Tier 3 — preclinical

Effects of Collagen Peptide Supplementation on Bone Turnover, Cytokine, and Inflammatory Markers in Female Distance Runners: A Randomized Pilot Study

Nicholas M. Kuhlman, Andrew R. Jagim, Christopher N. Blesso, Michael J. Puglisi, Ock K. Chun, Margaret T. Jones, Jennifer B. Fields
Frontiers in Nutrition 2026 13:1825906

Bibliography

PubMed
PMID 42221768
PubMed Central
PMC13215932
DOI
10.3389/fnut.2026.1825906
Funding
This research was funded by the National Strength and Conditioning Association (NSCA) Foundation.
Competing interests
The authors declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Study snapshot

DesignRandomised, double-blind, placebo-controlled pilot trial
ModelEndurance-trained premenopausal female distance runners, aged 18-35, running ≥35 miles (56 km) per week
Samplen=22 randomised (intervention n=11; control n=11)
Intervention20 g/day hydrolysed collagen peptide (INT) vs isocaloric maltodextrin (CON) for 4 weeks; testing sessions standardised to the early follicular phase of the menstrual cycle
Duration4 weeks
EndpointsSerum P1NP (bone formation marker); Plasma CTX-1 (bone resorption marker); Serum sRANKL, OPG and sRANKL/OPG ratio; Serum IL-6

What the study showed, in plain terms

Competitive female distance runners carry a real risk of bone stress injury from sustained high-impact training load. This small pilot trial tested a high dose — 20 g/day — of collagen peptide for just 4 weeks in this specific population, tracking blood markers of bone formation, bone breakdown, and inflammation rather than bone density itself.

The collagen group saw a significant increase in P1NP, a marker of new bone formation, while the placebo group showed no change. A marker of inflammation, IL-6, fell significantly in the collagen group. The bone-resorption marker CTX-1 didn't change significantly in either group, suggesting the shift may lean toward more bone-building activity rather than less bone breakdown.

This is genuinely early-stage evidence: a pilot study, in a narrow population, over 4 weeks, using blood biomarkers rather than a bone density scan or an actual injury outcome. It's a signal worth larger follow-up trials, not proof that collagen supplementation prevents bone stress injuries in runners.

Key findings

  • Significant group × time interaction for P1NP (p=0.04): increased in the collagen group, unchanged in the control group.
  • No significant group × time interaction for CTX-1 (p=0.13), the bone-resorption marker.
  • Significant group × time interaction for sRANKL (p=0.046 within-group pattern; between-group change score p=0.02), with sRANKL decreasing in the collagen group and increasing in the control group.
  • Significant group × time interaction for IL-6 (p=0.03): IL-6 fell from 5.72 to 4.53 ng/mL in the collagen group (p=0.03 within-group) versus a rise in the control group; the between-group change score remained significant after adjusting for running distance and vitamin D status (ANCOVA p=0.01).
  • No significant interaction effect for OPG or the sRANKL/OPG ratio.
  • No adverse events or unintended effects related to the intervention were reported.

What this study can and cannot tell us

  • P1NP and CTX-1 are surrogate biomarkers — they reflect bone remodelling activity, not structural or densitometric bone outcomes (e.g. DXA-measured bone mineral density) or actual bone stress injury rates.
  • The 4-week intervention period is very short and likely insufficient to capture downstream changes in bone mass or microarchitecture.
  • Small sample size (n=22) limits statistical power and the precision of effect-size estimates.
  • Menstrual cycle phase was standardised for testing but circulating sex hormone concentrations were not directly measured, and inter-individual hormonal variability within the follicular phase may have contributed to biomarker variability.
  • The study was not prospectively registered, and this is explicitly framed by the authors as a pilot study requiring larger, adequately powered, longer-duration trials with structural bone outcomes before conclusions can be drawn about injury prevention.

Related papers in the corpus

Tier 3
Specific Bioactive Collagen Peptides in Osteopenia and Osteoporosis: Long-Term Observation in Postmenopausal Women
Denise Zdzieblik et al. · Journal of Bone Metabolism · 2021

Citation network

Articles citing this research paper

1 article

Biohack Blueprint analyses that reference this study in their evidence base.

Editorial review

Reviewed by the Biohack Blueprint research team

Last verified

Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability Dr. Abdulla Mostafa, PhDCellular Senescence, Neurological, Mitochondrial & Brain-Ageing Biology