After drinking whey protein shakes every day for a week, older women’s muscles kept building up new protein even on days they didn’t exercise—collagen protein didn’t do this at all.

Scientific Claim

In healthy older women, 6 days of whey protein supplementation increases integrated (longer-term) muscle protein synthesis by 0.063%/day at rest and by 0.173%/day after resistance exercise, whereas collagen peptides do not significantly elevate integrated MPS above baseline in either condition.

Original Statement

“Longer-term MPS increased by 0.063 ± 0.059%/d in Rest and 0.173 ± 0.104%/d in Exercise (P < 0.0001) with WP; however, MPS was not significantly elevated above baseline in Rest (0.011 ± 0.042%/d) or Exercise (0.020 ± 0.034%/d) with CP.”

From study: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.

Evidence Quality Assessment

Claim Status

appropriately stated

Study Design Support

Design supports claim

Appropriate Language Strength

definitive

Can make definitive causal claims

Assessment Explanation

The use of deuterated water labeling over 6 days provides direct, quantitative evidence of integrated MPS changes. The RCT design and statistical significance (P < 0.0001) support definitive causal claims.

Evidence from Studies

Supporting (1)

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.

Randomized Controlled Trial

Human

2020 Mar 1

The study found that whey protein helped older women build muscle over 6 days, both when resting and after exercise, but collagen peptides didn’t make any meaningful difference.

Contradicting (0)

No contradicting evidence found

Source Study

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.

Score: 66

DOI: 10.1093/ajcn/nqz332

Similar Assertions

When older women drink whey protein shakes, their muscles start repairing and growing faster—especially if they also do leg exercises—while collagen protein shakes don’t do much unless they exercise, and even then, it’s much weaker.

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Even though whey protein made muscles build faster, it didn’t change the usual ‘on/off’ switches in muscle cells that are supposed to control growth—suggesting other mechanisms are at play.

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With collagen protein, the muscle-building effect was almost identical in the exercised and non-exercised leg—unlike whey, which responded more strongly where exercise happened.

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For middle-aged men doing strength training, whey protein and this collagen supplement have similar effects on muscle gain and fat loss.

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Even with daily exercise, collagen protein shakes didn’t help older women’s muscles build new protein over a week—whey did, but collagen didn’t.

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