Other relevant components of nuts: phytosterols, folate and minerals

Nut consumption and age-related disease

Current knowledge on the effects of nut consumption on human health has rapidly increased in recent years and it now appears that nuts may play a role in the prevention of chronic age-related diseases. Frequent nut consumption has been associated with better metabolic status, decreased body weight as well as lower body weight gain over time and thus reduce the risk of obesity. The effect of nuts on glucose metabolism, blood lipids, and blood pressure is still controversial. However, significant decreased cardiovascular risk has been reported in a number of observational and clinical intervention studies. Thus, findings from cohort studies show that increased nut consumption is associated with a reduced risk of cardiovascular disease and mortality (especially that due to cardiovascular-related causes). Similarly, nut consumption has been also associated with reduced risk of certain cancers, such as colorectal, endometrial, and pancreatic neoplasms. Evidence regarding nut consumption and neurological or psychiatric disorders is scarce, but a number of studies suggest significant protective effects against depression, mild cognitive disorders and Alzheimer's disease. The underlying mechanisms appear to include antioxidant and anti-inflammatory actions, particularly related to their mono- and polyunsaturated fatty acids (MUFA and PUFA, as well as vitamin and polyphenol content). MUFA have been demonstrated to improve pancreatic beta-cell function and regulation of postprandial glycemia and insulin sensitivity. PUFA may act on the central nervous system protecting neuronal and cell-signaling function and maintenance. The fiber and mineral content of nuts may also confer health benefits. Nuts therefore show promise as useful adjuvants to prevent, delay or ameliorate a number of chronic conditions in older people. Their association with decreased mortality suggests a potential in reducing disease burden, including cardiovascular disease, cancer, and cognitive impairments.

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.

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.

Dietary intakes of fats, fish and nuts and olfactory impairment in older adults

It is unclear whether lifestyle modifications, such as dietary changes, should be advocated to prevent olfactory dysfunction. We investigated the association between dietary intakes of fats (saturated, mono-unsaturated and polyunsaturated fats, and cholesterol) and related food groups (nuts, fish, butter, margarine) with olfactory impairment. There were 1331 and 667 participants (older than 60 years) at baseline and 5-year follow-up, respectively, with complete olfaction and dietary data. Dietary data were collected using a validated semi-quantitative FFQ. Olfaction was measured using the San Diego Odor Identification Test. In a cross-sectional analysis of baseline data, those in the highest v. lowest quartile of n-6 PUFA intake had reduced odds of having any olfactory impairment, multivariable-adjusted OR 0.66 (95% CI 0.44, 0.97), P for trend = 0.06. Participants in the highest v. lowest quartile of margarine consumption had a 65% reduced odds of having moderate/severe olfactory impairment (P for trend = 0.02). Participants in the highest quartile compared to the lowest quartile (reference) of nut consumption had a 46% (P for trend = 0.01) and 58% (P for trend = 0.001) reduced odds of having any or mild olfactory impairment, respectively. Older adults in the highest v. lowest quartile of fish consumption had 35% (P for trend = 0.03) and 50% (P for trend = 0.01) reduced likelihood of having any or mild olfactory impairment, respectively. In longitudinal analyses, a marginally significant association was observed between nut consumption and incidence of any olfactory impairment, highest v. lowest quartile of nut consumption: OR 0.61 (95% CI 0.37, 1.00). Older adults with the highest consumption of nuts and fish had reduced odds of olfactory impairment, independent of potential confounding variables.

Nut consumption on all-cause, cardiovascular, and cancer mortality risk: a systematic review and meta-analysis of epidemiologic studies

BACKGROUND

Recent pooled analyses supported a beneficial impact of nut consumption on health, but to our knowledge, whether nuts are associated with overall decreased mortality has not been previously reviewed.

OBJECTIVES

We aimed to systematically review prospective studies that explored the effects of nut consumption on all-cause, cardiovascular disease (CVD), and cancer mortality and quantify the size effect through a meta-analysis. We also reviewed confounding factors associated with nut consumption to assess potential clustering with other covariates.

DESIGN

We searched PubMed and EMBASE for studies published up to June 2014. Study characteristics, HRs, and 95% CIs were generated on the basis of quantitative analyses. A dose-response analysis was performed when data were available.

RESULTS

Seven studies for all-cause mortality, 6 studies for CVD mortality, and 2 studies for cancer mortality were included in the meta-analysis with a total of 354,933 participants, 44,636 cumulative incident deaths, and 3,746,534 cumulative person-years. Nut consumption was associated with some baseline characteristics such as lower body mass index and smoking status as well as increased intakes of fruit, vegetables, and alcohol. One-serving of nuts per week and per day resulted in 4% (RR: 0.96; 95% CI: 0.93, 0.98) and 27% (RR: 0.73; 95% CI: 0.60, 0.88) decreased risk of all-cause mortality, respectively, and decreased risk of CVD mortality [RR: 0.93 (95% CI: 0.88, 0.99) and 0.61 (95% CI: 0.42, 0.91), respectively]. Effects were primarily driven by decreased coronary artery disease deaths rather than stroke deaths. Nut consumption was also associated with decreased risk of cancer deaths when highest compared with lowest categories of intake were compared (RR: 0.86; 95% CI: 0.75, 0.98), but no dose-effect was shown.

CONCLUSION

Nut consumption is associated with lower risk of all-cause, CVD, and cancer mortality, but the presence of confounding factors should be taken into account when considering such findings.

Nut consumption has favorable effects on lipid profiles of Korean women with metabolic syndrome

Nut consumption has been studied for its cardioprotective effects. However, the findings of clinical intervention studies are inconsistent; and no intervention studies have been conducted in the Korean population. We hypothesized that nut supplementation may have favorable influence on metabolic markers. Therefore, this study aimed to investigate the effects of nut consumption on metabolic parameters and biomarkers related to inflammation, oxidative stress, and endothelial function in Korean adults with metabolic syndrome. To this end, we designed a randomized, parallel, controlled dietary intervention study (ClinicalTrials.gov NCT02023749). Subjects with metabolic syndrome and a body mass index of at least 23 kg/m(2) were randomized to the Control group and the Nut group, which received supplementation with 30 g/d of mixed nuts (walnuts, peanuts, and pine nuts) for 6 weeks. Sixty volunteers were included in the final analysis. Metabolic markers were evaluated at baseline and at the end of the study. Total cholesterol and non-high-density lipoprotein cholesterol levels significantly improved in the Nut group compared to those in the Control group (P = .023 and P = .016, respectively) in women. Biomarkers related to inflammation, oxidative stress, and endothelial function did not significantly change from baseline in either group. Thus, supplementing a usual diet with mixed nuts for 6 weeks had favorable effects on several lipid parameters in Korean women with metabolic syndrome. These findings present a possible mechanism for the cardioprotective effects of nut consumption.

Effect of tree nuts on glycemic control in diabetes: a systematic review and meta-analysis of randomized controlled dietary trials

Background

Tree nut consumption has been associated with reduced diabetes risk, however, results from randomized trials on glycemic control have been inconsistent.

Objective

To provide better evidence for diabetes guidelines development, we conducted a systematic review and meta-analysis of randomized controlled trials to assess the effects of tree nuts on markers of glycemic control in individuals with diabetes.

Data Sources

MEDLINE, EMBASE, CINAHL, and Cochrane databases through 6 April 2014.

Study Selection

Randomized controlled trials ≥3 weeks conducted in individuals with diabetes that compare the effect of diets emphasizing tree nuts to isocaloric diets without tree nuts on HbA1c, fasting glucose, fasting insulin, and HOMA-IR.

Data Extraction and Synthesis

Two independent reviewer’s extracted relevant data and assessed study quality and risk of bias. Data were pooled by the generic inverse variance method and expressed as mean differences (MD) with 95% CI’s. Heterogeneity was assessed (Cochran Q-statistic) and quantified (I²).

Results

Twelve trials (n = 450) were included. Diets emphasizing tree nuts at a median dose of 56 g/d significantly lowered HbA1c (MD = −0.07% [95% CI:−0.10, −0.03%]; P = 0.0003) and fasting glucose (MD = −0.15 mmol/L [95% CI: −0.27, −0.02 mmol/L]; P = 0.03) compared with control diets. No significant treatment effects were observed for fasting insulin and HOMA-IR, however the direction of effect favoured tree nuts.

Limitations

Majority of trials were of short duration and poor quality.

Conclusions

Pooled analyses show that tree nuts improve glycemic control in individuals with type 2 diabetes, supporting their inclusion in a healthy diet. Owing to the uncertainties in our analyses there is a need for longer, higher quality trials with a focus on using nuts to displace high-glycemic index carbohydrates.

Trial Registration

ClinicalTrials.gov NCT01630980

A review of the effects of nuts on appetite, food intake, metabolism, and body weight

Tree nuts and peanuts are good sources of many nutrients and antioxidants, but they are also energy dense. The latter often limits intake because of concerns about their possible contribution to positive energy balance. However, evidence to date suggests that nuts are not associated with predicted weight gain. This is largely due to their high satiety value, leading to strong compensatory dietary responses, inefficiency in absorption of the energy they contain, a possible increment in resting energy expenditure, and an augmentation of fat oxidation. Preliminary evidence suggests that these properties are especially evident when they are consumed as snacks.

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

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.

Novel multimetabolite prediction of walnut consumption by a urinary biomarker model in a free-living population: the PREDIMED study

The beneficial impact of walnuts on human health has been attributed to their unique chemical composition. In order to characterize the dietary walnut fingerprinting, spot urine samples from two sets of 195 (training) and 186 (validation) individuals were analyzed by an HPLC-q-ToF-MS untargeted metabolomics approach, selecting the most discriminating metabolites by multivariate data analysis (VIP ≥ 1.5). Stepwise logistic regression analysis was used to design a multimetabolite prediction biomarker model. The global performance of the model and each included metabolite in it was evaluated by receiver operating characteristic curves, using the area under the curve (AUC) values. Dietary exposure to walnuts was characterized by 18 metabolites, including markers of fatty acid metabolism, ellagitannin-derived microbial compounds, and intermediate metabolites of the tryptophan/serotonin pathway. The predictive model of walnut exposure included at least one compound of each class. The AUC (95% CI) for the combined biomarker model was 93.4% (90.1-96.8%) in the training set and 90.2% (85.9-94.6%) in the validation set. The AUCs for individual metabolites were ≤85%. As far as we know, this is the first study proposing a combination of biomarkers of walnut exposure in a population under free-living conditions, as considered in epidemiological studies examining associations between diet and health outcomes.

Functional foods-based diet as a novel dietary approach for management of type 2 diabetes and its complications: A review

Type 2 diabetes is a complicated metabolic disorder with both short- and long-term undesirable complications. In recent years, there has been growing evidence that functional foods and their bioactive compounds, due to their biological properties, may be used as complementary treatment for type 2 diabetes mellitus. In this review, we have highlighted various functional foods as missing part of medical nutrition therapy in diabetic patients. Several in vitro, animal models and some human studies, have demonstrated that functional foods and nutraceuticals may improve postprandial hyperglycemia and adipose tissue metabolism modulate carbohydrate and lipid metabolism. Functional foods may also improve dyslipidemia and insulin resistance, and attenuate oxidative stress and inflammatory processes and subsequently could prevent the development of long-term diabetes complications including cardiovascular disease, neuropathy, nephropathy and retinopathy. In conclusion available data indicate that a functional foods-based diet may be a novel and comprehensive dietary approach for management of type 2 diabetes.

Analysis of pecan nut (Carya illinoinensis) unsaponifiable fraction. Effect of ripening stage on phytosterols and phytostanols composition

Changes in 4-desmethylsterol, 4-monomethylsterol, 4,4-dimethylsterol and phytostanol composition were quantitatively and qualitatively investigated during the ripening of three varieties of Tunisian-grown pecan nuts (Mahan, Moore and Burkett). These components have many health benefits, especially in lowering LDL-cholesterol and preventing heart disease. The phytosterol composition of whole pecan kernel was quantified by Gas Chromatography-Flame Ionisation Detection (GC-FID) and identified by Gas Chromatography-Mass Spectrometry (GC-MS). Fifteen phytosterols and one phytostanol were quantified. The greatest amount of phytosterols (2852.5mg/100g of oil) was detected in Mahan variety at 20 weeks after the flowering date (WAFD). Moore had the highest level of phytostanols (7.3mg/100g of oil) at 20 WAFD. Phytosterol and phytostanol contents showed a steep decrease during pecan nut development. Results from the quantitative characterisation of pecan nut oils revealed that β-sitosterol, Δ5-avenasterol, and campesterol were the most abundant phytosterol compounds at all ripening stages.

Carbon-carbon double-bond reductases in nature

Reduction of C = C bonds by reductases, found in a variety of microorganisms (e.g. yeasts, bacteria, and lower fungi), animals, and plants has applications in the production of metabolites that include pharmacologically active drugs and other chemicals. Therefore, the reductase enzymes that mediate this transformation have become important therapeutic targets and biotechnological tools. These reductases are broad-spectrum, in that, they can act on isolation/conjugation C = C-bond compounds, α,β-unsaturated carbonyl compounds, carboxylic acids, acid derivatives, and nitro compounds. In addition, several mutations in the reductase gene have been identified, some associated with diseases. Several of these reductases have been cloned and/or purified, and studies to further characterize them and determine their structure in order to identify potential industrial biocatalysts are still in progress. In this study, crucial reductases for bioreduction of C = C bonds have been reviewed with emphasis on their principal substrates and effective inhibitors, their distribution, genetic polymorphisms, and implications in human disease and treatment.

Direct analysis of sterols by derivatization matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and tandem mass spectrometry

RATIONALE

Free sterols are neutral molecules that are difficult to analyze by MALDI or ESI and their molecular ions easily fragment. In order to increase their ionization efficiency and selectivity, sterols were derivatized by different reagents.

METHODS

Selected sterols were converted into their corresponding picolinyl esters, N-methylpyridyl ethers and sulphated esters. The derivatives were optimized for MALDI-TOFMS analysis through proper selection of the matrix. MALDI-TOF/TOF experiments were carried out to study the fragmentation pathways of the derivatives and their use in structural elucidation. Lipid extracts from mussels were used as test samples for MALDI analysis of sterols in biological samples also analyzed by GC/MS for comparison.

RESULTS

Sterol picolinyl esters were identified as sodiated adducts [M+Na](+) and the signal significantly enhanced after addition of sodium acetate (20 mM). Sterol N-methylpyridyl ethers were easily detected as [M](+) while sulphated sterols were best detected as [M-H](-). The ester bonds of picolinyl and sulphated esters easily cleaved in MS/MS resulting in diagnostic derivative fragments at m/z 146.03 and 96.89, respectively. Cleavage of the ether bond of N-methylpyridyl ethers gave a diagnostic fragment ion at m/z 110.04. Sterol profiles in mussels obtained by MALDI-TOFMS were in close agreement with those obtained by GC/MS. Two sterols (cholesterol and β-sitosterol) were selected for quantification as their sulphated and picolinyl esters. Calibration curves gave excellent correlation coefficients.

CONCLUSIONS

Suitable matrices for picolinyl esters are DHB and THAP, for N-methylpyridyl ethers THAP, and for sulphated esters p-nitroaniline and dithranol. Using cholesterol, the limits of detection (LODs) for sulphated esters were 0.2 µg/mL and for picolinyl esters, 1.5 µg/mL. N-Methylpyridyl ethers were found unsuitable for sterol quantitation.

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

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.Please see related commentary: http://www.biomedcentral.com/1741-7015/11/165.

TRIAL REGISTRATION

Clinicaltrials.gov. International Standard Randomized Controlled Trial Number (ISRCTN): 35739639. Registration date: 5 October 2005.

Bioaccessibility of Cd, Cu, Fe, Mn, Pb, and Zn in hazelnut and walnut kernels investigated by an enzymolysis approach

Bioaccessibility of four essential (Fe, Cu, Mn, Zn) and two toxic (Cd, Pb) elements in kernels of four walnut and four hazelnut cultivars was investigated using sequential enzymolysis approach and atomic absorption spectrometry. It was found that the assimilable part of elements was not dependent on nut cultivar. The bioaccessible fraction of Cu, Mn, and Zn was definitely higher for hazelnuts (62% Cu, 39% Mn, 58% Zn) than for walnuts (14% Cu, 21% Mn, 15% Zn). Bioaccessible Fe was 20-24% from its total content for both nut types. Solubility in the simulated intestinal juice is affected by both formation of stable soluble complexes and back sorption of dissolved elements on nut solid residues. Lead shows strong insolubility due to the high sorption affinity of lead ions to the insoluble fraction of nuts. Thus, walnuts and hazelnuts could act as effective biosorbents for lead detoxication.

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

Introduction

Prospective studies have consistently suggested that nut consumption is inversely related to fatal and non-fatal 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.

The relationship between nut consumption and lipid profile among the Iranian adult population; Isfahan Healthy Heart Program

BACKGROUND/OBJECTIVE

The study was carried out to assess the relationship between nut consumption and lipid profile among Iranian adults.

SUBJECT/METHODS

The study was based on data from the Isfahan Healthy Heart Program across three counties in central Iran in 2007. A cross-sectional survey of 9660 randomly selected adults aged ≥ 19 years were chosen based on sex, age and settlement distributions in each community. Nutritional behaviors were assessed by validated qualitative 48-item food frequency questionnaires, which covered regular intakes of four types of nuts: walnuts, almonds, pistachios and hazelnuts. Analysis of covariance and logistic regression tests were utilized to determine odds ratio (OR) 95% confidence interval of hyperlipidemia according to nut consumption patterns in unadjusted and three-adjusted models.

RESULTS

The results showed a significant link between high nut consumption and lower total cholesterol, triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) levels and apo B/apo A ratio (P<0.05) in female subjects and lower TG, LDL-C and apoB/apoA ratio in male subjects (P<0.05). The frequency of nut consumption was inversely associated with dyslipidemia, especially for those who had consumed nuts ≥ 4 times weekly (0.67 (0.57-0.79)). After adjusting for sex, age and other potential confounders, ORs increased enormously. Except for low apo A and high LDL-C, more frequent nut consumption (4 ≤ times per week) had a significant inverse effect on other dyslipidemia risk factors in all four models.

CONCLUSIONS

We concluded that frequent consumption of nuts, particularly ≥ 4 times a week, may result in lower dyslipidemia occurrences and may exert cardioprotective effects.

Nutrition and the healthy heart with an exercise boost

In this era of potent medications and major cardiovascular (CV) procedures, the value of nutrition can be forgotten. A healthy diet is essential, regardless of CV risk. Caloric balance is inherent to a good diet. Despite patients who say they eat little, ideal weight can be maintained if calories are burned. Composition is another component of a healthy diet. The Dietary Approaches to Stop Hypertension (DASH) and Mediterranean diets provide proof of CV benefit from their specific content. Metabolic syndrome (MS) is associated with poor diet and obesity. A healthy diet with good nutrition benefits the MS patient and associated conditions such as obesity and diabetes. Exercise, in conjunction with a healthy diet and good nutrition, helps maintain optimal weight and provides CV benefit such as decreased inflammation and increased vasodilatation. Whether vitamins or other nutritional supplements are important in a healthy diet is unproven. Nevertheless, the most promising data of added benefit to a healthy diet is with vitamin D. Some dietary supplements also have promise. Alcohol, in moderation, especially red wine, has nutritional and heart protective benefits. Antioxidants, endogenous or exogenous, have received increased interest and appear to play a favorable nutritional role. CV health starts with good nutrition.

Health benefits of almonds beyond cholesterol reduction

Almonds are rich in monounsaturated fat, fiber, α-tocopherol, minerals such as magnesium and copper, and phytonutrients, albeit being energy-dense. The favorable fat composition and fiber contribute to the hypocholesterolemic benefit of almond consumption. By virtue of their unique nutrient composition, almonds are likely to benefit other modifiable cardiovascular and diabetes risks, such as body weight, glucose homeostasis, inflammation, and oxidative stress. This paper briefly reviews the nutrient composition and hypocholesterolemic benefits; the effects of almond consumption on body weight, glucose regulation, oxidative stress, and inflammation, based on the data of clinical trials, will then be discussed. Although more studies are definitely warranted, the emerging evidence supports that almond consumption beneficially influences chronic degenerative disease risk beyond cholesterol reduction, particularly in populations with metabolic syndrome and type 2 diabetes mellitus.

Pistachio nuts: composition and potential health benefits

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.

Tree nut phytochemicals: composition, antioxidant capacity, bioactivity, impact factors. A systematic review of almonds, Brazils, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts

Tree nuts contain an array of phytochemicals including carotenoids, phenolic acids, phytosterols and polyphenolic compounds such as flavonoids, proanthocyanidins (PAC) and stilbenes, all of which are included in nutrient databases, as well as phytates, sphingolipids, alkylphenols and lignans, which are not. The phytochemical content of tree nuts can vary considerably by nut type, genotype, pre- and post-harvest conditions, as well as storage conditions. Genotype affects phenolic acids, flavonoids, stilbenes and phytosterols, but data are lacking for many other phytochemical classes. During the roasting process, tree nut isoflavones, flavanols and flavonols were found to be more resistant to heat than the anthocyanins, PAC and trans-resveratrol. The choice of solvents used for extracting polyphenols and phytosterols significantly affects their quantification, and studies validating these methods for tree nut phytochemicals are lacking. The phytochemicals found in tree nuts have been associated with antioxidant, anti-inflammatory, anti-proliferative, antiviral, chemopreventive and hypocholesterolaemic actions, all of which are known to affect the initiation and progression of several pathogenic processes. While tree nut phytochemicals are bioaccessible and bioavailable in humans, the number of intervention trials conducted to date is limited. The objectives of the present review are to summarise tree nut: (1) phytochemicals; (2) phytochemical content included in nutrient databases and current publications; (3) phytochemicals affected by pre- and post-harvest conditions and analytical methodology; and (4) bioactivity and health benefits in humans.

Nuts improve diet quality compared to other energy-dense snacks while maintaining body weight

Previous studies have reported that regular nut consumption reduces cardiovascular disease (CVD) risk and does not promote weight gain despite the fact that nuts are energy-dense. However, no studies have investigated the body composition of those regularly consuming nuts compared to similar intakes of other snacks of equal energy density. This parallel study (n = 118) examined the effects of providing daily portions (~1100 kJ/d) of hazelnuts, chocolate, or potato crisps compared to a control group receiving no snacks for twelve weeks. Effects on body weight and composition, blood lipids and lipoproteins, resting metabolic rate (RMR), appetite indices, and dietary quality were compared. At week 12, there was no significant difference in any of the outcome measurements between the groups except for dietary quality, which improved significantly in the nut group. Nuts can be incorporated into the diet without adversely affecting body weight and can improve diet quality.

Polymeric proanthocyanidins from Sicilian pistachio (Pistacia vera L.) nut extract inhibit lipopolysaccharide-induced inflammatory response in RAW 264.7 cells

BACKGROUND

Positive effects of pistachio nut consumption on plasma inflammatory biomarkers have been described; however, little is known about molecular events associated with these effects.

PURPOSE

We studied the anti-inflammatory activity of a hydrophilic extract from Sicilian Pistacia L. (HPE) in a macrophage model and investigated bioactive components relevant to the observed effects.

METHODS

HPE oligomer/polymer proanthocyanidin fractions were isolated by adsorbance chromatography, and components quantified as anthocyanidins after acidic hydrolysis. Isoflavones were measured by gradient elution HPLC analysis. RAW 264.7 murine macrophages were pre-incubated with either HPE (1- to 20-mg fresh nut equivalents) or its isolated components for 1 h, then washed before stimulating with lipopolysaccharide (LPS) for 24 h. Cell viability and parameters associated with Nuclear Factor-κB (NF-κB) activation were assayed according to established methods including ELISA, Western blot, or cytofluorimetric analysis.

RESULTS

HPE suppressed nitric oxide (NO) and tumor necrosis factor-α (TNF-α) production and inducible NO-synthase levels dose dependently, whereas inhibited prostaglandin E2 (PGE2) release and decreased cyclo-oxygenase-2 content, the lower the HPE amount the higher the effect. Cytotoxic effects were not observed. HPE also caused a dose-dependent decrease in intracellular reactive oxygen species and interfered with the NF-κB activation. Polymeric proanthocyanidins, but not isoflavones, at a concentration comparable with their content in HPE, inhibited NO, PGE2, and TNF-α formation, as well as activation of IκB-α. Oligomeric proanthocyanidins showed only minor effects.

CONCLUSIONS

Our results provide molecular evidence of anti-inflammatory activity of pistachio nut and indicate polymeric proanthocyanidins as the bioactive components. The mechanism may involve the redox-sensitive transcription factor NF-κB. Potential effects associated with pistachio nut consumption are discussed in terms of the proanthocyanidin bioavailability.

Cross-sectional association of nut intake with adiposity in a Mediterranean population

BACKGROUND AND AIMS

Nut intake has been inversely related to body mass index (BMI) in prospective studies. We examined dietary determinants of adiposity in an elderly Mediterranean population with customarily high nut consumption.

METHODS AND RESULTS

A cross-sectional study was conducted in 847 subjects (56% women, mean age 67 years, BMI 29.7kg/m(2)) at high cardiovascular risk recruited into the PREDIMED study. Food consumption was evaluated by a validated semi-quantitative questionnaire, energy expenditure in physical activity by the Minnesota Leisure Time Activity questionnaire, and anthropometric variables by standard measurements. Nut intake decreased across quintiles of both BMI and waist circumference (P-trend <0.005; both). Alcohol ingestion was inversely related to BMI (P-trend=0.020) and directly to waist (P-trend=0.011), while meat intake was directly associated with waist circumference (P-trend=0.018). In fully adjusted multivariable models, independent dietary associations of BMI were the intake of nuts inversely (P=0.002) and that of meat and meat products directly (P=0.042). For waist circumference, independent dietary associations were intake of nuts (P=0.002) and vegetables (P=0.040), both inversely, and intake of meat and meat products directly (P=0.009). From the regression coefficients, it was predicted that BMI and waist circumference decreased by 0.78kg/m(2) and 2.1cm, respectively, for each serving of 30g of nuts. Results were similar in men and women.

CONCLUSION

Nut consumption was inversely associated with adiposity independently of other lifestyle variables. It remains to be explored whether residual confounding related to a healthier lifestyle of nut eaters might in part explain these results.

Crossover study of diets enriched with virgin olive oil, walnuts or almonds. Effects on lipids and other cardiovascular risk markers

BACKGROUND AND AIMS

Virgin olive oil (VOO) and nuts are basic components of the Mediterranean diet, a heart-healthy dietary pattern. Nuts have well known cholesterol lowering effects, while evidence is unclear for VOO. We designed a study in hypercholesterolemic patients to assess the effects on serum lipids and other intermediate markers of cardiovascular risk of replacing 40% of the fat in the background diet with VOO, walnuts or almonds.

METHODS AND RESULTS

After a 4 week run-in period with a healthy diet, eligible candidates were randomized into three diet sequences in a crossover design, with a common background diet enriched with VOO, walnuts or almonds, lasting 4 weeks each. Outcomes were changes of serum lipids and oxidation and inflammation markers, measured by standard methods. Plasma fatty acids were determined by gas chromatography to assess compliance. In 18 participants completing the study (9 women, mean age 56 y, BMI 25.7 kg/m(2)), LDL-cholesterol was reduced from baseline by 7.3%, 10.8% and 13.4% after the VOO, walnut and almond diets, respectively (P = 0.001, Friedman test). Total cholesterol and LDL/HDL ratios decreased in parallel. LDL-cholesterol decreases were greater than predicted from dietary fatty acid and cholesterol exchanges among diets. No changes of other lipid fractions, oxidation analytes or inflammatory biomarkers were observed. Plasma fatty acid changes after each diet sequence supported good compliance.

CONCLUSION

The results confirm the cholesterol lowering properties of nut-enriched diets. They also suggest that phenolic-rich VOO has a cholesterol lowering effect independently of its fatty acid content, which clearly deserves further study.

Consumption of polyunsaturated fatty acids, fish, and nuts and risk of inflammatory disease mortality

BACKGROUND

n-3 (omega-3) Polyunsaturated fatty acids (PUFAs), fish, and nuts can regulate inflammatory processes and responses.

OBJECTIVE

We investigated whether dietary intakes of PUFAs [n-3, n-6 (omega-6), and α-linolenic acid], fish, and nuts were associated with 15-y mortality attributed to noncardiovascular, noncancer inflammatory diseases.

DESIGN

The analyses involved 2514 participants aged ≥49 y at baseline. Dietary data were collected by using a semiquantitative food-frequency questionnaire, and PUFA, fish, and nut intakes were calculated. Inflammatory disease mortality was confirmed from the Australian National Death Index.

RESULTS

Over 15 y, 214 subjects died of inflammatory diseases. Women in the highest tertiles of total n-3 PUFA intake, compared with those in the lowest tertile of intake at baseline, had a 44% reduced risk of inflammatory disease mortality (P for trend = 0.03). This association was not observed in men. In both men and women, each 1-SD increase in energy-adjusted intake of α-linolenic acid was inversely associated with inflammatory mortality (hazard ratio: 0.83; 95% CI: 0.71, 0.98). Subjects in the second and third tertiles of nut consumption had a 51% and 32% reduced risk of inflammatory disease mortality, respectively, compared with those in the first tertile (reference). Dietary intakes of long-chain n-3 and n-6 PUFAs and fish were not associated with inflammatory disease mortality.

CONCLUSIONS

We report on a novel link between dietary intake of total n-3 PUFA and risk of inflammatory disease mortality in older women. Furthermore, our data indicate a protective role of nuts, but not fish, against inflammatory disease mortality.

Nuts: anti-atherogenic food?

The prevalence of cardiovascular disease as the leading cause of morbidity and mortality is increasing worldwide. This fact is mainly attributed to the modern lifestyle with predominant characteristics the change of dietary habits and the reduced physical activity which lead to metabolic disorders such as obesity and diabetes. Therefore, drastic dietary interventions are considered necessary in order to reduce cardiovascular risk. Nuts, as a nutritional component have drawn particular attention, due to their beneficial cardiovascular properties derived from their nutrient composition. This is a comprehensive review concerning the potential general effects of nuts. It includes data from older large epidemiologic studies as well as recent significant information from clinical trials regarding this topic. All studies conclude that nuts can play an important role as part of a healthy diet in order to minimize cardiovascular risk and obtain multiple health benefits.

Nuts and berries for heart health

Nuts are nutrient-dense foods with complex matrices rich in unsaturated fatty acids and other bioactive compounds, such as L-arginine, fiber, minerals, tocopherols, phytosterols, and polyphenols. By virtue of their unique composition, nuts are likely to beneficially impact heart health. Epidemiologic studies have associated nut consumption with a reduced incidence of coronary heart disease in both genders and diabetes in women. Limited evidence also suggests beneficial effects on hypertension and inflammation. Interventional studies consistently show that nut intake has a cholesterol-lowering effect and there is emerging evidence of beneficial effects on oxidative stress, inflammation, and vascular reactivity. Blood pressure, visceral adiposity, and glycemic control also appear to be positively influenced by frequent nut consumption without evidence of undue weight gain. Berries are another plant food rich in bioactive phytochemicals, particularly flavonoids, for which there is increasing evidence of benefits on cardiometabolic risk that are linked to their potent antioxidant power.

Effects of one serving of mixed nuts on serum lipids, insulin resistance and inflammatory markers in patients with the metabolic syndrome

BACKGROUND AND AIMS

Knowledge of the effect of nut consumption on metabolic syndrome (MetS) components is limited. We assessed the effects of nut intake on adiposity, serum lipids, insulin resistance, and inflammatory biomarkers in patients with MetS.

METHODS AND RESULTS

In a randomized, parallel-group, 12-week feeding trial, 50 patients with MetS were given recommendations for a healthy diet with or without supplementation with 30 g/day of raw nuts (15 g walnuts, 7.5 g almonds and 7.5 g hazelnuts) (Nut and Control diet groups, respectively). Adiposity measures, serum lipids, insulin, Homeostasis Model Assessment (HOMA), interleukin-6 (IL-6) and other inflammatory biomarkers, and 48-h fecal fat were determined basally and at study's completion. Moderate weight loss, decreased adiposity, and lower blood pressure occurred similarly after both diets. The Control, but not the Nut diet, was associated with significant (P<0.05) reduction of LDL-cholesterol, with mean changes of -0.36 versus -0.13 mmol/L, respectively (between-group differences, P=0.154). The Nut diet reduced fasting insulin by 2.60 μU/mL (95% CI, -4.62 to -0.59) and HOMA-insulin resistance by 0.72 (-1.28 to -0.16) (P<0.05 versus Control diet; both). Among inflammatory markers, the Nut diet resulted in changes of median plasma IL-6 of -1.1 ng/L (-2.7 to -0.1; P=0.035 versus Control diet), but adjustment for weight loss attenuated the significance of the association. Stool fat decreased with the Control diet and slightly increased with the Nut diet (P<0.05 for between-group differences).

CONCLUSION

Patients with MetS show decreased lipid responsiveness but improved insulin sensitivity after daily intake of 30 g of mixed nuts.

Current guidelines for nut consumption are achievable and sustainable: a hazelnut intervention

Nuts are known for their hypocholesterolaemic properties; however, to achieve optimal health benefits, nuts must be consumed regularly and in sufficient quantity. It is therefore important to assess the acceptability of regular consumption of nuts. The present study examined the long-term effects of hazelnut consumption in three different forms on ‘desire to consume’ and ‘overall liking’. A total of forty-eight participants took part in this randomised cross-over study with three dietary phases of 4 weeks: 30 g/d of whole, sliced and ground hazelnuts. ‘Overall liking’ was measured in a three-stage design: a pre- and post-exposure tasting session and daily evaluation over the exposure period. ‘Desire to consume’ hazelnuts was measured during the exposure period only. Ratings were measured on a 150 mm visual analogue scale. Mean ratings of ‘desire to consume’ were 92 (sd 35) mm for ground, 108 (sd 33) mm for sliced and 116 (sd 30) mm for whole hazelnuts. For ‘overall liking’, the mean ratings were 101 (sd 29) mm for ground, 110 (sd 32) mm for sliced and 118 (sd 30) mm for whole hazelnuts. Ground hazelnuts had significantly lower ratings than both sliced (P ≤ 0·034) and whole hazelnuts (P < 0·001), with no difference in ratings between sliced and whole hazelnuts (P ≥ 0·125). For each form of nut, ratings of ‘overall liking’ and ‘desire to consume’ were stable over the exposure period, indicating that not only did the participants like the nuts, but also they wished to continue eating them. Therefore, the guideline to consume nuts on a regular basis appears to be a sustainable behaviour to reduce CVD.

What should medical practitioners know about the role of alternative medicines in cardiovascular disease management?

Alternative medications as a term call up many different meanings, significance, and perceptions to various medical practitioners. Some are good; others are bad. A wide range of alternative medications with relevance or connection to cardiovascular (CV) disease have been considered. While many are worthless, others have definite benefit, and at least one, chelation therapy, is associated with definite harm, significant risk, no benefit, and enrichment of the practitioners who prescribe it. The issues concerning alternative therapies will likely never be studied with randomized clinical trials due to the lack of a profit motive on the part of pharmaceutical companies--only rarely do other institutions, such as the National Institutes of Health, support medicinal studies. Basic knowledge of alternative therapies is essential for the CV specialist and other practicing physicians and other practitioners, since at least a few of their patients will take these medications regardless of medical advice. The result is that a number of these alternative medications will then interact with conventional CV medications, many times unfavorably.

Health benefits of nut consumption

Nuts (tree nuts and peanuts) are nutrient dense foods with complex matrices rich in unsaturated fatty and other bioactive compounds: high-quality vegetable protein, fiber, minerals, tocopherols, phytosterols, and phenolic compounds. By virtue of their unique composition, nuts are likely to beneficially impact health outcomes. Epidemiologic studies have associated nut consumption with a reduced incidence of coronary heart disease and gallstones in both genders and diabetes in women. Limited evidence also suggests beneficial effects on hypertension, cancer, and inflammation. Interventional studies consistently show that nut intake has a cholesterol-lowering effect, even in the context of healthy diets, and there is emerging evidence of beneficial effects on oxidative stress, inflammation, and vascular reactivity. Blood pressure, visceral adiposity and the metabolic syndrome also appear to be positively influenced by nut consumption. Thus it is clear that nuts have a beneficial impact on many cardiovascular risk factors. Contrary to expectations, epidemiologic studies and clinical trials suggest that regular nut consumption is unlikely to contribute to obesity and may even help in weight loss. Safety concerns are limited to the infrequent occurrence of nut allergy in children. In conclusion, nuts are nutrient rich foods with wide-ranging cardiovascular and metabolic benefits, which can be readily incorporated into healthy diets.

Health benefits of nut consumption

We investigated the effect of a mixture of long-chain fructo-oligosaccharides, galacto-oligosaccharides and acidic oligosaccharides on the number and consistency of stools and on immune system biomarkers in 104 supplemented and non-supplemented subjects (aged 9-24 months) with acute diarrhea. Interleukin-1 (IL-1), IL-1RA, IL-6, IL-8, IL-10, TNF-α and sIL-2R cytokine levels were determined. The significant decrease in number of stools and increase in stool consistency in the supplemented group was of little clinical relevance. The only significant change in pro- and anti-inflammatory cytokines was decreased TNF-α levels in the supplemented group. Prebiotic supplementation during acute diarrhea episodes did not influence the clinical course.

Nuts, metabolic syndrome and diabetes

The ability of nuts to improve the blood lipid profile and reduce the risk of CHD is now well established. The interest that health effects of nuts have gained recently has brought the possible benefits of consuming nuts, such as improvement in the conditions of the metabolic syndrome, and their potential to prevent and control diabetes into focus. Results from cohort studies have associated nut consumption with a reduced risk of developing diabetes and CVD. However, few randomised controlled trials have assessed the effect of nuts on diabetes control, and those that have been undertaken have shown improvements in blood lipids but not in the glycaemic control. Diabetes agencies are increasingly recognising the importance of controlling postprandial glycaemia fluctuations. Acute feeding studies indicate that nuts have minimal effects on rising postprandial blood glucose levels when eaten alone, and diminish the postprandial glycaemic response when consumed with high-glycaemic index carbohydrate foods in both normoglycaemic and type 2 diabetic individuals. Nuts have a healthy nutritional profile, high in MUFA and PUFA, are a good source of vegetable protein and are rich in fibre, vitamins and minerals. Incorporation of nuts in the diet may therefore improve the overall nutritional quality of the diet. While more research is required to establish the ability of nuts to improve glycaemic control in the long run, early data indicate that the inclusion of nuts in the diets of individuals with diabetes and the metabolic syndrome is warranted, in view of their potential to reduce CHD risk.

Prospective study of nut consumption, long-term weight change, and obesity risk in women

BACKGROUND

Data concerning the long-term association between nut consumption and weight change in a free-living population are sparse.

OBJECTIVE

The objective was to determine the relation between nut consumption and long-term weight change.

DESIGN

The participants were 51,188 women in the Nurses' Health Study II aged 20-45 y, who had no cardiovascular disease, diabetes, or cancer. We prospectively evaluated the dietary intake of nuts and subsequent weight changes from 1991 to 1999.

RESULTS

Women who reported eating nuts > or =2 times/wk had slightly less mean (+/- SE) weight gain (5.04 +/- 0.12 kg) than did women who rarely ate nuts (5.55 +/- 0.04 kg) (P for trend < 0.001). For the same comparison, when total nut consumption was subdivided into peanuts and tree nuts, the results were similar (ie, less weight gain in women eating either peanuts or tree nuts > or =2 times/wk). The results were similar in normal-weight, overweight, and obese participants. In multivariate analyses in which lifestyle and other dietary factors were controlled for, we found that greater nut consumption (> or =2 times/wk compared with never/almost never) was associated with a slightly lower risk of obesity (hazard ratio: 0.77; 95% CI: 0.57, 1.02; P for trend = 0.003).

CONCLUSIONS

Higher nut consumption was not associated with greater body weight gain during 8 y of follow-up in healthy middle-aged women. Instead, it was associated with a slightly lower risk of weight gain and obesity. The results of this study suggest that incorporating nuts into diets does not lead to greater weight gain and may help weight control.

Serum sterol responses to increasing plant sterol intake from natural foods in the Mediterranean diet

BACKGROUND

Phytosterols in natural foods are thought to inhibit cholesterol absorption. The Mediterranean diet is rich in phytosterol-containing plant foods.

AIM OF THE STUDY

To assess whether increasing phytosterol intake from natural foods was associated with a cholesterol-lowering effect in a substudy of a randomized trial of nutritional intervention with Mediterranean diets for primary cardiovascular prevention (PREDIMED study).

METHODS

One hundred and six high cardiovascular risk subjects assigned to two Mediterranean diets supplemented with virgin olive oil (VOO) or nuts, which are phytosterol-rich foods, or advice on a low-fat diet. Outcomes were 1-year changes in nutrient intake and serum levels of lipids and non-cholesterol sterols.

RESULTS

Average phytosterol intake increased by 76, 158 and 15 mg/day in participants assigned VOO, nuts and low-fat diets, respectively. Compared to participants in the low-fat diet group, changes in outcome variables were observed only in those in the Mediterranean diet with nuts group, with increases in intake of fibre, polyunsaturated fatty acids and phytosterols (P < 0.020, all) and significant (P < 0.05) reductions of LDL-cholesterol (0.27 mmol/l or 8.3%) and the LDL/HDL-cholesterol ratio (0.29 mmol/l or 11.5%). Variations in saturated fat, cholesterol or fibre intake were unrelated to LDL-cholesterol changes. In the whole group, changes in serum sitosterol-to-cholesterol, which reflect those of dietary phytosterol intake and absorption, correlated inversely to LDL-cholesterol changes (r = -0.256; P = 0.008). In multivariate analyses, baseline LDL-cholesterol, increases in serum sitosterol ratios and statin use were independently associated with LDL-cholesterol reductions.

CONCLUSIONS

Small amounts of phytosterols in natural foods appear to be bioactive in cholesterol lowering.

Nuts and novel biomarkers of cardiovascular disease

Nuts are energy-dense foods, rich in total fat and unsaturated fatty acids. The favorable fatty acid profile probably contributes to the beneficial effects of nut consumption observed in epidemiologic studies (prevention of coronary heart disease and diabetes) and feeding trials (cholesterol lowering). Besides fat, the complex matrices of nuts contain many bioactive compounds: vegetable protein, fiber, minerals, tocopherols, and phenolic compounds. By virtue of their unique composition, nuts are likely to benefit newer cardiovascular risk biomarkers, such as LDL oxidizability, soluble inflammatory molecules, and endothelial dysfunction. Protection of LDL oxidation by nut intake has been documented in some, but not all, clinical studies. In one study, feeding one daily serving of mixed nuts was associated with lower oxidized LDL concentrations. Regarding inflammation, cross-sectional studies have shown that nut consumption is associated with lower concentrations of circulating inflammatory molecules and higher plasma adiponectin, a potent antiinflammatory adipokine. Clinical studies with nuts have documented reduced inflammatory cytokine concentrations but no consistent changes of C-reactive protein. Only walnuts have been formally tested for effects on endothelial function. After both walnut diets and single walnut meals, favorable vasoreactivity changes have been observed. Walnut consumption also reduced expression of endothelin 1, a potent endothelial activator, in an animal model of accelerated atherosclerosis. Beneficial effects on vascular reactivity may be ascribed to several constituents of walnuts: l-arginine, the precursor of nitric oxide, alpha-linolenic acid, and phenolic antioxidants. Although more studies are warranted, the emerging picture is that nut consumption beneficially influences cardiovascular risk beyond cholesterol lowering.

Characterization of total, free and esterified phytosterols in tetraploid and hexaploid wheats

Dietary plant sterols have received increasing attention in recent years due to their favorable health benefits. The present research focused on quantification of phytosterols as free, esterified and total forms in different tetraploid (5 cultivars of Triticum durum Desf., 9 cultivars of Triticum dicoccon Schrank) and hexaploid (5 cultivars of T. aestivum L., 12 cultivars of Triticum spelta L.) wheats. Tetraploid wheats showed the highest content of total sterol (79.4 and 79.5 mg of sterols /100 g dry weight for T. durum and T. dicoccon, respectively). Hexaploid cultivars were the best source of esterified sterols (40.7% and 37.3% of total sterols for Triticum aestivum and T. spelta, respectively). Significant amounts of free sterols (65.5% and 60.7% of total sterols for T. durum and T. dicoccon, respectively) were found in the tetraploid cultivars. The most abundant phytosterol in all wheat samples was sitosterol accounting for 45.1-59.1, 46.6-57.4 and 38.6-59.5% of total, free and esterified sterol fraction, respectively. These results demonstrate that although the sterol profile present in tetraploid and hexaploid wheat species is the same, differences in their relative amounts and distribution allow statistical differentiation between hexaploids and tetraploids, and between soft and durum wheats.

Plant-based diets and control of lipids and coronary heart disease risk

Coronary heart disease (CHD) is a major cause of death worldwide. Dietary factors have an important role in influencing the outcome of this disease. Dietary guidelines around the world now recommend increased consumption of plant foods for the prevention of CHD. Epidemiologic and human intervention studies have documented an inverse relationship between the consumption of plant-based diets and deaths attributed to heart disease. Plant foods contain many beneficial compounds that, by acting through multiple mechanisms, provide protection against the disease. American and Canadian recommendations for the daily intake of fruits and vegetables provide a sound basis for a healthy diet and the prevention of CHD.

Impact of peanuts and tree nuts on body weight and healthy weight loss in adults

Nuts (ground and tree) are rich sources of multiple nutrients and their consumption is associated with health benefits, including reduced cardiovascular disease risk. This has prompted recommendations to increase their consumption. However, they are also high in fat (albeit largely unsaturated) and are energy dense. The associations between these properties, positive energy balance, and body weight raise questions about such recommendations. This issue is addressed through a review of the literature pertaining to the association between nut consumption and energy balance. Epidemiological studies document an inverse association between the frequency of nut consumption and BMI. Clinical trials reveal little or no weight change with inclusion of various types of nuts in the diet over 1-6 mo. Mechanistic studies indicate this is largely attributable to the high satiety property of nuts, leading to compensatory responses that account for 65-75% of the energy they provide. Limited data suggest chronic consumption is associated with elevated resting energy expenditure resulting in dissipation of another portion of the energy they provide. Additionally, due to poor bioaccessibility, there is limited efficiency of energy absorption from nuts. Collectively, these mechanisms offset much of the energy provided by nuts. The few trials contrasting weight loss through regimens that include or exclude nuts indicate improved compliance and greater weight loss when nuts are permitted. This consistent literature suggests nuts may be included in the diet, in moderation, to enhance palatability and nutrient quality without posing a threat for weight gain.