A Systematic Review and Meta‐analysis of the Effects of Soy Products on Blood Cholesterol Levels

Abstract

A systematic review was undertaken to assess the evidence for effects of soy products on blood cholesterol. Peer‐reviewed studies were included if they described intervention or observational (cohort and nested case‐control) studies; included a non‐soy protein control; quantified soy protein intake; included generally healthy or mildly hypercholesterolemic adults (蠅18 y) not taking lipid level‐altering medications, not dieting; lasted 蠅 3 weeks; and reported changes in serum triglycerides, total, LDL‐, and/or HDL‐cholesterol.Significant reductions in total cholesterol (TC) and LDL‐cholesterol (LDL‐C) levels were observed with soy products vs. non‐soy control. Weighted mean differences for TC were ‐5.8 (95% confidence interval ‐8.1 to ‐3.1) mg/dL and for LDL‐C ‐5.8 (‐7.3 to ‐4.3) mg/dL, representing reductions of 2.6% and 4% for TC and LDL‐C, respectively. For TC, reduction was significantly greater in hypercholesterolemic (p<0.00001) than normocholesterolemic subjects (p=0.08). For LDL‐C, subgroup analyses showed that baseline cholesterol levels, source of soy protein, study design, gender, type of diet, pattern of consumption, quality of studies and balancing of caloric and macronutrient profiles between control and treatments groups had little influence on weighted mean differences and statistical significance.Scientific evidence supports a cholesterol‐lowering effect for foods containing soy protein with associated isoflavones. Epidemiological and intervention data suggest that for every 1% reduction in LDL‐C there is a corresponding 1‐2% reduction in cardiovascular events, making reduction of elevated LDL‐C a significant public health goal.