Soy Protein Significantly Lowers Cholesterol

ST. LOUISSoy protein lowers total cholesterol and non-HDL (non-high-density lipoprotein) cholesterol significantly more than milk protein in patients with moderately high cholesterol levels, according to a new study published in the Journal of Clinical Lipidology.

Non-HDL cholesterol has been shown to be a somewhat stronger predictor of cardiovascular disease and mortality risk than LDL cholesterol in population studies," said Elaine Krul, co-author of the study and nutrition discovery lead at Solae. The fact that soy protein significantly decreased non-HDL cholesterol levels compared to milk protein in this study is very promising."

Researchers conducted a randomized, controlled, parallel arm trial to evaluate the effects of an insoluble fraction of soy protein, compared to total milk proteins with high calcium content, on the fasting lipid profile. They also assessed the potential contributions of increased excretion of bile acids and neutral sterols to their lipid-altering effects.

Study participants included men and women aged 18 to 79 years with elevated cholesterol, defined as fasting LDL-cholesterol concentrations of at least 100 mg/dL and less than 200 mg/dL while receiving no lipid altering therapy. Participants were asked to follow a Therapeutic Lifestyle Changes diet throughout the study. Subjects that still met the inclusion criteria were then screened for their ability to lower their cholesterol in response to a bile acid binding drug, colesevelam. A majority of subjects responded and were then randomized to the test protein groups.

Solaes soy protein that was used in the study was a relatively insoluble fraction of soy protein isolate that had been shown to lower plasma cholesterol and increase fecal bile acid excretion in animals. The levels of isoflavones in the soy protein were lower than the average commercial soy protein isolate further supporting the notion that isoflavones do not play a role in the cholesterol lowering. The milk protein supplemented group also showed a modest cholesterol lowering.

The results of this study also showed that soy protein lowered non-HDL through a mechanism that does not involve increased bile acid excretion, but some yet to be determined mechanism," said Kevin Maki, lead author of the study. Nonetheless, these results are supportive of the heart health claim for soy protein."