Nut consumption, body weight and insulin resistance

Association of nut consumption with insulin resistance and blood lipid profile in Spanish university students

AIMS

To examine whether nut consumption was associated with insulin resistance and blood lipid parameters in a sample of young healthy adults.

MATERIAL AND METHODS

A cross-sectional study was conducted involving 306 first-year students (aged 18-30 years) from the University of Castilla-La Mancha, Spain. Biochemical variables related to insulin resistance and blood lipid profile (glucose, insulin, HbA1c, total cholesterol (total-c), LDL-c, HDL-c, and triglycerides) were determined from morning fasting blood samples. Nut consumption was estimated using a 137-item Food-Frequency Questionnaire. The associations of walnuts, other nuts and total nut intakes with insulin resistance and lipid profile variables and surrogates were assessed by linear regression analysis. Differences in insulin resistance and lipid profiles between participants meeting or not meeting the nut consumption recommendations were examined by analysis of covariance (ANCOVA). Logistic regressions were used to analyze the likelihood of having higher levels of blood lipids or insulin resistance in participants who met or did not meet the recommended intake of nuts.

RESULTS

There was no association found between nut consumption, whether walnuts or other nut varieties, and insulin resistance and lipid profile variables. Additionally, there were no significant differences in insulin resistance or blood lipid profile variables between university students meeting or not meeting nut consumption recommendations. Finally, stratified analyses based on sex were consistent and did not substantially modify our estimates in the fully adjusted models.

CONCLUSIONS

In conclusion, our results suggest that walnuts, other types of nuts, and total nut consumption did not adversely influence metabolic or lipid profile variables among healthy young adults. Although nuts are recommended among healthy dietary patterns, our findings showed that nut consumption has a null effect on the cardiometabolic risk parameters explored in young healthy adults.

Time Domain NMR Approach in the Chemical and Physical Characterization of Hazelnuts (Corylus avellana L.)

'Tonda Gentile Romana' and 'Tonda di Giffoni' (Corylus avellana L.) are two Italian hazelnut cultivars, recognized under the quality labels "Protected Designation of Origin" (PDO) and "Protected Geographical Indication" (PGI), respectively. Hazelnut seeds are characterized by a complex microstructure and the presence of different physical compartments. This peculiarity has been studied and evidenced by Time Domain (TD) Nuclear Magnetic Resonance (NMR) experiments. This technique allowed the assessment of the presence of different diffusion compartments, or domains, by evaluating the distribution of the spin-spin relaxation time (T₂).The aim of this research was to develop a method based on ¹H NMR relaxometry to study the mobility in fresh hazelnut seeds ('Tonda di Giffoni' and 'Tonda Gentile Romana'), in order to determine differences in seed structure and matrix mobility between the two cultivars. TD-NMR measurements were performed from 8 to 55 °C in order to mimic post-harvest processing as well the microscopic textural properties of hazelnut. The Carr-Purcell-Meiboom-Gill (CPMG) experiments showed five components for 'Tonda Gentile Romana' and four components for 'Tonda di Giffoni' relaxation times. The two slowest components of relaxation (T_2,a about 30-40% of the NMR signal, and T_2,b about 50% of the NMR signal) were attributed to the protons of the lipid molecules organized in the organelles (oleosomes), both for the 'Tonda Gentile Romana' and for the 'Tonda di Giffoni' samples. The component of relaxation T_2,c was assigned to cytoplasmic water molecules, and showed a T₂ value dominated by diffusive exchange with a reduced value compared to that of pure water at the same temperature. This can be attributed to the water molecules affected by the relaxation effect of the cell walls. The experiments carried out as a function of temperature showed, for 'Tonda Gentile Romana', an unexpected trend between 30 and 45 °C, indicating a phase transition in its oil component. This study provides information that could be used to strengthen the specifications underlying the definitions of "Protected Designation of Origin" (PDO) and "Protected Geographical Indication" (PGI).

Dietary Factors and Pancreatic Cancer Risk: An Umbrella Review of Meta-Analyses of Prospective Observational Studies

Dietary factors may be associated with the occurrence of pancreatic cancer. This umbrella review aimed to review and grade the evidence for the associations between dietary factors and pancreatic cancer risk. We searched PubMed, EMBASE, Web of Science, Scopus, Cochrane Database of Systematic Reviews, and CINAHL for eligible literature. We included meta-analyses of randomized controlled trials (RCTs) or prospective observational studies. We used AMSTAR-2, a measurement tool to assess systematic reviews, to evaluate the methodological quality of the included meta-analyses. For each association, we calculated the summary effect size, 95% CI, heterogeneity, number of cases, 95% prediction interval, small-study effect, and excess significance bias. The protocol for this review was registered in the PROSPERO database (CRD42022333669). We included 41 meta-analyses of prospective observational studies describing 59 associations between dietary factors and pancreatic cancer risk. None of the retrieved meta-analyses included RCTs. No association was supported by convincing or highly suggestive evidence; however, there was suggestive evidence of a positive association between fructose intake and pancreatic cancer risk. There was weak evidence for an inverse association of nuts intake or adherence to the Mediterranean diet with pancreatic cancer incidence, and for positive associations between a higher intake of red meat or heavy alcohol intake and pancreatic cancer incidence. The remaining 54 associations were nonsignificant. Consistent with the American Institute for Cancer Research review, this umbrella review found that regular consumption of nuts and reduced intake of fructose, red meat, and alcohol were associated with a lower risk of pancreatic cancer. Emerging weak evidence supported an inverse association between adherence to the Mediterranean diet and pancreatic cancer risk. As some associations were rated as weak and most were considered nonsignificant, further prospective studies are needed to investigate the role of dietary factors and risk of pancreatic cancer.

Development of a Functional Dark Chocolate with Baobab Pulp

In recent years, cocoa and dark chocolate have attracted the interest of consumers not only for their sensory characteristics but also for their nutritional properties and positive impact on health. The baobab is a fruit of African origin with a sour and slightly sweet flavour, widely consumed by local communities due to its unique nutritional features. The aim of this work was to evaluate the impact of the concentration of baobab flour in the development of functional dark chocolate, including physical, chemical, nutritional and sensory evaluations. The results presented a positive correlation between the incorporation of baobab flour and the antioxidant activity (up to 2297 mmol TE/100 g), vitamin C content (up to 49.7 mg/100 g), calcium (up to 1052 mg/kg), potassium (up to 10,175 mg/kg), phosphorus (up to 795.9 mg/kg), chlorine (up to 235.4 mg/kg) and sulphur (up to 1158 mg/kg). The sensory evaluation of dark chocolate with 3% baobab presented the highest evaluation on the parameters "texture" and "overall flavour", while the parameter "overall flavour" presented the lowest evaluation on chocolate with 9% baobab. No influence was observed on fatty acid profile, protein, fat and hardness.

Effect of almond consumption on insulin sensitivity and serum lipids among Asian Indian adults with overweight and obesity- A randomized controlled trial

BACKGROUND

Asian Indians have an increased susceptibility to type 2 diabetes and premature coronary artery disease. Nuts, like almonds, are rich in unsaturated fat and micronutrients with known health benefits.

OBJECTIVES

This study aimed to assess the efficacy of almonds for reduction of insulin resistance and improving lipid profile in overweight Asian Indian adults.

METHODS

This parallel-arm, randomized, controlled trial was conducted in Chennai, India on 400 participants aged 25-65 years with a body mass index ≥ 23 kg/m2. The intervention group received 43 g of almonds/day for 12 weeks, while the control group was advised to consume a customary diet but to avoid nuts. Anthropometric, clinical, and dietary data were assessed at periodic intervals. Glucose tolerance, serum insulin, glycated hemoglobin, C-peptide and lipid profile were assessed at baseline and end of the study. Insulin resistance (homeostasis assessment model-HOMA IR) and oral insulin disposition index (DIo) were calculated.

RESULTS

A total of 352 participants completed the study. Significant improvement was seen in DIo [mean (95% CI) = + 0.7 mmol/L (0.1, 1.3); p = 0.03], HOMA IR (-0.4 (-0.7, -0.04; p = 0.03) and total cholesterol (-5.4 mg/dl (-10.2, -0.6); p = 0.03) in the intervention group compared to the control group. Incremental area under the curve (IAUC) and mean amplitude of glycemic excursion (MAGE) assessed using continuous glucose monitoring systems were also significantly lower in the intervention group. Dietary 24-h recalls showed a higher significant reduction in carbohydrate and increase in mono unsaturated fatty acid (MUFA) and polyunsaturated fatty acids (PUFA) intake in the intervention group compared to the control group.

CONCLUSION

Daily consumption of almonds increased the intake of MUFA with decrease in carbohydrate calories and decreases insulin resistance, improves insulin sensitivity and lowers serum cholesterol in Asian Indians with overweight/obesity. These effects in the long run could aid in reducing the risk of diabetes and other cardiometabolic disease.

High adherence to the Mediterranean diet and Alternative Healthy Eating Index are associated with reduced odds of metabolic syndrome and its components in participants of the ORISCAV-LUX2 study

Background

Metabolic syndrome (MetS) is a major risk factor for cardiometabolic complications. Certain dietary patterns play a pivotal role in improving MetS components. The aim of this investigation was to study associations between the Mediterranean Diet Score (MDS) and the Alternative Healthy Eating Index (AHEI) and the odds of MetS and its components in adults living in Luxembourg.

Methods

Data from 1,404 adults participating in the cross-sectional ORISCAV-LUX2 study were analyzed by a self-reported questionnaire, anthropometric measures, a food frequency questionnaire (174 items), and blood/urine samples.

Results

A significant association of dietary indices and MetS was not found except when expressing MetS as a score (continuous variable, log-transformed), based on the weighting of compounds using exploratory factor analysis with the MDS (β = -0.118, 95% CI: -0.346, -0.120) and AHEI (β = -0.133, 95% CI: -0.059, -0.019). Fully adjusted linear regression models further showed significant inverse associations between components of MetS and MDS (all as log-transformed variables), including body mass index (BMI) (β = -0.0067, 95% CI: -0.0099, -0.0036), waist-circumference (WC) (β = -0.0048, 95% CI: -0.0072, -0.0024), systolic blood pressure (SBP) (β = -0.0038, 95% CI: -0.0061, -0.0016), and diastolic blood pressure (DBP) (β = -0.0035, 95% CI: -0.0060, -0.0009). Similarly, significant inverse associations between AHEI and components of MetS (log-transformed) included BMI (β = -0.0001, 95% CI: -0.0016, -0.0002), WC (β = -0.0007, 95% CI: -0.0011, -0.0002), SBP (β = -0.0006, 95% CI: -0.0010, -0.0002), and DBP (β = -0.0006, 95% CI: -0.0011, -0.0001).

Conclusion

Higher adherence to a Mediterranean diet and following healthy eating guidelines were associated with reduced odds of MetS and several of its components in Luxembourgish residents, highlighting that balanced and healthy eating patterns are a crucial cornerstone in the fight against MetS.

The association between left ventricular hypertrophy and consumption of nuts, including peanuts, pine nuts, and almonds

BACKGROUND AND AIMS

Studies have reported that nut consumption is potentially beneficial in preventing cardiovascular disease. However, data are insufficient regarding the association between nut consumption and left ventricular hypertrophy (LVH).

METHODS AND RESULTS

In the Kangbuk Samsung Health Study, the participants were 34,617 men and 12,257 women who completed a food-frequency questionnaire for nut consumption and received echocardiography. Nut consumption was evaluated only for peanuts, pine nuts, and almonds defining 15 g as one serving/servings dose. Multivariable adjusted odds ratio (OR) and 95% confidence interval (CI) for LVH were evaluated according to the consumption frequency of one serving dose of nut. The frequency of nut consumption was categorized into five groups (<1/month, 1/month-1/week, 1-2/week, 2-4/week, and ≥4/week). The subgroup analysis was conducted by dividing the participants into the following two groups: the nonhypertensive/nondiabetic group and hypertensive or diabetic group. In women, nut consumption ≥2/week had the lower multivariable adjusted OR and 95% CI for LVH (2-4/week: 0.46 [0.26-0.81] and ≥4/week: 0.48 [0.25-0.92]) when compared with nut consumption <1/month. This association was identically observed in the subgroup analysis for women without hypertension and diabetes mellitus (DM) and women with hypertension or DM. However, men did not show the significant association.

CONCLUSION

In women, nut consumption ≥2/week was associated with the decreased probability of LVH. Further research studies should investigate whether the beneficial effect of nut consumption on LV structure results in better cardiovascular prognosis.

A comparison of fatty acid and sensory profiles of raw and roasted pecan cultivars

Five fatty acids comprise the bulk of the lipid content in pecans: palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid. Understanding the profiles of these fatty acids and how they relate to sensory characteristics may offer an explanation for flavor and flavor defects that may exist in certain cultivars of pecans. The objective of this study was to examine and compare fatty acid profiles of three cultivars of pecans (Major, Lakota, and Chetopa), over two crop years, under raw and roasted preparation methods, and understand the fatty acids association with sensory attributes. Percentages of palmitic, stearic, oleic, linoleic, and linolenic acids to total fatty acid content were determined using gas chromatography, and sensory profiles were generated using descriptive sensory analysis. Similar trends were seen across samples, with oleic acid comprising the majority of the total fatty acids and linolenic acid comprising the smallest percentage. There were significant differences in fatty acid content among cultivars and between pecans in the first and second crop year. Few associations were found between the fatty acids and sensory attributes, which suggest that combinations of the fatty acids contribute to certain pleasant or undesirable flavor attributes in the pecans. Subtle differences in fatty acid composition may lead to variation in flavor and flavor intensity or draw attention to or from certain attributes during consumption. Differences in crop year indicated that fatty acid content and therefore flavor are variable year to year. PRACTICAL APPLICATION: This study will help understand how fatty acid content of pecans varies from year to year. This should be taken into account when manufacturing products with pecans as the nutritional content of the product may change as the result.

Effects of walnut intake on anthropometric characteristics: A systematic review and dose-response meta-analysis of randomized controlled trials

BACKGROUND & OBJECTIVE

Effects of walnut intake on anthropometric measurements have been inconsistent among clinical studies. Thus, we conducted a meta-analysis of randomized clinical trials (RCTs) to evaluate and quantify the effects of walnut intake on anthropometric characteristics.

METHODS

We carried out a systematic search of all available RCTs up to June 2019 in the following electronic databases: PubMed, Scopus, Web of Science and Google Scholar. Pooled weight mean difference (WMD) of the included studies was estimated using random-effects model.

RESULTS

A total of 27 articles were included in this meta-analysis, with walnuts dosage ranging from 15 to 108 g/d for 2 wk to 2 y. Overall, interventions with walnut intake did not alter waist circumference (WC) (WMD: -0.193 cm, 95 % CI: -1.03, 0.64, p = 0.651), body weight (BW) (0.083 kg, 95 % CI: -0.032, 0.198, p = 0.159), body mass index (BMI) (WMD: -0.40 kg/m,²95 % CI: -0.244, 0.164, p = 0.703), and fat mass (FM) (WMD: 0.28 %, 95 % CI: -0.49, 1.06, p = 0.476). Following dose-response evaluation, reduced BW (Coef.= -1.62, p = 0.001), BMI (Coef.= -1.24, p = 0.041) and WC (Coef.= -5.39, p = 0.038) were significantly observed through walnut intake up to 35 g/day. However, the number of studies can be limited as to the individual analysis of the measures through the dose-response fashion.

CONCLUSIONS

Overall, results from this meta-analysis suggest that interventions with walnut intake does not alter BW, BMI, FM, and WC. To date, there is no discernible evidence to support walnut intake for improving anthropometric indicators of weight loss.

The association between metabolic syndrome and peanuts, pine nuts, almonds consumption: The Ansan and Ansung Study

BACKGROUND

Previous studies reported an inverted relationship between nut consumption and the incidence of metabolic syndrome (MetS). The present study investigated the incidental risk for MetS according to peanut, almond, and fine nut consumption in the Korean population.

METHODS

In a community-based Korean cohort, 5306 Korean adults were divided into four groups according to their peanut, almond, and fine nut intake (<1/month, 1/month-0.5/week, 0.5-1/week, and ≥1/week, in which one serving = 15 g) and were followed-up for 10 years. A Cox proportional hazard model was used to evaluate the hazard ratios (HRs) with confidence intervals (CI) for MetS in each study group. Age subgroup (≥50 or <50 years) analysis was also conducted.

RESULTS

The age and multivariable-adjusted HRs with 95% CIs for MetS showed a significant inverse dose-response relationship between peanut, almond, and fine nut intake and the incidence of MetS in men and women (multivariable-adjusted HRs [95% CI] in men; 0.91 [0.76-1.09] in 1/month-0.5/week, 1.03 [0.80-1.31] in 0.5-1/week, 0.72 [0.56-0.93] in ≥1/week and in women; 0.81 [0.65-1.003] in 1/month-0.5/week, 0.76 [0.54-1.07] in 0.5-1/week, 0.57 [0.41-0.79] ≥1/week)). Subgroup analysis showed a significant difference in middle-aged men (≥1/week) and old-aged women (≥0.5/week).

CONCLUSION

The results of the present study suggested that peanut, almond, and fine nut intake (≥15 g/week) may be inversely related to incidence risk of MetS in the Korean general population. Additionally, the association between nut consumption and MetS incidence risk may differ in sex and age subgroups.

In Vitro Digested Nut Oils Attenuate the Lipopolysaccharide-Induced Inflammatory Response in Macrophages

Nut consumption is known for its health benefits, in particular in inflammatory diseases. A possible mechanism for these effects could be their beneficial fatty acid composition. Nuts mainly contain mono- and polyunsaturated fatty acids, which have anti-inflammatory properties. However, studies investigating the effects of nut extracts on inflammatory processes on the molecular level are rare. We therefore prepared oily nut extracts after in vitro digestion and saponification of the fat-soluble constituents. Besides chromatographic analysis, cell culture experiments were performed using murine macrophages (RAW264.7) to study the capacity of different nut extracts (hazelnut, almond, walnut, macadamia, and pistachio) to modulate inflammatory processes. Oleic acid was the main fatty acid in hazelnut, almond, macadamia, and pistachio extracts. Both oily nut extracts and pure oleic acid significantly reduced the LPS-induced expression of iNos, Cox2, Tnfα, Il1β, and Il6 mRNAs. iNos protein expression was down-regulated followed by reduced nitric oxide formation. Thus, nut extracts at concentrations achievable in the digestive tract inhibit the expression and formation of inflammatory mediators in macrophages. Hence, a beneficial contribution of nut consumption to inflammatory diseases can be assumed. We are convinced that these results provide new insights on the molecular mechanisms involved in the health-beneficial effects of nuts.

Palm oil and cardiovascular disease: a randomized trial of the effects of hybrid palm oil supplementation on human plasma lipid patterns

This study examines, for the first time, the effect of hybrid Elaeis oleifera × E. guineensis palm oil supplementation on human plasma lipids related to CVD risk factors. One hundred sixty eligible participants were randomized and assigned to one of the two treatments: 25 mL hybrid palm oil (HPO group) or 25 mL extra virgin olive oil (EVOO group) daily for 3 months. Fasting venous samples were obtained at baseline and after 1, 2 and 3 months for measurement of plasma lipids (TC, LDL-C, HDL-C and TAGs). Changes in body mass index and waist circumference were also assessed. Although there was an overall reduction in TC (7.4%, p < 0.001) and in LDL-C (15.6%, p < 0.001), no significant differences were found between the treatment groups in a repeated measures analysis of variance for TC (p = 0.0525), LDL-C (p = 0.2356), HDL-C (p = 0.8293) or TAGs (p = 0.3749). Furthermore, HPO consumption had similar effects on plasma lipids to EVOO, thus providing additional support for the concept that hybrid Elaeis oleifera × E. guineensis palm oil can be seen as a "tropical equivalent of olive oil".

Walnuts Consumed by Healthy Adults Provide Less Available Energy than Predicted by the Atwater Factors

BACKGROUND

Previous studies have shown that the metabolizable energy (ME) content (energy available to the body) of certain nuts is less than predicted by the Atwater factors. However, very few nuts have been investigated to date, and no information is available regarding the ME of walnuts.

OBJECTIVE

A study was conducted to determine the ME of walnuts when consumed as part of a typical American diet.

METHODS

Healthy adults (n = 18; mean age = 53.1 y; body mass index = 28.8 kg/m(2)) participated in a randomized crossover study with 2 treatment periods (3 wk each). The study was a fully controlled dietary feeding intervention in which the same base diet was consumed during each treatment period; the base diet was unsupplemented during one feeding period and supplemented with 42 g walnuts/d during the other feeding period. Base diet foods were reduced in equal proportions during the walnut period to achieve isocaloric food intake during the 2 periods. After a 9 d diet acclimation period, subjects collected all urine and feces for ∼1 wk (as marked by a Brilliant Blue fecal collection marker) for analysis of energy content. Administered diets, walnuts, and fecal and urine samples were subjected to bomb calorimetry, and the resulting data were used to calculate the ME of the walnuts.

RESULTS

One 28-g serving of walnuts contained 146 kcal (5.22 kcal/g), 39 kcal/serving less than the calculated value of 185 kcal/serving (6.61 kcal/g). The ME of the walnuts was 21% less than that predicted by the Atwater factors (P < 0.0001).

CONCLUSION

Consistent with other tree nuts, Atwater factors overestimate the metabolizable energy value of walnuts. These results could help explain the observations that consumers of nuts do not gain excessive weight and could improve the accuracy of food labeling. This trial was registered at clinicaltrials.gov as NCT01832909.

Nutritional composition and fatty acids profile in cocoa beans and chocolates with different geographical origin and processing conditions

Nutritional composition and fatty acids (FA) profile were determined in cocoa and chocolates of different geographical origin and subject to different processing conditions. Cocoa butter was the major nutrient in cocoa beans and carbohydrates were the most important in chocolates. Cocoa composition and FA profile varied depending on geographical origin whilst in chocolates only carbohydrates and fat content varied significantly due to the effect of origin and no significant effect was observed for processing conditions. Both for cocoa and chocolates differences in FA profile were mainly explained as an effect of the geographical origin, and were not due to processing conditions in chocolate. For cocoa, differences in FA profile were found in C12:0, C14:0, C16:0, C16:1, C17:0, C17:1 and C18:0 whilst for chocolates only differences were found in C16:0, C18:0, C18:1 and C18:2. For all samples, C16:0, C18:0, C18:1 and C18:2 were quantitatively the most important FA. Ecuadorian chocolate showed a healthier FA profile having higher amounts of unsaturated FA and lower amounts of saturated FA than Ghanaian chocolate.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

The relationship between nut consumption and blood pressure in an Iranian adult population: Isfahan Healthy Heart Program

BACKGROUND AND AIMS

Few studies outside of Western countries have evaluated the relationship between consumption of nuts and blood pressure (BP). This study aimed to investigate the relationship between nut consumption and blood pressure in an Iranian adult population.

METHODS AND RESULTS

We performed a cross-sectional investigation among 9660 randomly selected Iranian adults, sampled to represent three large Iranian regions, using data collected in the Isfahan Healthy Heart Program in 2007. The frequency of nut consumption was assessed by a food frequency questionnaire. Systolic and diastolic BPs (SBP and DBP) were measured in duplicate by trained personnel using a standard protocol. Multiple linear and logistic regressions were applied to assess the relationship between nut intake and BP levels and the presence of hypertension as SBP ≥ 140 mmHg, and/or a DBP ≥ 90 mmHg and/or current use of at least one type of anti-hypertensive medication. Those with nut consumption ≥4 times/week showed less mean of BPs and hypertension prevalence, compared to those who consumed nuts <1 times/week (p < 0.001). Compared to no consumption, consuming nuts ≥4 times/week was associated with a 34% lower prevalence of hypertension (multivariate odds ratio (OR) = 0.66; confidence interval (CI) = 0.51-0.87; p for trend = 0.009).

CONCLUSIONS

More frequent nut consumption is associated with lower BP and lower risk of hypertension among Iranian adults.

Nut intake and adiposity: meta-analysis of clinical trials

BACKGROUND

Epidemiologic studies have shown an inverse association between the frequency of nut consumption and body mass index (BMI) and risk of obesity. However, clinical trials that evaluated nut consumption on adiposity have been scarce and inconclusive.

OBJECTIVE

We performed a systematic review and meta-analysis of published, randomized nut-feeding trials to estimate the effect of nut consumption on adiposity measures.

DESIGN

MEDLINE and the Cochrane Central Register of Controlled Trials databases were searched for relevant clinical trials of nut intake that provided outcomes of body weight, BMI (in kg/m(2)), or waist-circumference measures and were published before December 2012. There were no language restrictions. Two investigators independently selected and reviewed eligible studies. The weighted mean difference (WMD) between nut or control diets was estimated by using a random-effects meta-analysis with 95% CIs.

RESULTS

Thirty-three clinical trials met our inclusion criteria. Pooled results indicated a nonsignificant effect on body weight (WMD: -0.47 kg; 95% CI: -1.17, 0.22 kg; I(2) = 7%), BMI (WMD: -0.40 kg/m(2); 95% CI: -0.97, 0.17 kg/m(2); I(2) = 49%), or waist circumference (WMD: -1.25 cm; 95% CI: -2.82, 0.31 cm; I(2) = 28%) of diets including nuts compared with control diets. These findings were remarkably robust in the sensitivity analysis. No publication bias was shown.

CONCLUSION

Compared with control diets, diets enriched with nuts did not increase body weight, body mass index, or waist circumference in controlled clinical trials.

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

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

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.

In vitro fermented nuts exhibit chemopreventive effects in HT29 colon cancer cells

It is proven that nuts contain essential macro- and micronutrients, e.g. fatty acids, vitamins and dietary fibre (DF). Fermentation of DF by the gut microflora results in the formation of SCFA which are recognised for their chemopreventive potential, especially by influencing cell growth. However, little is known about cellular response to complex fermentation samples of nuts. Therefore, we prepared and analysed (pH, SCFA, bile acids, tocopherol, antioxidant capacity) fermentation supernatant (fs) fractions of nuts (almonds, macadamias, hazelnuts, pistachios, walnuts) after in vitro fermentation and determined their effects on growth of HT29 cells as well as their genotoxic/anti-genotoxic potential. The fermented nut samples contained 2- to 3-fold higher amounts of SCFA than the faeces control, but considerable reduced levels of bile acids. While most of the investigated native nuts comprised relatively high amounts of tocopherol (α-tocopherol in almonds and hazelnuts and γ- and δ-tocopherol in pistachios and walnuts), rather low concentrations were found in the fs. All nut extracts and nut fs showed a strong antioxidant potential. Furthermore, all fs, except the fs pistachio, reduced growth of HT29 cells significantly. DNA damage induced by H₂O₂ was significantly reduced by the fs of walnuts after 15 min co-incubation of HT29 cells. In conclusion, this is the first study which presents the chemopreventive effects (reduction of tumour-promoting desoxycholic acid, rise in chemopreventive SCFA, protection against oxidative stress) of different nuts after in vitro digestion and fermentation, and shows the potential importance of nuts in the prevention of colon cancer.

Effects of walnuts (Juglans regia) on learning and memory functions

Walnut has been regarded as a health food that is delicious and nutritious. Both preventive and therapeutic effects of walnut are well documented. Walnuts are rich in omega-3 fatty acids that are reported to have beneficial effects on brain function. The present work was designed to evaluate the effects of walnuts on learning and memory in male rats. The effect of oral intake of walnut was also monitored on food intake. Walnut was given orally to rats for a period of 28 days. Memory function in rats was assessed by elevated plus maze (EPM) and radial arm maze (RAM). A significant improvement in learning and memory of walnut treated rats compared to controls was observed. Walnut treated rats also exhibited a significant decrease in food intake while the change in growth rate (in terms of percentage) remained comparable between the two groups. Analysis of brain monoamines exhibited enhanced serotonergic levels in rat brain following oral intake of walnuts. The findings suggest that walnut may exert its hypophagic and nootropic actions via an enhancement of brain 5-HT metabolism.

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.

Effect of walnut-enriched meat on the relationship between VCAM, ICAM, and LTB4 levels and PON-1 activity in ApoA4 360 and PON-1 allele carriers at increased cardiovascular risk

BACKGROUND/OBJECTIVE

Cardiovascular risk depends largely on paraoxonase (PON-1) and apolipoprotein A4 (APOA4) gene polymorphisms. To compare the effects of consumption of walnut-enriched meat versus low-fat meat (LM) on selected soluble adhesion molecules and leukotrienes (LTB4).

SUBJECTS/METHODS

In all 22 subjects at increased cardiovascular risk were taken. It is a non-blinded, cross-over, placebo-controlled study. Two 5-week experimental periods separated by 4-6 week wash-out interval. Participants consumed walnut-enriched meat during one period and LM during the other. Diet characteristics, HDLc, Apo A1, paraoxonase, sVCAM-1, sICAM-1 and LTB4 were analysed. PON-1 55, PON-1 192 and APOA4 360 polymorphism effects were also assessed.

RESULTS

Individuals consuming walnut-enriched meat displayed higher paraoxonase activity (P<0.001), lower levels of sICAM and aVCAM (P=0.046, P=0.012, respectively) and leukotriene B4 (P=0.044), and lower paraoxonase-1/HDLc and paraoxonase-1/Apo A1 ratios (both, P<0.001) than those consuming LM. Paraoxonase levels correlated negatively with those of sICAM (r=-0.471, P<0.01). Significant decreases (at least P<0.05) were observed in sICAM concentrations in PON-1 55LM+MM, PON-1 QQ192 and APOA4-2 carriers while decreases in sVCAM in QR+RR and APOA4-1 carriers were observed. Paraoxonase-1/HDLc and paraoxonase-1/Apo A1 ratios were significantly influenced by paraoxonase polymorphisms.

CONCLUSIONS

Walnut-enriched meat appears as a functional meat as consumed in the framework of a mix diet lowered the concentration of some selected inflammatory chemoattractant biomarkers. This effect was largely influenced by PON-1 and Apo A4-360 polymorphisms.

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.

Pulse consumption, satiety, and weight management

The prevalence of obesity has reached epidemic proportions, making finding effective solutions to reduce obesity a public health priority. One part of the solution could be for individuals to increase consumption of nonoilseed pulses (dry beans, peas, chickpeas, and lentils), because they have nutritional attributes thought to benefit weight control, including slowly digestible carbohydrates, high fiber and protein contents, and moderate energy density. Observational studies consistently show an inverse relationship between pulse consumption and BMI or risk for obesity, but many do not control for potentially confounding dietary and other lifestyle factors. Short-term (≤1 d) experimental studies using meals controlled for energy, but not those controlled for available carbohydrate, show that pulse consumption increases satiety over 2-4 h, suggesting that at least part of the effect of pulses on satiety is mediated by available carbohydrate amount or composition. Randomized controlled trials generally support a beneficial effect of pulses on weight loss when pulse consumption is coupled with energy restriction, but not without energy restriction. However, few randomized trials have been conducted and most were short term (3-8 wk for whole pulses and 4-12 wk for pulse extracts). Overall, there is some indication of a beneficial effect of pulses on short-term satiety and weight loss during intentional energy restriction, but more studies are needed in this area, particularly those that are longer term (≥1 y), investigate the optimal amount of pulses to consume for weight control, and include behavioral elements to help overcome barriers to pulse consumption.

Cytoprotection by almond skin extracts or catechins of hepatocyte cytotoxicity induced by hydroperoxide (oxidative stress model) versus glyoxal or methylglyoxal (carbonylation model)

Oxidative and carbonyl stress are detrimental in the pathogenesis of diabetic complications, as well as in other chronic diseases. However, this process may be decreased by dietary bioactive compounds. Almond skin is an abundant source of bioactive compounds and antioxidants, including polyphenolic flavonoids, which may contribute to the decrease in oxidative and carbonyl stress. In this study, four Almond Skin Extracts (ASEI, ASEII, ASEIII, and ASEIV) were prepared by different methods and evaluated for their antioxidant activity. The order of the polyphenol content (total muM gallic acid equivalents) of the four extracts was found to be, in decreasing order of effectiveness: ASEI>ASEIII>ASEIV>ASEII. The order of Ferric-reducing antioxidant power (FRAP, microM FeSO(4)/g) value, in decreasing order was ASEI (216)>ASEIII (176)>ASEIV (89)>ASEII (85). The order of ASE effectiveness for decreasing protein carbonyation induced by the copper Fenton reaction was ASEI>ASEIV>ASEII>ASEIII. The order of antioxidant effectiveness for inhibiting tertiary-butyl hydroperoxide (TBH) induced microsomal lipid peroxidation was ASEI>ASEIV>ASEII, ASEIII. Also, the order of ASE effectiveness for inhibiting TBH induced hepatocyte cell death was: ASEIII, ASEIV>ASEI, ASEII. Catechin also protected hepatocytes from TBH induced hepatocyte, lipid peroxidation and cytotoxicity. In a cell free model, equimolar concentrations of catechin or epicatechin rescued serum albumin from protein carbonylation induced by methylglyoxal (MGO). Catechin, epicatechin and ASEI all decreased gloxal induced hepatocyte cell death and reactive oxygen species (ROS) formation in GSH-depleted hepatocytes. Catechin and epicatechin protected against GO or MGO induced hepatocyte cell death, protein carbonylation and ROS formation. Catechin was more effective than epicatechin. Our results suggest that (a) bioactive almond skin constituents in the non-lipophilic polyphenol extract were the most effective at protecting hepatocytes against hydroperoxide induced hepatocyte oxidative stress and in protecting against dicarbonyl induced cytotoxicity; (b) catechins, the major polyphenol in the extract, were also effective at preventing GO or MGO cytotoxicity likely by trapping GO and MGO and/or rescuing hepatocytes from protein carbonylation.

Mediterranean diet and metabolic syndrome: the evidence

BACKGROUND

The Mediterranean diet has long been related to a lower cardiovascular disease risk; however, more recent evidences also indicate that it has a favourable effect on adiposity and type 2 diabetes.

DESIGN

Review of the available literature in relation to Mediterranean diet and metabolic syndrome.

RESULTS

Several components of Mediterranean diet patterns have been inversely related with body mass index. They are considered to be modulators of insulin resistance, can exert beneficial effects on blood pressure, improve atherogenic dyslipidemia or attenuate the inflammatory burden associated with metabolic syndrome. Furthermore, a lower prevalence of metabolic syndrome has been associated with dietary patterns rich in fruits and vegetables, nuts, olive oil, legumes and fish, moderate in alcohol and low in red meat, processed meat, refined carbohydrates and whole-fat dairy products.

CONCLUSIONS

There is much evidence suggesting that the Mediterranean diet could serve as an anti-inflammatory dietary pattern, which could help to fight diseases related to chronic inflammation, including metabolic syndrome.

Effects of walnut consumption on blood lipids and other cardiovascular risk factors: a meta-analysis and systematic review

BACKGROUND

Consumption of nuts has been associated with a decreased risk of cardiovascular disease events and death. Walnuts in particular have a unique profile: they are rich in polyunsaturated fatty acids, which may improve blood lipids and other cardiovascular disease risk factors.

OBJECTIVES

We aimed to conduct a literature review and a meta-analysis to combine the results from several trials and to estimate the effect of walnuts on blood lipids.

DESIGN

Literature databases were searched for published trials that compared a specifically walnut-enhanced diet with a control diet. We conducted a random-effects meta-analysis of weighted mean differences (WMDs) of lipid outcomes.

RESULTS

Thirteen studies representing 365 participants were included in the analysis. Diets lasted 4-24 wk with walnuts providing 10-24% of total calories. When compared with control diets, diets supplemented with walnuts resulted in a significantly greater decrease in total cholesterol and in LDL-cholesterol concentrations (total cholesterol: WMD = -10.3 mg/dL, P < 0.001; LDL cholesterol: WMD = -9.2 mg/dL, P < 0.001). HDL cholesterol and triglycerides were not significantly affected by walnut diets more than with control diets (HDL cholesterol: WMD = -0.2, P = 0.8; triglycerides: WMD = -3.9, P = 0.3). Other results reported in the trials indicated that walnuts provided significant benefits for certain antioxidant capacity and inflammatory markers and had no adverse effects on body weight [body mass index (kg/m(2)): WMD = -0.4, P = 0.5; weight (kg): WMD = -0.05, P = 0.97].

CONCLUSIONS

Overall, high-walnut-enriched diets significantly decreased total and LDL cholesterol for the duration of the short-term trials. Larger and longer-term trials are needed to address the effects of walnut consumption on cardiovascular risk and body weight.

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.

Acute effects of three high-fat meals with different fat saturations on energy expenditure, substrate oxidation and satiety

BACKGROUND & AIMS

To compare the acute effects of three fatty meals with different fat quality on postprandial thermogenesis, substrate oxidation and satiety.

METHODS

Twenty-nine healthy men aged between 18 and 30 years participated in a randomised crossover trial comparing the thermogenic effects of three isocaloric meals: high in polyunsaturated fatty acids from walnuts, high in monounsaturated fatty acids from olive oil, and high in saturated fatty acids from fat-rich dairy products. Indirect calorimetry was used to determine resting metabolic rate, respiratory quotient, 5-h postprandial energy expenditure and substrate oxidation. Satiety was estimated by using visual analogue scales and measuring caloric intake in a subsequent ad libitum meal.

RESULTS

Five-h postprandial thermogenesis was higher by 28% after the high-polyunsaturated meal (p=0.039) and by 23% higher after the high-monounsaturated meal (p=0.035) compared with the high-saturated meal. Fat oxidation rates increased nonsignificantly after the two meals rich in unsaturated fatty acids and decreased nonsignificantly after the high-saturated fatty acid meal. Postprandial respiratory quotient, protein and carbohydrate oxidation, and satiety measures were similar among meals.

CONCLUSIONS

Fat quality determined the thermogenic response to a fatty meal but had no clear effects on substrate oxidation or satiety.

Nuts, body weight and insulin resistance

Traditionally, nuts have been considered a staple food, but because of their high energy and fat content are not considered good for body weight control or insulin sensitivity. Frequent consumption of nuts reduces the risk of coronary artery disease and type-2 diabetes and nut-enriched diets favourably alter blood lipids in normal and hypercholesterolemic individuals under controlled and free-living dietary conditions. However, whether or not frequent consumption of nuts can cause weight gain and impair insulin sensitivity is not fully understood. Review of the available data to date suggests that adding nuts to habitual diets of free-living individuals does not cause weight gain. In fact, nuts have a tendency to lower body weight and fat mass. In the context of calorie-restricted diets, adding nuts produces a more lasting and greater magnitude of weight loss among obese subjects while improving insulin sensitivity. Further studies are needed to clarify the effect of long-term (>/= year) consumption of nuts on body weight and their role in altering insulin sensitivity both in normal and type-2 diabetics. In the meantime, there is sufficient evidence to promote the inclusion of nuts as part of healthy diets.

Nuts: source of energy and macronutrients

On the basis of the high fat content of nuts, they are traditionally considered as foods that provide a high amount of energy. However, epidemiologic and clinical observations do not indicate an association between nut intake and increased BMI. There is a notorious variability in macronutrient composition among nuts, although they have some consistent patterns. Nuts contain all major macronutrients: protein, carbohydrate, and fat. The total protein content is relatively high, which makes them a good source of plant protein (especially for vegetarians). Although nuts contain low amounts of some essential amino acids, this is not a nutritional concern due to the complement of protein. In addition, nuts have a low lysine:arginine ratio, which is inversely associated with the risk of developing hypercholesterolemia and atherosclerosis. Carbohydrates are the second highest macronutrient in nuts in terms of total calories provided. The fat fraction is characterized by a high amount of unsaturated fatty acids and a low content of saturated fatty acids. In conclusion, the high content in unsaturated fatty acids, the low lysine:arginine ratio, and the presence of other bioactive molecules (such as fibre, phytosterols, vitamin and other antioxidants, and minerals) make the addition of nuts to healthy diets a useful tool for the prevention of cardiovascular heart diseases.

Effect of Walnut-Enriched Restructured Meat in the Antioxidant Status of Overweight/Obese Senior Subjects with at Least One Extra CHD-Risk Factor

BACKGROUND

A number of recent studies indicate that antioxidants reduce the oxidative stress associated with the development of coronary heart diseases (CHD).

OBJECTIVE

(i) To investigate whether the erythrocyte catalase (CAT), superoxide dismutase (SOD), total glutathione, reduced glutathione (GSH), oxidized glutathione (GSSG), and lipid peroxidation (LPO), and serum uric acid and paraoxonase-1 (PON1) are modified at increased CHD-risk individuals consuming walnut-enriched meat (WM), (ii) to evaluate whether these changes were influenced by basal serum cholesterol, body mass index or smoking habit.

DESIGN

The study was a non blinded, cross-over, placebo-controlled trial in which 22 volunteers (60% overweight and 40% obese) with increased CHD-risk were randomly assigned to receive WM or control meat (CM) during two different periods of 5 weeks.

RESULTS

A significant interaction time*treatment (p < 0.05) was observed in all enzymes and substrates tested except HDL-C, uric acid and LPO. The treatment significantly increased CAT activity, total glutathione and GSSG (p < 0.05). Significant gender*time*treatment interaction (p = 0.043) for total glutathione was found increasing at the end of the WM period in male but not changing in female. Total glutathione and GSH/GSSG ratio (p < 0.05) were lower in smokers. Hypercholesterolemics presented higher uric acid (p < 0.05) but no enzyme activities or substrate concentrations were different from those of normocholesterolemics.

CONCLUSIONS

The WM tested appears to be a functional food as it improved the antioxidant status of increased CHD-risk volunteers. Despite its high energy content, it also appears adequate for overweight and obese people because did not exert negative effect upon body weight.

The effects of high walnut and cashew nut diets on the antioxidant status of subjects with metabolic syndrome

BACKGROUND

Nut consumption is associated with a protective effect against coronary heart disease, partly due to its high antioxidant content. It is hypothesized that the inclusion of nuts in the diet will improve the antioxidant status of subjects with metabolic syndrome who may be vulnerable to impaired antioxidant status.

AIM

The effects of high cashew nut and high walnut diets on the antioxidant status of subjects with metabolic syndrome are investigated.

METHODOLOGY

Sixty-four volunteers (29 male and 35 female, 45 +/- 10y) with metabolic syndrome (diagnosed by using the ATP III criteria) received a prudent control diet, prepared in the metabolic kitchen of the North-West University, Potchefstroom campus (NWU-PC) for a period of 3 weeks (run-in). The participants were grouped according to gender and age and randomized into three groups, receiving either the walnut, cashew nut or the control diets for 8 weeks, while maintaining a stable body weight. Nuts provided 20% of daily energy intake. Fasting blood samples were taken after the run-in period (baseline) and at the end of the intervention period and analyzed for various antioxidant capacity markers.

RESULTS

The oxygen radical absorbance capacity (ORAC) of the walnut and cashew nut diets were significantly higher than the control diet. Despite this, the walnut and cashew nut diets had no significant effects on serum ORAC, reduced (GSH), oxidized (GSSG) glutathione, GSH:GSSG or diacron reactive metabolites (dRom) (total oxidant status) levels compared to the control group. However, all three groups showed significant improvements in antioxidant status from baseline to end (GSSG and dRom levels decreased; GSG:GSSG ratio and ORAC levels increased). This may be due to a general increased antioxidant intake from the prudent diet compared to the habitual diets.

CONCLUSION

Although the inclusion of walnuts and cashew nuts into a prudent diet resulted in an increased antioxidant capacity (ORAC) of the nut diets, compared to the control diet, it did not improve the serum antioxidant profiles of subjects with metabolic syndrome.

Edible nuts and metabolic health

PURPOSE OF REVIEW

This review summarizes evidence for metabolic health benefits of tree nuts and groundnuts (peanuts). While a role for nuts in the dietary management of LDL-cholesterol is well established, it is evident that regular consumption of nuts may also help to counteract other cardiovascular and metabolic risk factors.

RECENT FINDINGS

Nuts are not only energy dense foods, they are rich sources of monounsaturated and polyunsaturated fatty acids and other bioactive nutrients with important metabolic effects. Contrary to expectations, epidemiological studies indicate that regular consumption of nuts is unlikely to contribute to obesity or increased risk of diabetes. In fact, it may help to regulate body weight by suppressing appetite and fat absorption. Nut consumption counteracts dyslipidemia and has the capacity to improve circulatory function through the actions of multiple constituents (arginine, polyphenols) on endothelial mechanisms.

SUMMARY

Nuts are densely packaged nutrients with wide-ranging cardiovascular and metabolic benefits, which can be readily incorporated in healthy diets. Their potential role in counteracting obesity and the metabolic syndrome warrants further investigation.

Nut consumption and weight gain in a Mediterranean cohort: The SUN study

OBJECTIVE

To assess the association, in a Mediterranean population, between nut consumption and risk of weight gain (at least 5 kg) or the risk of becoming overweight/obese.

RESEARCH METHODS AND PROCEDURES

The Seguimiento Universidad de Navarra project is a prospective cohort of 8865 adult men and women who completed a follow-up questionnaire after a median of 28 months. Dietary habits were assessed with a previously validated semiquantitative food-frequency questionnaire.

RESULTS

Nine hundred thirty-seven participants reported a weight gain of > or =5 kg at follow-up. After adjusting for age, sex, smoking, leisure time physical activity, and other known risk factors for obesity, participants who ate nuts two or more times per week had a significantly lower risk of weight gain (odds ratio: 0.69; 95% confidence interval: 0.53 to 0.90, p for trend = 0.006) than those who never or almost never ate nuts. Participants with little nut consumption (never/almost never) gained an average of 424 grams (95% confidence interval: 102 to 746) more than frequent nut eaters. Nut consumption was not significantly associated with incident overweight/obesity in the cohort.

DISCUSSION

Frequent nut consumption was associated with a reduced risk of weight gain (5 kg or more). These results support the recommendation of nut consumption as an important component of a cardioprotective diet and also allay fears of possible weight gain.

The altered homeostatic theory: A hypothesis proposed to be useful in understanding and preventing ischemic heart disease, hypertension, and diabetes – including reducing the risk of age and atherosclerosis

Evidence will be presented to support the usefulness of the altered homeostatic theory in understanding basic pathogenetic mechanisms of ischemic heart disease (IHD), hypertension, and diabetes, and in improving prevention of these disorders. The theory argues that: IHD, hypertension, and diabetes share the same basic pathogenesis; risk factors favor a sympathetic homeostatic shift; preventative factors favor a parasympathetic homeostatic shift; risk and preventative factors oppose each other through a dynamic risk/prevention balance; and prevention should be based on improving the risk/prevention balance. Prevention based on improving the risk/prevention balance should be more effective, as this method is regarded as reflecting more accurately basic pathogenetic mechanisms. As example, the theory argues that the risk of supposedly nonmodifiable risk factors as age and the risk of relatively nonmodifiable atherosclerosis can be reduced significantly. The possible validity of the altered homeostatic theory was tested by a study based on multiple associations. Findings support a common pathogenesis for IHD, hypertension, and diabetes based on a sympathetic homeostatic shift, and the usefulness of prevention based on improving the risk/prevention balance by using standard pharmaceutical and lifestyle preventative measures. The same set of multiple and diverse risk factors favored IHD, hypertension, and diabetes, and the same set of multiple and diverse pharmaceutical and lifestyle preventative measures prevented these disorders. Also, the same set of preventative agents generally improved cognitive function and bone density, and reduced the incidence of Alzheimer's disease, atrial fibrillation, and cancer. Unexpectedly, evidence was developed that four major attributes of sympathetic activation represent four major risk factors; attributes of sympathetic activation are a tendency toward thrombosis and vasoconstriction, lipidemia, inflammation, and hyperglycemia, and corresponding risk factors are endothelial dysfunction (which expresses thrombosis/vasoconstriction and epitomizes this tendency), dyslipidemia, inflammation, and insulin resistance. These findings, plus other information, provide evidence that dyslipidemia acts mainly as a marker of risk of IHD, rather than being the basic mechanism of this disorder. However, prevention generally is based solely on improvement of dyslipidemia; basing prevention on dyslipidemia relatively underemphasizes the importance of other significant risk factors and, by certifying its validity, discourages alternate pathogenetic approaches. Also, development of myocardial infarction is approached differently. It seems generally accepted that dyslipidemia results rather automatically in infarction through the sequence of atherosclerosis, atherosclerotic complications, and thrombosis. In contrast, distinction is made between development of atherosclerosis and acute induction of infarction--where atherosclerosis is only one of multiple risk factors.

Dietary fibre, nuts and cardiovascular diseases

Dietary fibre has a range of metabolic health benefits. Through a variety of mechanisms, dietary fibre, and the viscous variety in particular, slows down gastric emptying and intestinal transit, decreases the rate of intestinal carbohydrate absorption, and increases faecal bile acid excretion. Therefore, consumption of some types of soluble fibre can enhance satiety, which is associated with a lower BMI, and reduce blood cholesterol and the postprandial glucose response. Surprisingly, the consumption of insoluble fibre from whole grains, though metabolically inert, has been associated with a reduction in the risk of developing coronary heart disease and diabetes in epidemiological studies. The likely reason is that whole grains, like nuts, legumes and other edible seeds, contain many bioactive phytochemicals and various antioxidants. After cereals, nuts are the vegetable foods that are richest in fibre, which may partly explain their benefit on the lipid profile and cardiovascular health.

Effects of a Mediterranean-style diet on cardiovascular risk factors: a randomized trial

BACKGROUND

The Mediterranean diet has been shown to have beneficial effects on cardiovascular risk factors.

OBJECTIVE

To compare the short-term effects of 2 Mediterranean diets versus those of a low-fat diet on intermediate markers of cardiovascular risk.

DESIGN

Substudy of a multicenter, randomized, primary prevention trial of cardiovascular disease (Prevención con Dieta Mediterránea [PREDIMED] Study).

SETTING

Primary care centers affiliated with 10 teaching hospitals.

PARTICIPANTS

772 asymptomatic persons 55 to 80 years of age at high cardiovascular risk who were recruited from October 2003 to March 2004.

INTERVENTIONS

Participants were assigned to a low-fat diet (n = 257) or to 1 of 2 Mediterranean diets. Those allocated to Mediterranean diets received nutritional education and either free virgin olive oil, 1 liter per week (n = 257), or free nuts, 30 g/d (n = 258). The authors evaluated outcome changes at 3 months.

MEASUREMENTS

Body weight, blood pressure, lipid profile, glucose levels, and inflammatory molecules.

RESULTS

The completion rate was 99.6%. Compared with the low-fat diet, the 2 Mediterranean diets produced beneficial changes in most outcomes. Compared with the low-fat diet, the mean changes in the Mediterranean diet with olive oil group and the Mediterranean diet with nuts group were -0.39 mmol/L (95% CI, -0.70 to -0.07 mmol/L) and -0.30 mmol/L (CI, -0.58 to -0.01 mmol/L), respectively, for plasma glucose levels; -5.9 mm Hg (CI, -8.7 to -3.1 mm Hg) and -7.1 mm Hg (CI, -10.0 to -4.1 mm Hg), respectively, for systolic blood pressure; and -0.38 (CI, -0.55 to -0.22) and - 0.26 (CI, -0.42 to -0.10), respectively, for the cholesterol-high-density lipoprotein cholesterol ratio. The Mediterranean diet with olive oil reduced C-reactive protein levels by 0.54 mg/L (CI, 1.04 to 0.03 mg/L) compared with the low-fat diet.

LIMITATIONS

This short-term study did not focus on clinical outcomes. Nutritional education about low-fat diet was less intense than education about Mediterranean diets.

CONCLUSION

Compared with a low-fat diet, Mediterranean diets supplemented with olive oil or nuts have beneficial effects on cardiovascular risk factors.

Walnuts and dietary approaches to the prevention and management of abnormal lipid profiles in Type 2 diabetes mellitus

Type 2 diabetes mellitus is associated with an increased risk of coronary heart disease, reflected in the presence of abnormal lipid profiles. Increasing the intake of polyunsaturated fat at the same time as reducing saturated fat can alleviate these risk factors. Including walnuts in a ‘whole of diet’ approach to managing fat consumption can help to ensure that the desired fatty acid profile is achieved. This comes via a food matrix that also delivers anti-oxidants, fibre and protein that may provide additional nutritional benefits. Thus there is good reason to include walnuts in dietary advice for patients with Type 2 diabetes mellitus.

The impact of nuts on diabetes and diabetes risk

Nuts have many nutritional benefits: they are high in monounsaturated and polyunsaturated fats, fiber, vitamin, minerals, and phytonutrients. Population studies indicate that individuals who regularly consume nuts have reduced risk for cardiovascular disease and diabetes. In clinical trials, nuts appear to have a neutral effect on glucose and insulin, and a beneficial effect on lipid profile. Thus, nuts can be a healthy dietary component for individuals with diabetes or those at risk for diabetes, providing overall caloric intake is regulated to maintain a healthy body weight.