Collagen powder has become one of the most popular scoops in the pantry, and a lot of people are counting it toward their daily protein — a spoonful in coffee standing in for a real protein serving. A run of controlled trials using the gold-standard method for measuring muscle protein synthesis gives a much clearer answer than the marketing does, and it’s not the one collagen tubs imply.
What the researchers did
The most direct evidence comes from stable-isotope tracer studies — infused labeled amino acids or deuterated water, paired with muscle biopsies — which is the gold-standard way to measure how fast the body is actually building new muscle protein. McKendry and colleagues (2024) gave 31 healthy older men (72 ± 4 years) an extra 50 g/day of whey, pea, or collagen protein on top of the recommended dietary allowance and tracked integrated muscle protein synthesis over the following week. Aussieker and colleagues (2023) took a different angle: 45 young recreational athletes did a single resistance-exercise session, then received 30 g of whey, 30 g of collagen, or a placebo, with blood and muscle samples collected over the next 5 hours of recovery.
The numbers
In the older-adult trial, the extra whey and the extra pea protein both significantly raised integrated muscle protein synthesis compared with the RDA-only baseline (1.59%/day vs. 1.46%/day, p < 0.001, for both). The extra collagen did not move the needle — synthesis rates stayed unchanged.
The post-exercise trial told the same story from a different angle. Myofibrillar protein synthesis rose significantly with whey compared with placebo (0.041 vs. 0.032%·h⁻¹, p < 0.05). Collagen came in at 0.036%·h⁻¹ — not statistically different from placebo. Even for muscle connective protein synthesis, the tissue collagen is theoretically best suited to support, there was no significant difference between whey, collagen, and placebo (p = 0.09).
There’s one wrinkle worth naming: a follow-up by the same Maastricht group (Aussieker et al., 2025) paired a smaller 5 g dose of collagen with 25 g of whey and found that blend raised both myofibrillar and connective protein synthesis versus placebo. But look at the ratio — that’s five times more whey than collagen in the blend. The benefit tracks with the whey doing the work, not the collagen.
Why collagen falls short
The explanation is in the amino acid profile, not the marketing copy. Collagen is dominated by glycine, proline, and hydroxyproline — structural amino acids that build connective tissue but don’t trigger muscle protein synthesis. It’s very low in leucine, the branched-chain amino acid that acts as the “on switch” for that process; a typical 2.5–2.7 g leucine dose per meal is what reliably flips the switch, and a standard collagen scoop supplies only a small fraction of that. Whey and pea protein, by contrast, are leucine-rich and built to trigger the response — which is exactly what the trials above show.
Why this matters in perimenopause and menopause
As estrogen declines, muscle becomes less responsive to a given amount of protein — a pattern researchers call anabolic resistance, and it’s the reason daily protein needs tend to go up, not down, through this transition. If a collagen scoop is quietly filling one of your daily “protein” slots without actually triggering muscle protein synthesis, you could be running a real protein shortfall at exactly the life stage where protecting muscle matters most. Worth flagging honestly: the trials above were run in men (McKendry: older men only; Aussieker: mostly young, mixed-sex), so direct evidence in perimenopausal and menopausal women specifically is still thin — but the underlying amino acid biology doesn’t change by sex.
Where collagen actually earns its place
None of this means collagen is useless — it means it’s doing a different job than protein powder. Paired with resistance training, the evidence for tendon and connective tissue is real and repeated:
Jerger and colleagues (2022) had 40 healthy men do 14 weeks of resistance training with either 5 g/day of specific collagen peptides or a placebo. The collagen group saw significantly greater gains in Achilles tendon cross-sectional area (+11.0% vs. +4.7%, p = 0.002) and muscle thickness (+7.3% vs. +2.7%, p = 0.014).
Miyamoto and colleagues (2025) gave 50 healthy young men 10 g/day of collagen peptides for 16 weeks and found significant increases in muscle and Achilles tendon stiffness, plus improved explosive strength (rate of torque development) — without any change in muscle or tendon size or maximal strength. A quick note on what “stiffness” means here, since it sounds like a downside but isn’t: stiffer tissue has less give — it stretches less for the same pull from the muscle. That matters for speed, not just strength: less energy gets lost to stretching the tendon before force reaches the joint, which is part of why the collagen group also saw faster force production.
Nulty and Erskine (2025) ran an 8-week trial in elite female masters field hockey athletes — premenopausal women, notably — combining eccentric resistance training with 30 g/day of collagen plus vitamin C. The collagen group showed greater gains in patellar tendon cross-sectional area and rate of force development than training alone produced.
The common thread: collagen’s wins show up in tendon and connective tissue adaptation, alongside a training stimulus, usually with vitamin C included to support collagen synthesis — not in building or maintaining muscle mass, and not as a stand-in for a protein serving.
What this doesn’t mean
Most of the muscle-protein-synthesis data here comes from men, and the tendon trials vary in dose (5–30 g/day) and duration (single sessions to 16 weeks), so results aren’t fully interchangeable across studies. Sample sizes are modest — 22 to 50 people per trial — and the acute-synthesis studies measure a single day’s response, not muscle mass outcomes over months or years. This is a real, replicated pattern, but not a closed case.
Why this matters for you
- Don’t count a collagen scoop as a protein serving. Its amino acid profile isn’t built to trigger muscle protein synthesis, no matter what the grams-per-scoop label suggests.
- Keep taking collagen if it’s working for you — for skin, joint comfort, or tendon support, the evidence is real. Just don’t let it replace an actual protein source.
- Prioritize complete, leucine-rich proteins for your protein target — whey, dairy, meat, fish, eggs, soy, or a well-blended plant source — aiming for roughly 25–30 g per meal.
- Stack collagen alongside your protein target, not instead of it, ideally with resistance training and vitamin C — that’s the combination behind the tendon benefits above.
- Read past “protein” on the label. “Collagen protein” and “hydrolyzed collagen” don’t do the same nutritional job as “whey protein” or “pea protein,” even when the grams per scoop look similar.
The bottom line
Collagen isn’t a bad supplement — it’s just not a protein supplement in the sense that matters for building or maintaining muscle. If you’re leaning on it to hit your protein target, especially through perimenopause or menopause when protecting muscle gets harder, it’s worth a second look at what’s actually in your daily total.
If you’d like help auditing your protein intake and building an approach that actually supports your muscle and hormones, book a free 25-minute introductory call and let’s talk through it.
Citation: Miyamoto N, Ishihara K, Oshima T, Kawai M, Oritani Y, Iemoto N. Collagen Peptide Supplementation Enhances Muscle-Tendon Stiffness and Explosive Strength: A 16-wk Randomized Controlled Trial. Med Sci Sports Exerc. 2025;57(12):2877–2886. McKendry J, Lowisz CV, Nanthakumar A, MacDonald M, Lim C, Currier BS, Phillips SM. The effects of whey, pea, and collagen protein supplementation beyond the recommended dietary allowance on integrated myofibrillar protein synthetic rates in older males: a randomized controlled trial. Am J Clin Nutr. 2024;120(1):34–46. Aussieker T, Hilkens L, Holwerda AM, Fuchs CJ, Houben LHP, Senden JM, van Dijk JW, Snijders T, van Loon LJC. Collagen Protein Ingestion during Recovery from Exercise Does Not Increase Muscle Connective Protein Synthesis Rates. Med Sci Sports Exerc. 2023;55(10):1792–1802. Aussieker T, Kaiser J, Hermans WJH, Hendriks FK, Holwerda AM, Senden JM, van Kranenburg JMX, Goessens JPB, Braun U, Baar K, Snijders T, van Loon LJC. Ingestion of a Whey Plus Collagen Protein Blend Increases Myofibrillar and Muscle Connective Protein Synthesis Rates. Med Sci Sports Exerc. 2025;57(3):544–554. Jerger S, Centner C, Lauber B, Seynnes O, Sohnius T, Jendricke P, Oesser S, Gollhofer A, König D. Effects of specific collagen peptide supplementation combined with resistance training on Achilles tendon properties. Scand J Med Sci Sports. 2022;32(7):1131–1141. Nulty CD, Erskine RM. Collagen Supplementation Augments Strength Training-Induced Gains in Tendon Size and Rate of Force Development in Elite Female Master Field Hockey Athletes. Int J Sport Nutr Exerc Metab. 2025.