Significant heterogeneity was not observed by nut type or other factors .
Tree nut intake  lowers total cholesterol , LDL cholesterol , ApoB , and triglycerides .
The major determinant of cholesterol lowering appears to be nut dose rather than nut type .
BACKGROUND The effects of nuts on major cardiovascular disease ( CVD ) risk factors , including dose-responses and potential heterogeneity by nut type or phytosterol content , are not well established .
OBJECTIVES We examined the effects of tree nuts ( walnuts , pistachios , macadamia nuts , pecans , cashews , almonds , hazelnuts , and Brazil nuts ) on blood lipids [ total cholesterol , low-density lipoprotein ( LDL ) cholesterol , high-density lipoprotein , and triglycerides ] , lipoproteins [ apolipoprotein A1 , apolipoprotein B ( ApoB ) , and apolipoprotein B100 ] , blood pressure , and inflammation ( C-reactive protein ) in adults aged ≥18 y without prevalent CVD .
Chronic and acute effects of walnuts on antioxidant capacity and nutritional status in humans: a randomized, cross-over pilot study
Background Compared with other common plant foods , walnuts ( Juglans regia ) are consistently ranked among the highest in antioxidant capacity . In vitro , walnut polyphenols inhibit plasma and LDL oxidation , while in animal models they lower biomarkers of oxidative stress and raise antioxidant capacity . A limited number of human feeding trials indicate that walnuts improve some measures of antioxidant status , but not others . Methods A 19 wk , r and omized crossover trial was conducted in 21 generally healthy men and postmenopausal women ≥50 y to study the dose-response effects of walnut intake on biomarkers of antioxidant activity , oxidative stress , and nutrient status . Subjects were r and omized to receive either 21 or 42 g raw walnuts/d during each 6 wk intervention phase with a 6 wk washout between phases . Subjects were instructed to consume their usual diet , but refrain from eating any other tree nuts , seeds , peanuts , or ellagitannin-rich foods during the entire study , and other polyphenol-rich foods for 2 d prior to each study visit . Results Compared to baseline levels , red blood cell ( RBC ) linoleic acid and plasma pyridoxal phosphate ( PLP ) were significantly higher after 6 wk with 42 g/d walnuts ( P < 0.05 for both ) . Overall , changes in plasma total thiols , and other antioxidant biomarkers , were not significant with either walnut dose . However , when compared to fasting levels , plasma total thiols were elevated within 1 h of walnut consumption with both doses during the baseline and end visits for each intervention phase ( P < 0.05 for all ) . Despite the observed increase in RBC linoleic and linolenic acids associated with walnut consumption , this substrate for lipid peroxidation only minimally affected malondialdehyde ( MDA ) and antioxidant capacity . The proportional changes in MDA and Oxygen Radical Absorbance Capacity ( ORAC ) were consistent with a dose-response effect , although no significant within- or between-group differences were observed for these measures . Conclusions Walnut consumption did not significantly change the plasma antioxidant capacity of healthy , well-nourished older adults in this pilot study . However , improvements in linoleic acid and pyridoxal phosphate were observed with chronic consumption , while total plasma thiols were enhanced acutely . Future studies investigating the antioxidant effects of walnuts in humans are warranted , but should include either a larger sample size or a controlled feeding intervention . Trial Registration Clinical Trials.gov :
Significant heterogeneity was not observed by nut type or other factors .
Tree nut intake  lowers total cholesterol , LDL cholesterol , ApoB , and triglycerides .
The major determinant of cholesterol lowering appears to be nut dose rather than nut type .
BACKGROUND The effects of nuts on major cardiovascular disease ( CVD ) risk factors , including dose-responses and potential heterogeneity by nut type or phytosterol content , are not well established .
OBJECTIVES We examined the effects of tree nuts ( walnuts , pistachios , macadamia nuts , pecans , cashews , almonds , hazelnuts , and Brazil nuts ) on blood lipids [ total cholesterol , low-density lipoprotein ( LDL ) cholesterol , high-density lipoprotein , and triglycerides ] , lipoproteins [ apolipoprotein A1 , apolipoprotein B ( ApoB ) , and apolipoprotein B100 ] , blood pressure , and inflammation ( C-reactive protein ) in adults aged ≥18 y without prevalent CVD .