Study designs of evaluations included in the review
Only randomised controlled trials (RCTs) with either a crossover or parallel design were eligible for inclusion in the review.
Specific interventions included in the review
Studies that included the ingestion of soy protein for 1 to 3 months, and had comparable groups with at least two different levels of IF (high and low) for the same soy protein intake level, were eligible. All of the studies included in the review used soy protein isolate with intakes ranging from 25 to 100 g/day, with measured IF intakes ranging from 3 to 132 mg/day. The mean low IF intake was 6 mg/day and the mean high IF intake was 96 mg/day.
Participants included in the review
Studies with human participants were eligible for inclusion; no further details were provided. Half of the included studies involved postmenopausal women only. The mean ages of the participants ranged from 26.3 to 62.7 years, the mean body mass index ranged from 22.8 to 26.6 kg/m2, and the mean baseline serum LDL-cholesterol concentrations ranged from 2.32 to 4.81 mmol/L. Participants in about half of the studies were mildly or moderately hypercholesterolaemic.
Outcomes assessed in the review
Studies that provided blood cholesterol and end point LDL-cholesterol concentrations were eligible for inclusion. Half of the eligible studies reported serum LDL cholesterol concentrations and half reported values in plasma.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.