Effects of soy supplementation on blood lipids and arterial function in hypercholesterolaemic subjects

Studies on soy supplementation suggest a cardioprotective potential.

To examine the effects on LDL cholesterol and arterial function as a result of dietary enrichment with soy supplementation.

A Randomized, double blind, parallel intervention trial.

Department of Endocrinology and Metabolism C, Aarhus University Hospital, and Department of Human Nutrition, The Royal Veterinary and Agricultural University, Denmark.

In all, 100 hypercholesterolaemic but otherwise healthy subjects were included in the study of which 89 completed it.

Subjects were randomly assigned to 24 weeks of daily intake of either a soy supplement, Abalon (30 g soy protein, 9 g cotyledon fibre and 100 mg isoflavones) or placebo (30 g of casein). The soy supplement and placebo were provided in two sachets daily that were stirred in water. Fasting plasma lipids, TNF-alpha, homocysteine, insulin sensitivity, homeostasis model assessment (HOMA-IR), serum insulin, serum glucose, blood pressure as well as Glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic peptide (GIP) and plasma lipids to a fat-rich meal were recorded before and after the intervention. In a sub study in 32 subjects, arterial dilatory capacity, compliance, and distensibility were recorded before and after the intervention.

In the main study, no difference in fasting plasma lipid levels or insulin sensitivity was found between soy-based supplement and placebo. A significant postprandial increase in GIP to the meal test was observed in the soy group (P < 0.05). In a substudy, no difference between the groups in changes in flow-mediated vasodilatation (P = 0.84) was detected, while the soy supplementation caused a reduction in LDL and total cholesterol.

No significant effects on blood lipids were observed in the main study to a soy supplementation in hypercholesterolaemic subjects after 24 weeks. In the substudy, the soy supplementation, however, reduced LDL and total cholesterol but did not influence markers of arterial function.