A randomized study comparing plant sterol- and soluble fiber-enriched soymilk with plain soymilk in adults with...

Lowering low-density lipoprotein cholesterol (LDL-C) is an effective strategy to reduce coronary heart disease risk. Plant sterols/stanols, soluble fiber, and soy protein have each shown LDL-C-lowering effects. This study compared the effects of plant sterol-and soluble fiber-enriched soymilk (SFSM) versus plain soymilk (SM) on LDL-C over 8 weeks.

A total of 242 adults aged ≥ 18 years with hypercholesterolemia (LDL-C > 130 mg/dL), either untreated or receiving stable lipid-lowering therapy were randomized to receive either plain soymilk (SM; n = 119) or plant sterol- and soluble fiber-enriched soymilk (SFSM; n = 123), with two 180-mL packs consumed daily for 8 weeks. Three participants discontinued the assigned intervention during the study (SM, n = 1; SFSM, n = 2); all three attended the week-2 visit and contributed post-baseline laboratory data, but had no week-8 measurements. Both products provided 5 g soy protein per 180-mL serving; SFSM additionally contained 1 g free plant sterol and 5 g inulin (soluble fiber), with a total dietary fiber content of 5.8 g per serving, corresponding to daily intakes of 2 g free plant sterol and 11.6 g total fiber. Fasting plasma glucose and lipid profiles were measured at baseline and at weeks 2, 4, 6, and 8. Dietary intake and physical activity were monitored throughout the study. The intention-to-treat analysis included all 242 randomized participants.

At week 8, SFSM group had a greater reduction in LDL-C than the SM group, with an adjusted between-group treatment effect of 5.5 mg/dL (95% CI 0.6 to 10.4, p = 0.028), favoring SFSM, after adjustment for baseline lipid values. No significant between-group differences were found in fasting plasma glucose, HDL-C, triglycerides, total cholesterol/HDL-C ratio, total energy intake, total fat intake, cholesterol intake, water consumption, or physical activity; however, fiber intake increased significantly more in the SFSM group.

These findings support the LDL-C-lowering benefit of plant sterol-and soluble fiber-enriched soymilk compared with plain soymilk over 8 weeks; however, secondary and subgroup findings should be interpreted cautiously because they were exploratory in nature. Trial registration Clinical Trials Registry Identifier: (NCT02459314) Retrospectively registered on May 15, 2015; first posted June 2, 2015. The study was conducted from April 2013 to April 2014. The original protocol date 22 October 2012 is provided as supplementary material.