Effects of walnut consumption on blood lipids and other cardiovascular risk factors: a meta-analysis and systematic review.
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.


OBJECTIVE
We aimed 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.


METHODS
Literature databases were searched for published trials that compared a specifically walnut-enhanced diet with a control diet. We conducted a random-effects meta-analysis of weighted mean differences (WMDs) of lipid outcomes.


RESULTS
Thirteen studies representing 365 participants were included in the analysis. Diets lasted 4-24 wk with walnuts providing 10-24% of total calories. When compared with control diets, diets supplemented with walnuts resulted in a significantly greater decrease in total cholesterol and in LDL-cholesterol concentrations (total cholesterol: WMD = -10.3 mg/dL, P < 0.001; LDL cholesterol: WMD = -9.2 mg/dL, P < 0.001). HDL cholesterol and triglycerides were not significantly affected by walnut diets more than with control diets (HDL cholesterol: WMD = -0.2, P = 0.8; triglycerides: WMD = -3.9, P = 0.3). Other results reported in the trials indicated that walnuts provided significant benefits for certain antioxidant capacity and inflammatory markers and had no adverse effects on body weight [body mass index (kg/m(2)): WMD = -0.4, P = 0.5; weight (kg): WMD = -0.05, P = 0.97].


CONCLUSIONS
Overall, high-walnut-enriched diets significantly decreased total and LDL cholesterol for the duration of the short-term trials. Larger and longer-term trials are needed to address the effects of walnut consumption on cardiovascular risk and body weight.
Banel
Deirdre K
DK
Department of Nutrition and Epidemiology, Harvard School of Public Health, Harvard University, Cambridge, MA, USA. dbanel@hsph.harvard.edu
Hu
Frank B
FB
D002318:Cardiovascular Diseases / Q000517:prevention & control*; D002784:Cholesterol / Q000097:blood*; D008078:Cholesterol, LDL / Q000097:blood*; D004032:Diet; D005260:Female; D006801:Humans; D031324:Juglans; D008055:Lipids / Q000097:blood*; D008297:Male; D012016:Reference Values; D012307:Risk Factors
D008078:Cholesterol, LDL; D008055:Lipids; D002784:Cholesterol