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

title: "Plant Sterol and Soluble Fiber Soymilk Lowers LDL-C More Than Plain Soymilk Over 8 Weeks"

description: "A randomized trial of 242 adults with elevated LDL cholesterol found that fortified soymilk produced a modest additional LDL-C reduction compared with plain soymilk."

TL;DR

In a randomized trial of 242 adults with elevated LDL cholesterol, soymilk fortified with plant sterols and soluble fiber produced a small but statistically significant additional LDL-C reduction over 8 weeks compared with plain soymilk (adjusted difference of 5.5 mg/dL).

What the study found

Elevated LDL cholesterol is a well-established modifiable risk factor for coronary heart disease, and lowering it is a central goal of cardiovascular prevention. Three dietary components have each shown LDL-C-lowering effects in prior research: plant sterols and stanols, soluble fiber, and soy protein. This trial asked a practical question: does combining plant sterols and soluble fiber in a soymilk base outperform plain soymilk, which already contains soy protein?

The study, published in the *European Journal of Nutrition*, randomized 242 adults aged 18 and older with LDL-C above 130 mg/dL to either plain soymilk (SM, n = 119) or plant sterol- and soluble fiber-enriched soymilk (SFSM, n = 123). Participants, who were either untreated or on stable lipid-lowering medication, drank two 180 mL packs daily for 8 weeks. Both products delivered 5 g of soy protein per serving. The enriched product added 1 g of free plant sterol and 5 g of inulin per serving, bringing total fiber to 5.8 g per serving, or roughly 2 g of plant sterol and 11.6 g of total fiber per day across two servings.

At week 8, the enriched group showed a greater LDL-C reduction than the plain soymilk group. The adjusted between-group treatment effect, controlling for baseline lipid values, was 5.5 mg/dL (95% CI 0.6 to 10.4, p = 0.028), favoring the enriched product. The confidence interval is wide and its lower bound sits close to zero, so while the result reached conventional statistical significance, the magnitude of the difference is modest and the precision is limited. Readers should weigh the result as a real but small signal rather than a large effect.

Several other outcomes did not differ meaningfully between groups. Fasting plasma glucose, HDL cholesterol, triglycerides, the total cholesterol to HDL ratio, total energy intake, total fat intake, cholesterol intake, water consumption, and physical activity were all similar across arms. The one clear divergence was fiber intake, which rose significantly more in the enriched group, as expected given the added inulin. Because the enriched product changed fiber intake as well as sterol intake, the trial cannot separate the contribution of sterols from that of fiber. The authors themselves note that secondary and subgroup analyses were exploratory and should be interpreted cautiously.

Attrition was low. Three participants discontinued the intervention (one in the plain group, two in the enriched group), and all three attended the week-2 visit and contributed post-baseline data, though they lacked week-8 measurements. The primary analysis followed the intention-to-treat principle and included all 242 randomized participants.

For context on the individual components, Fiber is the broader category that includes soluble fibers such as inulin, and the high-fiber diet pattern is a well-studied dietary approach. The sterol component relates to plant sterols and stanols, which have a longer research record for LDL-C lowering than soy protein alone.

What this means for you

Fortified soy products may offer a small additional LDL-C benefit over plain soymilk in adults with elevated cholesterol, based on this 8-week trial.

The effect size is modest. A 5.5 mg/dL difference is real but small, and it should be seen as one component of a broader approach rather than a standalone solution.

Consider the whole pattern. The participants' intake of fiber rose, so the benefit may reflect higher overall fiber consumption. Adding soluble fiber through diet is consistent with the high-fiber diet approach.

Discuss changes with a clinician if you take lipid-lowering medication. Participants in this trial were on stable therapy, but any dietary change should be coordinated with your care team, particularly if you have a cardiovascular condition.

Long-term outcomes are unknown. This study measured LDL-C over 8 weeks, not cardiovascular events over years, so it cannot establish whether these products reduce heart disease risk directly.

Study details

Item	Detail
Study type	Randomized controlled trial
Sample size	242 adults (intention-to-treat)
Population	Adults aged 18 and older with LDL-C above 130 mg/dL, untreated or on stable lipid-lowering therapy
Intervention	Plant sterol and soluble fiber-enriched soymilk (1 g free plant sterol and 5 g inulin per 180 mL serving), two servings daily
Comparator	Plain soymilk (5 g soy protein per 180 mL serving), two servings daily
Duration	8 weeks
Primary outcome	LDL-C change at week 8, adjusted for baseline
Key result	Adjusted between-group difference of 5.5 mg/dL favoring enriched soymilk (95% CI 0.6 to 10.4, p = 0.028)
Trial registration	NCT02459314
Journal	European Journal of Nutrition

Sources

1. Study title: "A randomized study comparing plant sterol- and soluble fiber-enriched soymilk with plain soymilk in adults with elevated LDL cholesterol." *European Journal of Nutrition*. PubMed. https://pubmed.ncbi.nlm.nih.gov/42927524/

2. ClinicalTrials.gov Identifier: NCT02459314.

ProtocolEngine provides general health information based on published research. This is not medical advice. Consult a healthcare professional before starting any supplement or health protocol.