Whey vs Soy Protein: Muscle and Heart Data | Dose Track
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Whey vs soy protein: which is better?

Muscle meta-analysis · Cholesterol · FDA claim · Allergens

Short answer: For muscle, a meta-analysis of 9 studies found soy gave similar strength and lean-mass gains to whey or other animal protein with resistance training.1 Whey has more leucine.2 Soy lowered LDL by about 3% to 4% in the trials FDA reviewed; FDA proposed revoking its soy heart claim in 2017, but the rule is still in place.34

How do whey and soy protein compare side by side?

From a muscle meta-analysis, an LDL meta-analysis, NIH, FDA rules and eCFR.
Whey proteinSoy protein
SourceMilk2Soybeans4
LeucineMore than casein or soy2Less than whey2
Muscle with training (9 studies, 266 people)Strength rose; no difference from soy1Similar strength and lean-mass gains1
CholesterolNot the focus of the sources checkedLDL down about 4.8 mg/dL vs other proteins (median 25 g a day)3
FDA heart claimNone25 g a day claim in 21 CFR 101.82; revocation proposed in 201745
AllergenMilk is a major food allergen6Soy is a major food allergen6

Reviewed . Half-life figures are shown only where the value Dose Track uses agrees with the cited source.

Which builds more muscle?

Short studies suggest whey stimulates muscle protein building more than soy, likely because of its leucine.1 Over 6 weeks or longer, a 2018 meta-analysis of 9 studies (5 comparing whey with soy) found no difference in strength or lean mass between soy and whey or other animal proteins with resistance training.1

These are study protocols, not personalized advice; confirm any dosing with your prescriber.

What about the soy heart claim?

Under 21 CFR 101.82, qualifying foods may say that 25 g of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce heart disease risk.4 In 2017 FDA proposed revoking the claim, saying the evidence no longer appeared to meet its standard.5 A meta-analysis of 43 of the 46 trials FDA identified found soy lowered LDL by 4.76 mg/dL, about 3% to 4%; one author is from a soy nutrition group.3

More detail: Whey vs pea protein: does plant protein build muscle as well?, Whey vs casein protein: what is the difference?, and the Whey Protein and Soy Protein guides.

This page summarizes labels and published studies. It is not personalized medical advice; confirm any dose or change with your prescriber.
Whey vs pea protein: does plant protein build muscle as well?Dairy protein vs plant protein, tested together Whey vs casein protein: what is the difference?Fast milk protein vs slow milk protein HMB vs leucine: is the leucine metabolite better?Leucine vs the compound the body makes from it

Frequently asked questions

Is soy protein as good as whey for muscle?+
Over 6 weeks or more, a meta-analysis of 9 studies found similar strength and lean-mass gains.1
Does soy protein lower cholesterol?+
Modestly: about 3% to 4% lower LDL in the trials FDA reviewed.3
Is the FDA soy heart claim still allowed?+
FDA proposed revoking it in 2017, but the regulation is still in place as of October 2026.54
Are whey and soy allergens?+
Yes. FDA lists both milk and soy as major food allergens.6
Can I track protein in Dose Track?+
Yes. Log grams per scoop with reminders.

Sources

  1. Messina M, et al. 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. Int J Sport Nutr Exerc Metab. 2018;28(6):674-685.
  2. NIH Office of Dietary Supplements. Dietary supplements for exercise and athletic performance, fact sheet for health professionals (updated April 1, 2024).
  3. Blanco Mejia S, et al. A meta-analysis of 46 studies identified by the FDA demonstrates that soy protein decreases circulating LDL and total cholesterol concentrations in adults. J Nutr. 2019;149(6):968-981.
  4. 21 CFR 101.82. Health claims: soy protein and risk of coronary heart disease (eCFR, read October 28, 2026).
  5. FDA. Food labeling: health claims; soy protein and coronary heart disease. Proposed rule. Federal Register, October 31, 2017.
  6. FDA. Food allergies: what you need to know.

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