(P06-14-26) Effect of Food Sources of Soy Protein on Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objectives: Approved health claims for soy protein and coronary heart disease risk reduction are based on its ability to lower cholesterol. The evidence for its ability to lower blood pressure remains unclear. To clarify the effects of soy protein from different food sources on blood pressure, we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs).

Methods: MEDLINE, Embase, and The Cochrane Central Register of Controlled Trials were searched through Dec 31, 2025. We included RCTs of the effect of soy protein food sources versus non-soy comparators over ≥3 weeks. Two independent reviewers extracted data and assessed risk of bias. Outcomes were systolic blood pressure (SBP) and diastolic blood pressure (DBP). Data were pooled using the inverse variance method and expressed as mean differences (MD) with 95% confidence intervals (95% CI). Certainty of evidence was assessed by GRADE. (ClinicalTrials.gov, NCT05638061)

Results: We included 57 RCTs with 79 trial comparisons in 4,179 adult participants across various health statuses with and without hypertension. Food sources of soy protein included 12 categories (e.g. soy protein beverages, supplements, soy nuts, soymilk, combined meat and dairy alternatives, soy pudding/yogurt, soy cookies and muffins, soy bread) at a median dose of 25 g/d of soy protein. Comparators were predominantly dairy based. Total soy protein food sources reduced SBP (MD -1.46 mmHg [95% CI, -2.38 to -0.55]) and DBP (-0.98mmHg [-1.68 to -0.27]). There was effect modification by food source (P < 0.001), with soymilk (-5.48 [-10.54 to -0.42], -4.24 [-7.77 to -0.70], moderate GRADE), soy nuts (-3.78 [-6.16 to -1.40], -1.79 [-3.49 to -0.08], low GRADE), soy cookies and muffins (-5.57 [-10.21 to -0.92], -2.84 [-4.96 to -0.71], moderate GRADE) showing reductions in SBP and DBP, respectively, and soy bread showing reductions in DBP (-5.65 [-9.80 to -1.50], low GRADE).

Conclusions: The effect of soy protein on blood pressure differs by food source in adults with and without hypertension. The available evidence provides a good indication that soymilk and soy cookies and muffins result in moderate reductions in SBP and DBP and some indication that soy nuts result in small important reductions in SBP and DBP and soy bread results in large reductions in DBP.

Funding Sources: OGS, CIHR