The effects of oral soybean phospholipid on serum total cholesterol, plasma triglyceride, and serum high-density lipoprotein cholesterol concentrations in hyperlipidemia

Beyond the Cholesterol-Lowering Effect of Soy Protein: A Review of the Effects of Dietary Soy and Its Constituents on Risk Factors for Cardiovascular Disease

The hypocholesterolemic effect of soy is well-documented and this has led to the regulatory approval of a health claim relating soy protein to a reduced risk of cardiovascular disease (CVD). However, soybeans contain additional components, such as isoflavones, lecithins, saponins and fiber that may improve cardiovascular health through independent mechanisms. This review summarizes the evidence on the cardiovascular benefits of non-protein soy components in relation to known CVD risk factors such as hypertension, hyperglycemia, inflammation, and obesity beyond cholesterol lowering. Overall, the available evidence suggests non-protein soy constituents improve markers of cardiovascular health; however, additional carefully designed studies are required to independently elucidate these effects. Further, work is also needed to clarify the role of isoflavone-metabolizing phenotype and gut microbiota composition on biological effect.

Cholesterol-lowering effects of a new isolated soy protein with high levels of nondenaturated protein in hypercholesterolemic patients

This study was undertaken to compare the effects on plasma cholesterol concentration of a new isolated soy protein in which the protein structure is kept in its native, nondenaturated form (verum 1) versus a conventional isolated soy protein (verum 2) and milk protein (placebo). This prospective, randomized, double-blind, placebo-controlled study was conducted in an outpatient clinical study center in Berlin, Germany. Over 8 wk, 120 patients (total cholesterol, 5.2-7.8 mmol/L) were given verum 1, verum 2, or placebo at a dosage of 25 g protein daily. At the end of the treatment period, total cholesterol levels were significantly reduced by 10.7% in the verum 1 group compared with placebo (P<.001), and levels were reduced by 5.8% in the verum 2 group (P=.008). The difference between the 2 verum groups was statistically significant (P=.008). Low-density lipoprotein cholesterol levels were significantly reduced with nondenaturated isolated soy protein only: levels were reduced by 9.4% in the verum 1 group (P=.002) and by 4.9% in the verum 2 group (P=.107). Again, the difference between the verum groups was significant (P=.05). The results of this study confirm that supplementation with isolated soy protein can lead to significant reductions in plasma concentrations of total and low-density lipoprotein cholesterol. These reductions are significantly more pronounced with an isolated soy protein that maintains the native protein structure than with a commercially available reference isolated soy protein.

Ultra heat treatment destroys cholesterol-lowering effect of soy protein

A randomized, placebo-controlled, double-blind clinical study was performed to investigate the dose-dependent response of serum cholesterol after consuming an ultra-heat-treated milk containing a soy protein preparation. Eighty hypercholesterolemic subjects were assigned to one of four study groups receiving 12.5 or 25 g soy protein (active treatment) or casein (placebo) daily over a period of 4 weeks. The trial substances were provided as ready-made, ultra-heated milk preparations. Before and after the treatment, serum concentrations of total, low-density lipoprotein, and high-density lipoprotein cholesterol were determined. Unexpectedly, at the end of the study, low-density lipoprotein cholesterol concentrations were significantly increased compared with baseline in all study groups. The magnitude of this increase (17-19%) was similar in all active and placebo study groups. Soy protein supplements previously shown to be effective in reducing serum cholesterol had in this study no such lipid-lowering effect after ultra heat treatment.