Collagen powders promise smoother skin, stronger joints and better recovery from exercise. When the same supplement is supposed to help with so many things, a fairly natural question arises: how much of this has actually been proven?
The sales pitch for collagen sounds logical. There is plenty of it in the body, the structure of connective tissue changes with age, and collagen production may decline. It follows that consuming extra collagen could make up for the shortfall. However, the processes in the body are a little more complex, and research does not support the benefits of collagen supplements as unequivocally as advertisements suggest.
I took a closer look at the findings on skin, joints, muscles and tendons. The evidence for these goals is worth considering separately: a benefit seen for one does not automatically confirm all the other promises.
What exactly is collagen?
Collagen is an important structural protein in connective tissue, found in the skin, tendons, cartilage and bones, among other places. It helps tissues withstand mechanical stress. There are several types of collagen, with different functions and locations in the body.
Powders and drinks often use hydrolysed collagen, meaning collagen that has already been broken down into shorter peptides during production. Studies on joints also use other preparations, such as undenatured type II collagen. These cannot be considered the same supplement, nor can their results be freely applied from one product to another.
What happens to collagen after you eat it?
During digestion, collagen is broken down into amino acids and short peptides. The body can use amino acids to make new proteins, but the collagen you eat does not travel unchanged directly to your facial skin or knee cartilage.
Studies show that after collagen consumption, some of the peptides produced by its breakdown appear in the blood. Their levels peak after about 1–2 hours and then decline. So some peptides do enter the bloodstream, but their subsequent benefits for the skin or joints need to be demonstrated separately (Iwai et al., 2005; Shigemura et al., 2018).
Why are they expected to be beneficial at all? In one laboratory experiment, a collagen-derived peptide promoted the growth of connective tissue cells in mouse skin (Shigemura et al., 2018). This is an interesting clue to a possible effect. However, we can only draw conclusions about human skin when people taking the supplement actually show an improvement compared with a control group.
Does collagen make skin smoother?
A 2023 meta-analysis pooled 26 randomized controlled trials involving a total of 1721 people. The pooled results showed greater improvements in skin hydration and elasticity among people taking collagen than among those receiving a placebo. However, the authors highlighted the potential for bias in the studies and the need for larger trials (Pu et al., 2023).
In 2025, Myung and Park reviewed 23 studies involving 1474 participants. The pooled results of all studies were positive for wrinkles as well. However, no statistically significant improvement was found in the subgroup of studies without industry funding or in the subgroup of high-quality studies (Myung and Park, 2025).
This cannot be interpreted as proof that there is definitely no effect. An effect is also harder to detect in a smaller subgroup. However, this finding does reduce confidence that collagen supplements genuinely improve skin condition.
The Collagen Stewardship Alliance, which represents the collagen industry, challenged, among other things, how the studies were grouped by funding source. According to the organization, the study by Choi et al. received no money from a company, although a company supplied the collagen peptides for it (CSA, 2025). Providing materials free of charge is also a form of industry support that should be considered when evaluating a study.
The debate is not just about funding. The data used in two earlier meta-analyses were also re-examined, revealing errors in how results from the original studies had been extracted and analyzed. The analysis also found no association between a higher collagen dose and greater improvements in skin hydration or elasticity. This gives reason to view earlier positive findings more cautiously (Grimes and Mahto, 2026).
For the reader, there is another important question: would the improvement measured in a study also be visible in the mirror? Skin hydration and elasticity are often assessed using measuring devices. A device may detect a small change that the person does not notice. This means that a better hydration or elasticity reading does not automatically mean smoother skin or fewer wrinkles.
Does funding matter?
The study design, number of participants, measurements and how the results are presented must always be assessed.
Company funding does not mean that the outcome will necessarily favour the company. For example, in a trial funded by the Collagen Research Institute, men performed resistance training and received either collagen or a collagen-free comparison supplement, or placebo. Strength increased by roughly the same amount in both groups (Balshaw et al., 2023a).
Critics’ ties are also worth examining. Stuart Phillips, who challenged collagen’s superiority over other proteins, noted in his letter that his university had received funding for his research from, among others, the dairy industry, whose products include whey protein, which is compared with collagen (Phillips, 2026). Alongside funding and interests, it is therefore necessary to examine whether the research findings support the claims made by either side.
Is the evidence stronger for joint pain?
Collagen preparations may offer some help for osteoarthritis: pooled results suggest pain relief and improved mobility. The average benefit is small to moderate. However, different preparations have been used, some taken orally and others injected into the joint. Therefore, not all of the observed benefits can be extrapolated to collagen powder sold in shops (Liang et al., 2024).
Pain relief can mean a great deal to a person, but it does not prove that collagen restores worn cartilage or stops osteoarthritis from progressing. Nor can the potential benefits for people with osteoarthritis be taken to mean that a healthy person needs the same supplement to maintain joint health.
The European Food Safety Authority, or EFSA, also assessed this specific claim about maintaining joint health in physically active people. The evidence submitted by collagen manufacturer Gelita was considered insufficient, and the European Commission did not authorise the use of this claim. The decision was based on the evidence available at the time and does not provide a definitive answer regarding later osteoarthritis studies (EFSA, 2011; Regulation (EU) No 379/2012).
Does collagen help build muscle?
Collagen has been found to offer potential additional benefits for muscle growth, but the results need closer analysis. Taking collagen alongside training has been associated with greater gains in fat-free mass, while the additional benefits for strength have been small. The evidence for fat-free mass is of moderate certainty, but the evidence for several other outcomes is less certain (Bischof et al., 2024).
So where does the claim that collagen is the best protein for muscle growth come from? One meta-analysis comparing different protein supplements ranked it first for gains in fat-free mass and strength (Drummond et al., 2026). However, ranking first does not mean that its superiority has been conclusively established. As Phillips noted in his critique, the difference in strength gains between collagen and whey protein was not statistically significant, and the estimate for fat-free mass with collagen was based on few participants (Phillips, 2026).
When whey and collagen were compared directly in the same trial, measured muscle thickness actually increased more in the whey group, even though both supplements provided equal amounts of leucine, an amino acid that supports muscle protein synthesis (Jacinto et al., 2022). Collagen’s potential additional benefits alongside training and its superiority over other proteins are therefore two separate questions. There are positive findings for the first, but the second has not been established with sufficient certainty.
What about tendons and vitamin C?
For tendons, some studies have found benefits from collagen, while others have not. An increase in tendon thickness does not automatically mean that it can withstand loading better, either. It is therefore still unclear how much collagen helps tendons alongside training (Balshaw et al., 2023b; Jerger et al., 2022; Nulty et al., 2025).
In a small study, vitamin C-enriched gelatin combined with exercise increased a blood marker associated with collagen synthesis. Whether this also leads to stronger tendons or fewer injuries requires further research (Shaw et al., 2017).
What should you check before buying?
If an advertisement refers to a study, it is worth taking a closer look at five things:
What was measured? Skin hydration, joint pain ratings and muscle volume answer different questions.
What was the supplement compared with? If the comparison group receives no additional protein at all, the collagen group's better results may simply be due to a higher protein intake.
How large and how reliable was the change? Statistical significance alone does not tell you whether the result is noticeable to an individual.
Was the same product studied? The form of collagen, dose and other ingredients may differ from those in your chosen supplement.
Who supported the study? Look at funding, the provision of materials, the authors' affiliations and whether the study design reduced the potential for bias.
Is collagen worth taking?
The answer depends on your goal. For osteoarthritis-related complaints, a collagen supplement may provide additional symptom relief, but it does not replace a treatment plan. There are positive findings on its effects on the skin, but their reliability is debatable. For muscle growth, collagen has no proven advantage over other protein sources, and its potential benefits for tendons need further confirmation. If your goal is muscle growth, it is worth looking first at your training and daily protein and energy intake.
The packaging may promise a lot. When deciding whether to buy, it is more useful to know whether there is enough reliable evidence for your specific goal and how much of a change you can realistically expect based on that evidence.
This article is not a substitute for personalised nutritional or medical advice.
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