The Study
Muscle Protein Synthesis in Response to Plant-Based Protein Isolates With and Without Added Leucine Versus Whey Protein in Young Men and Women
This study tested if a special plant protein with extra leucine makes muscles grow as fast as whey protein after drinking it. It found that, for a few hours, they worked about the same in young, healthy people. But it didn't test if this makes muscles bigger over weeks or months, or if it works for older people or athletes.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Plant proteins like pea and canola don't have enough leucine to build muscle as well as whey — but adding a little extra leucine fixes that.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 566 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this means plant-based athletes can get the same muscle-building effect as whey users by simply adding a small amount of leucine to their plant protein shake.
- 2Unfortified plant protein: +176% MPS vs fasting.
- 3With 1.5g added leucine: MPS matched whey protein.
- 4Leucine boost raised MPS by 16% compared to plain plant protein.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Current Developments in Nutrition
Year
2024
Authors
Changhyun Lim, Tom Anthonius Hubertus Janssen, Brad S. Currier, Nelani Paramanantharajah, James McKendry, Sidney Abou Sawan, S. Phillips
Related Content
Claims (7)
Taking leucine, a building block found in protein, tells your muscles to start making more protein, helping them grow and repair.
Adding leucine to plant-based proteins makes them just as good at building muscle as whey protein, which comes from milk.
If you're a healthy young adult, eating a plant-based protein shake with extra leucine can build muscle just as well as a whey protein shake, as long as both have the same essential amino acids — the leucine seems to be the secret ingredient.
Adding a little extra leucine to a plant-based protein shake makes your body absorb more leucine and builds more muscle compared to the shake without it, which means leucine was the missing piece your body needed.
Eating 20 grams of whey protein and 20 grams of a plant-based protein with added leucine both build muscle at about the same rate in young, healthy people—even though whey makes your insulin spike higher. That means insulin probably isn’t the main reason your muscles grow after protein.
If you're a healthy young adult, eating 20 grams of plant protein from peas and canola will help your muscles grow a little after fasting, but not as much as drinking whey protein — so animal-based proteins are better at building muscle without added supplements.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.