Simvastatin further enhances the hypocholesterolemic effect of soy protein in rabbits

The effects of three dietary proteins (casein, cod, soy) and low dose simvastatin, an inhibitor of hydroxymethyl-glutaryl coenzyme A (HMG-CoA) reductase, on serum lipids were investigated.

New Zealand rabbits were fed purified diet (20% protein, 11% fat and 0.06% cholesterol) for 28 days. Animals received either 1.4 mg simvastatin or placebo orally during the last 14 days. A randomized 3 x 2 factorial design was used for the administration of diet and drug treatments.

Mean food intake and body weight of the animals in all groups were similar. In placebo groups, soy protein decreased (p = 0.06) total cholesterolemia with significantly (p = 0.009) lower high-density lipoprotein (HDL) cholesterol, and significantly (p = 0.004) higher very low-density lipoprotein (VLDL) triglycerides (TG), compared to animal proteins. Addition of low dose simvastatin to soy protein induced a further decrease of serum total cholesterol, decreased VLDL and low-density lipoprotein (LDL) cholesterol, and LDL (apolipoprotein B), as well as improved VLDL-TG and HDL cholesterol levels. No similar reduction was seen when simvastatin was combined with casein or cod protein.

These results show that low dose simvastatin may enhance the hypocholesterolemic effect of soy protein compared to animal proteins in the rabbit.