Reading list: muscle, protein and nutrition in older age

Sarcopenia: revised European consensus on definition and diagnosis (EWGSOP2)Cruz-Jentoft AJ, Bahat G, Bauer J, et al. Age Ageing. 2019;48(1):16-31. doi:10.1093/ageing/afy169

Type

Consensus definition from a European expert working group.

What it says

Sarcopenia is a muscle disease. Low muscle strength is the key characteristic, low muscle quantity or quality confirms the diagnosis, and poor physical performance marks it as severe. It is common in older adults but can occur earlier in life. The paper sets out a pathway for case-finding, diagnosis and severity, with cut-off points.

Study context

Defines and diagnoses the condition.

Global prevalence of sarcopenia and severe sarcopeniaPetermann-Rocha F, Balntzi V, Gray SR, et al. J Cachexia Sarcopenia Muscle. 2022;13(1):86-99. doi:10.1002/jcsm.12783

Type

Systematic review and meta-analysis: 263 studies reviewed, 151 pooled (692,056 people, mean age 68.5).

What it found

Prevalence ranged from 10% to 27% in people aged 60 and older, and severe sarcopenia from 2% to 9%, depending on the classification and cut-off points used.

Study context

How common the condition is, not how to manage it.

SarcopeniaSayer AA, Cooper R, Arai H, et al. Nat Rev Dis Primers. 2024;10(1):68. doi:10.1038/s41572-024-00550-w

Type

Narrative review (primer).

What it says

Sarcopenia can lead to declining physical function and mobility and raises the risk of falls, fractures and premature mortality. Diagnosis increasingly centers on muscle strength. Resistance exercise is the mainstay of treatment but is not suitable for everyone, so other approaches are needed.

Study context

An overview of the condition.

ESPEN practical guideline: clinical nutrition and hydration in geriatricsVolkert D, Beck AM, Cederholm T, et al. Clin Nutr. 2022;41(4):958-989. doi:10.1016/j.clnu.2022.01.024

Type

Clinical practice guideline: 82 recommendations, graded for evidence and consensus.

Who

Older persons in all care settings.

What it says

Screen all older persons for malnutrition routinely, with a validated tool (recommendation 12). Protein intake should be at least 1 g/kg body weight per day, adjusted to the person (2). For people with or at risk of malnutrition: individualized counseling, fortified food, snacks, and supplement drinks when those are not enough (21 to 26), adapted to each person’s taste and eating capacities (31).

Study context

General practice guidance.

Evidence-based recommendations for optimal dietary protein intake in older people (PROT-AGE)Bauer J, Biolo G, Cederholm T, et al. J Am Med Dir Assoc. 2013;14(8):542-559. doi:10.1016/j.jamda.2013.05.021

Type

Position paper from an international expert group.

Who

Adults older than 65.

What it says

Older adults need more dietary protein than younger adults. Average intake of at least 1.0 to 1.2 g protein/kg/day; 1.2 g/kg/day or more for people who exercise or are otherwise active; 1.2 to 1.5 g/kg/day for most with acute or chronic disease. People with severe kidney disease (eGFR below 30) who are not on dialysis may need to limit protein. Evidence on protein quality and timing is not yet sufficient for specific recommendations.

Study context

Intake targets, not evidence that any product helps people meet them.

Protein intake and exercise for optimal muscle function with aging: recommendations from the ESPEN Expert GroupDeutz NE, Bauer JM, Barazzoni R, et al. Clin Nutr. 2014;33(6):929-936. doi:10.1016/j.clnu.2014.04.007

Type

Expert group recommendations.

Who

Older people, healthy and ill.

What it says

At least 1.0 to 1.2 g protein/kg/day for healthy older people; 1.2 to 1.5 g/kg/day for those malnourished or at risk because of acute or chronic illness; daily physical activity or exercise for all older people for as long as possible. Protein combined with exercise is considered optimal for maintaining muscle function.

Study context

General recommendations.

GLIM criteria for the diagnosis of malnutritionCederholm T, Jensen GL, Correia MITD, et al. Clin Nutr. 2019;38(1):1-9. doi:10.1016/j.clnu.2018.08.002

Type

Global consensus report.

Who

Adults in clinical settings.

What it says

Diagnosis has two steps: screening with any validated tool, then assessment. It needs at least one phenotypic criterion (unintended weight loss, low body mass index, reduced muscle mass) and one etiologic criterion (reduced food intake or assimilation, inflammation or disease burden).

Study context

How malnutrition is diagnosed.

Prevalence of protein intake below recommended in community-dwelling older adultsHengeveld LM, Boer JMA, Gaudreau P, et al. J Cachexia Sarcopenia Muscle. 2020;11(5):1212-1222. doi:10.1002/jcsm.12580

Type

Population study: meta-analysis of four cohorts and four national surveys (PROMISS project).

Who

8,107 community-dwelling adults aged 55 and older in the Netherlands, the UK, Canada, the USA, Finland and Italy.

What it found

Pooled prevalence of protein intake below 0.8, 1.0 and 1.2 g/kg adjusted body weight per day: 21.5%, 46.7% and 70.8%. Prevalence was higher among women, people with higher body mass index and people with poor appetite.

Study context

It measures the size of a gap, not how to close it.

Anabolic signaling deficits underlie amino acid resistance of wasting, aging muscleCuthbertson D, Smith K, Babraj J, et al. FASEB J. 2005;19(3):422-424. doi:10.1096/fj.04-2640fje

Type

Laboratory study.

Who

44 healthy young and older men of similar build, given different amounts of essential amino acids.

What it found

Resting muscle protein synthesis did not differ, but the older men showed less sensitivity and responsiveness to essential amino acids, with lower activation of signaling proteins such as mTOR.

Study context

A mechanism in healthy men.

Splanchnic and whole-body leucine kinetics in young and elderly menBoirie Y, Gachon P, Beaufrère B. Am J Clin Nutr. 1997;65(2):489-495. doi:10.1093/ajcn/65.2.489

Type

Laboratory study.

Who

6 young (mean age 22.7) and 6 older (68.2) men, during a standard meal.

What it found

The gut and liver took up about twice as much dietary leucine in the older men (50 ± 11% against 23 ± 2%), which could lower the leucine reaching the rest of the body.

Study context

Twelve men, one meal.

A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderlyKatsanos CS, Kobayashi H, Sheffield-Moore M, et al. Am J Physiol Endocrinol Metab. 2006;291(2):E381-E387. doi:10.1152/ajpendo.00488.2005

Type

Laboratory study.

Who

Two older and two young groups, each given 6.7 g of essential amino acids.

What it found

In the older adults, muscle protein synthesis rose only when the mix had a higher share of leucine (41%, against 26% in a mix patterned on whey protein). In the young adults it rose with both.

Study context

Free amino acid mixes in a laboratory, not food.

Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger menMoore DR, Churchward-Venne TA, Witard O, et al. J Gerontol A Biol Sci Med Sci. 2015;70(1):57-62. doi:10.1093/gerona/glu103

Type

Laboratory data, pooled and analyzed retrospectively.

Who

Healthy older (about 71) and younger (about 22) men, given 0 to 40 g of protein.

What it found

Muscle protein synthesis reached a plateau at 0.40 ± 0.19 against 0.24 ± 0.06 g/kg body mass (p = .055), and 0.60 ± 0.29 against 0.25 ± 0.13 g/kg lean body mass (p < .01), in older against younger men. Older men were less sensitive to low protein intakes.

Study context

Single meals in healthy men.

The effect of leucine-enriched beta-lactoglobulin versus an isonitrogenous whey protein isolate on skeletal muscle protein anabolism in young healthy malesEly IA, Paul M, Wall JJS, et al. Nutrients. 2025;17(21):3410. doi:10.3390/nu17213410

Type

Laboratory study, crossover. General science only.

Who

10 healthy young men (26 ± 2 years).

What it found

About 10 g of beta-lactoglobulin, a naturally leucine-rich protein found in whey, raised blood essential amino acids and leucine more than the same amount of whey protein isolate. Muscle protein synthesis rose similarly with both, at rest and after exercise.

Study context

Young men, not older adults. It shows that more leucine in the blood does not by itself mean more muscle building.

Effects of a vitamin D and leucine-enriched whey protein nutritional supplement on measures of sarcopenia in older adults (PROVIDE)Bauer JM, Verlaan S, Bautmans I, et al. J Am Med Dir Assoc. 2015;16(9):740-747. doi:10.1016/j.jamda.2015.05.021

Type

Trial: related formula. Randomized, double-blind, isocaloric control, 13 weeks.

Who

380 older adults with sarcopenia (SPPB 4 to 9, low muscle mass), mostly living independently.

What it found

Handgrip strength and SPPB, the primary outcomes, improved in both groups with no difference between them. Chair-stand time was 1.01 s faster and appendicular muscle mass 0.17 kg higher with the formula.

Study context

A different formula, with added leucine.

Improving rehabilitation in sarcopenia: a randomized-controlled trial utilizing a muscle-targeted food for special medical purposesRondanelli M, Cereda E, Klersy C, et al. J Cachexia Sarcopenia Muscle. 2020;11(6):1535-1547. doi:10.1002/jcsm.12532

Type

Trial: related formula. Randomized, double-blind, isocaloric control, 4 to 8 weeks.

Who

140 adults with sarcopenia (age 81 ± 6) in hospital physical rehabilitation.

What it found

Gait speed rose 0.063 m/s per month more than with the control formula. Muscle mass and the key secondary outcomes also favored the formula. 13 people, across both groups, stopped because they disliked the product.

Study context

A different formula with added leucine, given alongside rehabilitation exercise.

Whey protein, amino acids, and vitamin D supplementation with physical activity increases fat-free mass and strength, functionality, and quality of life and decreases inflammation in sarcopenic elderlyRondanelli M, Klersy C, Terracol G, et al. Am J Clin Nutr. 2016;103(3):830-840. doi:10.3945/ajcn.115.113357

Type

Trial: related formula. Randomized, double-blind, placebo-controlled, 12 weeks.

Who

130 adults with sarcopenia (mean age 80.3), all in a controlled physical activity program.

What it found

Fat-free mass was 1.7 kg higher than with placebo. Handgrip strength and activities of daily living also favored the supplement.

Study context

A different formula with added amino acids, including leucine, given with exercise.

Effects of whey protein, leucine, and vitamin D supplementation in patients with sarcopeniaChang MC, Choo YJ. Nutrients. 2023;15(3):521. doi:10.3390/nu15030521

Type

Review of trials: systematic review and meta-analysis of 3 trials (637 patients).

What it found

Appendicular muscle mass improved with or without exercise. Grip strength and SPPB improved only when exercise was added.

Study context

Three trials of formulas with added leucine.

Effect of beta-hydroxy-beta-methylbutyrate (HMB) on lean body mass during 10 days of bed rest in older adultsDeutz NE, Pereira SL, Hays NP, et al. Clin Nutr. 2013;32(5):704-712. doi:10.1016/j.clnu.2013.02.011

Type

Trial: HMB. Randomized, double-blind, inactive placebo.

Who

24 healthy adults aged 60 to 76 (20 women), 19 evaluable, on 10 days of complete bed rest.

What it found

The control group lost 2.05 kg of lean body mass; the HMB group lost 0.17 kg, with one participant excluded. Function did not differ. The authors call for a larger trial.

Study context

HMB on its own, in a small group of healthy volunteers.

Effects of beta-hydroxy-beta-methylbutyrate supplementation on older adults with sarcopeniaYang C, Song Y, Li T, et al. J Nutr Health Aging. 2023;27(5):329-339. doi:10.1007/s12603-023-1911-1

Type

Trial: HMB, with exercise. Randomized, double-blind, placebo-controlled, 12 weeks.

Who

34 adults aged 60 and older with sarcopenia; both groups did resistance training twice a week.

What it found

Handgrip strength, gait speed and chair-stand time were better than with placebo. Skeletal muscle mass did not differ.

Study context

HMB on its own, added to resistance training, in a small group.

Long-term effects of calcium beta-hydroxy-beta-methylbutyrate and vitamin D3 supplementation on muscular function in older adults with and without resistance trainingRathmacher JA, Pitchford LM, Khoo P, et al. J Gerontol A Biol Sci Med Sci. 2020;75(11):2089-2097. doi:10.1093/gerona/glaa218

Type

Trial: HMB with vitamin D. Randomized, double-blind, controlled, 12 months, with or without resistance training.

Who

238 adults over 60 with insufficient vitamin D enrolled; 117 completed the 12-month trial and were included in the per-protocol analysis.

What it found

Among those not exercising, lean mass at 6 months, knee extension torque at 3 months and a composite function index at 3, 6 and 12 months were better than with control. Among those exercising, it added no further function benefit.

Study context

HMB and vitamin D without protein, in people with low vitamin D.

Effects of oral supplementation of beta-hydroxy-beta-methylbutyrate on muscle mass and strength in individuals over the age of 50Li N, Chen S, He Y, et al. Front Nutr. 2025;12:1522287. doi:10.3389/fnut.2025.1522287

Type

Review of trials: meta-analysis of 21 trials (1,935 participants over 50).

What it found

Lean mass 0.28 kg higher (95% CI 0.16 to 0.41), with small differences in handgrip strength, chair-stand time and gait speed.

Study context

Many HMB products and populations, pooled.

An umbrella review of systematic reviews of beta-hydroxy-beta-methyl butyrate supplementation in ageing and clinical practicePhillips SM, Lau KJ, D’Souza AC, Nunes EA. J Cachexia Sarcopenia Muscle. 2022;13(5):2265-2275. doi:10.1002/jcsm.13030

Type

Review of reviews: 15 systematic reviews.

What it found

5 of 15 reviews found some evidence for lean soft-tissue mass and 4 of 12 for strength. None reported a positive effect on physical function. The authors describe “minor, inconsistent support” for HMB.

Study context

HMB in general, across many products and populations.

The effects of vitamin D on skeletal muscle strength, muscle mass, and muscle powerBeaudart C, Buckinx F, Rabenda V, et al. J Clin Endocrinol Metab. 2014;99(11):4336-4345. PubMed 25033068

Type

Systematic review and meta-analysis of 30 randomized trials.

Who

Varied populations (5,615 participants), not limited to older adults.

What it found

Vitamin D supplementation had a small positive effect on muscle strength. The effect on muscle mass was not significant.

Study context

Vitamin D as a single nutrient, pooled across mixed populations and doses.

Effect of vitamin D monotherapy on indices of sarcopenia in community-dwelling older adultsProkopidis K, Giannos P, Katsikas Triantafyllidis K, et al. J Cachexia Sarcopenia Muscle. 2022;13(3):1642-1652. doi:10.1002/jcsm.12976

Type

Systematic review and meta-analysis of 10 randomized trials of vitamin D alone.

Who

Community-dwelling older adults.

What it found

Vitamin D on its own gave no improvement in muscle strength, muscle mass or physical performance.

Study context

Vitamin D monotherapy, not a combination formula. It helps interpret the vitamin D in the related formulas above.

Anorexia of aging: risk factors, consequences, and potential treatmentsLandi F, Calvani R, Tosato M, et al. Nutrients. 2016;8(2):69. doi:10.3390/nu8020069

Type

Narrative review.

What it describes

Anorexia of aging, a decline in appetite or food intake in old age, is common and contributes to undernutrition. It is not an unavoidable part of aging, and its causes include physiological change, disease, and social and environmental factors.

Study context

Background on why intake falls.

Effects of dietary enrichment with conventional foods on energy and protein intake in older adultsTrabal J, Farran-Codina A. Nutr Rev. 2015;73(9):624-633. doi:10.1093/nutrit/nuv023

Type

Systematic review of nine studies.

What it tested

Enriching meals with conventional foods or powdered modules to raise energy and protein density without much more volume.

What it found

Enrichment can improve energy intake. It seems to increase protein intake, but the evidence was not of sufficient quality to confirm that, or to judge other outcomes.

Study context

Other foods and modules. The evidence on protein was limited even for those.

Can fortified foods and snacks increase the energy and protein intake of hospitalised older patients?Mills SR, Wilcox CR, Ibrahim K, Roberts HC. J Hum Nutr Diet. 2018;31(3):379-389. doi:10.1111/jhn.12529

Type

Systematic review of ten articles (546 patients).

Who

Hospital and rehabilitation patients with a mean age of 60 to 83.

What it found

Compared with usual care, six studies of energy- or protein-based fortification or snacks significantly increased energy (250 to 450 kcal/day) or protein (12 to 16 g/day) intake. Four studies reported good acceptability.

Study context

Hospital settings and other products.

Impact of food-based fortification on nutritional outcomes and acceptability in older adultsGeny A, Petitjean M, Van Wymelbeke-Delannoy V, Sulmont-Rossé C. Front Nutr. 2023;10:1232502. doi:10.3389/fnut.2023.1232502

Type

Systematic review of 44 studies (3,384 participants).

Who

Adults aged 60 and older, at home, in institutions or in hospital.

What it found

Compared with a standard diet, adding fortificants to everyday recipes seems to be a valuable way to raise energy and protein intake, but there was no strong evidence of an effect on nutritional status. The authors call for more acceptability research.

Study context

Other recipes and fortificants.

Older adults’ acceptability of and preferences for food-based protein fortification in the UK, France and NorwaySmith R, Methven L, Clegg ME, et al. Appetite. 2024;197:107319. doi:10.1016/j.appet.2024.107319

Type

Discussion groups, then a home-use trial (Fortiphy project).

Who

Discussions with 37 older adults and 15 caregivers; a home trial with 158 healthy adults aged 70 and older.

What it found

Participants were largely unaware of the role of protein in aging and did not want to fortify their own food at present, but were positive about the idea. Taste, familiar ingredients and preferred ways of preparing food mattered, and preferences differed by country.

Study context

Other recipes, made by healthy volunteers.

A systematic review of compliance to oral nutritional supplementsHubbard GP, Elia M, Holdoway A, Stratton RJ. Clin Nutr. 2012;31(3):293-312. doi:10.1016/j.clnu.2011.11.020

Type

Systematic review of 46 studies (4,328 participants).

What it found

Mean compliance with oral nutritional supplements was 78%: 67% in hospital and 81% in the community. Compliance was higher with more energy-dense supplements.

Note

The first author’s listed affiliation is a supplement manufacturer’s medical affairs department.

Study context

It concerns supplement drinks, not powders added to food.

Validation of the Mini Nutritional Assessment short-form (MNA-SF)Kaiser MJ, Bauer JM, Ramsch C, et al. J Nutr Health Aging. 2009;13(9):782-788. doi:10.1007/s12603-009-0214-7

Type

Validation study pooling twelve datasets.

Who

2,032 older participants with a mean age of 82.3.

What it found

The revised short form, which can use calf circumference when body mass index is unavailable, is a valid nutrition screening tool for geriatric health professionals.

Study context

A clinician’s screening tool, not a product assessment.