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 .
A macadamia nut-rich diet reduces total and LDL-cholesterol in mildly hypercholesterolemic men and women.
Epidemiologic studies and clinical trials have demonstrated that the unique fatty acid profile of nuts beneficially affects serum lipids/lipoproteins , reducing cardiovascular disease ( CVD ) risk .  Nuts are low in SFA and high in PUFA and monounsaturated fatty acids ( MUFA ) . Macadamia nuts are a rich source of MUFA . A r and omized , crossover , controlled feeding study ( 5-wk diet periods ) compared a Macadamia nut-rich diet [ 42.5 g ( 1.5 ounces)/8.79 MJ ( 2100 kcal ) ] [ MAC ; 33 % total fat ( 7 % SFA , 18 % MUFA , 5 % PUFA ) ] vs. an average American diet [ AAD ; 33 % total fat ( 13 % SFA , 11 % MUFA , 5 % PUFA ) ] on the lipid/lipoprotein profile of mildly hypercholesterolemic ( n = 25 ; 15 female , 10 male ) subjects .  Serum concentrations of total cholesterol ( TC ) and LDL cholesterol ( LDL-C ) following the MAC ( 4.94 + /- 0.17 mmol/L , 3.14 + /- 0.14 mmol/L ) were lower than the AAD ( 5.45 + /- 0.17 mmol/L , 3.44 + /- 0.14 mmol/L ; P < 0.05 ) . The serum non-HDL cholesterol ( HDL-C ) concentration and the ratios of TC : HDL-C and LDL-C : HDL-C were reduced following consumption of the MAC diet ( 3.83 + /- 0.17 , 4.60 + /- 0.24 , and 2.91 + /- 0.17 , respectively ) compared with the AAD ( 4.26 + /- 0.17 , 4.89 + /- 0.24 , and 3.09 + /- 0.18 , respectively ; P < 0.05 ) . There was no change in serum triglyceride concentration . Thus , macadamia nuts can be included in a heart-healthy dietary pattern that reduces lipid/lipoprotein CVD risk factors . Nuts as an isocaloric substitute for high SFA foods increase the proportion of unsaturated fatty acids and decrease SFA , thereby lowering CVD risk
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 .