REF-348 · Moore et al., 2015 / Bauer et al., 2013 (PROT-AGE) · The Journals of Gerontology, Series A: Biological Sciences and Medical Sciences, · Paper
Protein Ingestion to Stimulate Myofibrillar Protein Synthesis Requires Greater Relative Protein Intakes in Healthy Older Versus Younger Men
The per-meal dose for older muscle
Participants and method
Retrospective analysis of the authors' laboratory data on myofibrillar protein synthesis (MPS) in healthy older (~71 years) and younger (~22 years) men after a single bolus of 0-40 g high-quality protein, measured by primed constant infusion of L-[ring-13C6]phenylalanine, with dose normalized to body mass and, where available, lean body mass (LBM). Biphasic linear regression with breakpoint analysis. Sample size is not stated in the abstract.
Protocol
Retrospective analysis of the authors' laboratory data on myofibrillar protein synthesis (MPS) in healthy older (~71 years) and younger (~22 years) men (from the abstract); the abstract does not state the sample size.
Protein given as a single bolus of 0-40 g of high-quality dietary protein; MPS measured by primed constant infusion of L-ring-[13C6]phenylalanine; the dose normalised to body mass and, where available, lean body mass (LBM).
Analysis: biphase linear regression and breakpoint analysis of MPS against the relative protein dose; basal MPS compared between age groups.
Key Findings
Basal MPS did not differ between older (0.027 ± 0.04 %/h) and young (0.028 ± 0.03 %/h) men (p = .53) — the difference is in the response to feeding, not the baseline
The slope of the first regression segment was lower in older men (p < .05): the same protein dose produced less MPS
MPS plateaued at 0.40 ± 0.19 g/kg body mass in older vs 0.24 ± 0.06 g/kg in younger men (p = .055), and at 0.60 ± 0.29 vs 0.25 ± 0.13 g/kg LBM (p < .01)
Authors' conclusion: healthy older men are less sensitive to low protein intakes and need a greater relative protein intake per meal to maximally stimulate postprandial MPS
Practical Application
In healthy men, the per-meal protein dose that saturated muscle protein synthesis was ~0.40 g/kg body mass at age ~71 versus ~0.24 g/kg at age ~22 (0.60 vs 0.25 g/kg lean mass) — a masters athlete should size each protein feeding for roughly 0.4 g/kg, not the ~0.25 g/kg that suffices in the young.
Not from this paper; the base's own practice: daily protein for masters endurance athletes is set from the meta-analytic plateau in REF-579 (Morton 2018, ~1.6 g/kg/day) and the anabolic-resistance argument here, distributed across several feedings; the older per-meal figure above is why the distribution matters more with age.
Pair protein with resistance training — the anabolic stimulus of exercise is what the per-meal dose supports (REF-074).
Limitations
Retrospective pooling of the group's own acute studies; single-bolus MPS measured over hours, not hypertrophy or performance
Healthy men only; women and trained masters athletes not represented
The older-vs-younger difference per kg body mass reached p = .055; per kg LBM it was significant (p < .01)
PROT-AGE consensus (Bauer 2013) is cited as context but its numbers were not checked and are not stated here
How this entry was checked and changed
Why this level
regraded 2026-09-27 from A: pooled retrospective analysis of acute muscle-protein-synthesis trials, not an RCT or consensus
Content correction 2026-09-27
"Young 0.25-0.30 g/kg/meal; older (>60) 0.4-0.5 g/kg/meal" -> abstract: 0.24 ± 0.06 vs 0.40 ± 0.19 g/kg body mass (0.25 vs 0.60 g/kg LBM), ages ~22 and ~71.
"Daily 1.6-2.0 / 1.6-2.2 g/kg/day across 4-5 meals", "leucine 2.5-3 g per meal from 20-30 g protein", "pre-sleep casein 30-40 g", "up to 2.5 g/kg/day safe" -> none in this abstract; removed, with the daily target now pointed to REF-579 as the base's practice.
Type/Level "RCT-based recommendations + consensus, A" -> retrospective pooled dose-response analysis, B. Tier "mixed" -> Tier 0-1 (healthy non-athletes). Sport "strength" -> general. Title reworded to the paper's.
Cross-reference descriptions checked against the cited entries' current content; wrong years, wrong entries and claims the cited entry does not make were corrected.
2026-09-28: added Journal and Protocol from the Europe PMC record and abstract (PMID 25056502); sample size not stated in the abstract, so no n added.
Full text (checked 2026-10-12)
The analysis pooled six previous studies covering 43 elderly men (71±1 y, range 65-80) and 65 young men (22±4 y, range 18-37) (full text, Table 1).
Protein was a single bolus of whey (n=5 studies) or egg (n=1 study), 0-40g (equivalent to 0-0.64g protein/kg), with MPS measured over 3-4h at rest after at least 48 h without physical activity; from exercise or disuse studies only pre-intervention resting data were used (full text).
Breakpoints were 0.40g/kg BM (CI: 0.21-0.59) in older vs 0.25g/kg BM (CI: 0.18-0.30) in younger men, and 0.60g/kg LBM (CI 0.32-0.89) vs 0.25g/kg LBM (CI 0.12-0.38), with data presented as means ± 95% CI rather than SD (full text).
Maximal postprandial MPS was similar in young and older men (~0.058 and ~0.056%/h), but the slope of the first segment was lower in older men (0.071 vs 0.119 (%/h)/(g/kg BM)) (full text).
Body weight did not differ (79.3±4.1 vs 79.9±2.5 kg), but lean body mass was lower in the elderly (54.5±2.8 vs 65.9±1.8 kg) (full text, Table 1).
The authors extrapolate that with three balanced meals older adults would need 3 times 0.40g/kg or ~1.20g/kg/d (full text).
The authors state the estimates apply to high-quality, rapidly digested animal protein at rest, that prior contractile activity or leucine-enriched proteins could lower the requirement, that disuse or lower-quality protein could raise it, and that women were not studied (full text).