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

Lifestyle recommendations for the prevention and management of metabolic syndrome: an international panel recommendation

The importance of metabolic syndrome (MetS) lies in its associated risk of cardiovascular disease and type 2 diabetes, as well as other harmful conditions such as nonalcoholic fatty liver disease. In this report, the available scientific evidence on the associations between lifestyle changes and MetS and its components is reviewed to derive recommendations for MetS prevention and management. Weight loss through an energy-restricted diet together with increased energy expenditure through physical activity contribute to the prevention and treatment of MetS. A Mediterranean-type diet, with or without energy restriction, is an effective treatment component. This dietary pattern should be built upon an increased intake of unsaturated fat, primarily from olive oil, and emphasize the consumption of legumes, cereals (whole grains), fruits, vegetables, nuts, fish, and low-fat dairy products, as well as moderate consumption of alcohol. Other dietary patterns (Dietary Approaches to Stop Hypertension, new Nordic, and vegetarian diets) have also been proposed as alternatives for preventing MetS. Quitting smoking and reducing intake of sugar-sweetened beverages and meat and meat products are mandatory. Nevertheless, there are inconsistencies and gaps in the evidence, and additional research is needed to define the most appropriate therapies for MetS. In conclusion, a healthy lifestyle is critical to prevent or delay the onset of MetS in susceptible individuals and to prevent cardiovascular disease and type 2 diabetes in those with existing MetS. The recommendations provided in this article should help patients and clinicians understand and implement the most effective approaches for lifestyle change to prevent MetS and improve cardiometabolic health.

Prospective Study of Nut Consumption and Incidence of Metabolic Syndrome: Tehran Lipid and Glucose Study

This study aimed to assess the association of various types of nut per se, and total nut consumption with the incidence of metabolic syndrome (MetS). A 6.2 ± 0.7-year population-based prospective study was conducted among 1265 adults, aged 19–74 years, participants of the Tehran Lipid and Glucose Study. A 168-item semi-quantitative food frequency questionnaire was used to collect information on nut consumption. MetS was defined according to the Joint Interim Statement guidelines and 276 new cases of MetS were identified. Median ± interquartile range of nut consumption was 2.08 (0.88–5.68) servings/week. After adjusting for family history of diabetes, age, gender, smoking, physical activity, fasting serum glucose at baseline, serum high density lipoprotein cholesterol (HDL-C) at baseline, energy intake, fiber, macronutrients, cholesterol intake, fruit, vegetables, dairy products and body mass index (BMI), a statistically significant decrease was observed in MetS in the third (≥5 servings/week) tertile of nuts (odds ratio: 0.68, 95% CI: 0.44–0.91, p trend: 0.03) compared with the lowest (≤1 serving/week). Walnut consumption showed a significant, inverse association with MetS risk; associations for other nut varieties were not significant. For each additional serving/week of walnuts consumed, incidence of MetS decreased by 3% (ORs: 0.97 CI: 0.93–0.99), after adjusting for confounding factors. Total nut consumption, especially walnuts, reduces the risk of MetS.

Trending Cardiovascular Nutrition Controversies

The potential cardiovascular benefits of several trending foods and dietary patterns are still incompletely understood, and nutritional science continues to evolve. However, in the meantime, a number of controversial dietary patterns, foods, and nutrients have received significant media exposure and are mired by hype. This review addresses some of the more popular foods and dietary patterns that are promoted for cardiovascular health to provide clinicians with accurate information for patient discussions in the clinical setting.

Nuts and Dried Fruits: An Update of Their Beneficial Effects on Type 2 Diabetes

Nuts and dried fruit are essential foods in the Mediterranean diet. Their frequent consumption has been associated with the prevention and/or the management of such metabolic conditions as type 2 diabetes (T2D), metabolic syndrome and cardiovascular diseases. Several previous reviews of epidemiological studies and clinical trials have evaluated the associations of nuts and/or dried fruit with various metabolic disorders. However, no reviews have focused on the mechanisms underlying the role of nuts and/or dried fruit in insulin resistance and T2D. This review aims to report nut and dried-fruit nutritional interventions in animals and humans, and to focus on mechanisms that could play a significant role in the prevention and treatment of insulin resistance and T2D.

Polyphenol Levels Are Inversely Correlated with Body Weight and Obesity in an Elderly Population after 5 Years of Follow Up (The Randomised PREDIMED Study)

Overweight and obesity have been steadily increasing in recent years and currently represent a serious threat to public health. Few human studies have investigated the relationship between polyphenol intake and body weight. Our aim was to assess the relationship between urinary polyphenol levels and body weight. A cross-sectional study was performed with 573 participants from the PREDIMED (Prevención con Dieta Mediterránea) trial (ISRCTN35739639). Total polyphenol levels were measured by a reliable biomarker, total urinary polyphenol excretion (TPE), determined by the Folin-Ciocalteu method in urine samples. Participants were categorized into five groups according to their TPE at the fifth year. Multiple linear regression models were used to assess the relationships between TPE and obesity parameters; body weight (BW), body mass index (BMI), waist circumference (WC), and waist-to-height ratio (WHtR). After a five years follow up, significant inverse correlations were observed between TPE at the 5th year and BW (β = −1.004; 95% CI: −1.634 to −0.375, p = 0.002), BMI (β = −0.320; 95% CI: −0.541 to −0.098, p = 0.005), WC (β = −0.742; 95% CI: −1.326 to −0.158, p = 0.013), and WHtR (β = −0.408; 95% CI: −0.788 to −0.028, p = 0.036) after adjustments for potential confounders. To conclude, a greater polyphenol intake may thus contribute to reducing body weight in elderly people at high cardiovascular risk.

Paleolithic and Mediterranean Diet Pattern Scores Are Inversely Associated with All-Cause and Cause-Specific Mortality in Adults

Background: Poor diet quality is associated with a higher risk of many chronic diseases that are among the leading causes of death in the United States. It has been hypothesized that evolutionary discordance may account for some of the higher incidence and mortality from these diseases.Objective: We investigated associations of 2 diet pattern scores, the Paleolithic and the Mediterranean, with all-cause and cause-specific mortality in the REGARDS (REasons for Geographic and Racial Differences in Stroke) study, a longitudinal cohort of black and white men and women ≥45 y of age.Methods: Participants completed questionnaires, including a Block food-frequency questionnaire (FFQ), at baseline and were contacted every 6 mo to determine their health status. Of the analytic cohort (n = 21,423), a total of 2513 participants died during a median follow-up of 6.25 y. We created diet scores from FFQ responses and assessed their associations with mortality using multivariable Cox proportional hazards regression models adjusting for major risk factors.Results: For those in the highest relative to the lowest quintiles of the Paleolithic and Mediterranean diet scores, the multivariable adjusted HRs for all-cause mortality were, respectively, 0.77 (95% CI: 0.67, 0.89; P-trend < 0.01) and 0.63 (95% CI: 0.54, 0.73; P-trend < 0.01). The corresponding HRs for all-cancer mortality were 0.72 (95% CI: 0.55, 0.95; P-trend = 0.03) and 0.64 (95% CI: 0.48, 0.84; P-trend = 0.01), and for all-cardiovascular disease mortality they were 0.78 (95% CI: 0.61, 1.00; P-trend = 0.06) and HR: 0.68 (95% CI: 0.53, 0.88; P-trend = 0.01).Conclusions: Findings from this biracial prospective study suggest that diets closer to Paleolithic or Mediterranean diet patterns may be inversely associated with all-cause and cause-specific mortality.

Effects of canola and high-oleic-acid canola oils on abdominal fat mass in individuals with central obesity

OBJECTIVE

To determine the effect of diets low in saturated fatty acids and high in monounsaturated fatty acids (MUFA) or polyunsaturated fatty acids on body composition in participants at risk for metabolic syndrome (MetS).

METHODS

This study was a randomized, crossover, controlled feeding study. Participants (n = 101, ages 49.5 ± 1.2, BMI 29.4 ± 0.4 kg/m² ) were randomized to five isocaloric diets containing treatment oils: Canola, CanolaOleic, CanolaDHA, Corn/Safflower, and Flax/Safflower. Each diet period was 4 weeks followed by a 2- to 4-week washout period.

RESULTS

Canola (3.1 kg, P = 0.026) and CanolaOleic oil diets (3.09 kg, P = 0.03) reduced android fat mass compared with the Flax/Saff oil diet (3.2 kg), particularly in men. The decrease in abdominal fat mass was correlated with the reduction in blood pressure after the Canola (systolic blood pressure: r = 0.26, P = 0.062; diastolic blood pressure: r = 0.38, P = 0.0049) and CanolaOleic oil diets (systolic blood pressure: r = 0.39 P = 0.004; diastolic blood pressure: r = 0.45, P = 0.0006). The decrease in abdominal fat mass also was associated with a reduction in triglyceride levels after the CanolaOleic oil diet (r = 0.42, P = 0.002).

CONCLUSIONS

Diets high in MUFA (compared with PUFA) reduced central obesity with an accompanying improvement in MetS risk factors. Diets high in MUFA may be beneficial for treating and perhaps preventing MetS.

Contemporary issues regarding nutrition in cardiovascular rehabilitation

In this article, we discuss certain contemporary and controversial topics in cardiovascular (CV) nutrition including recent data regarding the health benefits of the Mediterranean diet, the role of saturated fatty acids, red meat and the microbiome in CV disease and the current role of personalized CV nutrition. Findings from the PREDIMED study now demonstrate the health benefits of the Mediterranean diet even in the absence of heart disease. The study highlighted that even small, sustained and easily implementable changes to diet can provide significant health benefits even in Mediterranean regions. Likewise, observational data in secondary prevention show that increased adherence to the Mediterranean diet is associated with good long-term clinical outcomes among subjects with stable coronary heart disease. The role of saturated fats in the development of CV disease remains controversial, although data suggest that these fats are associated with modestly increased risk of CV events. In contrast, the obesity epidemic currently driving the CV risk worldwide is in large part due to excess consumption of refined carbohydrates. Furthermore, a growing body of evidence suggests that the intestinal microbiome is highly sensitive to lifestyle choices and may play a pivotal role in modulating CV disease development. For example, recent evidence linking processed and unprocessed meats to increased CV risk pointed to the gut microbial metabolite trimethylamine N-oxide as a potential culprit. Finally, given the high interindividual variability in response to interventions including diet, personalized nutrition has potential to play a major role in tailoring diets based on genetic make-up to maximize health benefits. This approach is still in its infancy but is highly promising.

New insights into the role of nutrition in CVD prevention

Nutrition plays an increasingly significant role in lifestyle strategies for cardiovascular prevention. Foods and dietary patterns that encompass specific foods and beverages and their combinations, with synergies among their components, are the subject of much epidemiologic and clinical research in relation to health issues, including cardiovascular disease. Foods with the highest evidence for beneficial effects on cardiovascular outcomes (mainly fatal and nonfatal coronary artery disease and stroke) and intermediate risk markers (principally cholesterol and blood pressure) are fruits and vegetables, legumes, nuts, whole grains, dairy products, fish, and alcohol consumed in moderation. Epidemiologic and clinical trial evidence on cardiovascular health issues is reviewed for these foods and for the dietary pattern with the highest probability of a causal link with cardiovascular protection, namely the Mediterranean diet. When pertinent, mechanisms of protection derived from specific nutrients in foods are also examined. The explosion of knowledge in cardioprotective foods and diets needs to be translated to the public, as dietary quality is still far from optimal in large segments of the population.

Oily fish, coffee and walnuts: Dietary treatment for nonalcoholic fatty liver disease

Rates of non-alcoholic fatty liver disease (NAFLD) are increasing worldwide in tandem with the metabolic syndrome, with the progressive form of disease, non-alcoholic steatohepatitis (NASH) likely to become the most common cause of end stage liver disease in the not too distant future. Lifestyle modification and weight loss remain the main focus of management in NAFLD and NASH, however, there has been growing interest in the benefit of specific foods and dietary components on disease progression, with some foods showing protective properties. This article provides an overview of the foods that show the most promise and their potential benefits in NAFLD/NASH, specifically; oily fish/ fish oil, coffee, nuts, tea, red wine, avocado and olive oil. Furthermore, it summarises results from animal and human trials and highlights potential areas for future research.

Association of Nut Consumption with Cardiometabolic Risk Factors in the 2008/2009 New Zealand Adult Nutrition Survey

Nut consumption has been associated with improvements in risk factors for chronic disease in populations within North America, Europe and Iran. This relationship has not been investigated in New Zealand (NZ). The associations between nut consumption and cardiometabolic risk factors among New Zealanders were examined. Data from the 24-h diet recalls of 4721 participants from the NZ Adult Nutrition Survey 2008/2009 (2008/2009 NZANS) were used to determine whole and total nut intake. Anthropometric data and blood pressure were collected, as well as blood samples analysed for total cholesterol (total-C) and HDL cholesterol (HDL-C), glycated haemoglobin (HbA1c), C-reactive protein (CRP) and folate. Participants were classified according to their five-year cardiovascular disease (CVD) risk. Both whole and total nut consumers had significantly lower weight, body mass index (BMI), waist circumference and central adiposity than non-nut consumers (all p ≤ 0.044). Whole blood, serum and red blood cell folate concentrations were significantly higher among whole nut consumers compared to non-whole nut consumers (all p ≤ 0.014), with only serum folate higher in total nut consumers compared to non-total nut consumers (p = 0.023). There were no significant differences for blood pressure, total-C, HDL-C and HbA1c; however, significant negative associations between total nut consumption and CVD risk category (p < 0.001) and CRP (p = 0.045) were apparent. Nut consumption was associated with more favourable body composition and a number of risk factors, which could collectively reduce chronic disease.

TRAMP prostate tumor growth is slowed by walnut diets through altered IGF-1 levels, energy pathways, and cholesterol metabolism

Dietary changes could potentially reduce prostate cancer morbidity and mortality. Transgenic adenocarcinoma of the mouse prostate (TRAMP) prostate tumor responses to a 100 g of fat/kg diet (whole walnuts, walnut oil, and other oils; balanced for macronutrients, tocopherols [α-and γ]) for 18 weeks ad libitum were assessed. TRAMP mice (n=17 per group) were fed diets with 100 g fat from either whole walnuts (diet group WW), walnut-like fat (diet group WLF, oils blended to match walnut's fatty acid profile), or as walnut oil (diet group WO, pressed from the same walnuts as WW). Fasted plasma glucose was from tail vein blood, blood was obtained by cardiac puncture, and plasma stored frozen until analysis. Prostate (genitourinary intact [GUI]) was weighed and stored frozen at -80°C. Plasma triglyceride, lipoprotein cholesterol, plasma multianalyte levels (Myriad RBM Rat Metabolic MAP), prostate (GUI), tissue metabolites (Metabolon, Inc., Durham, NC, USA), and mRNA (by Illumina NGS) were determined. The prostate tumor size, plasma insulin-like growth factor-1 (IGF-1), high density lipoprotein, and total cholesterol all decreased significantly (P<.05) in both WW and WO compared to WLF. Both WW and WO versus WLF showed increased insulin sensitivity (Homeostasis Model Assessment [HOMA]), and tissue metabolomics found reduced glucose-6-phosphate, succinylcarnitine, and 4-hydroxybutyrate in these groups suggesting effects on cellular energy status. Tissue mRNA levels also showed changes suggestive of altered glucose metabolism with WW and WO diet groups having increased PCK1 and CIDEC mRNA expression, known for their roles in gluconeogenesis and increased insulin sensitivity, respectively. WW and WO group tissues also had increased MSMB mRNa a tumor suppressor and decreased COX-2 mRNA, both reported to inhibit prostate tumor growth. Walnuts reduced prostate tumor growth by affecting energy metabolism along with decreased plasma IGF-1 and cholesterol. These effects are not due to the walnut's N-3 fatty acids, but due to component(s) found in the walnut's fat component.

Nuts and CVD

Nuts are nutrient-dense foods with complex matrices rich in unsaturated fatty acids and other bioactive compounds, such as l-arginine, fibre, healthful minerals, vitamin E, phytosterols and polyphenols. By virtue of their unique composition, nuts are likely to beneficially affect cardiovascular health. Epidemiological studies have associated nut consumption with a reduced incidence of CHD in both sexes and of diabetes in women, but not in men. Feeding trials have clearly demonstrated that consumption of all kinds of nuts has a cholesterol-lowering effect, even in the context of healthy diets. There is increasing evidence that nut consumption has a beneficial effect on oxidative stress, inflammation and vascular reactivity. Blood pressure, visceral adiposity and the metabolic syndrome also appear to be positively influenced by nut consumption. Contrary to expectations, epidemiological studies and clinical trials suggest that regular nut consumption is not associated with undue weight gain. Recently, the PREvención con DIeta MEDiterránea randomised clinical trial of long-term nutrition intervention in subjects at high cardiovascular risk provided first-class evidence that regular nut consumption is associated with a 50 % reduction in incident diabetes and, more importantly, a 30 % reduction in CVD. Of note, incident stroke was reduced by nearly 50 % in participants allocated to a Mediterranean diet enriched with a daily serving of mixed nuts (15 g walnuts, 7·5 g almonds and 7·5 g hazelnuts). Thus, it is clear that frequent nut consumption has a beneficial effect on CVD risk that is likely to be mediated by salutary effects on intermediate risk factors.

Tree Nut consumption is associated with better adiposity measures and cardiovascular and metabolic syndrome health risk factors in U.S. Adults: NHANES 2005-2010

INTRODUCTION

Previous research has shown inconsistencies in the association of tree nut consumption with risk factors for cardiovascular disease (CVD) and metabolic syndrome (MetS).

OBJECTIVE

To determine the association of tree nut consumption with risk factors for CVD and for MetS in adults.

METHODS

NHANES 2005-2010 data were used to examine the associations of tree nut consumption with health risks in adults 19+ years (n = 14,386; 51% males). Tree nuts were: almonds, Brazil nuts, cashews, filberts [hazelnuts], macadamias, pecans, pine nuts, pistachios, and walnuts. Group definitions were non-consumers < ¼ ounce/day and consumers of ≥ ¼ ounce/day tree nuts using data from 24-h dietary recalls. Means and ANOVA (covariate adjusted) were determined using appropriate sample weights. Using logistic regression, odds ratios of being overweight (OW)/obese (OB) (body mass index [BMI] >25/<30 and ≥30, respectively) and having CVRF or MetS, were determined.

RESULTS

Tree nut consumption was associated with lower BMI (p = 0.004), waist circumference (WC) (p = 0.008), systolic blood pressure (BP) (p = 0.001), Homeostatic Model Assessment-Insulin Resistance (p = 0.043), and higher high density lipoprotein-cholesterol (p = 0.022), compared with no consumption, and a lower likelihood of OB (-25%), OW/OB (-23%), and elevated WC (-21%).

CONCLUSIONS

Tree nut consumption was associated with better weight status and some CVRF and MetS components.

Benefits of the Mediterranean Diet: Insights From the PREDIMED Study

The PREDIMED (PREvención con DIeta MEDiterránea) multicenter, randomized, primary prevention trial assessed the long-term effects of the Mediterranean diet (MeDiet) on clinical events of cardiovascular disease (CVD). We randomized 7447 men and women at high CVD risk into three diets: MeDiet supplemented with extra-virgin olive oil (EVOO), MeDiet supplemented with nuts, and control diet (advice on a low-fat diet). No energy restriction and no special intervention on physical activity were applied. We observed 288 CVD events (a composite of myocardial infarction, stroke or CVD death) during a median time of 4.8years; hazard ratios were 0.70 (95% CI, 0.53-0.91) for the MeDiet+EVOO and 0.70 (CI, 0.53-0.94) for the MeDiet+nuts compared to the control group. Respective hazard ratios for incident diabetes (273 cases) among 3541 non-diabetic participants were 0.60 (0.43-0.85) and 0.82 (0.61-1.10) for MeDiet+EVOO and MeDiet+nuts, respectively versus control. Significant improvements in classical and emerging CVD risk factors also supported a favorable effect of both MeDiets on blood pressure, insulin sensitivity, lipid profiles, lipoprotein particles, inflammation, oxidative stress, and carotid atherosclerosis. In nutrigenomic studies beneficial effects of the intervention with MedDiets showed interactions with several genetic variants (TCF7L2, APOA2, MLXIPL, LPL, FTO, M4CR, COX-2, GCKR and SERPINE1) with respect to intermediate and final phenotypes. Thus, the PREDIMED trial provided strong evidence that a vegetable-based MeDiet rich in unsaturated fat and polyphenols can be a sustainable and ideal model for CVD prevention.

Meta-analysis of prospective studies on the effects of nut consumption on hypertension and type 2 diabetes mellitus

BACKGROUND

Inconclusive reports have been published on the consumption of nuts and the risk of hypertension and type 2 diabetes mellitus (T2DM). We performed a meta-analysis of prospective studies to assess the effects of nut consumption on hypertension and T2DM risks.

METHODS

A PUBMED and EMBASE database search was performed. Summary relative risks (SRRs) and 95% confidence intervals (CIs) were calculated using a random-effects model. Q and I2 statistics were used to examine between-study heterogeneity.

RESULTS

A total of eight articles with nine prospective cohort studies (three hypertension studies and six T2DM studies) were selected. Using random effects models, we found that compared with never/rare consumers of nuts, those consuming >2 servings per week had an 8% lower risk of hypertension (SRR = 0.92, 95% CI: 0.87-0.97, P(heterogeneity)  = 0.590, I2  = 0%), while consumption of nuts at one serving per week had similar risk (SRR = 0.97, 95% CI: 0.83-1.13). In addition, nuts consumption was not associated with risk of T2DM (SRRs = 0.98, 95% CI: 0.84-1.15; P(heterogeneity)  = 0.008, I2  = 67.7%) on the basis of the highest versus lowest analysis. This null association was also shown in the dose-response analysis.

CONCLUSION

Findings from this meta-analysis indicate that consumption of nuts (>2 servings/week) may be inversely associated with hypertension risk, but not with T2DM risk.

Effects of daily almond consumption on cardiometabolic risk and abdominal adiposity in healthy adults with elevated LDL-cholesterol: a randomized controlled trial

BACKGROUND

Evidence consistently shows that almond consumption beneficially affects lipids and lipoproteins. Almonds, however, have not been evaluated in a controlled-feeding setting using a diet design with only a single, calorie-matched food substitution to assess their specific effects on cardiometabolic risk factors.

METHODS AND RESULTS

In a randomized, 2-period (6 week/period), crossover, controlled-feeding study of 48 individuals with elevated LDL-C (149±3 mg/dL), a cholesterol-lowering diet with almonds (1.5 oz. of almonds/day) was compared to an identical diet with an isocaloric muffin substitution (no almonds/day). Differences in the nutrient profiles of the control (58% CHO, 15% PRO, 26% total fat) and almond (51% CHO, 16% PRO, 32% total fat) diets were due to nutrients inherent to each snack; diets did not differ in saturated fat or cholesterol. The almond diet, compared with the control diet, decreased non-HDL-C (-6.9±2.4 mg/dL; P=0.01) and LDL-C (-5.3±1.9 mg/dL; P=0.01); furthermore, the control diet decreased HDL-C (-1.7±0.6 mg/dL; P<0.01). Almond consumption also reduced abdominal fat (-0.07±0.03 kg; P=0.02) and leg fat (-0.12±0.05 kg; P=0.02), despite no differences in total body weight.

CONCLUSIONS

Almonds reduced non-HDL-C, LDL-C, and central adiposity, important risk factors for cardiometabolic dysfunction, while maintaining HDL-C concentrations. Therefore, daily consumption of almonds (1.5 oz.), substituted for a high-carbohydrate snack, may be a simple dietary strategy to prevent the onset of cardiometabolic diseases in healthy individuals.

CLINICAL TRIAL REGISTRATION URL

www.clinicaltrials.gov; Unique Identifier: NCT01101230.

An evidence-based review of oral magnesium supplementation in the preventive treatment of migraine

Background

Migraine is an incompletely understood, debilitating disorder that lacks a universally effective treatment. Magnesium participates in a variety of biochemical processes related to migraine pathophysiology, and a deficiency could contribute to migraine development.

Methods

A review of the literature from 1990 to the present on magnesium and migraine was conducted.

Review

The authors identified 16 studies aimed at magnesium status assessment in migraine, and four intervention trials assessing the efficacy of oral magnesium supplementation, independent of other therapies, in the prevention of migraine.

Conclusion

The strength of evidence supporting oral magnesium supplementation is limited at this time. With such limited evidence, a more advantageous alternative to magnesium supplementation, in patients willing to make lifestyle changes, may be to focus on increasing dietary magnesium intake.

Can we say what diet is best for health?

Diet is established among the most important influences on health in modern societies. Injudicious diet figures among the leading causes of premature death and chronic disease. Optimal eating is associated with increased life expectancy, dramatic reduction in lifetime risk of all chronic disease, and amelioration of gene expression. In this context, claims abound for the competitive merits of various diets relative to one another. Whereas such claims, particularly when attached to commercial interests, emphasize distinctions, the fundamentals of virtually all eating patterns associated with meaningful evidence of health benefit overlap substantially. There have been no rigorous, long-term studies comparing contenders for best diet laurels using methodology that precludes bias and confounding, and for many reasons such studies are unlikely. In the absence of such direct comparisons, claims for the established superiority of any one specific diet over others are exaggerated. The weight of evidence strongly supports a theme of healthful eating while allowing for variations on that theme. A diet of minimally processed foods close to nature, predominantly plants, is decisively associated with health promotion and disease prevention and is consistent with the salient components of seemingly distinct dietary approaches. Efforts to improve public health through diet are forestalled not for want of knowledge about the optimal feeding of Homo sapiens but for distractions associated with exaggerated claims, and our failure to convert what we reliably know into what we routinely do. Knowledge in this case is not, as of yet, power; would that it were so.

Inverse association between the frequency of nut consumption and obesity among Iranian population: Isfahan Healthy Heart Program

PURPOSE

Recently, controversies have arisen concerning the association between nut intake and obesity. This study was performed to investigate the relationship between nut consumption and obesity among Iranian adults.

METHODS

In a cross-sectional survey, 9,660 randomly chosen adults aged ≥19 years were selected based on gender, age and their settlement distributions in three districts of central Iran in 2007. Nutritional behaviors including regular intake of walnuts, almonds, pistachios, hazelnuts and sunflower seed were assessed by validated 48-item-food-frequency questionnaire and a 24-h recall questionnaire. Using hierarchical logistic regression test, odds ratio (OR) 95% CI of obesity based on nut consumption was determined in an unadjusted and four adjusted models.

RESULTS

The results showed a significant association between high nut consumption and lower prevalence of overweight or general obesity as well as abdominal obesity in women (p = 0.01 and p = 0.047, respectively), but not men. The frequency of nut consumption was associated with lower risk of overweight or general obesity [OR (95% CI) 0.57 (0.38-0.86)] and abdominal obesity [OR (95% CI) 0.51 (0.28-0.95)] only in women. After adjusting for gender, age and other potential confounders, the strength of the associations was blunted, but they were still significant.

CONCLUSIONS

Frequent nuts and seeds consumption, particularly ≥1 time/day, had an inverse association with all classes of obesity among women.

Cancer chemoprevention with nuts

It is well established that increased nut consumption is associated with a reduced risk of major chronic diseases, such as cardiovascular disease and type 2 diabetes mellitus. On the other hand, the association between nut consumption and cancer mortality is less clear. Recent studies have suggested that nut consumption is associated with reduced cancer mortality. This evidence reinforces the interest to investigate the chemopreventive properties of nuts, and it raises questions about the specific cancer type(s) and setting that can be more affected by nut consumption, as well as the cellular mechanisms involved in this protective effect. Here we discuss recent studies on the association of nut consumption and cancer, and we propose specific cellular mechanisms by which nut components can affect cancer progression.

Communicating clinical research to reduce cancer risk through diet: Walnuts as a case example

Inflammation is one mechanism through which cancer is initiated and progresses, and is implicated in the etiology of other conditions that affect cancer risk and prognosis, such as type 2 diabetes, cardiovascular disease, and visceral obesity. Emerging human evidence, primarily epidemiological, suggests that walnuts impact risk of these chronic diseases via inflammation. The published literature documents associations between walnut consumption and reduced risk of cancer, and mortality from cancer, diabetes, and cardiovascular disease, particularly within the context of the Mediterranean Diet. While encouraging, follow-up in human intervention trials is needed to better elucidate any potential cancer prevention effect of walnuts, per se. In humans, the far-reaching positive effects of a plant-based diet that includes walnuts may be the most critical message for the public. Indeed, appropriate translation of nutrition research is essential for facilitating healthful consumer dietary behavior. This paper will explore the translation and application of human evidence regarding connections with cancer and biomarkers of inflammation to the development of dietary guidance for the public and individualized dietary advice. Strategies for encouraging dietary patterns that may reduce cancer risk will be explored.

Effect of tree nuts on metabolic syndrome criteria: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To provide a broader evidence summary to inform dietary guidelines of the effect of tree nuts on criteria of the metabolic syndrome (MetS).

DESIGN

We conducted a systematic review and meta-analysis of the effect of tree nuts on criteria of the MetS.

DATA SOURCES

We searched MEDLINE, EMBASE, CINAHL and the Cochrane Library (through 4 April 2014).

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

We included relevant randomised controlled trials (RCTs) of ≥3 weeks reporting at least one criterion of the MetS.

DATA EXTRACTION

Two or more independent reviewers extracted all relevant data. Data were pooled using the generic inverse variance method using random effects models and expressed as mean differences (MD) with 95% CIs. Heterogeneity was assessed by the Cochran Q statistic and quantified by the I(2) statistic. Study quality and risk of bias were assessed.

RESULTS

Eligibility criteria were met by 49 RCTs including 2226 participants who were otherwise healthy or had dyslipidaemia, MetS or type 2 diabetes mellitus. Tree nut interventions lowered triglycerides (MD=-0.06 mmol/L (95% CI -0.09 to -0.03 mmol/L)) and fasting blood glucose (MD=-0.08 mmol/L (95% CI -0.16 to -0.01 mmol/L)) compared with control diet interventions. There was no effect on waist circumference, high-density lipoprotein cholesterol or blood pressure with the direction of effect favouring tree nuts for waist circumference. There was evidence of significant unexplained heterogeneity in all analyses (p<0.05).

CONCLUSIONS

Pooled analyses show a MetS benefit of tree nuts through modest decreases in triglycerides and fasting blood glucose with no adverse effects on other criteria across nut types. As our conclusions are limited by the short duration and poor quality of the majority of trials, as well as significant unexplained between-study heterogeneity, there remains a need for larger, longer, high-quality trials.

TRIAL REGISTRATION NUMBER

NCT01630980.

Nuts in the prevention and treatment of metabolic syndrome

Nuts are rich in many bioactive compounds that can exert beneficial effects on cardiovascular health. We reviewed the evidence relating nut consumption and the metabolic syndrome (MetS) and its components. Nuts reduce the postprandial glycemic response; however, long-term trials of nuts on insulin resistance and glycemic control in diabetic individuals are inconsistent. Epidemiologic studies have shown that nuts may lower the risk of diabetes incidence in women. Few studies have assessed the association between nuts and abdominal obesity, although an inverse association with body mass index and general obesity has been observed. Limited evidence suggests that nuts have a protective effect on blood pressure and endothelial function. Nuts have a cholesterol-lowering effect, but the relation between nuts and hypertriglyceridemia and high-density lipoprotein cholesterol is not well established. A recent pooled analysis of clinical trials showed that nuts are inversely related to triglyceride concentrations only in subjects with hypertriglyceridemia. An inverse association was found between the frequency of nut consumption and the prevalence and the incidence of MetS. Several trials evaluated the effect of nuts on subjects with MetS and found that they may have benefits in some components. Compared with a low-fat diet, a Mediterranean diet enriched with nuts could be beneficial for MetS management. The protective effects on metabolism could be explained by the modulation of inflammation and oxidation. Further trials are needed to clarify the role of nuts in MetS prevention and treatment.

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

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.

Clinical Trial Registration

URL: www.clinicaltrials.gov. Unique identifier: NCT00956735.

Nut consumption for vascular health and cognitive function

Nuts are rich in many nutrients that can benefit multiple cardiometabolic functions, including arterial compliance, blood pressure, inflammation, glucoregulation and endothelial vasodilatation. Impaired vasodilatation may contribute to impaired cognitive performance due to poor cerebral perfusion. The present narrative review examines associations between nut consumption, vascular health and cognitive function. It includes a systematic search which identified seventy-one epidemiological or intervention studies in which effects of chronic nut consumption on blood pressure, glucoregulation, endothelial vasodilator function, arterial compliance, inflammatory biomarkers and cognitive performance were evaluated. Weighted mean changes were estimated where data were available; they indicate that nut consumption reduces blood pressure and improves glucoregulation, endothelial vasodilator function and inflammation, whilst a limited number of studies suggest that nut consumption may also improve cognitive performance. Further clinical trials are warranted to explore relationships between nut consumption, endothelial function and cognitive function.

Nutrition and health during mid-life: searching for solutions and meeting challenges for the aging population

Interactions between genetic (genome) and environmental factors (epigenome) operate during a person's entire lifespan. The aging process is associated with several cellular and organic functional alterations that, at the end, cause multi-organic cell failure. Epigenetic mechanisms of aging are modifiable by appropriate preventive actions mediated by sirtuins, caloric input, diet components, adipose tissue-related inflammatory reactions, and physical activity. The Mediterranean lifestyle has been for many millennia a daily habit for people in Western civilizations living around the Mediterranean sea who worked intensively and survived with very few seasonal foods. A high adherence to the traditional Mediterranean diet is associated with low mortality (higher longevity) and reduced risk of developing chronic diseases, including cancer, the metabolic syndrome, depression and cardiovascular and neurodegenerative diseases. Reports indicate that some dietary components, such as olive oil, antioxidants, omega-3 and -6 polyunsaturated acids, polyphenols and flavonoids, mediate beneficial anti-aging effects (anti-chronic diseases and increased longevity). Equally, physical activity displays a positive effect, producing caloric consumption and regulation of adipose and pancreatic function. The predictive strength of some food patterns may be a way of developing recommendations for food and health policies. This paper will discuss several ways of improving health during mid-life, focusing on certain groups of functional foods and healthy habits which may reduce or prevent age-related chronic diseases.

Tree nuts are inversely associated with metabolic syndrome and obesity: the Adventist health study-2

OBJECTIVE

To examine the relationships of nut consumption, metabolic syndrome (MetS), and obesity in the Adventist Health Study-2, a relatively healthy population with a wide range of nut intake.

RESEARCH DESIGN AND METHODS

Cross-sectional analysis was conducted on clinical, dietary, anthropometric, and demographic data of 803 adults. MetS was defined according to the American Heart Association and the National Heart, Lung, and Blood Institute diagnostic criteria. We assessed intake of total nuts, tree nuts and peanuts, and also classified subjects into low tree nut/low peanut (LT/LP), low tree/high peanut (LT/HP), high tree nut/high peanut (HT/HP), and high tree/low peanut (HT/LP) consumers. Odds ratios were estimated using multivariable logistic regression.

RESULTS

32% of subjects had MetS. Compared to LT/LP consumers, obesity was lower in LT/HP (OR = 0.89; 95% CI = 0.53, 1.48), HT/HP (OR = 0.63; 95% CI = 0.40, 0.99) and HT/LP (OR = 0.54; 95% CI = 0.34, 0.88) consumers, p for trend = 0.006. For MetS, odds ratios (95% CI) were 0.77 (0.47, 1.28), 0.65 (0.42, 1.00) and 0.68 (0.43, 1.07), respectively (p for trend = 0.056). Frequency of nut intake (once/week) had significant inverse associations with MetS (3% less for tree nuts and 2% less for total nuts) and obesity (7% less for tree nuts and 3% less for total nuts).

CONCLUSIONS

Tree nuts appear to have strong inverse association with obesity, and favorable though weaker association with MetS independent of demographic, lifestyle and dietary factors.