Almonds have a neutral effect on serum lipid profiles: a meta-analysis of randomized trials

Almond consumption may be associated with improvements in serum lipid profiles. The aim was to evaluate the influence of almonds on lipid parameters to help define the role of almonds as a lipid modulator. MEDLINE, EMBASE, Cochrane CENTRAL, and the Natural Medicines Comprehensive Database were searched through July 2008, with no language restrictions, for randomized controlled trials of almonds in human patients that reported efficacy data on at least one of the following endpoints: total, low-density lipoprotein (LDL), or high-density lipoprotein (HDL) cholesterol, triglycerides, or the LDL:HDL ratio. A manual search of references from primary or review articles was performed to identify additional relevant trials. Five randomized, controlled trials (totaling 142 participants) met all inclusion criteria. Upon meta-analysis, almond consumption ranging from 25 to 168 g/day significantly lowered total cholesterol [weighted mean difference -6.95 mg/dL (95% confidence interval [CI] -13.12 to -0.772) (-0.18 mmol/L [95% CI -0.34 to -0.02])] and showed a strong trend toward reducing LDL cholesterol [weighted mean difference -5.79 mg/dL (95% CI -11.2 to 0.00) (-0.15 mmol/L [95% CI -0.29 to 0.00])]. No significant effect on HDL cholesterol, triglycerides, or LDL:HDL ratio was found. No statistical heterogeneity was observed for any analysis (I2=0% for all). Review of funnel plots and the Egger's weighted regression statistic P values suggested a low likelihood of publication bias in all analyses (P>0.25 for all). Almond consumption may decrease total cholesterol and does not significantly affect LDL or HDL cholesterol, triglycerides, or the LDL:HDL ratio. The current body of randomized trials does not support the ingestion of almonds solely for their lipid modifying effects. Both the lipid modulating effects and the safety/tolerability of almonds should be further investigated through the conduction of larger randomized, double-blinded trials of longer duration. Such studies might focus specifically on whether the efficacy of almonds as a lipid modulator varies by dose or comorbidity.