meta analysis1,125 participants

Oral Collagen for Skin: 2021 Meta-Analysis of 19 RCTs

Supplement Science Editorial Team·Evidence-Based Supplement Research

Published Mar 25, 2026·Reviewed Oct 30, 2026

This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

The 2021 de Miranda review included 19 trials and 1,125 participants and found pooled improvements in skin hydration,...

Key Findings

The review included 19 randomized, double-blind controlled studies with 1,125 participants aged 20-70;95% were women.
The pooled analyses favored hydrolyzed collagen for hydration, elasticity and wrinkles, with hydration and elasticity findings also supported in subgroup analyses.
The review described benefits over approximately 90 days. Individual trial products, doses and measurement methods varied.
In a separate 69-woman trial,2.5 g or 5 g/day for 8 weeks improved skin elasticity. Its moisture and evaporation subgroup findings did not reach statistical significance.
These studies do not establish that every collagen source, collagen type or commercial product has the same effect.

Study Details

Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis

de Miranda RB, Weimer P, Rossi RC — Int J Dermatol (2021)

Review of19 trials found pooled improvements in hydration, elasticity and wrinkles versus placebo; participants were predominantly women.

1,125 participantsModerate

Oral supplementation of specific collagen peptides has beneficial effects on human skin physiology: a double-blind, placebo-controlled study

Proksch E, Segger D, Degwert J, Schunck M, Zague V, Oesser S — Skin Pharmacol Physiol (2014)

2.5 g or5 g/day for 8 weeks improved skin elasticity; moisture and evaporation findings did not reach significance.

69 participantsModerate

Study	Participants	Finding	Quality
Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis de Miranda RB, Weimer P, Rossi RC — Int J Dermatol (2021)	1,125	Review of19 trials found pooled improvements in hydration, elasticity and wrinkles versus placebo; participants were predominantly women.	Moderate
Oral supplementation of specific collagen peptides has beneficial effects on human skin physiology: a double-blind, placebo-controlled study Proksch E, Segger D, Degwert J, Schunck M, Zague V, Oesser S — Skin Pharmacol Physiol (2014)	69	2.5 g or5 g/day for 8 weeks improved skin elasticity; moisture and evaporation findings did not reach significance.	Moderate

Practical Takeaway

Match a collagen product to the preparation and serving used in its research, and assess skin changes over the trial timeframe. The 2021 review supports an average benefit in measured skin outcomes; it does not promise a fixed percentage improvement or show that added vitamin C is required for the supplement to work.

Summary

A 2021 systematic review and meta-analysis of 19 trials included 1,125 adults, mostly women, and assessed hydrolyzed collagen for skin hydration, elasticity and wrinkles.

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Frequently Asked Questions

Does collagen improve skin measurements?

The 2021 review found average improvements in hydration, elasticity and wrinkles versus placebo. Results are measured group effects and may vary with the formulation, outcome and individual.

Do effect sizes of 0.53 or 0.49 mean 53% or 49% improvement?

No. A standardized mean difference expresses an effect in standard-deviation units. It cannot be converted directly into a percentage change in hydration or elasticity.

How long were collagen supplements studied?

The review summarized trials over weeks to months and described benefit over about 90 days. The separately cited Proksch trial used daily supplementation for 8 weeks.

Is marine collagen better than bovine collagen?

The studies used different preparations and do not establish a universal winner between marine and bovine sources. Choose a preparation that fits dietary requirements and has directly relevant research.

Should I add vitamin C to collagen?

Adequate vitamin C is needed for normal collagen synthesis. The reviewed trials do not establish a mandatory extra 50-100 mg dose with collagen or prove that this addition increases the supplement’s benefit.

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References

de Miranda RB, Weimer P, Rossi RC (2021). Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis. Int J Dermatol. DOI PubMed
Proksch E, Segger D, Degwert J, Schunck M, Zague V, Oesser S (2014). Oral supplementation of specific collagen peptides has beneficial effects on human skin physiology: a double-blind, placebo-controlled study. Skin Pharmacol Physiol. DOI PubMed