Substituting Walnuts for Monounsaturated Fat Improves the Serum Lipid Profile of Hypercholesterolemic Men and Women Nut Consumption and Risk of Cardiovascular Disease. Walnut Consumption in Hyperlipidemic Patients Crossover study of diets enriched with virgin olive oil, walnuts or almonds. Effects on lipids and other cardiovascular risk markers. Effects of Diets High in Walnuts and Flax Oil on Hemodynamic Responses to Stress and Vascular Endothelial Function Long-term walnut supplementation without dietary advice induces favorable serum lipid changes in free-living individuals Including walnuts in a low-fat/modified-fat diet improves HDL cholesterol-to-total cholesterol ratios in patients with type 2 diabetes. A Walnut Diet Improves Endothelial Function in Hypercholesterolemic Subjects: A Randomized Crossover Trial Walnut-enriched diet increases the association of LDL from hypercholesterolemic men with human HepG2 cells. A possible protective effect of nut consumption on risk of coronary heart disease. The Adventist Health Study. Effects of walnut consumption as part of a low-fat, low-cholesterol diet on serum cardiovascular risk factors. Almonds and almond oil have similar effects on plasma lipids and LDL oxidation in healthy men and women. [Nutrient content and health effects of nuts]. Nut Consumption in Relation to Cardiovascular Disease Incidence and Mortality Among Patients With Diabetes Mellitus Walnut Consumption Is Associated with Lower Risk of Type 2 Diabetes in Women12 Effects of Walnuts on Endothelial Function in Overweight Adults with Visceral Obesity: A Randomized, Controlled, Crossover Trial Nut consumption and decreased risk of sudden cardiac death in the Physicians' Health Study.
Lifestyle modification is the cornerstone of population -based strategies for prevention of coronary heart disease and is the first line of therapy in patients with hypercholesterolemia . Diets low in saturated fatty acids and cholesterol have long been recommended to decrease low-density lipoprotein ( LDL ) cholesterol levels and reduce cardiovascular risk ( 1 ) . Ample evidence suggests that polyunsaturated fatty acids and monounsaturated fatty acids have a similar cholesterol-lowering effect when substituted for saturated fatty acids ( 2 - 4 ) . However , most studies of fatty acids and blood lipids have been done with fats and oils , rarely with whole fatty foods . Because people usually buy and consume whole food products , it is desirable to know the effects of specific foods on risk factors for coronary heart disease . Recent reports suggest that the regular consumption of nuts might reduce cardiovascular risk ( 5 ) . Walnuts are particularly rich in polyunsaturated fatty acids ( 6 ) , and epidemiologic evidence suggests that frequent walnut consumption protects against coronary heart disease ( 7 ) . In a controlled feeding trial by Sabat and colleagues ( 8) , a diet in which walnuts represented 55 % of the energy from fat reduced blood cholesterol levels in normal young men when compared with a st and ard low-fat diet . However , the results can not easily be extrapolated to the population at risk for coronary heart disease because women , older age groups , and hypercholesterolemic persons were not studied ( 8) . In addition , because meals were served at a metabolic kitchen , the study did not address the question of whether free-living persons would incorporate substantial quantities of walnuts into their diets . Because oxidized LDL plays a key role in atherogenesis ( 9 ) and oxidative damage involves peroxidation of polyunsaturated fatty acids in LDL lipids ( 10 ) , there is concern that walnut intake may promote LDL oxidation . Therefore , we design ed a dietary intervention study in free-living adult men and women with polygenic hypercholesterolemia to compare the effects of a walnut-rich diet with those of a cholesterol-lowering Mediterranean diet on serum lipid levels , lipoprotein levels , and LDL resistance to oxidation . Methods Patients Adult men and women with polygenic hypercholesterolemia attending the Lipid Clinic of the Hospital Clnic of Barcelona were eligible if they had serum LDL cholesterol concentrations greater than 3.36 mmol/L ( 130 mg/dL ) and triglyceride concentrations less than 2.82 mmol/L ( 250 mg/dL ) ; no evidence of alcohol , tobacco , or drug abuse ; absence of diabetes mellitus and liver , kidney , thyroid , or other endocrine diseases , as assessed by medical history , a complete physical examination , and laboratory tests ; no intake in the previous 8 weeks of medications known to affect lipid metabolism , including hypolipidemic agents and estrogen compounds in women ; infrequent consumption of nuts and no known history of allergy to them ; and no use of multivitamin or vitamin E supplements  . Because the target population had common ( polygenic ) hypercholesterolemia , we excluded persons whose elevated blood cholesterol levels had a strong genetic basis ( such as heterozygous familial hypercholesterolemia or familial combined hyperlipidemia ) , as established by st and ard criteria . On admission to the Lipid Clinic , all patients were advised to follow a  Mediterranean-type hypolipidemic diet ( 11 ) . For a crossover design , statistical power calculations indicated that to detect mean differences of 0.39 mmol/L ( 15 mg/dL ) , 34 patients would need to complete the two treatment periods ( statistic , 0.05 ; power>0.8 ) . From a computerized register of clinical records , 75 hypercholesterolemic patients ( 35 women and 40 men ) who initially met the eligibility criteria were selected for screening and were asked to participate in the study . They were offered free walnuts but no monetary compensation . Study Design A crossover design was used . Patients were r and omly assigned to the two diet sequences by using a computer-generated r and om-number table , with stratification by sex . Because patients followed each diet for 6 weeks and lipoprotein changes due to dietary intervention stabilize in less than 4 weeks ( 12 ) , we did not incorporate a washout period between diets . In their crossover feeding study with walnuts , Sabat and colleagues ( 8) did not observe a carryover effect . In the week before the trial began , patients received expert dietary counseling individually and in a group class . Twice during the pretrial week and on weeks 5 and 6 of each one of the two dietary periods , patients came to the clinic for a medical visit , an interview with the dietitian , anthropometric measurements , and blood extraction . The main outcomes of the study were changes in serum levels of total and LDL cholesterol from the control diet period to the walnut diet period . Secondary outcomes were changes in other lipid variables and oxidizability of LDL particles . The study protocol was approved by the institutional review board of the Hospital Clnic of Barcelona , and all patients gave informed consent . Diets The experimental diets were individually prescribed and were based on estimated energy requirements . Because participants ate on their own , detailed dietary information was provided to them and , if appropriate , to their partners .  Diets were calculated in increments of 200 kcal to cover the range from 1600 to 2200 kcal . The control diet was Mediterranean and was composed of natural foodstuffs . Red meat and eggs were limited , vegetable products and fish were emphasized , olive oil was indicated for culinary use , and no nuts were allowed . The walnut diet was similar to the control diet , but walnuts partially replaced olive oil and other fatty foods . Prepackaged daily allowances of raw , shelled walnuts were provided daily in amounts varying from 41 g to 56 g ( the equivalent of 8 to 11 walnuts ) , according to the participants ' total energy intake . Walnuts were consumed as snacks or with meals in desserts or salads . In the walnut diet , walnuts contributed approximately 18 % of the total energy and 35 % of the total fat . To improve compliance , each family unit was given 1000-g packs of walnuts at the beginning of the walnut diet period .  Adherence to the study diets was carefully monitored . Unannounced 24-hour diet recalls were performed weekly by telephone during the two dietary periods , for a total of 12 recalls per patient . This method allows reliable estimations of food intake ( 13 ) . The nutrient composition of the diets was calculated with Food Processor Plus software , version 5.0 ( ESHA Research , Salem , Oregon ) , which was adapted to nutrient data bases of specific Mediterranean foods when appropriate . We defined noncompliance as at least 20 % deviation from dietary instructions regarding walnut or nutrient intake . Compliance during the walnut diet was also assessed at each clinic visit by a count of the empty walnut packages . The fatty acid content of LDL lipids was analyzed as a biological measure of adherence to the prescribed diets . Laboratory Measurements Blood sample s were obtained after an overnight fast , and serum and EDTA plasma were collected and processed immediately . Serum lipid and apolipoprotein levels were determined as described elsewhere ( 11 ) . In brief , serum cholesterol and triglyceride levels were measured by using enzymatic reagents ( Trinder , Bayer Diagnostics , Tarrytown , New York ) adapted to a Cobas Mira automated analyzer ( Hoffmann-LaRoche , Basel , Switzerl and ) . High-density lipoprotein ( HDL ) cholesterol was quantified after precipitation with phosphotungstic acid and magnesium chloride . Levels of apolipoprotein A-I and apolipoprotein B were determined by an immunoturbidimetric method ( Unimate 3 , Roche Diagnostic Systems , Basel , Switzerl and ) . Measurements of the cholesterol content of very-low-density lipoprotein particles and LDL particles were based on preparative ultracentrifugation ( 11 ) . Lipoprotein(a ) levels were measured by using an immunoturbidimetric method ( Lipoprotein[a ] SPQ II Test Kit , DiaSorin , Stillwater , Minnesota ) . To obtain the LDL fraction for fatty acid and oxidizability studies , lipoproteins were fractionated by sequential centrifugation adjusting with NaBr to separate very-low-density lipoprotein particles ( d=1.006 g/mL ) and to obtain LDL particles ( d=1.063 g/mL ) , as described elsewhere ( 14 ) . Low-density lipoprotein fatty acids were measured by capillary gas chromatography in the cholesteryl ester , phospholipid , and triglyceride lipid fractions ( 14 ) . Low-density lipoprotein susceptibility to oxidation was determined by measuring the -tocopherol content of LDL particles and conjugated diene kinetics after incubation of 50 g of LDL protein with 5 mol of copper sulfate at 37 C ( 15 , 16 ) . Statistical Analysis The two measurements obtained at baseline and at the end of each dietary period were averaged . Means and SDs are presented for each measurement . With methods described by Fleiss ( 17 ) , two-tailed t-tests were used to compare changes in outcome variables in response to dietary treatment and diet period and carryover effects for the two-period crossover design . Differences between the walnut and control diets were also tested by analysis of covariance using general linear models ; baseline values or sex were used as covariates . Analyses were performed by using SAS software ( SAS , Inc. , Cary , North Carolina ) ( 18 ) . Role of the Funding Sources The California Walnut Commission provided funding and walnuts . Research grants were also obtained from national and local nonprofit agencies . The funding sources were not involved in the design of the study and had no role in the collection , analysis , or interpretation of the data or in the decision to su bmi t the manuscript for publication . None of the authors has any financial interest in the nut food industry . Results Patient Characteristics Of the 75 eligible patients , 20 left the study before r and omization for BACKGROUND The associations between specific types of nuts , specifically peanuts and walnuts , and cardiovascular disease remain unclear . OBJECTIVES The authors sought to analyze the associations between the intake of total and specific types of nuts and cardiovascular disease , coronary heart disease , and stroke risk . METHODS The authors included 76,364 women from the Nurses ' Health Study ( 1980 to 2012 ) , 92,946 women from the Nurses ' Health Study II ( 1991 to 2013 ) , and 41,526 men from the Health Professionals Follow-Up Study ( 1986 to 2012 ) who were free of cancer , heart disease , and stroke at baseline .  Nut consumption was assessed using food frequency question naires at baseline and was up date d every 4 years . RESULTS During 5,063,439 person-years of follow-up , the authors documented 14,136 incident cardiovascular disease cases , including 8,390 coronary heart disease cases and 5,910 stroke cases . Total nut consumption was inversely associated with total cardiovascular disease and coronary heart disease after adjustment for cardiovascular risk factors . The pooled multivariable hazard ratios for cardiovascular disease and coronary heart disease among participants who consumed 1 serving of nuts ( 28 g ) 5 or more times per week , compared with the reference category ( never or almost never ) , were 0.86 ( 95 % confidence interval : 0.79 to 0.93 ; p for trend = 0.0002 ) and 0.80 ( 95 % confidence interval : 0.72 to 0.89 ; p for trend < 0.001 ) , respectively . Consumption of peanuts and tree nuts ( 2 or more times/week ) and walnuts ( 1 or more times/week ) was associated with a 13 % to 19 % lower risk of total cardiovascular disease and 15 % to 23 % lower risk of coronary heart disease . CONCLUSIONS In 3 large prospect i ve cohort studies , higher consumption of total and specific types of nuts was inversely associated with total cardiovascular disease and coronary heart disease Walnut ( Juglans regia L. ) is described as an anticancer , tonic , blood purifier , and detoxifier agent . It is said that nuts have favorable fatty acids and nutrients . This study was performed to determine the lipid-lowering properties of walnut in a population in Shiraz , Southern Iran . In a r and omized case-control study , 52 volunteers were divided into 2 groups : Group A consumed walnuts , 20 grams per day for 8 weeks and the control group ( group B ) consumed no walnuts .  Triglycerides , total high-density lipoprotein ( HDL ) , and low-density lipoprotein ( LDL ) levels were checked for each subject prior to , after 4 weeks , and at 8 weeks after the beginning of the study . In group A , the mean plasma TG level dropped by 17.1 % from the baseline and HDL cholesterol also increased significantly by 9 % . It was shown that frequent consumption of nuts in the daily diet was associated with a potentially decreased risk of coronary artery disease by decreasing the level of triglyceride and increasing the level of HDL BACKGROUND AND AIMS Virgin olive oil ( VOO ) and nuts are basic components of the Mediterranean diet , a heart-healthy dietary pattern . Nuts have well known cholesterol lowering effects , while evidence is unclear for VOO . We design ed a study in hypercholesterolemic patients to assess the effects on serum lipids and other intermediate markers of cardiovascular risk of replacing 40 % of the fat in the background diet with VOO , walnuts or almonds . METHODS AND RESULTS After a 4 week run-in period with a healthy diet , eligible c and i date s were r and omized into three diet sequences in a crossover design , with a common background diet enriched with VOO , walnuts or almonds , lasting 4 weeks each . Outcomes were changes of serum lipids and oxidation and inflammation markers , measured by st and ard methods . Plasma fatty acids were determined by gas chromatography to assess compliance . In 18 participants completing the study ( 9 women , mean age 56 y , BMI 25.7 kg/m(2 ) ) , LDL-cholesterol was reduced from baseline by 7.3 % , 10.8 % and 13.4 % after the VOO , walnut and almond diets , respectively ( P = 0.001 , Friedman test ) . Total cholesterol and LDL/HDL ratios decreased in parallel . LDL-cholesterol decreases were greater than predicted from dietary fatty acid and cholesterol exchanges among diets . No changes of other lipid fractions , oxidation analytes or inflammatory biomarkers were observed . Plasma fatty acid changes after each diet sequence supported good compliance . CONCLUSION The results confirm the cholesterol lowering properties of nut-enriched diets . They also suggest that phenolic-rich VOO has a cholesterol lowering effect independently of its fatty acid content , which clearly deserves further study Background : Polyunsaturated fatty acids ( PUFA ) have beneficial effects on cardiovascular risk , although the mechanisms are incompletely understood . In a previous article , we showed significant reductions in low-density lipoprotein cholesterol and several markers of inflammation with increasing intake of alpha-linolenic acid ( ALA ) from walnuts and flax . Objective : To examine effects of ALA on cardiovascular responses to acute stress , flow-mediated dilation ( FMD ) of the brachial artery , and blood concentrations of endothelin-1 and arginine-vasopressin ( AVP ) . Design : Using a r and omized , crossover study design , cardiovascular responses to acute stress were assessed in 20 hypercholesterolemic subjects , a subset of whom also underwent FMD testing ( n = 12 ) . Participants were fed an average American diet ( AAD ) and 2 experimental diets that varied in the amount of ALA and linoleic acid ( LA ) that they contained . The AAD provided 8.7 % energy from PUFA ( 7.7 % LA , 0.8 % ALA ) . On the LA diet , saturated fat was reduced , and PUFA from walnuts and walnut oil provided 16.4 % of energy ( 12.6 % LA , 3.6 % ALA ) . On the ALA diet , walnuts , walnut oil , and flax oil provided 17 % energy from PUFA ( 10.5 % LA , 6.5 % ALA ) . Results : The ALA and LA diets significantly reduced diastolic blood pressure ( −2 to −3 mm Hg ) and total peripheral resistance ( −4 % ) , and this effect was evident at rest and during stress ( main effect of diet , p < 0.02 ) . FMD increased ( + 34 % ) on the diet containing additional ALA . AVP also increased by 20 % , and endothelin-1 was unchanged . Conclusions : These results suggest novel mechanisms for the cardioprotective effects of walnuts and flax , and further work is needed to identify the bioactives responsible for these effects Background / Objectives : Walnuts have been shown to reduce serum lipids in short-term well-controlled feeding trials . Little information exists on the effect and sustainability of walnut consumption for longer duration in a free-living situation . Subjects/ Methods : A r and omized crossover design in which 87 subjects with normal to moderate high plasma total cholesterol were initially assigned to a walnut-supplemented diet or habitual ( control ) diet for a 6-month period , then switched to the alternate dietary intervention for a second 6-month period . Each subject attended seven clinics 2 months apart . At each clinic , body weight was measured , and in five clinics ( months 0 , 4 , 6 , 10 and 12 ) , a blood sample was collected . Results : Our study showed that supplementing a habitual diet with walnuts ( 12 % of total daily energy intake equivalent ) improves the plasma lipid profile . This beneficial effect was more significant in subjects with high plasma total cholesterol at baseline . Significant changes in serum concentrations of total cholesterol ( P=0.02 ) and triglycerides ( P=0.03 ) were seen and nearly significant changes in low-density lipoprotein cholesterol ( LDL-C ) ( P=0.06 ) were found . No significant change was detected in either high-density lipoprotein ( HDL ) cholesterol LDL to HDL ratio . Conclusions : Including walnuts as part of a habitual diet favorably altered the plasma lipid profile . The lipid-lowering effects of walnuts were more evident among subjects with higher lipid baseline values , precisely those people with greater need of reducing plasma total and OBJECTIVE The aim of this study was to examine the effect of a moderate-fat diet inclusive of walnuts on blood lipid profiles in patients with type 2 diabetes . RESEARCH DESIGN AND METHODS This was a parallel r and omized controlled trial comparing three dietary advice groups each with 30 % energy as fat : low fat , modified low fat , and modified low fat inclusive of 30 g of walnuts per day .  Fifty-eight men and women , mean age 59.3 + /- 8.1 years , started the trial . Dietary advice was given at baseline with monthly follow-up and fortnightly phone calls for support .  Body weight , percent body fat , blood lipids , HbA1c , total antioxidant capacity , and erythrocyte fatty acid levels were measured at 0 , 3 , and 6 months . Data were assessed by repeated- measures ANOVA with an intention-to-treat model . RESULTS The walnut group achieved a significantly greater increase in HDL cholesterol-to-total cholesterol ratio ( P=0.049 ) and HDL ( P=0.046 ) than the two other treatment groups . A 10 % reduction in LDL cholesterol was also achieved in the walnut group , reflecting a significant effect by group ( P=0.032 ) and time ( P=0.036 ) . There were no significant differences between groups for changes in body weight , percent body fat , total antioxidant capacity , or HbA1c levels . The higher dietary polyunsaturated fat-to-saturated fat ratio and intakes of omega-3 fatty acids in the walnut group were confirmed by erythrocyte biomarkers of dietary intake . CONCLUSIONS Structured " whole of diet " advice that included 30 g of walnuts/day delivering substantial amounts of polyunsaturated fatty acid improved the lipid profile of patients with type 2 diabetes Background —Epidemiological studies suggest that nut intake decreases coronary artery disease ( CAD ) risk . Nuts have a cholesterol-lowering effect that partly explains this benefit . Endothelial dysfunction is associated with CAD and its risk factors and is reversed by antioxidants and marine n-3 fatty acids . Walnuts are a rich source of both antioxidants and & agr;-linolenic acid , a plant n-3 fatty acid . Methods and Results —To test the hypothesis that walnut intake will reverse endothelial dysfunction , we r and omized in a crossover design 21 hypercholesterolemic men and women to a cholesterol-lowering Mediterranean diet and a diet of similar energy and fat content  in which walnuts replaced ≈32 % of the energy from monounsaturated fat . Participants followed each diet for 4 weeks . After each intervention , we obtained fasting blood and performed ultrasound measurements of brachial artery vasomotor function . Eighteen subjects completing the protocol had suitable ultrasound studies . Compared with the Mediterranean diet , the walnut diet improved endothelium-dependent vasodilation and reduced levels of vascular cell adhesion molecule-1 ( P < 0.05 for both ) . Endothelium-independent vasodilation and levels of intercellular adhesion molecule-1 , C-reactive protein , homocysteine , and oxidation biomarkers were similar after each diet . The walnut diet significantly reduced total cholesterol ( −4.4±7.4 % ) and LDL cholesterol ( −6.4±10.0 % ) ( P < 0.05 for both ) . Cholesterol reductions correlated with increases of both dietary & agr;-linolenic acid and LDL & ggr;-tocopherol content , and changes of endothelium-dependent vasodilation correlated with those of cholesterol-to-HDL ratios ( P < 0.05 for all ) . Conclusions —Substituting walnuts for monounsaturated fat in a Mediterranean diet improves endothelium-dependent vasodilation in hypercholesterolemic subjects . This finding might explain the cardioprotective effect of nut intake beyond cholesterol lowering In a r and omized , cross-over feeding trial involving 10 men with polygenic hypercholesterolemia , a control , Mediterranean-type cholesterol-lowering diet , and a diet of similar composition in which walnuts replaced approximately 35 % of energy from unsaturated fat , were given for 6 weeks each . Compared with the control diet , the walnut diet reduced serum total and LDL cholesterol by 4.2 % ( P = 0.176 ) , and 6.0 % ( P = 0.087 ) , respectively . No changes were observed in HDL cholesterol , triglycerides , and apolipoprotein A-I levels or in the relative proportion of protein , triglycerides , phospholipids , and cholesteryl esters in LDL particles . The apolipoprotein B level declined in parallel with LDL cholesterol ( 6.0 % reduction ) . Whole LDL , particularly the triglyceride fraction , was enriched in polyunsaturated fatty acids from walnuts ( linoleic and alpha-linolenic acids ) . In comparison with LDL obtained during the control diet , LDL obtained during the walnut diet showed a 50 % increase in association rates to the LDL receptor in human hepatoma HepG2 cells . LDL uptake by HepG2 cells was correlated with alpha-linolenic acid content of the triglyceride plus cholesteryl ester fractions of LDL particles ( r(2 ) = 0.42 , P < 0.05 ) . Changes in the quantity and quality of LDL lipid fatty acids after a walnut-enriched diet facilitate receptor-mediated LDL clearance and may contribute to the cholesterol-lowering effect of walnut consumption BACKGROUND Although dietary factors are suspected to be important determinants of coronary heart disease ( CHD ) risk , the direct evidence is relatively sparse . METHODS The Adventist Health Study is a prospect i ve cohort investigation of 31,208 non-Hispanic white California Seventh-Day Adventists . Extensive dietary information was obtained at baseline , along with the values of traditional coronary risk factors . These were related to risk of definite fatal CHD or definite nonfatal myocardial infa rct ion . RESULTS Subjects who consumed nuts frequently ( more than four times per week ) experienced substantially fewer definite fatal CHD events ( relative risk , 0.52 ; 95 % confidence interval [ CI ] , 0.36 to 0.76 ) and definite nonfatal myocardial infa rct ions ( relative risk , 0.49 ; 95 % CI , 0.28 to 0.85 ) , when compared with those who consumed nuts less than once per week . These findings persisted on covariate adjustment and were seen in almost all of 16 different subgroups of the population . Subjects who usually consumed whole wheat bread also experienced lower rates of definite nonfatal myocardial infa rct ion ( relative risk , 0.56 ; 95 % CI , 0.35 to 0.89 ) and definite fatal CHD ( relative risk , 0.89 ; 95 % CI , 0.60 to 1.33 ) when compared with those who usually ate white bread . Men who ate beef at least three times each week had a higher risk of definite fatal CHD ( relative risk , 2.31 ; 95 % CI , 1.11 to 4.78 ) , but this effect was not seen in women or for the nonfatal myocardial infa rct ion end point . CONCLUSION Our data strongly suggest that the frequent consumption of nuts may protect against risk of CHD events . The favorable fatty acid profile of many nuts is one possible explanation for such an effect Serum components , such as lipoproteins , coagulation factors ( factor VII , tissue plasminogen activator ( tPA ) , plasminogen activator inhibitor-1 ( PAI-1 ) , fibrinogen ) , and homocysteine have been associated with cardiovascular disease . Dietary intervention with a low-fat , low-cholesterol diet has favorably influenced cardiovascular disease and certain food , specifically the consumption of nuts , has been associated with reduced cardiovascular risks . The effects of walnuts , as part of a low-fat , low-cholesterol diet , on serum cardiovascular risk factors were determined . Sixty-seven ( 67 ) out patients with borderline high total cholesterol following a low-fat , low-cholesterol diet for six weeks before being r and omly assigned to continue the diet or have 64 grams/day of walnuts in conjunction with the diet . After six weeks , the patients ' diets were switched . Therefore , all patients consumed 64 grams/day of walnuts for six weeks during part of the trial as part of a low-fat , low cholesterol diet .  Serum lipids demonstrated a significant reduction in triacyglycerols and favorable trend with decreases in total cholesterol , low-density lipoprotein ( LDL ) cholesterol , and a slight increase in high-density lipoprotein ( HDL ) cholesterol . No statistical effects on homocysteine or the coagulation factors were observed . However , there was a slight favorable trend for tPA and PAI-1 . This study demonstrated that walnuts , when consumed as part of a low fat , low-cholesterol diet , have a beneficial effect on serum cardiovascular risk factors . However , these changes may not explain all of the beneficial effects that walnut consumption has on cardiovascular disease Epidemiologic and clinical studies have shown that nut consumption is associated with favorable plasma lipid profiles and reduced cardiovascular risk . These effects may result from their high monounsaturated fat ( MUFA ) content but nuts contain constituents other than fatty acids that might be cardioprotective . We conducted a study to compare the effects of whole-almond vs. almond oil consumption on plasma lipids and LDL oxidation in healthy men and women . Using a r and omized crossover trial design , 22 normolipemic men and women replaced half of their habitual fat ( approximately 14 % of approximately 29 % energy ) with either whole almonds ( WA ) or almond oil ( AO ) for 6-wk periods . Compliance was ascertained by monitoring dietary intake via biweekly 5-d food records , return of empty almond product packages and weekly meetings with a registered dietitian . Fat replacement with either WA and AO result ed in a 54 % increase in percentage of energy as MUFA with declines in both saturated fat and cholesterol intake and no significant changes in total energy , total or polyunsaturated fat intake . The effects of  WA  and  AO  on plasma lipids did not differ compared with baseline ; plasma triglyceride , total and LDL cholesterol significantly decreased , 14 , 4 and 6 % respectively , whereas HDL cholesterol increased 6 % . Neither treatment affected in vitro LDL oxidizability . We conclude that WA and AO do not differ in their beneficial effects on the plasma lipid variables measured and that this suggests that the favorable effect of almonds is mediated by components in the oil fraction of these nuts Nuts are foods with a high energy density , due in part to its small water content . They also present a low saturated fat content ( < 7 % ) but a high unsaturated fat contribution ( 40 - 60 % ) . They represent one of the richest sources of dietary fiber , which is basically of the insoluble type . The effects of nut intake on health have been widely studied . Several prospect i ve epidemiological studies performed on large cohorts have consistently shown that regular consumption of small amounts of nuts is negatively related to the risk of cardiovascular disease and to the risk of cardiovascular or all-cause mortality . From these studies can be concluded that regular consumption of small amounts of nuts leads to a 30 - 50 % reduction in the risk of cardiovascular disease . Additionally , intervention studies have shown a positive effect of nut intake on lipid profile with significant reductions in total and LDL cholesterol levels and small or null effects on the HDL fraction . More recently , some studies have focused on the effect of  nuts on body weight . At present , no evidence s support a detrimental effect of nut consumption on body weight . On the contrary some weight loss studies suggest a beneficial effect of nut intake on body weight regulation Rationale : The evidence regarding the potential health benefits of nut consumption among individuals with type 2 diabetes mellitus is limited . Objective : To examine intake of total and specific types of nuts , including tree nuts and peanuts , in relation to subsequent risk of cardiovascular disease ( CVD ) , including coronary heart disease and stroke , and all-cause and cause-specific mortality among individuals with diabetes mellitus . Methods and Results : This prospect i ve analysis included 16 217 men and women with diabetes mellitus at baseline or diagnosed during follow-up ( Nurses ’ Health Study : 1980–2014 , Health Professionals Follow-Up Study : 1986–2014 ) .  Nut consumption was assessed using a vali date d food frequency question naire and up date d every 2 to 4 years . During 223 682 and 254 923 person-years of follow-up , there were 3336 incident CVD cases and 5682 deaths , respectively . Higher total nut consumption was associated with a lower risk of CVD incidence and mortality . The multivariate-adjusted hazard ratios ( 95 % CIs ) for participants who consumed 5 or more servings of total nuts per week ( 1 serving=28 g ) , compared with those who consumed < 1 serving per month , were 0.83 ( 0.71–0.98 ; P trend=0.01 ) for total CVD incidence , 0.80 ( 0.67–0.96 ; P trend=0.005 ) for coronary heart disease incidence , 0.66 ( 0.52–0.84 ; P trend < 0.001 ) for CVD mortality , and 0.69 ( 0.61–0.77 ; P trend < 0.001 ) for all-cause mortality .  Total nut consumption was not significantly associated with risk of stroke incidence or cancer mortality . For specific types of nuts , higher tree nut consumption was associated with lower risk of total CVD , coronary heart disease incidence , and mortality because of CVD , cancer , and all causes , whereas peanut consumption was associated with lower all-cause mortality only ( all P trend < 0.001 ) . In addition , compared with participants who did not change the consumption of total nuts from pre- to post-diabetes mellitus diagnosis , participants who increased consumption of total nuts after diabetes mellitus diagnosis had an 11 % lower risk of CVD , a 15 % lower coronary heart disease risk , a 25 % lower CVD mortality , and a 27 % lower all-cause mortality . The associations persisted in subgroup analyses stratified by sex/cohort , body mass index at diabetes mellitus diagnosis , smoking status , diabetes mellitus duration , nut consumption before diabetes mellitus diagnosis , or diet quality . Conclusions : Higher consumption of nuts , especially tree nuts , is associated with lower CVD incidence and mortality among participants with diabetes mellitus . These data provide novel evidence that supports the recommendation of incorporating nuts into healthy dietary patterns for the prevention of CVD complications and premature deaths among individuals with diabetes mellitus Walnuts are rich in polyunsaturated fatty acids and have been shown to improve various cardiometabolic risk factors . We aim ed to investigate the association between walnut intake and incident type 2 diabetes  in 2 large cohort studies : the Nurses ’ Health Study ( NHS ) and NHS II . We prospect ively followed 58,063 women aged 52–77 y in NHS ( 1998–2008 ) and 79,893 women aged 35–52 y in NHS II ( 1999–2009 ) without diabetes , cardiovascular disease , or cancer at baseline .  Consumption of walnuts and other nuts was assessed every 4 y using vali date d food frequency question naires .  Self-reported type 2 diabetes was confirmed by a vali date d supplemental question naire . We documented a total of 5930 incident type 2 diabetes cases during 10 y of follow-up . In the multivariable-adjusted Cox proportional hazards model without body mass index ( BMI ) , walnut consumption was associated with a lower risk of type 2 diabetes , and the HRs ( 95 % CIs ) for participants consuming 1–3 servings/mo ( 1 serving = 28 g ) , 1 serving/wk , and ≥2 servings/wk of walnuts were 0.93 ( 0.88–0.99 ) , 0.81 ( 0.70–0.94 ) , and 0.67 ( 0.54–0.82 ) compared with women who never/rarely consumed walnuts ( P-trend < 0.001 ) . Further adjustment for up date d BMI slightly attenuated the association and the HRs ( 95 % CIs ) were 0.96 ( 0.90–1.02 ) , 0.87 ( 0.75–1.01 ) , and 0.76 ( 0.62–0.94 ) , respectively ( P-trend = 0.002 ) . The consumption of total nuts ( P-trend < 0.001 ) and other tree nuts ( P-trend = 0.03 ) was also inversely associated with risk of type 2 diabetes , and the associations were largely explained by BMI . Our results suggest that higher walnut consumption is associated with a significantly lower risk of type 2 diabetes in women Objectives : Metabolic syndrome is a precursor of diabetes and cardiovascular disease ( CVD ) . Walnut ingestion has been shown to reduce CVD risk indices in diabetes . This r and omized controlled crossover trial was performed to investigate the effects of daily walnut consumption on endothelial function and other biomarkers of cardiac risk in a population of overweight individuals with visceral adiposity . Methods : Forty-six overweight adults ( average age , 57.4 years ; 28 women , 18 men ) with elevated waist circumference and 1 or more additional signs of metabolic syndrome were r and omly assigned to two 8-week sequences of walnut-enriched ad libitum diet and ad libitum diet without walnuts , which were separated by a 4-week washout period . The primary outcome measure was the change in flow-mediated vasodilation ( FMD ) of the brachial artery . Secondary measures included serum lipid panel , fasting glucose and insulin , Homeostasis Model Assessment –Insulin Resistance values , blood pressure , and anthropometric measures . Results : FMD improved significantly from baseline when subjects consumed a walnut-enriched diet as compared with the control diet ( 1.4 % ± 2.4 % versus 0.3 % ± 1.5 % ; p = 0.019 ) . Beneficial trends in systolic blood pressure reduction were seen , and maintenance of the baseline anthropometric values was also observed . Other measures were unaltered . Conclusion : Daily ingestion of 56 g of walnuts improves endothelial function in overweight adults with visceral adiposity . The addition of walnuts to the diet does not lead to weight gain . Further study of the potential role of walnut intake in diabetes and CVD prevention is warranted BACKGROUND Dietary nut intake has been associated with a reduced risk of coronary heart disease mortality ; however , the mechanism is unclear . Since components of nuts may have antiarrhythmic properties , part of the benefit may be due to a reduction in sudden cardiac death . METHODS We prospect ively assessed whether increasing frequency of nut consumption , as ascertained by an abbreviated food frequency question naire at 12 months of follow-up , was associated with a lower risk of sudden cardiac death and other coronary heart disease end points among 21 454 male participants enrolled in the US Physicians ' Health Study . Participants were followed up for an average of 17 years . RESULTS Dietary nut intake was associated with a significantly reduced risk of sudden cardiac death after controlling for known cardiac risk factors and other dietary habits ( P for trend,.01 ) . Compared with men who rarely or never consumed nuts , those who consumed nuts 2 or more times per week had reduced risks of sudden cardiac death ( relative risk , 0.53 ; 95 % confidence interval , 0.30 - 0.92 ) and total coronary heart disease death ( relative risk , 0.70 ; 95 % confidence interval , 0.50 - 0.98 ) . In contrast , nut intake was not associated with significantly reduced risks of nonsudden coronary heart disease death or nonfatal myocardial infa rct ion . CONCLUSION These prospect i ve data in US male physicians suggest that the inverse association between nut consumption and total coronary heart disease death is primarily due to a reduction in the risk of sudden cardiac death
Overall , high-walnut-enriched diets significantly decreased total and LDL cholesterol for the duration of the short-term trials .
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 aim ed 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 .