What About Skin, Wrinkles, and “Anti-Aging”?
This is probably collagen's most heavily marketed use.
Earlier systematic reviews generally looked encouraging.
For example, a 2023 meta-analysis of 26 randomized trials involving 1,721 participants found statistically significant improvements in skin hydration and elasticity after hydrolyzed collagen supplementation.
But newer evidence raises an important concern.
A 2025 American Journal of Medicine meta-analysis examined 23 randomized trials with 1,474 participants and initially found improvements in hydration, elasticity, and wrinkles.
The picture changed when study quality and funding were considered.
Studies without pharmaceutical-industry funding showed no significant improvement in those outcomes. Higher-quality studies also failed to show consistent benefits, while the more favorable findings tended to come from lower-quality or industry-funded studies.
That does not prove collagen has no effect on skin.
It means the confidence behind the popular claim:
“Collagen supplements improve your skin”
is substantially lower than advertising often suggests.
What About Joint Pain?
Here the case is stronger.
A 2024 systematic review and trial-sequential meta-analysis included 35 randomized controlled trials involving 3,165 people with osteoarthritis.
Collagen derivatives produced small-to-moderate improvements in pain and physical function, and the authors rated the evidence for function highly while finding no significant increase in adverse events compared with control groups.
Another updated meta-analysis focused on knee osteoarthritis included 11 RCTs and 870 participants and also found improvements in pain and function.
There is an important caveat:
“Collagen supplement” does not describe one standardized intervention.
Studies have used hydrolyzed collagen peptides, gelatin-derived products, undenatured type II collagen, and different doses and formulations.
So evidence supporting a particular collagen intervention for knee osteoarthritis should not automatically be transferred to every tub of collagen powder on the market.
What About Tendons?
This is one of the more interesting emerging areas.
A 2026 systematic review identified eight randomized trials involving 257 participants in which collagen supplementation was combined with resistance or plyometric training.
Several studies reported greater increases in tendon cross-sectional area, while higher-dose protocols in some studies improved tendon stiffness.
But almost all participants were men, trials were short typically 3 to 15 weeks and protocols differed considerably.
The key point is that collagen was not acting in isolation.
The participants were loading the tendon through exercise.
So this evidence supports:
collagen as a possible adjunct to appropriately designed training,
not:
collagen powder rebuilding tendons by itself.
Is Collagen a Good Protein for Building Muscle?
Not compared with higher quality protein sources.
Collagen is rich in glycine and proline but relatively poor in essential amino acids involved in stimulating myofibrillar protein synthesis.
A 2024 randomized controlled trial in older men compared additional whey, pea, and collagen protein.
Whey and pea protein increased integrated muscle protein synthesis above the baseline diet.
Collagen did not.
Similar results have been observed in older women, where whey stimulated both acute and longer-term muscle protein synthesis substantially more effectively than collagen.
This does not mean collagen contains no usable protein.
It means that if your main goal is:
muscle growth, muscle retention, or maximizing muscle protein synthesis,
collagen should generally not replace higher quality dietary proteins.
That distinction becomes especially important in older adults or during weight loss, when preserving muscle may already be challenging.