Ritter, M.M.C., G.P. Savage, 2007. Soluble and insoluble oxalate content of nuts. Journal of Food Composition and Analysis. 20:169-174.
This study was conducted to determine the oxalate contents in common nuts either locally grown or imported into New Zealand. Samples of imported nuts were purchased from supermarkets in Christchurch while locally grown nuts were obtained directly from the growers. In this experiment gastric soluble and intestinal soluble oxalates were extracted from the nuts using an in vitro assay, which involved incubations of the food samples for 2 h at 37 1C in gastric and intestinal juice. The extracted oxalates were then determined by HPLC chromatography. Roasted pistachio nuts and chestnuts contained very low levels (<85 mg/100 g fresh weight (FW)) of gastric soluble oxalate. Peanuts, Spanish peanuts, peanut butter, ginkgo, cashew nuts and pecan nuts all contained relatively low levels of gastric soluble oxalate (147–250 mg gastric soluble oxalate/100 g FW). Almonds, Brazil, pine and candle nuts contained high levels of gastric soluble oxalate (492.0–556.8 mg/100 g FW). The intestinal soluble oxalate is the fraction that will be absorbed in the small intestine. Peanuts, Spanish peanuts, peanut butter, ginkgo and pecan nuts all contained relatively low levels of intestinal soluble oxalate (129–173 mg intestinal soluble oxalate/100 g FW). Almonds, Brazil, cashew and candle nuts contained higher levels of intestinal soluble oxalate (216–305 mg/100 g FW). Pine nuts contained the highest levels of intestinal soluble oxalate (581 mg/100 g FW), while chestnuts and roasted pistachio nuts were low (72 and 77 mg /100 g FW). Overall the mean soluble oxalate content of nuts was 78% of the gastric soluble oxalate content (41–100%). The results obtained in this study confirm that the intestinal soluble oxalate contents of nuts range widely and people who have a tendency to form kidney stones would be wise to moderate their consumption of certain nuts.
Davis, L., W. Stonehouse, D.T. Loots, J. Mukuddem-Petersen, F.H. van der Westhuizen, S.M. Hanekom, J.C. Jerling, 2007. The effects of high walnut and cashew nut diets on the antioxidant status of subjects with metabolic syndrome. Eur J Nutr. 46:155-164.
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 and35 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.
Simon J., J. Sabaté, J. Tanzman, 2007. Lack of effect of walnut on serum levels of prostate specific antigen: A brief report. AJCN. 26; 4; 317-320.
Objective: To examine whether the short-term consumption of walnuts, a food rich in α-linolenic acid, affects levels of serum prostate-specific antigen (PSA), a marker of prostate enlargement, inflammation, and cancer. Methods: Using data from a 12-month randomized crossover study examining the effect of walnut consumption on body composition, we examined whether increased walnut consumption (mean 35 grams daily, 12% total energy) affected serum PSA levels among 40 middle-aged men. Results: There was no significant difference between mean PSA level at the conclusion of the 6-month walnut-supplemented diet (1.05 μg/L, 95% CI [0.81, 1.37]) and the conclusion of the 6-month control diet (1.06 μg/L, 95% CI [0.81, 1.38]) (P = 0.86) (or a mean proportional decrease in PSA of -1%). Conclusions: Our results suggest that short-term consumption of walnuts is unlikely to affect PSA levels adversely among otherwise normal men.
Griel A.E., P.M. Kris-Etherton, K.F. Hilpert, G. Zhao, S.G. West, R.L. Corwin, 2007. An increase in dietary n-3 fatty acids improves bone health in humans. Nutrition Journal. 6:2.
Human, animal, and in vitro research indicates a beneficial effect of appropriate amounts of omega-3 (n-3) polyunsaturated fatty acids (PUFA) on bone health. This is the first controlled feeding study in humans to evaluate the effect of dietary plant-derived n-3 PUFA on bone turnover, assessed by serum concentrations of N-telopeptides (NTx) and bone-specific alkaline phosphatase (BSAP). Twenty-three subjects consumed each diet for 6 weeks in a randomized, 3-period crossover design: 1) Average American Diet (AAD; [34% total fat, 13% saturated fatty acids (SFA), 13% monounsaturated fatty acids (MUFA), 9% PUFA (7.7% LA, 0.8% ALA)]), 2) Linoleic Acid Diet (LA; [37% total fat, 9% SFA, 12% MUFA, 16% PUFA (12.6% LA, 3.6% ALA)]), and 3) α-Linolenic Acid Diet (ALA; [38% total fat, 8% SFA, 12% MUFA, 17% PUFA (10.5% LA, 6.5% ALA)]). Walnuts and flaxseed oil were the predominant sources of ALA. NTx levels were significantly lower following the ALA diet (13.20 ± 1.21 nM BCE), relative to the AAD (15.59 ± 1.21 nM BCE) (p < 0.05). Mean NTx level following the LA diet was 13.80 ± 1.21 nM BCE. There was no change in levels of BSAP across the three diets. Concentrations of NTx were positively correlated with the proinflammatory cytokine TNFα for all three diets. The results indicate that plant sources of dietary n-3 PUFA may have a protective effect on bone metabolism via a decrease in bone resorption in the presence of consistent levels of bone formation.
Fitó, M., M. Guxens, D. Corella, G. Sáez, R. Estruch, R. de la Torre, F. Francés, C. Cabezas, M. del C. López-Sabaterl, J. Marrugat, A. García-Arellano, F. Arós, V. Ruiz-Gutierrez, E. Ros, J. Salas-Salvadó, M. Fiol, R. Solá, M.I. Covas; for the PREDIMED Study, 2007. Effect of a traditional Mediterranean diet on lipoprotein oxidation: a randomized controlled trial. Arch Intern Med. 167:1195-203.
Background: Despite the richness in antioxidants of the Mediterranean diet, to our knowledge, no randomized controlled trials have assessed its effect on in vivo lipoprotein oxidation. Methods: A total of 372 subjects at high cardiovascular risk (210 women and 162 men; age range, 55-80 years), who were recruited into a large, multicenter, randomized, controlled, parallel-group clinical trial (the Prevencio’n con Dieta Mediterra’nea [PREDIMED] Study) directed at testing the efficacy of the traditional Mediterranean diet (TMD) on the primary prevention of coronary heart disease, were assigned to a low-fat diet (n=121) or one of 2 TMDs (TMD + virgin olive oil or TMD + nuts). The TMD participants received nutritional education and either free virgin olive oil for all the family (1 L/wk) or free nuts (30 g/d). Diets were ad libitum. Changes in oxidative stress markers were evaluated at 3 months. Results: After the 3-month interventions, mean (95% confidence intervals) oxidized low-density lipoprotein (LDL) levels decreased in the TMD + virgin olive oil (−10.6 U/L [−14.2 to −6.1]) and TMD + nuts (−7.3 U/L [−11.2 to −3.3]) groups, without changes in the low-fat diet group (−2.9 U/L [−7.3 to 1.5]). Change in oxidized LDL levels in the TMD + virgin olive oil group reached significance vs that of the low-fat group (P=.02). Malondialdehyde changes in mononuclear cells paralleled those of oxidized LDL. No changes in serum glutathione peroxidase activity were observed. Conclusions: Individuals at high cardiovascular risk who improved their diet toward a TMD pattern showed significant reductions in cellular lipid levels and LDL oxidation. Results provide further evidence to recommend the TMD as a useful tool against risk factors for CHD.
Davis, P., G. Valacchi, E. Pagnin, Q. Shao, H.B. Gross, L. Calo, W. Yokoyama, 2006. Walnuts reduce aortic ET-1 mRNA levels in hamsters fed a high-fat, atherogenic diet. J. Nutr. 136(2):428-32
Walnut consumption is associated with reduced coronary vascular disease (CVD) risk; however, the mechanisms responsible remain incompletely understood. Recent clinical studies suggested that these mechanisms involve nonplasma lipid related effects on endothelial function. Male Golden Syrian hamsters (12 groups, n ý 10ý15) were fed for 26 wk atherosclerotic, high-fat, hyperlipidemic diets with increasing concentrations of whole walnuts (61ý150 g/kg diet), or a-tocopherol (a-T, 8.1ý81 mg/kg diet) and single diets with either walnut oil (32 g/kg diet) or pure g-tocopherol (g-T; 81 mg/kg diet) added. Aortic endothelin 1 (ET-1), an important endothelial regulator, was assayed as mRNA. Aortic cholesterol ester (CE) concentration along with other vascular stress markers (Cu/Zn and Mn superoxide dismutase, biliverdin reductase) and plasma lipid concentrations were determined. Hyperlipidemia (plasma LDL cholesterol ;6 times normal) occurred in all groups. Aortic CE concentration, a measure of atherosclerotic plaque, was highest in the lowest a-T only group and declined significantly with increasing a-T. The aortic CE of all walnut groups was decreased significantly relative to the lowest a-T only group but showed no dose response. The diets did not produce changes in the other vascular stress markers, whereas aortic ET-1 mRNA levels declined dramatically with increasing dietary walnuts (to a 75% reduction in the highest walnut content group compared with the lowest a-T group) but were unaltered in the a-T groups or g-T group. The study results are consistent with those of human walnut feeding studies and suggest that the mechanisms underlying those results are mediated in part by ET-1ýdependent mechanisms. The contrasting results between the a-tocopherol or g-tocopherol diets and the walnut diets also make it unlikely that the nonplasma lipid related CVD effects of walnuts are due to their a-tocopherol or g-tocopherol content. Finally, the results indicate that the walnut fat compartment is a likely location for the components responsible for the reduced aortic CE concentration. This study was designed to determine the mechanisms behind walnuts’ ability to reduce coronary vascular disease risk. Male Golden Syrian hamsters fed high-fat, hyperlipidemic diets supplemented with either walnuts; alpha-tocopherol, a form of vitamin E; walnut oil; or gamma-tocopherol, the form of vitamin E found in walnuts. Hamsters fed the walnut supplemented diet had the greatest reduction in aortic endothelin, an endothelial cell regulator, and the lowest concentration of aortic cholesterol ester, a measure of arterial plaque development.
Cortés, B., I. Núñez, M. Cofán, R. Gilabert, A. Pérez-Heras, E. Casals, R. Deulofeu, E. Ros, 2006. Acute effects of high-fat meals enriched with walnuts or olive oil on postprandial endothelial function. J Am Coll Cardiol. 48:1666 -71.
Objectives: We sought to investigate whether the addition of walnuts or olive oil to a fatty meal have differential effects on postprandial vasoactivity, lipoproteins, markers of oxidation and endothelial activation, and plasma asymmetric dimethylarginine (ADMA). Background: Compared with a Mediterranean diet, a walnut diet has been shown to improve endothelial function in hypercholesterolemic patients. We hypothesized that walnuts would reverse postprandial endothelial dysfunction associated with consumption of a fatty meal. Methods: We randomized in a crossover design 12 healthy subjects and 12 patients with hypercholesterolemia to 2 high-fat meal sequences to which 25 g olive oil or 40 g walnuts had been added. Both test meals contained 80 g fat and 35% saturated fatty acids, and consumption of each meal was separated by 1 week. Venipunctures and ultrasound measurements of brachial artery endothelial function were performed after fasting and 4 h after test meals. Results: In both study groups, flow-mediated dilation (FMD) was worse after the olive oil meal than after the walnut meal (p = 0.006, time-period interaction). Fasting, but not postprandial, triglyceride concentrations correlated inversely with FMD (r = -0.324; p = 0.024). Flow independent dilation and plasma ADMA concentrations were unchanged, and the concentration of oxidized low-density lipoproteins decreased (p = 0.051) after either meal. The plasma concentrations of soluble inflammatory cytokines and adhesion molecules decreased (p < 0.01) independently of meal type, except for E-selectin, which decreased more (p = 0.033) after the walnut meal. Conclusions: Adding walnuts to a high-fat meal acutely improves FMD independently of changes in oxidation, inflammation, or ADMA. Both walnuts and olive oil preserve the protective phenotype of endothelial cell
Wu, X., Beecher, G.R., Holden, J.M., Haytowitz, D.B., Gebhardt, S.E., R.L. Prior, 2006. Concentrations of anthocyanins in common foods in the United States and estimation of normal consumption. J. Agric. Food Chem. 54:4069-75.
Anthocyanins (ACNs) are water-soluble plant pigments that have important functions in plant physiology as well as possible health effects. Over 100 common foods were screened for ACNs, and 24 of them were found to contain ACNs. Concentrations of total ACNs varied considerably from 0.7 to 1480 mg/100 g of fresh weight in gooseberry (‘Careless’ variety) and chokeberry, respectively. Not only does the concentration vary, but the specific anthocyanins present in foods are also quite different. Only six common aglycones, delphinidin, cyanidin, petunidin, pelargonidin, peonidin, and malvidin, were found in all of these foods. However, their sugar moieties and acylation patterns varied from food to food. Results from this study will add to the available data for the USDA Nutrient Database of flavonoids. On the basis of the concentration data and updated food intake data from NHANES 2001-2002, the daily intake of ACNs is estimated to be 12.5 mg/day/person in the United States. Of the different aglycones, cyanidin, delphinidin, and malvidin were estimated to contribute 45, 21, and 15%, respectively, of the total ACN intake. Nonacylated contributed 77% compared to 23% from acylated ACNs.
Venkatachalam, M., S.K. Sathe. 2006. Chemical composition of selected edible nut seeds. J Agric Food Chem. 54, 4705-4714.
Commercially important edible nut seeds were analyzed for chemical composition and moisture sorption. Moisture (1.47-9.51%), protein (7.50-21.56%), lipid (42.88-66.71%), ash (1.16-3.28%), total soluble sugars (0.55-3.96%), tannins (0.01-0.88%), and phytate (0.15-0.35%) contents varied considerably. Regardless of the seed type, lipids were mainly composed of mono- and polyunsaturated fatty acids (>75% of the total lipids). Fatty acid composition analysis indicated that oleic acid (C18:1) was the main constituent of monounsaturated lipids in all seed samples. With the exception of macadamia, linoleic acid (C18:2) was the major polyunsaturated fatty acid. In the case of walnuts, in addition to linoleic acid (59.79%) linolenic acid (C18:3) also significantly contributed toward the total polyunsaturated lipids. Amino acid composition analyses indicated lysine (Brazil nut, cashew nut, hazelnut, pine nut, and walnut), sulfur amino acids methionine and cysteine (almond), tryptophan (macadamia, pecan), and threonine (peanut) to be the first limiting amino acid as compared to human (2-5 year old) amino acid requirements. The amino acid composition of the seeds was characterized by the dominance of hydrophobic (range = 37.16-44.54%) and acidic (27.95-33.17%) amino acids followed by basic (16.16-21.17%) and hydrophilic (8.48-11.74%) amino acids. Trypsin inhibitory activity, hemagglutinating activity, and proteolytic activity were not detected in the nut seed samples analyzed. Sorption isotherms (Aw range = 0.08-0.97) indicated a narrow range for monolayer water content (11-29 mg/g of dry matter). No visible mold growth was evident on any of the samples stored at Aw < 0.53 and 25 °C for 6 months.
Segura, R., C. Javierre, M.A. Lizarraga, E. Ros, 2006. Other relevant components of nuts: phytosterols, folate and minerals. British Journal of Nutrition. 96, Suppl. 2, S36-S44.
Nuts contain significant amounts of essential micronutrients that are associated with an improved health status when consumed at doses beyond those necessary to prevent deficiency states. Nuts do not contain cholesterol, but they are rich in chemically related phytosterols, a class of compounds that interfere with intestinal cholesterol absorption and thus help lower blood cholesterol. Nuts also contain folate, a B-vitamin necessary for normal cellular function that plays an important role in detoxifying homocysteine, a sulphur-containing amino acid with atherothrombotic properties that accumulates in plasma when folate status is subnormal. Compared to other common foodstuffs, nuts have an optimal nutritional density with respect to healthy minerals, such as calcium, magnesium and potassium. Like that of most vegetables, the sodium content of nuts is very low. A high intake of calcium, magnesium and potassium, together with a low sodium intake, is associated with protection against bone demineralization, arterial hypertension, insulin resistance, and overall cardiovascular risk. Phytosterols might justify part of the cholesterol-lowering effect of nut intake beyond that attributable to fatty acid exchange, while the mineral richness of nuts probably contributes to the prevention of diabetes and coronary heart disease observed in epidemiological studies in association with frequent nut consumption.
