Collagen peptides are widely promoted as a natural way to help build bone. Is there evidence for this?
First, what is collagen and what are collagen peptides.
Collagen is the most abundeant protein in the human body. It provides structural scaffolding for skin, bones, muscles, tendons, ligaments and other connective tissue. As with any other protein in our bodies, collagen is made from the basic 20 amino acids. We do not directly use protein that is ingested - rather the protein in our food is broken down into amino acids which are then absorbed into our blood and taken up by the cells in our organs to build the necessary proteins.
Collagen has a few distinguishing qualities
- structurally, it is a triple helix - meaning it is made from 3 strands of amino acid chains (long peptides) that are twisted around each other forming a helix
- the amino acid composition is primarily glycine, proline and hydroxyproline. The latter is a modification of proline that happens after proline is added to the peptide chain
- the 3 chains making a collagen fibril are cross-linked together
- the peptide bonds (bonds linking individual amino acids) in collagen are resistant to standard digestive enzymes
When collagen peptides are sold as a supplement, it generally refers to the hydrolyzation (breakdown, as it would occur in our stomachs) of collagen into smaller fragments. Each strand of the triple helix of native collagen consists of approximately 1000 amino acids. Collagen peptides in supplements are typically 20 to 50 amino acids in length. Low molecular weight peptides may be as small as 5 amino acids.
Regardless of the size of the peptides in the supplement, the peptides are resistant to breakdown in the stomach, but are broken down in the intestine into lengths of 2 or 3 amino acids. These di- and tri-peptides can pass into the bloodstream intact
- proline-hydroxyproline
- hydroxyproline-glycine
- glycine-proline-hydroxyproline
Rather than acting as nutritional building blocks for making new protein, these peptides function as bioactive signalling moledules. They bind to receptors in target tissue (skin, joints, bone) to stimulate the body's own natural collagen (and hyaluronic acid) synthesis. According to GELITA, the manufacturer of FORTIBONE collagen peptides, these di- and tri-peptides stimulate osteoblasts and inhibit osteoclasts.
There are 28 different types of collagen in the human body. The 5 main types are
- Type I: 90% of body's collagen; found in skin, bones, tendons and teeth
- Type II: found mainly in elastic cartilage, acting as a shock absorber.
- Type III: found in muscles, blood vessels and organs. Along with Type I, supports tissue structure
- Type IV: found in thin layers of skin and basement membranes
- Type V: found in the cornea of eye, some skin layers, hair and tissue
The above should establish some plausability for collagen peptides providing bone building support. Is there clinical data to support this? To date (2026) the only commercially available collagen peptide that has shown clinical efficacy is FORTIBONE. It is unclear whether others have been tested. There are two published clinical trials with FORTIBONE; and the second is an extension of the first.
References to look up:
Daniel König, Steffen Oesser, Stephan Scharla, Denise Zdzieblik, Albert Gollhofer. Nutrients (2018) 10:97
This is a double-blind randomized study of 131 post-menopausal women evenly distributed into two groups: treatment group received 5 g Specific Collagen Peptides (FORTIBONE); control group received maltodextrin. All subjects were encouraged to get regular physical activity and to take calcium supplement (500 - 800 mg/day depending on weight) and vitamin D (400 - 800 IU) daily. 102 subjects completed the 12 month study - the dropouts were evenly divided between the groups and were due to non-compliance or lost to follow-up. There were some significant differences in the baseline characteristics of the two groups. The analysis at 12 months showed an average improvement in T score for the treatement group of 0.07 at the spine and 0.09 at the femoral neck. The control group saw an average worsening of T score by 0.03 and 0.01 at the lumbar spine and femoral neck, respectively. While these results showed a statistically significant difference between the two groups, the absolute difference was not very remarkable. However, given the apparent low risk of continuing collagen supplementation, if this trend were to continue over the course of 5 years, it might be a viable option for post-menopausal women close to the osteopenia range.
Journal of Bone Metabolism (2021) 28:207-213
this is a follow-up to above study in Nutrients. Uses Fortibone.
Efficacy of collagen peptide supplementation on bone and muscle health: a meta-analysis
Frontiers in Nutrition (2025) 12:1646090
references for collagen
https://my.clevelandclinic.org/health/articles/23089-collagen