Subgroup analyses indicated that walnuts significantly improved FMD (WMD: 0.39%; 95% CI: 0.16%, 0.63%; P = 0.001). In addition, nut consumption had a significant effect on FMD in the trials with study duration <18 weeks, nut dose <67 g/d, or subjects with baseline FMD ≥8.6%. Conclusions: Nut consumption significantly improved endothelial function. However, the beneficial effect was limited to walnuts. More studies examining the effect of other nuts on endothelial function are needed in the future.

Replacing American snacks with tree nuts increases consumption of key nutrients among US children and adults: results of an NHANES modeling study.

Rehm, C.D., A. Drewnowski. 2017. Replacing American snacks with tree nuts increases consumption of key nutrients among US children and adults: results of an NHANES modeling study. Nutr. J. doi:10.1186/s12937017-0238-5.

Background: Replacing typical American snacks with tree nuts may be an effective way to improve diet quality and compliance with the 2015–2020 Dietary Guidelines for Americans (DGAs). Objective: To assess and quantify the impact of replacing typical snacks with composite tree nuts or almonds on diet metrics, including empty calories (i.e., added sugars and solid fats), individual fatty acids, macronutrients, nutrients of public health concern, including sodium, fiber and potassium, and summary measures of diet quality. Methods: Food pattern modeling was implemented in the nationally representative 2009–2012 National Health and Examination Survey (NHANES) in a population of 17,444 children and adults. All between-meal snacks, excluding beverages, were replaced on a per calorie basis with a weighted tree nut composite, reflecting consumption patterns in the population. Model 1 replaced all snacks with tree nuts, while Model 2 exempted whole fruits, non-starchy vegetables, and whole grains (>50% of total grain content). Additional analyses were conducted using almonds only. Outcomes of interest were empty calories (i.e., solid fats and added sugars), saturated and mono- and polyunsaturated fatty acids, fiber, protein, sodium, potassium and magnesium. The Healthy Eating Index-2010, which measures adherence to the 2010 Dietary Guidelines for Americans, was used as a summary measure of diet quality. Results: Compared to observed diets, modeled food patterns were significantly lower in empty calories (−20.1% and −18.7% in Model 1 and Model 2, respectively), added sugars (−17.8% and −16.9%), solid fats (−21.0% and −19.3%), saturated fat (−6.6% and −7.1%)., and sodium (−12.3% and −11.2%). Modeled patterns were higher in oils (65.3% and 55.2%), monounsaturated (35.4% and 26.9%) and polyunsaturated fats (42.0% and 35.7%), plant omega 3 s (53.1% and 44.7%), dietary fiber (11.1% and 14.8%), and magnesium (29.9% and 27.0%), and were modestly higher in potassium (1.5% and 2.9%). HEI-2010 scores were significantly higher in Model 1 (67.8) and in Model 2 (69.7) compared to observed diets (58.5). Replacing snacks with almonds only produced similar results; the decrease in sodium was more modest and no increase in plant omega-3 fats was observed. Conclusion: Replacing between-meal snacks with tree nuts or almonds led to more nutrient-rich diets that were lower in empty calories and sodium and had more favorable fatty acid profiles. Food pattern modeling using NHANES data can be used to assess the likely nutritional impact of dietary guidance.