Collagen in food (e.g. in bone broth, leather, gelatin) is broken down during digestion to amino acids and small peptides. These are used by the body according to its needs, but are not converted directly into collagen in the skin, joints or tendons.
In other words: eating collagen does not mean that it is automatically „incorporated“ as collagen in the body.
Collagen consists mainly of glycine, proline and hydroxyproline, and vitamin C is required as a cofactor for its synthesis.
For optimal collagen production in the body are important:
Several randomized controlled trials (RCTs) have shown that hydrolyzed collagen peptides can moderately improve skin elasticity and hydration and relieve joint discomfort, possibly because:
Important: this effect is seen with hydrolysed collagen supplements, not collagen foods such as bone broth, where the amount and bioavailability are low and inconsistent.
| Factor | Scientific evidence | Influence on collagen synthesis |
|---|---|---|
| Collagen foods (broth, skin, etc.) | Weak | Provide amino acids but do not directly stimulate collagen synthesis |
| Hydrolysed collagen (supplements) | Moderate | Some RCTs show small but real benefits for skin and joints |
| Adequate total protein intake | Strong | Critical for collagen synthesis and repair processes |
| Vitamin C, zinc, copper | Strong | Necessary cofactors for collagen formation |
For better collagen production, the most important are:
Proksch E. et al. (2014), Skin Pharmacol Physiol.
Zdzieblik D. et al. (2015), Br J Nutr: Collagen peptides reduce joint pain in active adults.
De Simone C. et al. (2021), Nutrients.
Iwai K. et al. (2005), J Agric Food Chem.
