Tier 2 — strong

Glycine increases fat-free mass in malnourished haemodialysis patients: a randomized double-blind crossover trial

Genton L, Teta D, Pruijm M, Stoermann C, Marangon N, Mareschal J, Bassi I, Wurzner-Ghajarzadeh A, Lazarevic V, Cynober L, Cani PD, Herrmann FR, Schrenzel J
Journal of cachexia, sarcopenia and muscle 2021 12(6):1540-1552

Bibliography

PubMed
PMID 34519439
PubMed Central
PMC8718019
DOI
10.1002/jcsm.12780
Trial registry
View on ClinicalTrials.gov Registered trial — results not yet published in a peer-reviewed journal.
Funding
Swiss National Science Foundation, Alfred and Alice Lachmann Foundation and Fresenius Kabi Deutschland; additional investigator support is listed in the source.
Competing interests
Reported relationships include nutrition/renal-industry grants, fees and travel support, plus microbiome-company cofounding and patents for certain investigators.

Study snapshot

DesignPost hoc secondary body-composition analysis of a multicenter randomized double-blind crossover trial
ModelAdult humans
Sample37 randomized; 36 started and had baseline measurements; 27 compliant completers in the per-protocol analysis
InterventionGlycine 14 g/day (7 g twice daily) versus BCAA 14 g/day in malnourished hemodialysis patients
DurationTwo 4-month supplementation periods separated by a 1-month washout; 9 months total
EndpointsFat-free mass index; Lean body mass; Strength and physical function; Quality of life

What the study showed, in plain terms

In malnourished dialysis patients, glycine performed better than BCAA supplementation for fat-free mass index. This was a post hoc nutritional comparison in a specialist population, not a general muscle-building trial.

Key findings

  • Fat-free mass index measured by bioimpedance favored glycine over BCAA supplementation.
  • DXA lean body mass and the broader functional and biochemical outcomes did not show consistent benefit.
  • Six participants reported nausea or vomiting during glycine treatment; adverse-event rates were not statistically different between treatments, and causation was not established.

What this study can and cannot tell us

This is a post hoc secondary analysis of the same trial reported in the microbiota paper, not an independent randomized cohort.

Only 27 compliant completers contributed to the principal per-protocol analysis. Attrition and the active BCAA comparator limit inference.

Bioimpedance fat-free mass in dialysis is influenced by hydration. These findings do not establish muscle hypertrophy in healthy adults.

Related papers in the corpus

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The effect of enteral glycine on plasma glycine and muscle structure, size, and function in the critically ill: A randomized controlled trial
Ali Abdelhamid Y et al. · Clinical nutrition (Edinburgh, Scotland) · 2025
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Gut barrier and microbiota changes with glycine and branched-chain amino acid supplementation in chronic haemodialysis patients
Genton L et al. · Journal of cachexia, sarcopenia and muscle · 2021
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The effect of arginine or glycine supplementation on gastrointestinal function, muscle injury, serum amino acid concentrations and performance during a marathon run
Buchman AL et al. · International journal of sports medicine · 1999
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An Update of the Promise of Glycine Supplementation for Enhancing Physical Performance and Recovery
Ramos-Jiménez A et al. · Sports (Basel, Switzerland) · 2024
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High-Intensity Interval Training Combined with Glycine Supplementation Drives Ferroptosis Resistance to Counteract Skeletal Muscle Atrophy in Aging Mice
Ni PS et al. · Medicine and science in sports and exercise · 2025
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The effect of glycine administration on the characteristics of physiological systems in human adults: A systematic review
Soh J et al. · GeroScience · 2024

Editorial review

Reviewed by the Biohack Blueprint research team

Last verified

Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction