Effect of Two Types of Soy Milk and Dairy Milk on Plasma Lipids in Hypercholesterolemic Adults: A Randomized Trial

Abstract

Objective: To compare the effects of two commercially available soy milks (one made using whole soy beans, the other using soy protein isolate) with low-fat dairy milk on plasma lipid, insulin, and glucose responses.

Design: Randomized clinical trial, cross-over design.

Subjects: Participants were 30–65 years of age, n = 28, with pre-study LDL-cholesterol (LDL-C) concentrations of 160–220 mg/dL, not on lipid lowering medications, and with an overall Framingham risk score of ≤10%.

Intervention: Participants were required to consume sufficient milk to provide 25 g protein/d from each source. The protocol included three 4-week treatment phases, each separated from the next by a wash-out period of ≥4 weeks.

Results: Mean LDL-C concentration at the end of each phase (± SD) was 161 ± 20, 161 ± 26 and 170 ± 24 mg/dL for the whole bean soy milk, the soy protein isolate milk, and the dairy milk, respectively (p = 0.9 between soy milks, p = 0.02 for each soy milk vs. dairy milk). No significant differences by type of milk were observed for HDL-cholesterol, triacylglycerols, insulin, or glucose.

Conclusion: A 25 g dose of daily soy protein from soy milk led to a modest 5% lowering of LDL-C relative to dairy milk among adults with elevated LDL-C. The effect did not differ by type of soy milk and neither soy milk significantly affected other lipid variables, insulin or glucose.

• soy protein
• soy milk
• lipids
• LDL-cholesterol
• hypercholesterolemic adults

We gratefully acknowledge the contributions of the nursing, dietary and laboratory staff of the General Clinical Research Center of the Stanford University Hospital who contributed significantly to the success of this project.

This investigation was supported by an unrestricted gift from the White Wave Foods company, by NCI/NIH grant CA71789, and by Human Health Service grant M01-RR00070, General Clinical Research Centers, National Center for Research Resources, National Institutes of Health.

Notes

Disclosures: M.M. has provided consulting services to White Wave Foods. C.D.G. received the unrestricted gift funds from White Wave Foods that were used to fund this trial. None of the other authors has potential conflicts of interest.

Presented in part at the Sixth International Soy Symposium, Chicago, Illinois, October 2005.