Cholesterol Study Pits Soy versus Milk

Soy protein may outperform milk protein when it comes to managing lipid levels in healthy adults, according to a study performed by researchers from the University of Mississippi and Tulane University. Their research is now published in the European Journal of Clinical Nutrition.

In a three-phase crossover study on 352 adults, individuals were assigned to 40 g/day of soy protein, milk protein, or complex carbohydrates from wheat for eight weeks. Each supplementation phase was separated by a three-week washout period. After gathering fasting blood samples at the end of each phase, researchers collected individual fasting blood samples to check for any cholesterol and triglyceride changes.

When compared to complex carbohydrate supplementation, soy supplementation significant reduced total cholesterol and total-to-HDL (“good’) cholesterol ratios.  Reductions of LDL (“bad”) cholesterol and triglycerides reached near-significant levels.

When compared to milk protein supplementation, soy protein supplementation brought a significant increase in HDL and reduced total-to-HDL ratios. Again, reductions in LDL cholesterol reached near-significant levels.

Milk protein did not provide a significant benefit to any incorporated lipid measurements over complex carbohydrates.

Previous meta-analyses have linked soy protein consumption to statistically significant drops in LDL cholesterol. Since many of those studies focused on patients with elevated cholesterol, the lack of a greater impact in this study is likely due to its use of healthy subjects. Future studies, the researchers wrote, should start to look for a dose-response relationship between soy protein intake and lipid levels.

The soy-versus-milk study was supported by a research grant from the National Heart, Lung, and Blood Institute of the NIH. All supplements were provided by soy ingredients manufacturer Solae (St. Louis).