Tier 2 — strong

Effect of oral glycine on the clinical, spirometric and inflammatory status in subjects with cystic fibrosis: a pilot randomized trial

Vargas MH, Del-Razo-Rodríguez R, López-García A, Lezana-Fernández JL, Chávez J, Furuya MEY, Marín-Santana JC
BMC pulmonary medicine 2017 17(1):206

Bibliography

PubMed
PMID 29246256
PubMed Central
PMC5732413
DOI
10.1186/s12890-017-0528-x
Trial registry
View on ClinicalTrials.gov Registered trial — results not yet published in a peer-reviewed journal.
Funding
The authors reported no funding from outside their institutions.
Competing interests
The authors declared no competing interests.

Study snapshot

DesignRandomized double-blind placebo-controlled crossover pilot in cystic fibrosis
ModelHumans with cystic fibrosis, ages 6–23 years; pediatric and young-adult participants
Sample15 recruited; 13 completed both treatment periods (8 female), ages 6–23 years
InterventionOral glycine 0.5 g/kg/day versus the same weight of powdered sugar placebo, added to usual cystic-fibrosis treatment
Duration8 weeks per treatment with a 2-week washout; 18 weeks total
EndpointsSymptoms and dyspnea; Spirometry including FEV1; Pulse oximetry; Serum and sputum inflammatory markers

What the study showed, in plain terms

A small crossover pilot in children, adolescents and young adults with cystic fibrosis reported improvements in selected symptoms and lung-function measures during glycine treatment. This disease-specific result does not establish benefits for healthy adults or a general pediatric supplement regimen.

Key findings

  • Thirteen participants completed both periods; symptom questionnaire scores favored glycine over placebo.
  • FEV1 fell 8.6% during placebo and rose 9.7% during glycine, each relative to the respective period baseline; these are findings from a small pilot.
  • Selected inflammatory results were mixed: TNF-alpha and IL-6 differences were not statistically significant; sputum G-CSF was lower.
  • Glycine was reported as well tolerated during the study; the sample and follow-up cannot establish broad or long-term safety.

What this study can and cannot tell us

Only 13 completers, multiple outcomes and mixed ages limit precision and generalizability. Two recruited participants left during placebo treatment.

Participants continued their usual therapies, and the analysis does not establish whether glycine improves long-term exacerbations, hospitalization or survival.

This is preliminary cystic-fibrosis evidence, including children; it does not support self-treatment or replacing standard care.

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Editorial review

Reviewed by the Biohack Blueprint research team

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