A systematic review and meta-analysis recently published in The American Journal of Medicine had challenged widely held assumptions about collagen supplementation and skin health.
The paper, authored by Korean researchers Seung-Kwon Myung, MD, PhD, and Yunseo Park, analyzed a set of randomized controlled trials (RCTs) and concluded there is “currently no clinical evidence to support the use of collagen supplements to prevent or treat skin aging.”
Study overview
The review assessed 23 RCTs involving 1,474 participants. Upon initial review, the researchers stated that the pooled analysis showed improvements: Collagen supplementation was linked to measurable gains in hydration, elasticity and a reduction in wrinkles.
However, subgroup analyses showed that trials not funded by pharmaceutical or supplement companies showed no benefit, while those with industry backing reported positive effects, the researchers reported. Similarly, when only higher-quality studies were considered, no significant impact was observed across hydration, elasticity or wrinkles, they continued.
These discrepancies prompted the authors to question whether earlier meta-analyses had overstated collagen’s role in skin health. In contrast to those reports, they concluded that “high-quality studies revealed no significant effect in all categories, while low-quality studies revealed a significant improvement in elasticity.”
Market and scientific context
The researchers noted that collagen is a structural protein that makes up “over 90% of skin mass and provides its mechanical integrity.” With aging, synthesis declines by “1%–1.5% annually, causing deeper wrinkles and facial lines.”
The decline is compounded by reduced elastin and other molecules critical to moisture retention and firmness, which is why supplementation has been promoted as a strategy to improve hydration and elasticity, they explained.
Interest in collagen supplements has grown rapidly. The analysis reported that the market “doubled in 4 years (2019–2022) and is projected to grow at over 6.5% annually from 2023 to 2032 in North America," and since 2014, clinical research and consumer adoption of collagen supplements have “been gaining continuous interest,” the researchers noted.
Previous reviews have supported the category. According to the authors, “two recent meta-analyses of RCTs concluded that collagen supplements improved skin hydration and elasticity.” In contrast, their own analysis is the first to find that funding source and study quality alter the overall picture, leading them to report no confirmed clinical benefit.
Industry response
BioCell Technology: Ingredient variability and research dynamics
For Douglas Jones, head of sales and marketing at BioCell Technology, LLC, the study overlooked the diversity of collagen types and formulations used in trials.
He told NutraIngredients that “collagen’s a generic term… that describes a very diverse and wide variety of different ingredients,” making broad comparisons problematic.
“In many regards… they’re comparing apples and oranges when they just lump everything together,” he said.
He also pushed back on the suggestion that industry funding compromises research integrity.
“Most research that is done…on ingredients and products are done by the companies that make them,” he explained, stressing that clinical trials are typically outsourced to independent contract research organizations. “We don’t have influence.”
On scientific integrity, Jones said, “the fact of the matter is the science is the science is the science is the science, and the data is going to be whatever it is...sometimes you get an expected outcome, and sometimes you don’t. I mean, that’s why clinical research is done.”
CSA: Technical critique of misclassifications and data errors
NI also spoke to the Collagen Stewardship Alliance (CSA), which focused on the technical reliability of the meta-analysis. In its view, the paper’s conclusions about funding bias collapse under scrutiny because the classification of industry involvement was often wrong.
For example, Choi et al. (2014) was listed as industry-influenced despite having no direct funding, while other studies with clear company ties, such as Sugihara et al. (2015) and Inoue et al. (2016), were marked as independent. As CSA noted, if two-thirds of “independent” trials are in fact commercially supported, then the subgroup analysis loses its credibility.
CSA also documented a series of data reporting errors that affect dose, source and duration. Yoon et al. (2014) recorded 0.75 g/day, though participants actually consumed 3 g.
Lin et al. (2021) reported a 50 g dose, whereas the actual intake was closer to 5.5 g. Seong et al. (2024) reported 2.5 g/day, but the original article only shows 2 g. Even study durations were misstated: Bolke et al. (2019) was described as lasting 16 weeks when, in fact, the intervention lasted only 12 weeks.
Taken together, CSA argued, these errors not only distort the quantitative analysis but also raise questions about the review’s overall reliability.
On the issue of study quality, they emphasized that “industry-funded studies are not necessarily of lower quality than non-industry-funded studies,” pointing out that in this meta-analysis, “the majority of the industry-funded studies scored 3 to 5 out of 5” on the Jadad scale, which evaluates randomization, blinding and participant follow-up.
GROW: Framing, interpretation and the bigger picture
NI also spoke with the Gelatin Manufacturers of the World (GROW), who took issue with both the framing and execution of the Myung meta-analysis. While the group stated that it “welcomes rigorous, independent scientific scrutiny,” it cautioned that “this paper contains methodological flaws and interpretive inconsistencies that risk distorting the scientific record, misleading readers and undermining credible research in the field.”
GROW first pointed to what it characterized as contradictory abstract messaging. The abstract itself, they noted, confirmed that collagen supplements “show significant benefits in improving skin hydration, elasticity and wrinkles when all studies are considered.”
Yet the authors later concluded that there is “no clinical evidence” to support collagen use for skin aging, which GROW argued “creates a confusing and contradictory narrative.”
The organization also highlighted problems in the way the subgroup analysis was conducted, saying it “is based on unclear, unpublished criteria” and that “the method for categorizing studies into ‘high’ and ‘low’ quality is not disclosed, nor are validated tools (such as CONSORT, Cochrane, or GRADE) used or cited.”
Without transparency, GROW maintained, “such subgroup interpretations cannot serve as a credible basis for dismissing a significant body of evidence.”
On the issue of funding, GROW rejected the paper’s implication that commercial involvement automatically undermines research integrity.
“Dismissing studies with industry funding as inherently biased discredits the work of renowned research institutions and independent scientists,” the group stated. “Funding alone does not compromise scientific integrity when proper methodology and peer review are followed.”
Methodological inconsistencies, GROW added, further weaken the analysis. It noted that several studies labeled as ‘independent’ (e.g., Sugihara et al., 2015; Genovese et al., 2017; Kim et al., 2018) had commercial affiliations.
They also pointed out that the meta-analysis failed to differentiate between pure collagen peptides and multi-ingredient blends, that the studies included “vary by different raw materials, dosage, duration and topical or oral administration,” and that 17 of the 23 trials were conducted in Asia with lower reported daily doses (around 3 g/day) that may not reflect global consumption patterns.
Therefore, GROW said, the review’s conclusions were “drawn from small, unbalanced subgroups.”
Most importantly, GROW emphasized that the review does not exist in isolation. Other meta-analyses, such as De Miranda et al. (2021), found “statistically significant improvements in skin hydration, elasticity and wrinkle reduction, at daily doses of 2.5 to 10 g of hydrolyzed collagen.” The group noted that Pu et al. (2023) and Dewi et al. (2023) likewise demonstrated “skin improving effects of collagen.”
GROW also concluded that “the benefits of collagen peptides for skin are widely recognized, not just in research literature but by health authorities around the world.”
They noted that Food Standards Australia, Korea’s Ministry of Food and Drug Safety, Health Canada, the Consumer Affairs Agency Japan and the Brazilian Health Regulatory Agency (ANVISA) have formally recognized skin-related claims for collagen supplements, lending weight to a global scientific consensus that collagen peptides are beneficial for skin health.
Source: The American Journal of Medicine, 2025, ISSN 0002-9343, doi: 10.1016/j.amjmed.2025.04.034, “Effects of Collagen Supplements on Skin Aging: A Systematic Review and Meta-Analysis of Randomized Controlled Trials” Authors: Seung-Kwon Myung, Yunseo Park
