Effects of a new low dose soy protein/β-sitosterol association on plasma lipid levels and oxidation

Background High doses of soy protein are able to decrease plasma cholesterolemia significantly, but they unbalance daily protein intake and strongly modify nutritional habits in patients. Aim of the study To evaluate the antihypercholesterolemic efficacy of a low dose soy protein product with added beta-sitosterol (rapport=4:1) in 36 moderately hypercholesterolemic subjects. Methods The study was divided into 3 separate periods of 40 days each: a stabilization diet period, followed by a treatment period during which all subjects took 10 g of the test product once daily and, finally, a wash out period. The following parameters were monitored: weight, dietary habits, plasma lipid levels, glycemia, uric acid, fibrinogenemia and antibodies against oxidized LDL (ox-LDL Ab). Results From the end of the stabilization diet period to the end of the supplementation with the soy protein product with added beta-sitosterol we observed a 19.64+/-20.32 mg/dL, 8.47+/-54.61 mg/dL, 1.69+/-10.92 mg/dL, and 7.06+/-16.66 mg/dL mean+/-SD decrease respectively in LDL-C (p<0.001), TG (p=0.358), VLDLs (p=0.358) and apoB (p=0.016) levels, associated with a 1.31 +/- 8.08 mg/dL and 1.03 +/- 19.09 mg/dL mean increase respectively in HDLC (p=0.251) and apoAI (p=0.749) plasma concentrations. The dietary supplementation did not influence Lp(a) (p=0.984) and ox-LDL Ab (p=0.953) plasma levels. A statistically significant correlation was observed for LDL-C plasma levels, between the end of the stabilization diet period and the end of the period of supplementation with soy proteins with added beta-sitosterols (p<0.001). Conclusion Although further long-term clinical studies are necessary before claims can be made regarding the therapeutic effects of the tested formulation, the preliminary findings regarding its efficacy and safety as an antihypercholesterolemic agent are encouraging.