Does Collagen Work? A Look at the Evidence

What collagen is

Collagen is the most abundant protein in the body. In the skin, it forms a framework that helps keep skin firm and elastic. Starting in early adulthood, the body gradually makes less collagen, and sun exposure, smoking and other factors speed up its breakdown. This is part of why skin becomes thinner, drier and more wrinkled with age.

Most collagen supplements contain hydrolyzed collagen, also called collagen peptides. This is collagen broken down into small pieces so it dissolves easily and can be absorbed. It usually comes from cow hides, pig skin, fish skin and scales, or chicken cartilage.

How it's supposed to work

When you eat collagen, your body digests it into amino acids and small peptides, the same as any other protein. It doesn't travel directly to your skin as intact collagen. The theory is that some of these small peptides reach the skin and signal skin cells to produce more collagen and related compounds. This has been shown in lab and animal studies. Whether it leads to visible changes in people is the key question.

What the research says

Studies that found a benefit

A 2023 systematic review and meta-analysis published in Nutrients pooled 26 randomized controlled trials with 1,721 participants. It found that hydrolyzed collagen significantly improved skin hydration and elasticity compared with placebo. The authors concluded the results support a positive effect but called for larger trials to confirm it.

A 2025 review that found no clear benefit

In 2025, a meta-analysis in The American Journal of Medicine looked at 23 randomized trials with 1,474 participants. When all studies were combined, collagen appeared to improve hydration, elasticity and wrinkles. But when the researchers split the studies:

• Trials funded by supplement companies showed benefits.
• Trials without industry funding showed no significant benefit.
• Higher-quality trials showed no significant effect on any measure.

The authors concluded there is currently no clinical evidence to support collagen supplements for preventing or treating skin aging. Industry groups disputed the analysis, arguing it grouped different types of collagen together and misclassified some studies' funding.

How to read these mixed results

Both reviews draw on many of the same small trials. Many lasted only 8 to 12 weeks, used different doses and collagen sources, and measured skin with different tools. A large share were funded by companies that sell collagen. That doesn't automatically make the results wrong, but it's a known source of bias, and it's why independent, well-designed trials matter.

Our assessment: collagen may modestly improve skin hydration and elasticity for some people, but the effect is small at best, and the strongest studies haven't confirmed it.

Evidence: Limited

What about hair, nails and joints?

• Nails: a few small, uncontrolled studies reported less brittle nails. That's not strong enough to draw conclusions.
• Hair: there is little human research on collagen for hair growth.
• Joints: some trials suggest collagen may ease joint discomfort in people with osteoarthritis or athletes, but results are mixed and the studies are small.

Is it safe?

Collagen is a food-derived protein and is generally well tolerated. Some people report mild stomach upset or a feeling of fullness. Things to keep in mind:

• Allergies: marine collagen comes from fish, and some products use egg or shellfish sources. Check the label if you have food allergies.
• Not vegan: collagen always comes from animals. "Vegan collagen" products contain other ingredients meant to support collagen production, not collagen itself.
• Quality: supplements aren't approved by the FDA before sale. Look for third-party testing seals such as USP or NSF.
• Pregnancy and medical conditions: talk to your doctor first.

A note on biotin

Many "hair, skin and nails" products combine collagen with high doses of biotin. Biotin deficiency is rare, and there's no good evidence that extra biotin helps hair or nails in people who aren't deficient. More importantly, the FDA has warned that high-dose biotin can interfere with some lab tests, including a test used to diagnose heart attacks. If you take biotin, tell your doctor before any blood test.

What has stronger evidence for your skin

1. Daily broad-spectrum sunscreen (SPF 30 or higher). Sun damage is the main cause of premature skin aging.
2. Not smoking. Smoking speeds collagen breakdown.
3. Topical retinoids, such as tretinoin (prescription) or retinol (over the counter), which have good evidence for fine wrinkles.
4. Enough protein and vitamin C in your diet. Your body needs both to make collagen.

The bottom line

Collagen supplements are safe for most people, and some studies suggest a modest effect on skin hydration and elasticity. But the best independent studies haven't confirmed a benefit, so the evidence is weaker than the marketing implies. If you want to try collagen, think of it as an optional extra, give it about three months, and keep using sunscreen. That's still the most proven thing you can do for your skin.