The Lipid-Lowering Effects of 4 Weeks of Daily Soymilk or Dairy Milk Ingestion in a Postmenopausal Female Population

Alterations in plasma cholesterol concentrations, especially increases in low-density lipoprotein (LDL), are well-known risk factors in the development of atherosclerosis. Numerous studies have examined the lipid-lowering effects of functional soy-containing foods, but few have specifically examined soymilk, with equivocal findings reported. In September 2008, a single-blind, randomized, controlled trial was conducted on 32 postmenopausal women at Baylor University, Waco, TX, USA. After a 2-week run-in period, subjects were randomly assigned to consume three servings of vanilla soy (n = 16) or reduced-fat dairy (n = 16) milk per day for 4 weeks. Plasma lipid profiles were obtained pre-and post-supplementation. Plasma high-density lipoprotein, LDL, and triglycerides were not significantly different between groups post-intervention (P = .45) or from baseline (P = .83). Separate analysis of plasma total cholesterol levels yielded similar results (P = .19 and P = .92, respectively). Furthermore, subanalyses controlling for dyslipidemia (n = 23) and lipid-lowering medication usage (n = 28) did not significantly alter results. Despite good dietary compliance, our study failed to show a significant hypocholesterolemic effect of soymilk consumption in this postmenopausal female population. Potential reasons for this nonsignificant finding are discussed, and future research directions are presented.