Almonds reduce biomarkers of lipid peroxidation in older hyperlipidemic subjects

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 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.

The effect of almond consumption on elements of endurance exercise performance in trained athletes

Background

Almonds are a healthy tree nut food with high nutrient density. Their consumption has been shown to ameliorate oxidative stress, inflammation, etc. The objective of the study was to examine the effect of almonds on elements of endurance exercise performance in trained athletes.

Methods

A 10-week crossover, placebo controlled study was conducted. Eight trained male cyclists and two triathletes were randomly assigned to consume 75 g/d whole almonds (ALM) or isocaloric cookies (COK) with equal subject number. They consumed the assigned food for 4 wks and then the alternate food for another 4 wks. They underwent 3 performance tests including 125-min steady status exercise (SS) and 20-min time trial (TT) on an indoor stationary trainer at the start of the study (BL) and at the end of each intervention phase. Venous blood was collected in the morning prior to the performance test for biochemical measurements and finger blood during the test for glucose determination. Carbohydrate and fat oxidation, energy expenditure, and oxygen use were calculated using respiratory gas analysis.

Results

ALM increased cycling distance during TT by 1.7 km as compared BL (21.9 vs. 20.2 km, P = 0.053) and COK increased 0.6 km (20.8 vs. 20.2 km, P > 0.05). ALM, but not COK, led to higher CHO and lower fat oxidation and less oxygen consumption during TT than BL (P < 0.05), whereas there was no significant difference in heart rate among BL, ALM and COK. ALM maintained higher blood glucose level after TT than COK (P < 0.05). ALM had higher vitamin E and haemoglobin and lower serum free fatty acid (P < 0.05), slightly elevated serum arginine and nitric oxide and plasma insulin (P > 0.05) than BL, and a higher total antioxidant capacity than COK (P < 0.05).

Conclusions

Whole almonds improved cycling distance and the elements related to endurance performance more than isocaloric cookies in trained athletes as some nutrients in almonds may contribute to CHO reservation and utilization and effective oxygen utilization. The results suggest that almonds can be incorporated into diets of those who undertake exercise training for performance improvement.

Walnuts decrease risk of cardiovascular disease: a summary of efficacy and biologic mechanisms

Given the pressing need to reduce cardiovascular disease (CVD) morbidity and mortality, there has been a focus on optimizing dietary patterns to reduce the many contributing risk factors. Over the past 2 decades, many studies have been conducted that have evaluated the effects of walnut consumption on CVD risk factors. Walnuts have been shown to decrease low density lipoprotein cholesterol (by ∼9-16%) and blood pressure (diastolic blood pressure by ∼2-3 mm Hg), 2 major risk factors for CVD. In addition, walnuts improve endothelial function, decrease both oxidative stress and some markers of inflammation, and increase cholesterol efflux. The effect of walnuts on multiple CVD targets over relatively short periods of time supports recommendations for their inclusion in a heart-healthy diet.

Effect of a walnut meal on postprandial oxidative stress and antioxidants in healthy individuals

Background

In vitro studies rank walnuts (Juglans regia) among the plant foods high in antioxidant capacity, but whether the active constituents of walnuts are bioavailable to humans remains to be determined. The intention of this study was to examine the acute effects of consuming walnuts compared to refined fat on meal induced oxidative stress. At issue is whether the ellagitannins and tocopherols in walnuts are bioavailable and provide postprandial antioxidant protection.

Methods

A randomized, crossover, and controlled-feeding study was conducted to evaluate a walnut test meal compared to one composed of refined ingredients on postprandial serum antioxidants and biomarkers of oxidative status in healthy adults (n = 16) with at least 1 week between testing sessions. Following consumption of a low phenolic diet for one day and an overnight fast, blood was sampled prior to the test meals and at intervals up to 24 hours post ingestion and analyzed for total phenols, malondiadehyde (MDA), oxidized LDL, ferric reducing antioxidant power (FRAP), hydrophilic and lipophilic oxygen radical absorbance capacity (ORAC), uric acid, catechins and urinary excretion of phenylacetate metabolites and of urolithin A.

Results

Mixed linear models demonstrated a diet effect (P < 0.001) for plasma γ-tocopherol but not for α-tocopherol with the walnut meal. Following the walnut test meal, the incremental 5 hour area under the curve (AUC_0-5h) was reduced 7.4% for MDA, increased 7.5% for hydrophilic and 8.5% for lipophilic ORAC and comparable for total phenols, FRAP and uric acid. Oxidized LDL was reduced at 2 hours after the walnut meal. Plasma concentrations of gallocatechin gallate (GCG), epicatechin gallate (ECG) and epicallocatechin gallate (EGCG) increased significantly at 1 hour after the walnut test meal. Quantities of urolithin-A excreted in the urine were significantly higher following the walnut meal.

Conclusions

Compared to the refined control meal, the walnut meal acutely increased postprandial γ-tocopherol and catechins and attenuated some measures of oxidative stress.

Almond protein hydrolysate fraction modulates the expression of proinflammatory cytokines and enzymes in activated macrophages

Simulated gastrointestinal treatment of almond proteins with pepsin and pancreatic proteases resulting in 16.6% degree of hydrolysis or 1.33 milliequivalent leucine per g protein yielded a hydrolysate that modulated excessive nitric oxide production in lipopolysaccharide-activated RAW264.7 macrophages. After fractionation, a resulting fraction of molecular size > 5 kDa retained the nitric oxide modulatory effect observed initially in the crude hydrolysate. The high molecular size fraction was found to modulate levels of proinflammatory cytokines, interleukin (IL)-6, IL-1β, and tumour necrosis factor (TNF)-α in the activated cells. Immunoblotting analysis indicated that the hydrolysate fraction decreased the expression levels of inflammatory enzyme indicators, inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 in the activated cells. RT-PCR analysis showed that treatment of the activated cells with the hydrolysate fraction resulted in the inhibition of relative gene expressions of proinflammatory IL-6, IL-1β, TNF-α, iNOS and COX-2. These results indicate a potential application of almond protein hydrolysates against inflammatory conditions, and will contribute to delineating the possible contributions of proteins to health benefits attributed to almond consumption.

Eugenosedin-A ameliorates hyperlipidemia-induced vascular endothelial dysfunction via inhibition of α1-adrenoceptor/5-HT activity and NADPH oxidase expression

Eugenosedin-A (Eu-A) effects on vascular endothelial dysfunction and oxidative stress in a hyperlipidemic rat model were investigated. Rats were randomly divided into four groups: two control groups and two treatment groups. The control rats received a regular diet or high fat diet (HFD); the treatment rats fed received an HFD with 5 mg/kg Eu-A or atorvastatin for 10 weeks. No changes in serotonin levels were observed in the four groups; norepinephrine levels were enhanced in the HFD group which was attenuated by Eu-A and atorvastatin. In the HFD group, the vascular reactivity was increased by vasoconstrictors (5-nonyloxytryptamine, 5-HT, and phenylephrine) and decreased by an endothelium-dependent vasorelaxant, carbachol. Protein levels of α1-adrenergic receptors (not 5-HT1B/2A), reactive oxygen species (ROS) p47(phox), p67(phox), and gp91(phox), and oxidative damage markers 3-nitrotyrosine (3-NT) and 4-hydroxy-2-nonenal (4-HNE) were increased, but endothelial nitric oxide synthase (eNOS), P-eNOS and vasodilator-stimulated phosphoprotein phosphorylation (P-VASP) were decreased. Catalase and superoxide dismutase (SOD-1 and SOD-2) proteins were increased, but glutathione peroxidase (GPx) was decreased in the aorta. Eu-A and atorvastatin reduced vasoconstrictor-induced aortic contractions that might be related to 5-HT1B/2A and α1-adrenergic receptors inhibitory activities. Eu-A and atorvastatin improved eNOS/P-eNOS, P-VASP, GPx, and malondialdehyde (MDA) levels, and decreased ROS and oxidative damage markers. Taken together, we suggest that Eu-A can ameliorate hyperlipidemia-induced vascular endothelial dysfunction and oxidative dysregulation.

Appetitive, dietary and health effects of almonds consumed with meals or as snacks: a randomized, controlled trial

BACKGROUND/OBJECTIVES

Snacks contribute toward a significant proportion of human total daily energy intake. This study investigated the effects of almonds, a satiating and nutrient-rich, common snack, on postprandial glycemia, appetite, short-term body weight and fasting blood parameters when consumed with meals or alone as a snack.

METHODS

This was a 4-week randomized, parallel-arm study that entailed consuming almonds (43 g/day) with breakfast (BF) or lunch (LN), alone as a morning (MS) or afternoon (AS) snack or no almonds (CL). Participants (N=137) with increased risk for type 2 diabetes completed an oral glucose tolerance test (OGTT) and acute-feeding session at baseline, followed by almond consumption for 4 weeks before repeating the OGTT and acute-feeding trials. Anthropometric, biochemical and appetite responses were assessed.

RESULTS

Almonds lowered serum glucose responses postprandially. Effects were most prominent in the snack groups. Almonds, consumed as snacks, also reduced hunger and desire to eat during the acute-feeding session. After 4 weeks, anthropometric measurements and fasting blood biochemistries did not differ from the control group or across intervention groups. Without specific guidance, daily energy intake was reduced to compensate for energy from the provided almonds. Dietary monounsaturated fat and α-tocopherol intakes were significantly increased in all almond groups.

CONCLUSION

Almonds provide post-ingestive metabolic and appetitive benefits and did not increase the risk for weight gain. This suggests that almonds may be a healthful snack option.

Plasma and dietary antioxidant status as cardiovascular disease risk factors: a review of human studies

Extensive evidence has demonstrated that many antioxidants such as vitamin C, vitamin E, carotenoids and polyphenols have protective effects in preventing cardiovascular disease (CVD), a chronic disease that is mediated by oxidative stress and inflammation. This review focuses on evidence from prospective cohort studies and clinical trials in regard to the associations between plasma/dietary antioxidants and cardiovascular events. Long-term, large-scale, population-based cohort studies have found that higher levels of serum albumin, bilirubin, glutathione, vitamin E, vitamin C, and carotenoids were associated with a lower risk of CVD. Evidence from the cohort studies in regard to dietary antioxidants also supported the protective effects of dietary vitamin E, vitamin C, carotenoids, and polyphenols on CVD risk. However, results from large randomized controlled trials did not support long-term use of single antioxidant supplements for CVD prevention due to their null or even adverse effects on major cardiovascular events or cancer. Diet quality indexes that consider overall diet quality rather than single nutrients have been drawing increasing attention. Cohort studies and intervention studies that focused on diet patterns such as high total antioxidant capacity have documented protective effects on CVD risk. This review provides a perspective for future studies that investigate antioxidant intake and risk of CVD.

Walnut consumption is associated with lower risk of type 2 diabetes in women

Walnuts are rich in polyunsaturated fatty acids and have been shown to improve various cardiometabolic risk factors. We aimed to investigate the association between walnut intake and incident type 2 diabetes in 2 large cohort studies: the Nurses' Health Study (NHS) and NHS II. We prospectively followed 58,063 women aged 52-77 y in NHS (1998-2008) and 79,893 women aged 35-52 y in NHS II (1999-2009) without diabetes, cardiovascular disease, or cancer at baseline. Consumption of walnuts and other nuts was assessed every 4 y using validated food frequency questionnaires. Self-reported type 2 diabetes was confirmed by a validated supplemental questionnaire. We documented a total of 5930 incident type 2 diabetes cases during 10 y of follow-up. In the multivariable-adjusted Cox proportional hazards model without body mass index (BMI), walnut consumption was associated with a lower risk of type 2 diabetes, and the HRs (95% CIs) for participants consuming 1-3 servings/mo (1 serving = 28 g), 1 serving/wk, and ≥2 servings/wk of walnuts were 0.93 (0.88-0.99), 0.81 (0.70-0.94), and 0.67 (0.54-0.82) compared with women who never/rarely consumed walnuts (P-trend < 0.001). Further adjustment for updated BMI slightly attenuated the association and the HRs (95% CIs) were 0.96 (0.90-1.02), 0.87 (0.75-1.01), and 0.76 (0.62-0.94), respectively (P-trend = 0.002). The consumption of total nuts (P-trend < 0.001) and other tree nuts (P-trend = 0.03) was also inversely associated with risk of type 2 diabetes, and the associations were largely explained by BMI. Our results suggest that higher walnut consumption is associated with a significantly lower risk of type 2 diabetes in women.

Is Almond Consumption More Effective Than Reduced Dietary Saturated Fat at Decreasing Plasma Total Cholesterol and LDL-c Levels? A Theoretical Approach

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

Nutrition and oxidative stress: a systematic review of human studies

Oxidative stress (OS) - defined as the imbalance between free radical production and antioxidant defences - is a condition associated with chronic-degenerative disease, such as cancer, metabolic and disease cardiovascular diseases (CVDs). Several studies have shown that diet and some of its components could influence the intensity of OS damage. The aim of this review was to critically examine some pieces of evidence from observational and intervention study in human beings to assess whether diet and its components can really modify OS in vivo. Furthermore, we tried to find out the possible mechanism behind this association. We considered all studies in MEDLINE which fitted with the following criteria: (1) adult subjects who were healthy or affected by metabolic disease and CVDs; (2) no food supplements, pillows, powder but only common foods and beverages and (3) OS assessment with well-known and validated in vivo biomarkers.

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.

Mapping quantitative trait loci for kernel composition in almond

BACKGROUND

Almond breeding is increasingly taking into account kernel quality as a breeding objective. Information on the parameters to be considered in evaluating almond quality, such as protein and oil content, as well as oleic acid and tocopherol concentration, has been recently compiled. The genetic control of these traits has not yet been studied in almond, although this information would improve the efficiency of almond breeding programs.

RESULTS

A map with 56 simple sequence repeat or microsatellite (SSR) markers was constructed for an almond population showing a wide range of variability for the chemical components of the almond kernel. A total of 12 putative quantitative trait loci (QTL) controlling these chemical traits have been detected in this analysis, corresponding to seven genomic regions of the eight almond linkage groups (LG). Some QTL were clustered in the same region or shared the same molecular markers, according to the correlations already found between the chemical traits. The logarithm of the odds (LOD) values for any given trait ranged from 2.12 to 4.87, explaining from 11.0 to 33.1 % of the phenotypic variance of the trait.

CONCLUSIONS

The results produced in the study offer the opportunity to include the new genetic information in almond breeding programs. Increases in the positive traits of kernel quality may be looked for simultaneously whenever they are genetically independent, even if they are negatively correlated. We have provided the first genetic framework for the chemical components of the almond kernel, with twelve QTL in agreement with the large number of genes controlling their metabolism.

Nut consumption is associated with decreased health risk factors for cardiovascular disease and metabolic syndrome in U.S. adults: NHANES 1999-2004

BACKGROUND

Few recent epidemiologic studies have assessed the effect that nut consumption (including tree nuts and peanuts) has on health risks, including metabolic syndrome (MetS).

OBJECTIVE

This study compared the health risk for cardiovascular disease, type 2 diabetes, and MetS of nut consumers with that of nonconsumers.

DESIGN

Adults 19+ years (n = 13,292) participating in the 1999-2004 National Health and Nutrition Examination Survey were used. Intake from 24-hour recalls was used to determine intake. Nut/tree nut consumers consumed ≥¼; ounce per day. Covariate-adjusted means, standard errors, and prevalence rates were determined for the nut consumption groups.

RESULTS

The prevalence of nut consumers was 18.6% ± 0.7% and 21.0% ± 0.9% in those 19-50 years and 51 years and older, respectively. Nut consumption was associated with a decreased body mass index (27.7 kg/m(2) ± 0.2 vs 28.1 ± 0.1 kg/m(2), p < 0.05), waist circumference (95.6 ± 0.4 cm vs 96.4 ± 0.3 cm, p < 0.05), and systolic blood pressure (121.9 ± 0.4 mmHg vs 123.20 ± 0.3 mmHg, p < 0.01) compared with nonconsumers. Tree nut consumers also had a lower weight (78.8 ± 0.7 kg vs 80.7 ± 0.3 kg, p < 0.05). Nut consumers had a lower percentage of two risk factors for MetS: hypertension (31.5% ± 1.0% vs 34.2% ± 0.8%, p < 0.05) and low high density lipoprotein-cholesterol (HDL-C) (29.6% ± 1.0% vs 34.8% ± 0.8%, p < 0.01). Tree nut consumers had a lower prevalence of four risk factors for MetS: abdominal obesity (43.6% ± 1.6% vs 49.5% ± 0.8%, p < 0.05), hypertension (31.4% ± 1.2% vs 33.9% ± 0.8%, p < 0.05), low HDL-C (27.9% ± 1.7% vs 34.5% ± 0.8%, p < 0.01), high fasting glucose (11.4% ± 1.4% vs 15.0% ± 0.7%, p < 0.05), and a lower prevalence of MetS (21.2% ± 2.1% vs 26.6% ± 0.7%, p < 0.05).

CONCLUSION

Nut/tree nut consumption was associated with a decreased prevalence of selected risk factors for cardiovascular disease, type 2 diabetes, and MetS.

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.

The biological relevance of direct antioxidant effects of polyphenols for cardiovascular health in humans is not established

Human studies provide evidence for beneficial effects of polyphenol-rich foods on cardiovascular health. The antioxidant activity of polyphenols potentially explains these effects, but is the antioxidant activity a reliable predictor for these effects? An International Life Sciences Institute Europe working group addressed this question and explored the potential of antioxidant claims for polyphenols in relation to cardiovascular health by using the so-called Process for the Assessment of Scientific Support for Claims on Foods project criteria. In this process, analytical aspects of polyphenols, their occurrence in foods, dietary intake, and bioavailability were reviewed. Human studies on polyphenols and cardiovascular health were reviewed together with methods for biomarkers of oxidative damage and total antioxidant capacity (TAC). In retrospective studies, F2-isoprostanes and oxidized LDL, the most reliable biomarkers of lipid peroxidation, and measures for TAC showed the expected differences between cardiovascular disease patients and healthy controls, but prospective studies are lacking, and a causal relationship between these biomarkers and cardiovascular health could not be established. Therefore, the physiological relevance of a potential change in these biomarkers is unclear. We found limited evidence that some types of polyphenol-rich products modify these biomarkers in humans. A direct antioxidant effect of polyphenols in vivo is questionable, however, because concentrations in blood are low compared with other antioxidants and extensive metabolism following ingestion lowers their antioxidant activity. Therefore, the biological relevance of direct antioxidant effects of polyphenols for cardiovascular health could not be established. Overall, although some polyphenol-rich foods exert beneficial effects on some biomarkers of cardiovascular health, there is no evidence that this is caused by improvements in antioxidant function biomarkers (oxidative damage or antioxidant capacity).

Almond consumption and cardiovascular risk factors in adults with prediabetes

OBJECTIVE

The authors tested the hypothesis that in adults with prediabetes, an almond-enriched American Diabetes Association (ADA) diet improves measures of insulin sensitivity and other cardiovascular risk factors compared with an ADA nut-free diet.

METHODS

DESIGN

Randomized parallel-group trial.

SETTING

Outpatient dietary counseling and blood analysis.

SUBJECTS

Sixty-five adult participants with prediabetes.

INTERVENTION

Sixteen weeks of dietary modification featuring an ADA diet containing 20% of energy from almonds (approximately 2 oz per day).

MEASURES OF OUTCOME

Outcomes included fasting glucose, insulin, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides, TC:HDL-C, and HbA1c, which were measured at weeks 0, 8, and 16. Body weight, body mass index (BMI), waist circumference, blood pressure, and nutrient intake were measured at weeks 0, 4, 8, 12, and 16.

RESULTS

The almond-enriched intervention group exhibited greater reductions in insulin (-1.78 µU/ml vs. +1.47 µU/ml, p  =  0.002), homeostasis model analysis for insulin resistance (-0.48 vs. +0.30, p  =  0.007), and homeostasis model analysis for beta-cell function (-13.2 vs. +22.3, p  =  0.001) compared with the nut-free control group. Clinically significant declines in LDL-C were found in the almond-enriched intervention group (-12.4 mg/dl vs. -0.4 mg/dl) as compared with the nut-free control group. No changes were observed in BMI (-0.4 vs. -0.7 kg/m(2), p  =  0.191), systolic blood pressure (-4.4 mm Hg vs. -3.5 mm Hg, p  =  0.773), or for the other measured cardiovascular risk factors.

CONCLUSIONS

An ADA diet consisting of 20% of calories as almonds over a 16-week period is effective in improving markers of insulin sensitivity and yields clinically significant improvements in LDL-C in adults with prediabetes.

Sensitive and specific detection of potentially allergenic almond (Prunus dulcis) in complex food matrices by Taqman(®) real-time polymerase chain reaction in comparison to commercially available protein-based enzyme-linked immunosorbent assay

Currently, causative immunotherapies are lacking in food allergy. The only option to prevent allergic reactions in susceptible individuals is to strictly avoid the offending food. Thus, reliable labelling of allergenic constituents is of major importance, but can only be achieved if appropriate specific and sensitive detection techniques for foods with allergenic potential are available. Almond is an allergenic food that requires mandatory labelling on prepackaged foods and belongs to the genus Prunus. Species of this genus are phylogenetically closely related. We observed commercially available almond specific ELISA being highly cross-reactive with other foods of the Prunoideae family, resulting in a false-positive detection of up to 500,000 mg kg(-1) almond. Previously published PCR methods were reported to be cross-reactive with false positive results >1200 mg kg(-1). We describe the development of a novel almond specific real-time PCR, based on mutated mismatch primers and sequence specific Taqman(®) probe detection, in comparison with two quantitative commercially available ELISA. PCR sensitivity was investigated with chocolate, chocolate coating and cookies spiked between 5 and 100,000 mg kg(-1) almond. In all matrices almond was reproducibly detected by real-time PCR at the lowest spike level of 5 mg kg(-1). Further, between 100 and 100,000 mg kg(-1) spiked almond, the method featured good correlation between quantified copy numbers and the amount of spiked almond. Within this range a similar relation between detectable signal and amount of almond was observed for both PCR and ELISA. In contrast to ELISA the Taqman(®) real-time PCR method was highly specific in 59 food items with negligible cross-reactivity for a very limited number of Prunoideae foods. The real-time PCR analysis of 24 retail samples was in concordance with ELISA results: 21% (n=5) contained undeclared almond. This is the first completely disclosed real-time PCR method for a specific and potentially quantitative almond detection. This PCR method detects almond at a level where severe allergic reactions should not be expected for the majority of the almond allergic individuals.

Polyphenol content and antioxidant activity of California almonds depend on cultivar and harvest year

The polyphenol content and antioxidant activity of Nonpareil, Carmel, Butte, Sonora, Fritz, Mission, and Monterey almond cultivars harvested over three seasons in California were examined. LC-MS was employed to quantify 16 flavonoids and two phenolic acids in acidified methanol extracts of almond skins. The 3-year mean polyphenol content of cultivars ranged from 4.0 to 10.7 mg/100 g almonds. Isorhamnetin-3-O-rutinoside was the most abundant flavonoid, present at 28-49% of total polyphenols among cultivars. Almonds from 2006 and 2007 had 13% fewer polyphenols than 2005, but FRAP and total phenols were comparable. Cultivar, but not season, had a differential impact on individual polyphenol synthesis. Using the results of polyphenol, total phenol, and FRAP, multivariate analysis distinguished harvest years and most cultivars with 80% confidence. Flavonoid content and antioxidant activity of almonds may be more dependent on cultivar than on seasonal differences.

Targeted analysis of conjugated and microbial-derived phenolic metabolites in human urine after consumption of an almond skin phenolic extract

A single-blind, placebo-controlled, and randomized trial study was carried out with 16 healthy volunteers (7 men and 5 women). The test group ingested an encapsulated almond skin phenolic extract (884 mg of total polyphenols/dose) containing flavan-3-ols, flavonols, and flavanones, whereas the placebo group ingested microcrystalline cellulose. Our aim in this study was to determine changes in the urinary excretion of conjugated and microbial-derived phenolic metabolites before (-2 to 0 h) and after (0-2, 2-6, 6-10, and 10-24 h) intake of the almond polyphenols compared with the placebo group. For the test group, maximum urinary excretion of (epi)catechin and naringenin conjugates derived from phase II metabolism was attained at 2-6 h after consumption of the almond skin extract and excretions differed from the placebo group during this time period (P ≤ 0.0001). However, excretion of conjugated metabolites of isorhamnetin was highest at 10-24 h and did not differ from the placebo group during this time (P > 0.05). Hydroxyphenylvalerolactones reached maximum urinary levels at 6-10 h after consumption of almond polyphenols, and excretion differed from the placebo group during this time period (P = 0.0004). For the test group, excretions of phenolic acids (hydroxyphenylpropionic, hydroxyphenylacetic, hydroxybenzoic, and hydroxycinnamic acids) did not differ from the placebo group at any time period of urine collection (P > 0.05). The findings presented in this work provide evidence concerning the bioavailability of almond skin polyphenols considering the effects of both phase II and microbial metabolism.

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.

Classification of individuals with dyslipidaemia controlled by statins according to plasma biomarkers of oxidative stress using cluster analysis

Oxidative stress is a physiological condition that is associated with atherosclerosis, and it can be influenced by diet. Our objective was to group fifty-seven individuals with dyslipidaemia controlled by statins according to four oxidative biomarkers, and to evaluate the diet pattern and blood biochemistry differences between these groups. Blood samples were collected and the following parameters were evaluated: diet intake; plasma fatty acids; lipoprotein concentration; glucose; oxidised LDL (oxLDL); malondialdehyde (MDA); total antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing ability power assays. Individuals were separated into five groups by cluster analysis. All groups showed a difference with respect to at least one of the four oxidative stress biomarkers. The separation of individuals in the first axis was based upon their total antioxidant activity. Clusters located on the right side showed higher total antioxidant activity, higher myristic fatty acid and lower arachidonic fatty acid proportions than clusters located on the left side. A negative correlation was observed between DPPH and the peroxidability index. The second axis showed differences in oxidation status as measured by MDA and oxLDL concentrations. Clusters located on the upper side showed higher oxidative status and lower HDL cholesterol concentration than clusters located on the lower side. There were no differences in diet among the five clusters. Therefore, fatty acid synthesis and HDL cholesterol concentration seem to exert a more significant effect on the oxidative conditions of the individuals with dyslipidaemia controlled by statins than does their food intake.

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.

Position of the American Dietetic Association: functional foods

All foods are functional at some physiological level, but it is the position of the American Dietetic Association (ADA) that functional foods that include whole foods and fortified, enriched, or enhanced foods have a potentially beneficial effect on health when consumed as part of a varied diet on a regular basis, at effective levels. ADA supports research to further define the health benefits and risks of individual functional foods and their physiologically active components. Health claims on food products, including functional foods, should be based on the significant scientific agreement standard of evidence and ADA supports label claims based on such strong scientific substantiation. Food and nutrition professionals will continue to work with the food industry, allied health professionals, the government, the scientific community, and the media to ensure that the public has accurate information regarding functional foods and thus should continue to educate themselves on this emerging area of food and nutrition science. Knowledge of the role of physiologically active food components, from plant, animal, and microbial food sources, has changed the role of diet in health. Functional foods have evolved as food and nutrition science has advanced beyond the treatment of deficiency syndromes to reduction of disease risk and health promotion. This position paper reviews the definition of functional foods, their regulation, and the scientific evidence supporting this evolving area of food and nutrition. Foods can no longer be evaluated only in terms of macronutrient and micronutrient content alone. Analyzing the content of other physiologically active components and evaluating their role in health promotion will be necessary. The availability of health-promoting functional foods in the US diet has the potential to help ensure a healthier population. However, each functional food should be evaluated on the basis of scientific evidence to ensure appropriate integration into a varied diet.