The target side of the protein question for the over-65 stratum: how much, and distributed how, to maintain and regain lean mass and function. The lever exists because of Anabolic Resistance — old muscle needs a bigger per-meal protein stimulus for the same building response — so the general-adult RDA is a floor set for a different question and undershoots this stratum. The evidence is expert consensus on surrogates (Bauer PROT-AGE, endorsed by four geriatric societies), backed by small metabolic studies — not a hard-outcome (fracture / disability / mortality) trial.
The target ladder — by health and activity status
PROT-AGE recommends, for adults >65:
| Stratum | Daily protein target | Locus |
|---|---|---|
| Healthy older adult | 1.0-1.2 g/kg BW/d | «consume an average daily intake in the range of 1.0 to 1.2 g/kg BW/d» |
| Exercising / otherwise active | 1.2 g/kg BW/d | «higher protein intake (ie, 1.2 g/kg body weight/d) is advised for those who are exercising and otherwise active» |
| Acute or chronic illness | 1.2-1.5 g/kg BW/d | «who have acute or chronic diseases need even more dietary protein (ie, 1.2e1.5 g/kg body weight/d)» |
| Severe kidney disease (eGFR <30, not on dialysis) | LIMIT — the exception | «Older people with severe kidney disease … are an exception to this rule; these individuals may need to limit protein intake» |
The ladder rises with catabolic load (illness > active > healthy) and inverts only at severe renal impairment. All figures are g protein per kg body weight per day.
The number this replaces — and why the RDA is a floor, not a target
(Bauer et al., 2013) The general-adult RDA is 0.8 g/kg BW/d, defined as the minimum daily protein to prevent deficiency in 97% of the population, derived from nitrogen-balance studies. PROT-AGE holds this «too low for older people»: N-balance likely underestimates requirements (it cannot see muscle redistribution and uses short adaptation windows), and in one 14-week study «consuming the RDA for protein resulted in the loss of mid-thigh muscle area» in healthy older adults even while whole-body composition looked stable. So 0.8 answers deficiency prevention; it is a floor deployed as a 100% Daily Value target, and for maintaining muscle in this stratum it is the start line, not the finish -> The Descriptive-Normative Category Error, Deficiency Repletion vs Enhancement.
The parameter table — daily and per-meal are DIFFERENT quantities (do not collapse them)
(Bauer et al., 2013) The single most common error with these numbers is treating a per-day target, a per-meal dose, and a hypertrophy target as one quantity. They sit on different denominators; only the same-denominator rows are directly comparable.
| Quantity | Value + locus | Denominator | Directly comparable to… |
|---|---|---|---|
| RDA (general adult) | 0.8 g/kg BW/d [EXTRACTED (Bauer …) chunk 01] | protein g / kg BW / day | the PROT-AGE daily rows (same denominator) |
| PROT-AGE healthy older | «1.0 to 1.2 g/kg BW/d» [EXTRACTED (Bauer …) chunk 01] | protein g / kg BW / day | RDA — Bauer raises the same quantity |
| PROT-AGE illness | «1.2e1.5 g/kg body weight/d» [EXTRACTED (Bauer …) chunk 01] | protein g / kg BW / day | rows above |
| Hypertrophy target (healthy adults, RT) | ~1.6 g/kg/d, CI 1.03-2.20 (Morton) -> Protein and Resistance Training for Muscle and Strength | protein g / kg BW / day | SAME UNIT, DIFFERENT objective + population — a ladder by goal, not a contradiction |
| Moore per-meal breakpoint (older) | «0.40 ± 0.19 … g/kg body mass» (0.60/kg LBM) [EXTRACTED (Moore …) chunk 01] | protein g / kg BM / meal | NOT comparable to any per-day row |
| Bauer per-meal threshold | «25 to 30 g protein per meal» [EXTRACTED (Bauer …) chunk 01] | absolute protein g / meal | NOT comparable — different denominator again |
| Bauer per-meal leucine | «about 2.5 to 2.8 g leucine» [EXTRACTED (Bauer …) chunk 01] | leucine g / meal | NOT comparable — a within-meal amino-acid quantity |
- The daily rows are a coherent ladder (RDA 0.8 -> older 1.0-1.2 -> ill 1.2-1.5 -> hypertrophy ~1.6), same unit throughout, ordered by goal and stratum — the higher hypertrophy number does not conflict with the lower maintenance number; they answer maximize muscle during training vs maintain muscle.
- The per-meal rows are a different axis — the distribution constraint, not the daily total. They reconcile with the daily target only through Moore’s own within-programme arithmetic (three meals × ~0.40 g/kg = ~1.20 g/kg/d), which is a consistency check, not independent confirmation -> Anabolic Resistance.
- The young RET breakpoint is a WEAK, non-transporting anchor — do not import it downward as a ceiling. Morton’s ~1.6 g/kg-total knee is statistically non-significant (p=0.079) and the supplement effect it rests on declines with age in a largely-young pooled sample — both extracted on -> Protein and Resistance Training for Muscle and Strength. Combined with Anabolic Resistance (more protein needed per anabolic stimulus with age), the transport direction runs up, not down: an older adult training for hypertrophy should read ~1.6 as a floor, not a ceiling — the non-significant young plateau is no reason to cap intake — while the maintenance floor stays 1.0-1.2 from this page’s own (different) evidence base. This is a stratum distinction, not a contradiction: the two numbers answer maximize muscle in the young vs maintain muscle in the old, and the honest object for the older stratum is a direction + a floor, not a point optimum -> The Underivable Optimum.
Per-meal distribution — clear the threshold at each meal
(Bauer et al., 2013) Because anabolic resistance raises the per-meal trigger, hitting the daily total is not enough if it is unevenly distributed. PROT-AGE: «The per-meal anabolic threshold … is higher in older individuals (ie, 25 to 30 g protein per meal, containing about 2.5 to 2.8 g leucine)». Moore’s breakpoint (0.40 g/kg body mass per meal in older vs 0.24 in younger men — «~68%» greater) is the metabolic basis for the same advice: spread protein across breakfast, lunch and dinner so each meal clears the breakpoint, rather than back-loading it at dinner (the typical Western pattern that wastes the sub-threshold meals). Bauer notes an unsettled alternative — pulse feeding (most protein at midday) also showed benefit — so even distribution is the default, not a proven optimum.
Renal safety — the healthy-kidney vs impaired-kidney split
(Bauer et al., 2013) The routine worry — that higher protein harms aging kidneys — is not supported for healthy kidneys: «reviews of research studies reveal little or no evidence that high-protein diets cause kidney damage in healthy individuals, including those who are older», and 1.0-1.2 g/kg/d «is expected to help maintain nitrogen balance without affecting renal function». The contraindication is a genuine stratum flip, not a general caution: severe kidney disease (eGFR <30, not on dialysis) is where protein should be limited (route (c) contraindication).
Bauer’s statement is a consensus-review direction; the pooled RCT evidence now backs it -> Protein Intake and Kidney Function (Devries 2018 SR-MA, 28 RCTs): in adults without CKD, the change in GFR does not differ between higher- and lower-protein diets, and the GFR rise HP does produce is benign kidney functional reserve, not damage (Devries et al., 2018). Two caveats carry over here: the evidence is low-GRADE surrogate-level (GFR, not hard kidney outcomes — the dedicated protein-to-kidney-outcome trial is still the named gap), and Devries shares Phillips with PROT-AGE, so this is one lineage’s coherent position, not two independent confirmations. The stratum flip (severe CKD -> restrict) is unchanged.
The chronic-outcome evidence — mass yes (in the deficit stratum), strength no (Komar)
(Komar et al., 2015) PROT-AGE and the per-meal breakpoint rest on consensus + acute surrogates. Komar 2015 (gold SR+MA, 16 RCTs, 999 subjects aged >=65, leucine-rich protein 2-7.8 g/d for >=10 days — a different research lineage from the Phillips/Wolfe programme) is the closest chronic clinical-outcome test held for this stratum, and it both supports and bounds the target:
- Supports the mass rationale — where there is a deficit. Leucine-rich protein raised lean body mass +0.99 kg [95% CI 0.43, 1.55; p=0.0005] and body weight +1.02 kg [0.19, 1.85], but subgroup analysis confines the effect to the sarcopenic stratum (LBM +1.14 kg [0.55, 1.74] in sarcopenia vs null, -0.05 kg [-1.55, 1.46], in healthy elderly). So raise protein to protect muscle is cashed at the mass endpoint mainly for those already losing it — a repletion reading, not enhancement in the replete Deficiency Repletion vs Enhancement.
- Bounds it — strength did not move. Grip WMD +0.23 [-0.26, 0.73; p=0.36; I2=65%] and knee
extension +0.07 Nm/kg [-0.26, 0.40; p=0.68] were null — the mass gain did not read out as measured
strength (Surrogate Outcomes). Komar itself flags this as likely under-powered («a small number
of trials potentially insufficient to yield significant results»; broader-inclusion SRs did find grip
gains), so it is insufficient evidence on strength, not proof of no effect — but it withholds any
strength claim from this stratum’s protein target. A different lineage reaches the same grip null:
Coelho-Junior’s observational MA (below) also found no grip/chair-rise advantage for higher intake
[E-independent]— an RCT-pool and an observational-cohort route agreeing that raising protein does not move strength in this stratum. `Corroborated by (Coelho-Júnior et al., 2018) - The exposure is protein+energy, not isolated leucine or protein-per-se. Komar cannot separate leucine from the co-ingested protein/AA matrix, and «an increase in total energy consumption might be a prerequisite for the success of these supplementations with respect to parameters such as LBM» — a reminder that in frail/undernourished elderly the energy the supplement carries may be doing much of the work, so the lever is enough protein and energy, not a leucine trick.
- Pool-overlap caveat (no independence lift). Komar’s elderly-protein RCTs (Tieland, Chalé, Leenders, …) plausibly overlap Tagawa’s protein-supplement pool below, so their agreement that protein raises LBM in older adults is partly shared-evidence, not a second independent route.
The direct-function outcome test — observational, outcome-specific, no knee (Coelho-Junior)
(Coelho-Júnior et al., 2018) Every source above sets the target against a surrogate (nitrogen balance, LBM, acute MPS) or, in Komar, a chronic mass endpoint. Coelho-Junior 2018 (gold SR+MA, 7 observational studies, 8754 community-dwelling adults >=60 across 6 countries) is the closest thing held to a direct physical-function test of the intake bins — one level up the outcome ladder, but bought at the cost of design: it pooled cohorts/cross-sectional/case-control studies and excluded all RCTs and interventions, so it estimates association, not effect. It both partly supports the ladder and bounds it hard.
- Supports raising above the RDA — but only at the widest contrast. Very-high (>=1.2 g/kg/d) vs low (<0.8) reached a small significant SMD 0.18 [95% CI 0.01 to 0.35], p=0.04 on pooled lower-limb function, and high (>=1.0) vs low reached significance on walking speed (SMD ~0.06 [0.02, 0.11]). The authors read this as «findings … indicate that a very high (>=1.2 g/kg/day) and high protein intake (>=1.0 g/kg/day) are associated with better lower-limb physical performance when compared to low protein (<0.80 g/kg/day) intake in community-dwelling older adults».
- Outcome-specific — strength did not move. «relative high protein intake does not seem to propitiate a better performance on isometric handgrip (IHG) and chair rise in comparison to relative low protein intake» — high-vs-low was null on grip (SMD -0.36 [-1.15, 0.44]) and lower-limb strength (-0.09 [-0.26, 0.08]). The association is confined to mobility/walking, not force-generation — the same grip/chair-rise null Komar found by a different route (Surrogate Outcomes).
- No knee is located; the 1.0 cutpoint is imposed, not found. The bins (0.8 / 1.0 / 1.2) were set a priori from the RDA debate, so a categorical contrast cannot show a curve feature — and «there were no significant differences in the physical functioning of high and middle protein intake groups» (0.8-0.99 vs >=1.0 came up empty). Only the widest contrast separated. So the direct-function data cannot distinguish the RDA boundary from the 1.0 target and gives no warrant for a knee at 1.0 — consistent with this page’s direction + a floor, not a point optimum reading The Underivable Optimum. «there is a lack of direct evidence testing the proposed cut-off points for protein consumption».
(inferred from Coelho-Júnior et al., 2018)
- Relative protein (g/kg) is confounded by body weight. The low-intake bin had the highest mean BMI (29.1 vs 27.1 in very-high): a heavier or more adipose person mechanically shows lower g/kg at the same absolute grams, so “low relative protein” partly indexes higher adiposity/lower lean mass, not lower eating. And in raw Table 2 the very-high bin had the lowest absolute grip (19.1 kg) and slowest chair-rise — the classic reverse-causation / frailty pattern, where lighter frailer people land in the high-g/kg bin -> The U-Shaped Association Artifact.
- Self-reported intake (24-h recall, 3-4 day records, FFQ) carries the field’s binding measurement error -> Measurement Error in Dietary Assessment, which attenuates a real gradient toward null — so the flat middle-vs-high result is weak evidence of no gradient, not proof of one. Heterogeneity was «considerable» (I2 up to 96% on mobility); the authors themselves conclude «our results should be taken with caution and should be confirmed with further studies», and call for RCTs.
- One effect-modification hint, held loosely (route (b), the false-positive generator). A single included cohort found protein-function association «in non-sarcopenic, but not in sarcopenic older women» — a subgroup signal running against the expectation that illness raises the need, though the authors also invoke the hypothesis that illness/frailty «may require higher protein levels (1.2-1.5 g/kg)». A single-study subgroup is a candidate to test, not a stratum rule.
Decision relevance
(inferred from Bauer et al., 2013; Moore et al., 2014)
- For a healthy older adult, aim ~1.0-1.2 g/kg/d (1.2 if active), from ~25-30 g protein per meal across three meals — the move is raising and distributing, not loading. Most older adults eat less than young adults, so the common failure is undershoot, not excess.
- Bias the target UP within a stratum when the cost of undershoot is high — during illness,
weight loss, or an energy deficit (protect lean mass), the illness row (1.2-1.5) or the active row
applies; the plateau is forgiving on the high side for healthy kidneys, so a modest overshoot is
low-harm -> The Estimate-to-Action Gap. The one hard flip down is severe renal disease.
- The weight-loss case is directly evidenced in adults >=50 (Kim et al., 2016): a gold MA of 20 energy-restricted RCTs found HP (>=1.0 g/kg/d) vs normal protein spared lean mass (WMD +0.45 to +0.83 kg) and increased fat loss at the same total weight loss, at a magnitude essentially identical to younger adults -> the deficit-specific target and dose-response live on Protein Intake During Energy Restriction.
- Protein quality rides the number silently. The per-meal leucine threshold (2.5-2.8 g) is why a high-quality/animal or leucine-dense source clears the bar with fewer grams; hitting the target from low-leucine plant sources needs more grams or deliberate complementation -> Protein Quality and the DIAAS Score. This is a distinct decision from the source-substitution (mortality) question on Dietary Protein and Mortality.
- The daily amount and the source are two decisions, not one. This page sets the amount and distribution for the older stratum; the animal-vs-plant source choice (mortality) and the hypertrophy target (RT) are separate -> Protein and Resistance Training for Muscle and Strength.
- Protein may raise muscle even where resistance training is NOT on the table — a plausibility pointer, not a stratum-specific proof. For the frail, the dysphagic, or those who cannot train, the PROT-AGE targets above rest on trials that mostly paired protein with exercise. Tagawa’s MA (a different research lineage — Miyachi lab, no PROT-AGE overlap) «demon- strates for the first time that protein supplementation is significantly effective without resistance training in a di- verse population», and even «less than 0.3 g/kg BW/d (0.17 g/kg BW/d, on average) was suffi- cient to significantly increase LBM» — «Daily addition of a high-protein food item such as an egg (6-8 g protein) or 1 cup (200 mL) of milk (6.8 g protein)» is Tagawa’s named lever for «the elderly or people with dys- phagia, as well as in low-income, food-insufficient populations». But the finding is in a diverse population, not specifically the anabolic-resistant old — and Anabolic Resistance predicts a blunted fed-state response at low doses in exactly this stratum, so the without-RT effect may attenuate where it is most wanted. So: protein-by-diet-alone is a reasonable move when training is infeasible (small, distributed top-ups, not loading), and it is a separate lineage from PROT-AGE (partly answering the one research school limit below) — but treat it as a directional pointer to test, not as elderly-specific corroboration; it sets no age-specific dose of its own. (Tagawa et al., 2020)
Limits — consensus on surrogates, one research school, sponsor exposure
(inferred from Bauer et al., 2013; Katsanos et al., 2006; Moore et al., 2014)
- Surrogate, not patient-important, endpoints. The targets are set against nitrogen balance, lean body mass, and acute MPS — surrogates. No fracture, disability, or mortality trial shows that hitting 1.0-1.2 vs 0.8 g/kg/d changes what the person experiences; muscle function and sarcopenia are on the outcome menu, but the causal link from raising protein to better function is asserted, not proven -> Surrogate Outcomes. The loop is open.
- Consensus + small studies, one programme — partly widened by Komar. Bauer is a Delphi consensus
(
recommendationtier — cite its underlying reviews for any effect/certainty claim); Moore and Katsanos are small, acute, male-only metabolic studies. Their agreement is coherence within one research school (shared authors and cross-citation), not independent corroboration -> Anabolic Resistance. Moore is male-only; Katsanos is a mixed-sex parallel-group study. Komar 2015 (gold SR+MA, Vienna group) adds a different-lineage chronic-outcome confirmation of the mass claim (in sarcopenic elderly) — partly answering the one-school limit — but it still cites Katsanos and leaves strength and hard outcomes unproven, so it upgrades the mass rationale without closing the surrogate loop. - Sponsor exposure. PROT-AGE was funded by a Nestlé Nutrition grant and most authors disclose medical-nutrition-industry ties (Nestlé, Nutricia, Abbott); Moore and Katsanos are dairy / amino-acid funded. Under symmetric standards this is a directional-bias flag on the “eat more protein / supplement / leucine” conclusion — held loosely, not dismissed, since the underlying tracer physiology is hard to confound.
- Sex, and the >65 label. Moore’s per-meal dose-response is men only (Katsanos included women, so the leucine-threshold finding is not male-restricted); the female per-meal protein breakpoint is only partly evidenced. “Older adult” is treated as >65, but anabolic resistance is a gradient, not a switch at a birthday.