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Research Nut: Almonds

Should we go nuts about nuts?

Rohrmann, S., D. Faeh, 2013. Should we go nuts about nuts? BMC Medicine. 11:165.

Since the beginning of the 1990s, increasing evidence supports beneficial effects of nut consumption on health. A new analysis of the Spanish PREDIMED trial, published in BMC Medicine, has expanded our knowledge. The study showed that individuals eating nuts more than three times per week died less often from cardiovascular disease and cancer than non-consumers. The study also adds an important finding that previous epidemiological studies could not provide: a protective effect on premature mortality was only seen in the intervention group in which nut consumption increased during the 4.8 years of follow-up, not in the intervention group with additional olive oil consumption or in the control group. Nut consumption actually decreased during follow-up in the latter two groups. Questions remain to be answered on the quantity of nuts to be consumed for health benefits, on possible mechanisms of action, and on whether some types of nuts should be favored.

Frequency of nut consumption and mortality risk in the PREDIMED nutrition intervention trial.

Guasch-Ferré, M., M. Bulló, M.Á. Martínez-González, E. Ros, D. Corella, R. Estruch, M. Fitó, F. Arós, J. Wärnberg, M. Fiol, J. Lapetra, E. Vinyoles, R.M. Lamuela-Raventós, L. Serra-Majem, X. Pintó, V. Ruiz-Gutiérrez, J. Basora, J. Salas-Salvadó, on behalf of the PREDIMED study group, 2013. Frequency of nut consumption and mortality risk in the PREDIMED nutrition intervention trial. BMC Med. 11:164.

Background: Prospective studies in non-Mediterranean populations have consistently related increasing nut consumption to lower coronary heart disease mortality. A small protective effect on all-cause and cancer mortality has also been suggested. To examine the association between frequency of nut consumption and mortality in individuals at high cardiovascular risk from Spain, a Mediterranean country with a relatively high average nut intake per person. Methods: We evaluated 7,216 men and women aged 55 to 80 years randomized to 1 of 3 interventions (Mediterranean diets supplemented with nuts or olive oil and control diet) in the PREDIMED (‘PREvención con DIeta MEDiterránea’) study. Nut consumption was assessed at baseline and mortality was ascertained by medical records and linkage to the National Death Index. Multivariable-adjusted Cox regression and multivariable analyses with generalized  estimating equation models were used to assess the association between yearly repeated measurements of nut consumption and mortality. Results: During a median follow-up of 4.8 years, 323 total deaths, 81 cardiovascular deaths and 130 cancer deaths occurred. Nut consumption was associated with a significantly reduced risk of all-cause mortality (P for trend <0.05, all). Compared to non-consumers, subjects consuming nuts >3 servings/week (32% of the cohort) had a 39% lower mortality risk (hazard ratio (HR) 0.61; 95% CI 0.45 to 0.83). A similar protective effect against cardiovascular and cancer mortality was observed. Participants allocated to the Mediterranean diet with nuts group who consumed nuts >3 servings/week at baseline had the lowest total mortality risk (HR 0.37; 95% CI 0.22 to 0.66). Conclusions: Increased frequency of nut consumption was associated with a significantly reduced risk of mortality in a Mediterranean population at high cardiovascular risk.

Mediterranean diet improves cognition: the PREDIMED-NAVARRA randomized trial.

Martínez-Lapiscina, E.H., P. Clavero, E. Toledo, R. Estruch, J. Salas-Salvadó, B. San Julián, A. Sanchez-Tainta, E. Ros, C. Valls-Pedret, M.Á. Martinez-Gonzalez, 2013. Mediterranean diet improves cognition: the PREDIMED-NAVARRA randomized trial. J Neurol Neurosurg Psychiatry. doi:10.1136/jnnp-2012-304792.

Objective: Previous observational studies reported beneficial effects of the Mediterranean diet (MedDiet) on cognitive function, but results were inconsistent. We assessed the effect on cognition of a nutritional intervention using MedDiets in comparison with a low-fat control diet. Methods: We assessed 522 participants at high vascular risk (44.6% men, age 74.6 ± 5.7 years at cognitive evaluation) enrolled in a multicentre, randomised, primary prevention trial (PREDIMED), after a nutritional intervention comparing two MedDiets (supplemented with either extra-virgin olive oil (EVOO) or mixed nuts) versus a low-fat control diet. Global cognitive performance was examined by Mini-Mental State Examination (MMSE) and Clock Drawing Test (CDT) after 6.5 years of nutritional intervention. Researchers who assessed the outcome were blinded to group assignment. We used general linear models to control for potential confounding. Results: After adjustment for sex, age, education, Apolipoprotein E genotype, family history of cognitive impairment/dementia, smoking, physical activity, body mass index, hypertension, dyslipidaemia, diabetes, alcohol and total energy intake, participants allocated to the MedDiet+EVOO showed higher mean MMSE and CDT scores with significant differences versus control (adjusted differences: +0.62 95% CI +0.18 to +1.05, p=0.005 for MMSE, and +0.51 95% CI +0.20 to +0.82, p=0.001 for CDT). The adjusted means of MMSE and CDT scores were also higher for participants allocated to the MedDiet+Nuts versus control (adjusted differences: +0.57 (95% CI +0.11 to +1.03), p=0.015 for MMSE and +0.33 (95% CI +0.003 to +0.67), p=0.048 for CDT). These results did not differ after controlling for incident depression. Conclusions: An intervention with MedDiets enhanced with either EVOO or nuts appears to improve cognition compared with a low-fat diet.

Cross-sectional assessment of nut consumption and obesity, metabolic syndrome and other cardiometabolic risk factors: The PREDIMED study.

Ibarrola-Jurado, N, M. Bulló, M. Guasch-Ferré, E. Ros, M.A. Martínez-González, D. Corella, M. Fiol, J. Wärnberg, R. Estruch, P. Román, F. Arós, E. Vinyoles, L. Serra-Majem, X. Pintó, M.I. Covas, J. Basora, J. Salas-Salvadó, on behalf of the PREDIMED Study Investigators, 2013. Cross-sectional assessment of nut consumption and obesity, metabolic syndrome and other cardiometabolic risk factors: The PREDIMED study. PLoS ONE 8(2): e57367. doi:10.1371/journal.pone.0057367.

Introduction: Prospective studies have consistently suggested that nut consumption is inversely related to fatal and nonfatal coronary heart disease. Limited data are available on the epidemiological associations between nut intake and cardiometabolic risk factors. Objective: To evaluate associations between frequency of nut consumption and prevalence of cardiometabolic risk factors [obesity, metabolic syndrome (MetS), type-2 diabetes, hypertension, and dyslipidemia] in a Mediterranean population at high cardiovascular risk. Materials and Methods: Cross-sectional study of 7,210 men and women (mean age, 67 y) recruited into the PREDIMED study. MetS was defined by the harmonized ATPIII and IDF criteria. Diabetes and hypertension were assessed by clinical diagnosis and dyslipidemia (high triglycerides, low HDL-cholesterol, and hypercholesterolemia) by lipid analyses. Nut consumption was assessed using a validated food frequency questionnaire and categorized as <1, 1–3, and >3 servings/wk. Control of confounding was done with multivariate logistic regression. Results: Compared to participants consuming <1 serving/wk of nuts, those consuming >3 servings/wk had lower adjusted odds ratios (OR) for obesity (0.61, 95% confidence interval 0.54 to 0.68; P-trend <0.001), MetS (0.74, 0.65 to 0.85; P-trend, 0.001), and diabetes (0.87, 0.78 to 0.99; P-trend = 0.043). Higher nut consumption was also associated with lower risk of the abdominal obesity MetS criterion (OR 0.68, 0.60 to 0.79; P-trend <0.001). No significant associations were observed for the MetS components high blood pressure, dyslipidemia, or elevated fasting glucose. Conclusions: Nut consumption was inversely associated with the prevalence of general obesity, central obesity, MetS, and diabetes in subjects at high cardiovascular risk.

 

Phytosterol content and fatty acid pattern of ten different nut types.

Kornsteiner-Krenn, M., K.-H. Wagner, I. Elmadfa, 2013. Phytosterol content and fatty acid pattern of ten different nut types. International Journal for Vitamin and Nutrition Research. 83:263-270. 

Ten different nut kinds (almonds, Brazil nuts, cashews, hazelnuts, macadamias, peanuts, pecans, pine nuts, pistachios, and walnuts) were evaluated for their total oil and phytosterol content as well as their fatty acid composition. The total oil content was the predominant component; mean values oscillated between 45.2 % (cashews) and 74.7 % (macadamias). Mean total phytosterol content ranged from 71.7 mg (Brazil nuts) to 271.9 mg (pistachios) per 100 g oil. ß-sitosterol was the major sterol (mean >71.7 mg/100 g oil) followed by minor contents of campesterol, ergosterol, and stigmasterol. Almonds, cashews, hazelnuts, macadamias, and pistachios were high in monounsaturated fatty acids (MUFA; > 55 %). MUFA- and polyunsaturated fatty acid (PUFA)-rich nuts were peanuts and pecans, whereas Brazil nuts, pine nuts, and walnuts had the highest PUFA content (> 50 %); the high unsaturated/saturated fatty acid ratio ranged from 4.5 to 11.8. However, the fatty acid pattern of every nut is unique.

Primary prevention of cardiovascular disease with a Mediterranean diet.

Estruch, R., E. Ros, J. Salas-Salvadó, M.-I. Covas, D. Corella, F. Arós, E. Gómez-Gracia, V. Ruiz-Gutiérrez, M. Fiol, J. Lapetra, R.M. Lamuela-Raventos, L. Serra-Majem, X. Pintó, J. Basora, M.A. Muñoz, J.V. Sorlí, J.A. Martínez, M.A. Martínez-González, for the PREDIMED Study Investigators, 2013. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med. DOI: 10.1056/NEJMoa1200303.

Background: Observational cohort studies and a secondary prevention trial have shown an inverse association between adherence to the Mediterranean diet and cardiovascular risk. We conducted a randomized trial of this diet pattern for the primary prevention of cardiovascular events. Methods: In a multicenter trial in Spain, we randomly assigned participants who were at high cardiovascular risk, but with no cardiovascular disease at enrollment, to one of three diets: a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a control diet (advice to reduce dietary fat). Participants received quarterly individual and group educational sessions and, depending on group assignment, free provision of extra-virgin olive oil, mixed nuts, or small nonfood gifts. The primary end point was the rate of major cardiovascular events (myocardial infarction, stroke, or death from cardiovascular causes). On the basis of the results of an interim analysis, the trial was stopped after a median follow-up of 4.8 years. Results: A total of 7447 persons were enrolled (age range, 55 to 80 years); 57% were women. The two Mediterranean-diet groups had good adherence to the intervention, according to self-reported intake and biomarker analyses. A primary end-point event occurred in 288 participants. The multivariable-adjusted hazard ratios were 0.70 (95% confidence interval [CI], 0.54 to 0.92) and 0.72 (95% CI, 0.54 to 0.96) for the group assigned to a Mediterranean diet with extra-virgin olive oil (96 events) and the group assigned to a Mediterranean diet with nuts (83 events), respectively, versus the control group (109 events). No diet-related adverse effects were reported. Conclusions: Among persons at high cardiovascular risk, a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events.

Almond allergens: molecular characterization, detection, and clinical relevance.

Costa, J., I. Mafra, I. Carrapatoso, M.B.P.P. Oliveira, 2012. Almond allergens: molecular characterization, detection, and clinical relevance. J Agr Food Chem. 60:1337−1349.

Almond (Prunus dulcis) has been widely used in all sorts of food products (bakery, pastry, snacks), mostly due to its pleasant flavor and health benefits. However, it is also classified as a potential allergenic seed known to be responsible for triggering several mild to life-threatening immune reactions in sensitized and allergic individuals. Presently, eight groups of allergenic proteins have been identified and characterized in almond, namely, PR-10 (Pru du 1), TLP (Pru du 2), prolamins (Pru du 2S albumin, Pru du 3), profilins (Pru du 4), 60sRP (Pru du 5), and cupin (Pru du 6, Pru du γ-conglutin), although only a few of them have been tested for reactivity with almond-allergic sera. To protect sensitized individuals, labeling regulations have been implemented for foods containing potential allergenic ingredients, impelling the development of adequate analytical methods. This work aims to present an updated and critical overview of the molecular characterization and clinical relevance of almond allergens, as well as review the main methodologies used to detect and quantitate food allergens with special emphasis on almond.

Is almond consumption more effective than reduced dietary saturated fat at decreasing plasma total cholesterol and LDL-c levels? A theoretical approach.

Ortiz, R.M., S. Garcia, A.D. Kim, 2012. Is almond consumption more effective than reduced dietary saturated fat at decreasing plasma total cholesterol and LDL-c levels? A theoretical approach. J Nutr Metab. doi:10.1155/2012/265712.

Hypercholesterolemia can be a consequence of excessive dietary saturated fatty acid (SFA), while almond-supplemented diets can improve lipid profiles. However, the differential and independent impacts of dietary SFA and almond supplemented diets on plasma total cholesterol (pTC) and low-density lipoprotein (pLDL-c) concentrations have not been directly compared and are not well described. We reviewed the available data to construct multiple regression analyses to theoretically assess the impact of relative almond intake (RAI) and dietary SFA on reducing pTC and pLDL-c concentrations. Strong, negative correlations between RAI and percent change in mean pTC (R = 0.776; P = 0.005) and RAI and percent change in mean pLDL-c (R = 0.818; P = 0.002) were detected. The relationships between percent change in mean dietary SFA, and percent change in mean pTC and mean pLDL-c were weaker and only significant for pLDL-c. The multiple regression analyses demonstrated modest improvements in the strength of the correlations for both pTC (R = 0.804; P = 0.016) and pLDL-c (R = 0.855; P = 0.005). The models suggest that the increase in RAI contributes to the reduction in pTC and pLDL-c to a greater extent than a reduction in dietary SFA, but a simultaneous decrease in dietary SFA should further improve lipid profiles.

Almond consumption reduces oxidative DNA damage and lipid peroxidation in male smokers

Li, N., X. Jia, C.-Y.O. Chen, J.B. Blumberg, Y. Song, W. Zhang, X. Zhang, G. Ma, J. Chen, 2007. Almond consumption reduces oxidative DNA damage and lipid peroxidation in male smokers. J. Nutr. 137:2717 -2722.

Smoking increases the risk of several chronic diseases associated with elevated oxidative stress status. Almonds are a good source of antioxidant nutrients and may diminish smoking-related biomarkers of oxidative stress. This study investigated whether almond consumption decreases biomarkers of oxidative stress in young male Chinese smokers. The Chinese CDC researchers conducted a randomized, crossover clinical trial with 60 healthy male soldiers (18-25 y) who were habitual smokers (5-20 cigarettes/d) and supplemented their diet with 84 g almonds or 120 g pork (to control for calories) daily for 4 wk with a 4-wk washout period between treatment periods. In addition, 30 healthy nonsmoking men were provided the same daily serving of pork as reference comparison. Blood and urine were collected and assessed for biomarkers of oxidative stress. Baseline values of urinary 8-hydroxy-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) and peripheral lymphocyte DNA strand breaks were significantly higher by 185, 64, and 97% in smokers than nonsmokers, whereas activities of plasma superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase were significantly lower by 15, 10, and 9%, respectively. After the almond intervention, serum a-tocopherol, SOD, and GPX increased significantly in smokers by 10, 35, and 16%, respectively and 8-OHdG, MDA, and DNA strand breaks decreased significantly by 28, 34, and 23%. No significant changes were found in smokers or nonsmokers after pork treatment. In smokers, after almond supplementation, the concentration of 8-OHdG remained significantly greater than in nonsmokers by 98%. These results suggest almond intake can enhance antioxidant defenses and diminish biomarkers of oxidative stress in smokers.

Health benefits of nut consumption with special reference to body weight control.

Vadivel, V., C.N. Kunyanga, H.K. Biesalski, 2012. Health benefits of nut consumption with special reference to body weight control. Nutrition.  28:1089–1097.

Nuts are an integral part of the Mediterranean food patterns, and their incorporation into the regular diets of human beings is believed to provide many health benefits. The recent recognition of nuts as “heart-healthy” foods by the U.S. Food and Drug Administration has given a major boost to the positive image of nuts. Nut consumption has been associated with several health benefits, such as antioxidant, hypocholesterolemic, cardioprotective, anticancer, anti-inflammatory, and antidiabetic benefits, among other functional properties. However, although nuts possess these many health benefits, their consumption has been hampered by a lack of adequate information regarding those benefits. In addition, because nuts are energy-dense foods with high-fat content, there is a misconception among consumers that increased consumption may lead to unwanted gain in body weight with the risk of developing overweight/obesity. Nonetheless, available epidemiologic studies and short-term controlled feeding trials have supported the theory that the inclusion of nuts in the typical diet does not induce weight gain, despite an expected increase in total caloric intake. To address the misperception about nuts and body weight gain, the present review focuses mainly on the relation between nut consumption and body weight gain, in the context of the many health benefits of nuts.