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

Why It Matters

Improving bone turnover and reducing inflammation could lower stress‑fracture risk in female endurance athletes, a population prone to bone injuries and hormonal disruptions.

Key Takeaways

• 20 g daily collagen peptides raised P1NP, a bone‑formation marker
• sRANKL levels fell, suggesting reduced osteoclast signaling
• IL‑6 decreased, indicating lower systemic inflammation
• No significant change in CTX‑1 or OPG observed
• Study limited to 22 athletes; larger trials needed

Pulse Analysis

Female distance runners face a unique convergence of high‑impact loading, potential low energy availability, and hormonal fluctuations that can compromise bone remodeling. Traditional sports‑nutrition advice emphasizes calcium, vitamin D, and overall protein intake, yet these nutrients do not directly target the organic collagen matrix that gives bone its tensile strength. Collagen peptides, rich in glycine, proline, and hydroxyproline, are rapidly absorbed as bioactive di‑ and tripeptides that may stimulate osteoblast activity and modulate the RANKL‑OPG axis, a key pathway governing bone resorption. By delivering 20 g of hydrolyzed type I collagen each morning, the study observed a measurable increase in P1NP, indicating enhanced type I collagen synthesis, while simultaneously reducing sRANKL and IL‑6, markers linked to osteoclast activation and systemic inflammation.

The reduction in IL‑6 is particularly noteworthy because this cytokine not only drives inflammatory responses but also promotes osteoclastogenesis, thereby accelerating bone loss under chronic stress. In endurance athletes, even modest declines in inflammatory tone can translate to better recovery, lower perceived fatigue, and a more favorable environment for bone repair. Although CTX‑1, a direct resorption marker, remained unchanged, the combined biochemical profile suggests that collagen peptide supplementation may shift the bone remodeling balance toward formation without exacerbating resorption, a desirable outcome for athletes seeking to mitigate stress‑fracture risk.

While the pilot’s sample size (n=22) limits definitive conclusions, the effect sizes for P1NP and IL‑6 were moderate to large, underscoring the potential clinical relevance. Future research should expand participant numbers, extend intervention duration, and incorporate imaging outcomes such as DXA or peripheral quantitative CT to verify structural bone benefits. If larger trials confirm these findings, collagen peptides could become a low‑cost, easily implemented component of sports‑nutrition protocols aimed at preserving skeletal integrity in high‑volume female runners.