Soy beats milk protein for cholesterol improvements: RCT

Forty grams per day of soy protein was associated with significant decreases in total cholesterol levels, compared to carbohydrate supplements, and improvements in HDL levels, compared with milk protein, according to findings published in the European Journal of Clinical Nutrition​.

“Our study is the first randomized controlled trial to compare the effects of soy protein, milk protein and complex carbohydrate on serum lipids,”​ report researchers from the University of Mississippi, Tulane University, and Kaiser Permanente Southern California.

“There is increasing evidence that consumption of soy protein in place of animal protein lowers blood cholesterol levels and may provide other cardiovascular benefits. Our study provides additional evidence that consumption of soy protein in place of carbohydrate might improve the lipid profile,”​ they added.

Industry welcome​

The study used supplements provided by Solae, and the Missouri based company welcomed the study’s findings. Elaine Krul, PhD, nutrition discovery lead at Solae said that: “The results of this study reveal that soy protein supplementation intake can help lower blood lipids, thus helping to reduce the risk of CHD in healthy individuals.”​

“It’s the simple lifestyle changes, such as including soy protein in your diet, that can often have a positive impact on your health,” ​she added.

“Research continues to demonstrate that soy protein can help lower LDL cholesterol, an important biomarker for coronary heart disease.”​

Study details​

Led by Dr Jiang He from Tulane University, the researchers recruited 352 US healthy adults with an average age of 47.7 to participate in their randomized, controlled trial.

Participants were assigned to receive 40 g/day supplementation of soy protein, milk protein or complex carbohydrate for eight weeks in a random order.

Results showed that, compared with carbohydrates, the soy protein was associated with a 3.97 mg/dl reduction in total cholesterol levels, and a 0.12 mg/dl reduction in the ratio of total:HDL cholesterol.

In addition, compared to milk protein, the soy protein was associated with a 1.54 mg/dl increase in HDL cholesterol levels and a 0.14 mg/dl decrease in the ratio of total:HDL cholesterol.

On the other hand, milk protein supplementation was significantly associated with a 1.13 mg/dL decrease in HDL levels, compared to carb supplements, added the researchers.

“Our study suggests that soy protein supplement reduces total cholesterol and total/HDL cholesterol ratio compared with carbohydrate, and increases HDL and reduces total/HDL cholesterol ratio compared with milk protein,”​ wrote the researchers.

“The effect of milk protein did not confer a significant favorable effect on any lipid measures compared with carbohydrate. ​

“Further randomized controlled trials are warranted to examine the effect of various amounts of soy proteins on lipid levels to recommend a particular optimal level to increase soy protein intake as part of a nutrition intervention strategy for the prevention and treatment of hypercholesterolemia and subsequent CVD,”​ they concluded.

Source: European Journal of Clinical Nutrition ​
Published online ahead of print, doi: 10.1038/ejcn.2011.168
“Effect of soy and milk protein supplementation on serum lipid levels: a randomized controlled trial”​​
Authors: M.R. Wofford, C.M. Rebholz, K. Reynolds, J. Chen, C-S. Chen, L. Myers, J. Xu, D.W. Jones, P.K. Whelton, J. He