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Spr4.5

Soy Protein Research

Mostly mechanism / observationalHigh safety

5 peer-reviewed studies

What the evidence says

Mostly mechanism / observational

Most Soy Protein studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.

Most evidence is from high-quality meta-analyses and randomised trials published 1995–2025 with a typical study size of 248 participants.

Based on 5 studies · 4 meta-analyses · 1 RCT · 582 total participants

Confidence

High

By outcome

Muscle strength & powerSupports strength and lean-mass gains with resistance training, comparable to whey over ≥6 weeks · 6-12 weeks
Too few graded studies2 studies
Heart & blood pressureModestly lowers total and LDL cholesterol (FDA-recognized claim) · 4-12 weeks
Too few graded studies1 study

Active research area

2 studies in the last 5 years · Latest meta-analysis: 2025

199520102025

1Meta-Analysis1995

Consumption of soy protein rather than animal protein significantly decreased total cholesterol, LDL cholesterol, and triglycerides without significantly affecting HDL.

Anderson JW, Johnstone BM, Cook-Newell ME · N Engl J Med (1995)

38 controlled clinical trials; mean soy intake ~47g/day
Total cholesterol fell ~9.3% (−23.2 mg/dL), LDL fell ~12.9% (−21.7 mg/dL), triglycerides ~10.5%
Effect was greater in people with higher baseline cholesterol; HDL essentially unchanged

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2Meta-Analysisn=266 · medium study2018

This meta-analysis found soy protein supplementation produces similar gains in strength and lean body mass in response to resistance training as whey protein.

Messina M, Lynch H, Dickinson JM, Reed KE · Int J Sport Nutr Exerc Metab (2018)

Nine studies (266 participants); soy vs whey/animal protein with resistance training ≥6 weeks
No significant between-group difference in strength (bench press, squat) or lean body mass
Soy produces comparable long-term muscle and strength gains to animal protein despite lower leucine

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3Meta-AnalysisCited 11×2024

Soy protein supplementation decreased systolic blood pressure, total cholesterol, and LDL cholesterol.

Zhou S, Cheng F, He J, et al. · Clin Nutr (2024)

63 RCTs across soy, milk, whey, and casein protein
Soy lowered systolic BP (−1.42 mmHg), total cholesterol (−0.18 mmol/L) and LDL (−0.16 mmol/L)
Whey ranked top for cardiometabolic risk in hypertensive/obese subgroups; soy still beneficial

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4RCTn=68 · small study2016

Soy-dairy protein blend supplementation during 3 months of resistance training showed a non-significant trend toward greater whole-body lean-mass gain vs placebo; whey alone did not differ from placebo.

Reidy PT, Borack MS, Markofski MM, et al. · J Nutr (2016)

Double-blind RCT in healthy young men: 22g soy-dairy blend vs whey isolate vs carbohydrate placebo, 12 weeks
Strength, muscle thickness, and fiber cross-sectional area increased similarly across all groups
Soy-blend and whey both modestly (non-significantly) enhanced lean-mass gains vs placebo; no strength advantage

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5Meta-Analysisn=248 · medium study2025

Increased plant protein intake, mainly from soy, reduces total cholesterol, LDL, triglycerides, and ApoB.

Papaodyssea I, Lagiou A, Tzoulaki I, Valanou E, Naska A · Nutrients (2025)

11 trials, 248 patients; plant (mostly soy) protein vs animal-based diet
Reductions in total cholesterol (−24.5 mg/dL), LDL (−21.7 mg/dL), triglycerides (−21.9 mg/dL) and ApoB
HDL and ApoA unchanged; effect driven primarily by soy

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View in Research Library

Soy Protein Research

Mostly mechanism / observational

Meta-analysis of the effects of soy protein intake on serum lipids.

No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance Exercise.

Effects of high-quality protein supplementation on cardiovascular risk factors in individuals with metabolic diseases: A systematic review and meta-analysis of randomized controlled trials.

Protein Supplementation Has Minimal Effects on Muscle Adaptations during Resistance Exercise Training in Young Men: A Double-Blind Randomized Clinical Trial.

The Effect of Increased Plant Protein Intake on the Lipid Profile of Chronic Kidney Disease Patients: A Meta-Analysis of Controlled Clinical Trials.