Kris-Etherton, P.M., F.B. Hu, E. Ros, J. Sabaté, 2008. The role of tree nuts and peanuts in the prevention of coronary heart disease: multiple potential mechanisms. J Nutr. 138, 1746S-1751.
Epidemiologic and clinical trial evidence has demonstrated consistent benefits of nut and peanut consumption on coronary heart disease (CHD) risk and associated risk factors. The epidemiologic studies have reported various endpoints, including fatal CHD, total CHD death, total CHD, and nonfatal myocardial infarct. A pooled analysis of 4 U.S. epidemiologic studies showed that subjects in the highest intake group for nut consumption had a 35% reduced risk of CHD incidence. The reduction in total CHD death was due primarily to a decrease in sudden cardiac death. Clinical studies have evaluated the effects of many different nuts and peanuts on lipids, lipoproteins, and various CHD risk factors, including oxidation, inflammation, and vascular reactivity. Evidence from these studies consistently shows a beneficial effect on these CHD risk factors. The LDL cholesterol-lowering response of nut and peanut studies is greater than expected on the basis of blood cholesterol-lowering equations that are derived from changes in the fatty acid profile of the diet. Thus, in addition to a favorable fatty acid profile, nuts and peanuts contain other bioactive compounds that explain their multiple cardiovascular benefits. Other macronutrients include plant protein and fiber; micronutrients including potassium, calcium, magnesium, and tocopherols; and phytochemicals such as phytosterols, phenolic compounds, resveratrol, and arginine. Nuts and peanuts are food sources that are a composite of numerous cardioprotective nutrients and if routinely incorporated in a healthy diet, population risk of CHD would therefore be expected to decrease markedly.
Djoussé, L., T. Rudich, J.M. Gaziano, 2008. Nut consumption and risk of heart failure in the Physicians’ Health Study I. Am J Clin Nutr. 88:930 -3.
Background: Heart failure is highly prevalent among older adults and is associated with high cost and societal burden. Although previous studies have reported beneficial effects of dietary factors on heart failure predictors, no previous study has examined whether frequent consumption of nuts is associated with a lower risk of heart failure in a large prospective cohort. Objective: We examined the association between nut consumption and incident heart failure to determine whether such a relation is modified by overweight or obesity. Design: This was a prospective cohort study of 20 976 participants from the Physicians’ Health Study I. Nut consumption was assessed with a simple abbreviated food questionnaire, and self-reported heart failure was ascertained by follow-up questionnaires. We used Cox regression to estimate relative risks of heart failure. Results: After an average follow-up of 19.6 y, 1093 new cases of heart failure occurred. Nut consumption was not associated with the risk of developing heart failure in this cohort: multivariable adjusted hazard ratios were 1.0 (reference), 0.98 (95% CI: 0.83, 1.15), 1.06 (95% CI: 0.89, 1.27), and 1.01 (95% CI: 0.84, 1.22) for nut consumption of <1, 1, and ≥2 servings/wk, respectively (P for linear trend: 0.64). The lack of a meaningful relation between nut intake and incident heart failure was seen in both lean and overweight or obese participants (P for interaction: 0.96). Conclusion: Our data do not provide evidence for an association between nut consumption and incident heart failure in US male physicians. However, our data cannot rule out possible benefits of nut consumption on subtypes of heart failure not prevalent in this cohort.
Natoli, S., P. McCoy, 2007. A review of the evidence: nuts and body weight. Asia Pac J Clin Nutr. 16 (4):588-597 588.
There is currently no single dietary or lifestyle intervention that is effective in long-term weight loss. Traditional weight loss diets tend to be low in total fat and therefore often restrict nut consumption. However, nuts are an important source of many vitamins, minerals, monounsaturated and polyunsaturated fatty acids. This paper reviewed all the available evidence from the literature in relation to nut consumption and body weight. The findings show that the role of nut consumption in body weight management is varied. Nuts, when included as part of an energy-controlled diet, were found in some instances to assist with weight loss. However, when nuts were added to an existing diet without controlling for energy intake, body weight increased, although to a lesser extent than theoretically predicted. There is limited evidence on the effect nut consumption has on type 2 diabetes, although available evidence indicates that nuts as part of a healthy diet do not cause weight gain and can have a positive influence on the fatty acid profile of a person with diabetes. This review shows there is a lack of evidence to support the restriction of nut consumption in weight management, indicating that further research is needed to assess the role of nuts in weight management.
Fleischer, D.M., 2007. The natural history of peanut and tree nut allergy. Current Allergy and Asthma Reports. 7:175–181.
Peanut and tree nut allergies were once thought to be permanent. Recent studies have shown that about 20% and 10%, respectively, of young patients may outgrow peanut and tree nut allergies. For the majority of patients, however, the natural history is not favorable. In addition, approximately 8% of patients who outgrow peanut allergy may suffer a recurrence. The rising prevalence of these allergies, coupled with the knowledge that allergic reactions to these foods have the potential to be severe or fatal and that accidental exposures are common, makes developing effective treatments to alter the natural history of peanut and tree nut allergies even more crucial for those who will not outgrow them. At this time, avoidance of the offending foods and being prepared to treat a potential reaction after accidental ingestion is the only treatment, but many promising therapeutic interventions are being investigated.
Zhao, G., T.D. Etherton, K.R. Martin, P.J. Gillies, S.G. West, P.M. Kris-Etherton, 2007. Dietary α-linolenic acid inhibits proinflammatory cytokine production by peripheral blood mononuclear cells in hypercholesterolemic subjects. Am J Clin Nutr. 85:385-91.
Background: Atherosclerosis is a chronic inflammatory disease. We previously reported that a diet high in α-linolenic acid (ALA) reduces lipid and inflammatory cardiovascular disease risk factors in hypercholesterolemic subjects. Objective: The objective was to evaluate the effects of a diet high in ALA on serum proinflammatory cytokine concentrations and cytokine production by cultured peripheral blood mononuclear cells (PBMCs) from subjects fed the experimental diets. Design: A randomized, controlled, 3-diet, 3-period crossover study design was used. Hypercholesterolemic subjects (n = 23) were assigned to 3 experimental diets: a diet high in ALA (ALA diet; 6.5% of energy), a diet high in linoleic acid (LA diet; 12.6% of energy), and an average American diet (AAD) for 6 wk. Serum interleukin (IL)-6, IL-1β, and tumor necrosis factor-α (TNF-α) concentrations and the production of IL-6, IL-1β, and TNF-α by PBMCs were measured. Results: IL-6, IL-1β, and TNF-α production by PBMCs and serum TNF-α concentrations were lower (P < 0.05 and P < 0.08, respectively) with the ALA diet than with the LA diet or AAD. PBMC production of TNF-α was inversely correlated with ALA (r = – 0.402, P = 0.07) and with eicosapentaenoic acid (r = – 0.476, P = 0.03) concentrations in PBMC lipids with the ALA diet. Changes in serum ALA were inversely correlated with changes in TNF-α produced by PBMCs (r = – 0.423, P < 0.05). Conclusions: Increased intakes of dietary ALA elicit anti-inflammatory effects by inhibiting IL-6, IL-1β, and TNF-α production in cultured PBMCs. Changes in PBMC ALA and eicosapentaenoic acid (derived from dietary ALA) are associated with beneficial changes in TNF-α release. Thus, the cardioprotective effects of ALA are mediated in part by a reduction in the production of inflammatory cytokines.
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.
