Whey protein but not collagen peptides stimulate acute and longer-term muscle protein synthesis with and without resistance exercise in healthy older women: a randomized controlled trial.
Level 2 - randomized trial
Double-blind parallel-group randomized controlled trial
PubMed 31919527 · doi:10.1093/ajcn/nqz332
What was done
Twenty-two healthy older women (mean ± SD age: 69 ± 3 y) were randomly assigned in a double-blind, parallel-group trial to consume 30 g of either whey protein (WP, n = 11) or collagen protein peptides (CP, n = 11) twice daily for 6 days. Participants performed unilateral resistance exercise (RE) twice during the 6-day protocol. Primary outcome measures were acute muscle protein synthesis (MPS) determined via [13C6]-phenylalanine infusion and longer-term cumulative MPS measured over 6 days via deuterated water ingestion.
What was found
Acutely, WP increased MPS by 0.017 ± 0.008%/h in the resting leg and 0.032 ± 0.012%/h in the exercised leg (both P < 0.01). CP increased acute MPS only in the exercised leg (0.012 ± 0.013%/h, P < 0.01), with WP eliciting greater acute MPS than CP in both legs (P = 0.02). Longer-term 6-day MPS increased by 0.063 ± 0.059%/d at rest and 0.173 ± 0.104%/d with exercise (P < 0.0001) in the WP group. CP did not significantly increase longer-term MPS above baseline at rest (0.011 ± 0.042%/d) or with exercise (0.020 ± 0.034%/d). Longer-term MPS was significantly greater with WP than CP in both conditions (P < 0.001).
Why it matters
This study shows that protein quality dictates muscle anabolism in older adults; collagen peptides fail to match whey protein's stimulation of muscle protein synthesis even when paired with resistance exercise.
Limits
The sample size was small (n = 22 total, 11 per group) and limited to healthy older women, precluding direct generalization to men or sarcopenic populations. The study evaluated synthetic rate tracers over 6 days rather than clinical endpoints such as muscle mass, strength, or functional capacity.
Cited by
- supports Collagen protein contains less than 3% leucine, making it a poor driver of muscle protein synthesis compared to whole proteins.