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The Evidence

Research

Peer-reviewed studies on collagen peptides, grouped by category for easy reference. We cite the research and stay honest about where the evidence is strong and where it's still emerging.

Skin, Hair & Nails (5)

Skin elasticity significantly improved after 8 weeks of daily collagen peptides vs. placebo

Oral Supplementation of Specific Collagen Peptides Has Beneficial Effects on Human Skin Physiology: A Double-Blind, Placebo-Controlled Study2014

Proksch, E., Segger, D., Degwert, J., Schunck, M., Zague, V., & Oesser, S.

Significant gains in skin hydration and elasticity, and reduced wrinkling, over 12 weeks

Oral Intake of Low-Molecular-Weight Collagen Peptide Improves Hydration, Elasticity, and Wrinkling in Human Skin: A Randomized, Double-Blind, Placebo-Controlled Study2018

Kim, D.U., Chung, H.C., Choi, J., Sakai, Y., & Lee, B.Y.

Significant improvements in skin hydration, elasticity, roughness, and density at 12 weeks

A Collagen Supplement Improves Skin Hydration, Elasticity, Roughness, and Density: Results of a Randomized, Placebo-Controlled, Blind Study2019

Bolke, L., Schlippe, G., Gerß, J., & Voss, W.

Nail growth +12%, broken nails −42% after 24 weeks of daily collagen peptides

Oral Supplementation with Specific Bioactive Collagen Peptides Improves Nail Growth and Reduces Symptoms of Brittle Nails2017

Hexsel, D., Zague, V., Schunck, M., Siega, C., Camozzato, F.O., & Oesser, S.

Pooled evidence from 19 trials: collagen reliably improves skin hydration and elasticity

Effects of Hydrolyzed Collagen Supplementation on Skin Aging: A Systematic Review and Meta-Analysis2021

de Miranda, R.B., Weimer, P., & Rossi, R.C.

Joints & Mobility (3)

Significantly reduced activity-related joint pain in athletes over 24 weeks vs. placebo

24-Week Study on the Use of Collagen Hydrolysate as a Dietary Supplement in Athletes with Activity-Related Joint Pain2008

Clark, K.L., Sebastianelli, W., Flechsenhar, K.R., Aukermann, D.F., Meza, F., Millard, R.L., Deitch, J.R., Sherbondy, P.S., & Albert, A.

5g/day significantly reduced activity-related knee discomfort over 12 weeks

Improvement of Activity-Related Knee Joint Discomfort Following Supplementation of Specific Collagen Peptides2017

Zdzieblik, D., Oesser, S., Gollhofer, A., & König, D.

Significant improvement in knee discomfort in young active adults after 12 weeks

The Influence of Specific Bioactive Collagen Peptides on Knee Joint Discomfort in Young Physically Active Adults: A Randomized Controlled Trial2021

Zdzieblik, D., Brame, J., Oesser, S., Gollhofer, A., & König, D.

Gut & Digestion (2)

Bloating down ~31%; 93% of women reported reduced bloating over 8 weeks

Effect of a Daily Collagen Peptide Supplement on Digestive Symptoms in Healthy Women: 2-Phase Mixed Methods Study2022

Abrahams, M., O'Grady, R., & Prawitt, J.

Collagen peptides supported intestinal barrier integrity and tight junctions in a cell model

Collagen Peptides Ameliorate Intestinal Epithelial Barrier Dysfunction in Immunostimulatory Caco-2 Cell Monolayers via Enhancing Tight Junctions2017

Chen, Q., Chen, O., Martins, I.M., Hou, H., Zhao, X., Blumberg, J.B., & Li, B.

Bone, Muscle & Recovery (2)

5g/day increased spine and femoral-neck bone density over 12 months vs. placebo

Specific Collagen Peptides Improve Bone Mineral Density and Bone Markers in Postmenopausal Women — A Randomized Controlled Study2018

König, D., Oesser, S., Scharla, S., Zdzieblik, D., & Gollhofer, A.

Greater gains in muscle mass and strength vs. placebo when combined with training

Collagen Peptide Supplementation in Combination with Resistance Training Improves Body Composition and Increases Muscle Strength in Elderly Sarcopenic Men: A Randomised Controlled Trial2015

Zdzieblik, D., Oesser, S., Baumstark, M.W., Gollhofer, A., & König, D.

Note: Studies cited for educational purposes. Doses in these trials vary and some exceed the 5g in a Two Birds pod; results reflect controlled trial conditions and individual results may vary. Two Birds products are not intended to diagnose, treat, cure, or prevent any disease. Consult a healthcare professional before starting any supplementation regimen.

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