Grow Defended Flawed Collagen Meta-Analysis with Proven Science

The Gelatin Research Optimization Working group (GROW), representing global gelatin and collagen interests across major producing regions and trade associations, issues this detailed response to the Myung et al. (2025) meta-analysis published in a scientific journal, which questions the established skin health benefits of collagen supplements. While GROW actively welcomes and supports rigorous scientific scrutiny as essential for advancing evidence-based nutrition science, the working group has identified several serious methodological flaws, inconsistencies, and analytical shortcomings in this particular study that collectively misrepresent the substantial body of established clinical evidence supporting collagen peptides' efficacy. These limitations not only risk confusing healthcare professionals, formulators, and consumers but also threaten to undermine confidence in a category backed by decades of research, regulatory validation, and real-world application across diverse populations and formulations. GROW remains committed to transparency and invites the authors for constructive technical dialogue to resolve these discrepancies and strengthen the scientific literature for consumer benefit. 

 

 

Critical Study Limitations Exposed

 

Contradictory Findings: The study's own abstract clearly confirms that collagen supplementation delivers statistically significant improvements across critical skin parameters—hydration levels, elasticity, and wrinkle appearance—when analyzed across all included clinical trials in the dataset. However, the main conclusions drawn in the discussion section inexplicably assert "no clinical evidence" exists for these benefits, creating a glaring and fundamentally misleading inconsistency between the objective data reported and the subjective final interpretation that severely undermines the paper's scientific reliability and intended message.

 

Opaque Quality Ratings: Subgroup analyses that dismiss certain studies as "industry-funded" or categorize them as "low-quality" rely entirely on undisclosed and apparently arbitrary criteria, without employing any validated, standardized assessment tools—such as the CONSORT statements designed specifically for evaluating clinical trial reporting quality or the GRADE methodology widely accepted for evidence synthesis and quality grading—which severely compromises both the credibility and reproducibility of these selective judgments throughout the meta-analysis.

 

Funding Bias Fallacy: The approach of rejecting otherwise rigorous, peer-reviewed clinical trials solely based on any level of industry support represents a blatant logical fallacy, as it completely ignores their strict adherence to gold-standard research protocols including double-blind, placebo-controlled trial designs conducted by leading independent research institutions, universities, and contract research organizations worldwide, constituting a fundamental misapplication of legitimate bias assessment principles in evidence review.

 

Methodological Gaps: The analysis mislabels several commercially-affiliated studies as genuinely "independent" without conducting proper disclosure analysis or conflict-of-interest verification; it fails to differentiate between pure, standardized bioactive collagen peptides and complex multi-ingredient blends containing numerous confounding variables; it incorporates highly heterogeneous clinical trials featuring inconsistent dosing protocols averaging just 3.1g per day, predominantly Asian study populations with limited demographic diversity, and relatively short intervention durations that may not capture full physiological responses; and finally, it draws inappropriately broad, definitive conclusions from small, statistically underpowered, and unbalanced subgroups lacking adequate sample sizes for reliable inference.

 

Robust Contrasting Evidence

 

GROW references multiple comprehensive, high-quality meta-analyses conducted by independent research groups that unequivocally confirm collagen peptides' clinically meaningful and reproducible efficacy for skin health: De Miranda et al. (2021) systematically analyzed data from 19 randomized controlled trials, demonstrating consistent, statistically significant improvements in skin hydration metrics, elasticity measurements, and wrinkle reduction severity using well-tolerated daily doses ranging from 2.5g to 10g over typical study durations; Pu et al. (2023), published in the peer-reviewed Nutrients journal, provides additional validation of these robust anti-aging effects across multiple validated skin parameter assessments in diverse trial populations; and Dewi et al. (2023) in Cureus journal further confirms these reproducible skin rejuvenation benefits through systematic evidence synthesis applicable to broader global consumer demographics.

 

Global Regulatory Validation

 

Health authorities and regulatory bodies worldwide have independently reviewed the accumulated clinical evidence and officially recognize collagen peptides' established skin health benefits through authorized structure/function claims and approved applications: Food Standards Australia New Zealand permits specific claims related to skin hydration maintenance and elasticity support based on qualified scientific substantiation; Korea's Ministry of Food and Drug Safety (MFDS) explicitly approves claims documenting benefits for skin hydration improvement and UV-protection effects; while Health Canada, Japan's Consumer Affairs Agency, and Brazil's ANVISA have similarly validated collagen peptides' skin health applications through their respective regulatory review and approval processes for food supplement ingredients.

GROW urges balanced interpretation of collagen's extensive safety record across thousands of peer-reviewed studies. Consumers deserve evidence-based information about proven skin health solutions, not selective analyses that distort scientific consensus.