Supplement

Soy Protein

Soy protein is a plant protein made from soybeans that supplies amino acids for building tissue, and it also carries isoflavones, plant compounds that bind estrogen receptors in bone. People mostly look at it for osteoporosis, but the evidence there is limited, and no clear bone findings stand out yet. Research is firmer for muscle, where trials found small gains in muscle mass and strength.

Sources: PMID 39813010; PMID 29722584

Updated 30 September 2026
How we grade
6 studies cited

Best evidence: Grade B
Conditions studied: 13
Outcomes: 49
Graded outcomes: 0405

Evidence by condition

Strong
Moderate
Limited
Very limited

13 conditions

Muscle Size Strength

Muscle Size Strength: outcomes studied for Soy Protein
Grade	Outcome	Effect	Size	Studies	People
	Muscle Mass Small Improvement	Improves (the measure goes up)	Small effect	2 studies	1,048 people
Studies that measured muscle mass No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance ExerciseInt J Sport Nutr Exerc Metab · PMID 29722584 Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials.Nutr Rev · PMID 39813010
	Strength Small Improvement	Improves (the measure goes up)	Small effect		266 people

General Athletic Performance

General Athletic Performance: outcomes studied for Soy Protein
Grade	Outcome	Effect	Size	Studies	People
	Muscle Mass Small Improvement	Improves (the measure goes up)	Small effect	2 studies	266 people
Studies that measured muscle mass No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance ExerciseInt J Sport Nutr Exerc Metab · PMID 29722584 Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials.Nutr Rev · PMID 39813010
	Strength	Improves (the measure goes up)			266 people

Muscle Size & Strength

Muscle Mass: improves
Strength: improves

Muscle Size & Strength: outcomes studied for Soy Protein
Grade	Outcome	Effect	Size	Studies	People
	Muscle Mass Small Improvement	Improves (the measure goes up)	Small effect	2 studies	1,048 people
Studies that measured muscle mass No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance ExerciseInt J Sport Nutr Exerc Metab · PMID 29722584 Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials.Nutr Rev · PMID 39813010
	Strength	Improves (the measure goes up)			266 people

Chronic Kidney Disease (CKD)

Blood Urea Nitrogen
Serum Albumin: improves
C-Reactive Protein (CRP): improves

Chronic Kidney Disease (CKD): outcomes studied for Soy Protein
Grade	Outcome	Effect	Size	Studies	People
	Blood Urea Nitrogen No effect		NoneNo effect		522 people
	Serum Albumin	Improves (the measure goes up)		1 study	522 people
Studies that measured serum albumin The effects of soy protein and soy isoflavones intake on chronic kidney disease: a systematic review and meta-analysis.Int Urol Nephrol · PMID 39611889
	C-Reactive Protein (CRP)	Improves (the measure goes down)			522 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			522 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			522 people
	Proteinuria	Improves (the measure goes up)			522 people
	Serum Calcium	Improves (the measure goes up)			522 people
	Serum Phosphorus	Changes; see studies			522 people
	Total cholesterol	Improves (the measure goes down)			522 people
	Triglycerides	Improves (the measure goes down)			522 people

High Blood Pressure

Blood glucose
Blood Pressure: improves
High-density lipoprotein (HDL): improves

High Blood Pressure: outcomes studied for Soy Protein
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose No effect		NoneNo effect		521 people
	Blood Pressure	Improves (the measure goes down)		1 study	1,203 people
Studies that measured blood pressure The Effects of Isolated Soy Protein, Isolated Soy Isoflavones and Soy Protein Containing Isoflavones on Serum Lipids in Postmenopausal Women: A Systematic Review and Meta-AnalysisCrit Rev Food Sci Nutr · PMID 31858808
	High-density lipoprotein (HDL)	Improves (the measure goes up)			1,008 people
	Insulin	Changes; see studies			4,229 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			982 people
	Total cholesterol	Improves (the measure goes down)			998 people
	Triglycerides	Improves (the measure goes down)			1,087 people

High Cholesterol

Blood glucose
Blood Pressure: improves
High-density lipoprotein (HDL): improves

High Cholesterol: outcomes studied for Soy Protein
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose No effect		NoneNo effect		521 people
	Blood Pressure	Improves (the measure goes down)		1 study	1,203 people
Studies that measured blood pressure The Effects of Isolated Soy Protein, Isolated Soy Isoflavones and Soy Protein Containing Isoflavones on Serum Lipids in Postmenopausal Women: A Systematic Review and Meta-AnalysisCrit Rev Food Sci Nutr · PMID 31858808
	High-density lipoprotein (HDL)	Improves (the measure goes up)			1,008 people
	Insulin	Changes; see studies			4,229 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			982 people
	Total cholesterol	Improves (the measure goes down)			998 people
	Triglycerides	Improves (the measure goes down)			1,087 people

Type 2 Diabetes

Blood glucose
Blood Pressure: improves
High-density lipoprotein (HDL): improves

Type 2 Diabetes: outcomes studied for Soy Protein
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose No effect		NoneNo effect		521 people
	Blood Pressure	Improves (the measure goes down)		1 study	1,203 people
Studies that measured blood pressure The Effects of Isolated Soy Protein, Isolated Soy Isoflavones and Soy Protein Containing Isoflavones on Serum Lipids in Postmenopausal Women: A Systematic Review and Meta-AnalysisCrit Rev Food Sci Nutr · PMID 31858808
	High-density lipoprotein (HDL)	Improves (the measure goes up)			1,008 people
	Insulin	Changes; see studies			4,229 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			982 people
	Total cholesterol	Improves (the measure goes down)			998 people
	Triglycerides	Improves (the measure goes down)			1,087 people

Metabolic Syndrome

Blood glucose
Blood Pressure: improves
High-density lipoprotein (HDL): improves

Metabolic Syndrome: outcomes studied for Soy Protein
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose No effect		NoneNo effect		521 people
	Blood Pressure	Improves (the measure goes down)		1 study	1,203 people
Studies that measured blood pressure The Effects of Isolated Soy Protein, Isolated Soy Isoflavones and Soy Protein Containing Isoflavones on Serum Lipids in Postmenopausal Women: A Systematic Review and Meta-AnalysisCrit Rev Food Sci Nutr · PMID 31858808
	High-density lipoprotein (HDL)	Improves (the measure goes up)			1,008 people
	Insulin	Changes; see studies			4,229 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			982 people
	Total cholesterol	Improves (the measure goes down)			998 people
	Triglycerides	Improves (the measure goes down)			1,087 people

Sarcopenia

Muscle Mass: improves

Sarcopenia: outcomes studied for Soy Protein
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Muscle Mass	Improves (the measure goes up)		2 studies	1,048 people
Studies that measured muscle mass No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance ExerciseInt J Sport Nutr Exerc Metab · PMID 29722584 Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials.Nutr Rev · PMID 39813010

Menopause

Blood Pressure: improves

Menopause: outcomes studied for Soy Protein
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Blood Pressure	Improves (the measure goes down)		1 study	3,456 people
Studies that measured blood pressure The Effects of Isolated Soy Protein, Isolated Soy Isoflavones and Soy Protein Containing Isoflavones on Serum Lipids in Postmenopausal Women: A Systematic Review and Meta-AnalysisCrit Rev Food Sci Nutr · PMID 31858808

Osteoporosis

Bone Mineral Density: improves

Osteoporosis: outcomes studied for Soy Protein
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Bone Mineral Density	Improves (the measure goes up)		1 study	393 people
Studies that measured bone mineral density Animal Versus Plant Protein and Adult Bone Health: A Systematic Review and Meta-Analysis From the National Osteoporosis FoundationPLoS One · PMID 29474360

Bone Health

Bone Mineral Density: improves

Bone Health: outcomes studied for Soy Protein
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Bone Mineral Density	Improves (the measure goes up)		1 study	393 people
Studies that measured bone mineral density Animal Versus Plant Protein and Adult Bone Health: A Systematic Review and Meta-Analysis From the National Osteoporosis FoundationPLoS One · PMID 29474360

Fatigue Symptoms: improves

Key findings

Muscle MassImproves (the measure goes up)
StrengthImproves (the measure goes up)
Blood Urea NitrogenChronic Kidney Disease (CKD)

Shop the evidence-backed picks

Third-party tested Soy Protein products, in the forms the graded studies used where we can match them.

Grade B

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Studies cited

6 studies from PubMed

The combined effect of physical exercise, pranayama, and diet on fatigue in adult cancer patients undergoing chemotherapy: a randomized controlled trial.Support Care Cancer · PMID 39207544
Animal Versus Plant Protein and Adult Bone Health: A Systematic Review and Meta-Analysis From the National Osteoporosis FoundationPLoS One · PMID 29474360
The Effects of Isolated Soy Protein, Isolated Soy Isoflavones and Soy Protein Containing Isoflavones on Serum Lipids in Postmenopausal Women: A Systematic Review and Meta-AnalysisCrit Rev Food Sci Nutr · PMID 31858808
No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance ExerciseInt J Sport Nutr Exerc Metab · PMID 29722584
Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials.Nutr Rev · PMID 39813010
The effects of soy protein and soy isoflavones intake on chronic kidney disease: a systematic review and meta-analysis.Int Urol Nephrol · PMID 39611889

Evidence by condition

Muscle Size Strength

Key findings

Shop the evidence-backed picks

Studies cited

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