Collagen Supplements: Promising Benefits and Persistent Controversies

Introduction

Collagen, a protein found in our bodies, forms a network of fibers that provides structure and strength to connective tissues such as skin, bones, tendons, and cartilage. With age, collagen production naturally decreases, leading to wrinkles, joint pain, and muscle weakness. As a result, collagen supplements have gained popularity in recent years. These supplements come in various forms, including hydrolyzed collagen peptides, undenatured collagen type II, and gelatin. While they may offer benefits for skin, joint, and bone health, the scientific evidence is not yet conclusive.

Type and Sources of Collagen

Collagen is classified into three main types: I, II, and III. Type I collagen is found in bones, skin, and teeth, while type II provides support for articular cartilage. Type III collagen is present in muscles, blood vessels, and lungs. Raw collagen material is primarily obtained from animal sources, such as bovine hides and porcine skin. Marine fish skins, poultry waste, and ovine tissues offer sustainable alternatives. However, the efficacy of these alternatives is less well-established.

Raw Material and Processing Conditions

Raw collagen material is processed into various products, including hydrolyzed collagen peptides, undenatured collagen type II, and gelatin. The processing conditions, molecular weight, and raw material origin can affect the absorption and efficacy of collagen supplements.

Absorption and Bioavailability

Oral collagen hydrolysates are fragmented by gastric and pancreatic enzymes into free amino acids and short peptides. These peptides are then transported across the intestinal wall, where they can be absorbed and utilized by the body.

Mechanisms of Action

Collagen peptides may improve skin elasticity, joint comfort, bone mineral density, and muscle recovery. They act by providing bioactive peptides and amino acids that stimulate fibroblast proliferation, increase type I and type III procollagen mRNA levels, and support hyaluronic acid and decorin production.

Clinical Evidence

Randomized controlled trials and meta-analyses suggest that oral collagen peptides improve skin, joint, bone, and muscle outcomes. A meta-analysis of 19 studies and 1,124 adults reported that 60-90 days of collagen supplementation increased elasticity and density while reducing wrinkle depth.

Benefits and Safety

Collagen supplements are generally well-tolerated, with mild gastrointestinal symptoms, allergic reactions, or taste disturbances rarely reported. However, those with allergies to fish, bovine, porcine, or avian proteins should avoid products from those sources.

Limitations and Controversies

Collagen supplements vary widely in source, peptide length, and added nutrients. The efficacy of these supplements can be affected by processing conditions, molecular weight, and raw material origin. Moreover, the safety profiles differ between marine and bovine products.

Future Directions

Future studies should investigate the long-term effects of collagen supplementation on bone mineral density, joint health, and muscle recovery. Additionally, the development of personalized collagen products based on genomic and microbiome signatures is an area of ongoing research.

References

The references cited in this article are:

* Campos et al. (2023)

* León-López et al. (2019)

* Virgilio et al. (2024)

* Cole et al. (2018)

* Shan et al. (2025)

* Wang et al. (2021)

* Martini Nataly (2019)

* Shiloah et al. (2023)

* Collagen Supplementation for Joint Health: The Link between Composition and Scientific Knowledge (2023)

* Inácio et al. (2023)