Studies that reported a clear definition of total and low-density lipoprotein cholesterol levels and had a duration of at least three weeks were eligible for inclusion. The included studies were crossover or parallel controlled trials of four to 24 weeks duration. The included participants were males and females with a mean age of 25 to 67 years. Participants were menopausal, postmenopausal, hypercholesterolaemic, low cholesterol, diabetic and dialysis patients. The included studies were of isolated soya proteins or soya drink with isoflavones compared with control diet of casein, milk proteins, milk, wheat, egg, dairy or animal proteins (various doses). The outcomes assessed in the included studies were net changes in total cholesterol and low-density lipoprotein cholesterol (LDL-C).
The authors stated neither how the papers were selected for review nor how many reviewers performed the selection.