Collagen is the most abundant protein in the human body, comprising approximately 30 percent of total protein mass, and is the primary structural component of skin, tendons, ligaments, cartilage, bone, and the walls of blood vessels. Collagen production declines at a rate of approximately 1 percent per year from the late twenties onwards, and this decline is directly responsible for many of the visible and functional changes of ageing. Hydrolysed collagen peptides, produced by enzymatic digestion of collagen proteins into short peptide chains of 2 to 10 amino acids, are absorbed intact through the intestinal wall and accumulate in skin, cartilage, and bone tissue, where they are believed to stimulate local collagen synthesis through fibroblast receptor activation.
The Evidence for Skin Health
A systematic review and meta-analysis published in the International Journal of Dermatology in 2019 examined 19 randomised controlled trials of hydrolysed collagen supplementation with a total of 1,125 participants. The review found significant improvements in skin hydration, elasticity, and dermal collagen density compared to placebo, with the strongest effects seen after 8 to 12 weeks of supplementation. The mechanism involves the absorption of collagen peptides, particularly the hydroxyproline-proline sequence, which activates fibroblast receptors and stimulates new collagen and hyaluronic acid synthesis. The typical dose used in trials is 2.5 to 10 grams daily.
The Evidence for Joint Health
The evidence for collagen peptides in joint health is somewhat more mixed but generally positive. A randomised controlled trial published in Current Medical Research and Opinion in 2008 enrolled 147 athletes with activity-related joint pain and found that collagen hydrolysate at 10 grams daily significantly improved joint pain scores compared to placebo over 24 weeks, with the greatest improvements in those with the most severe baseline pain. A meta-analysis published in the British Journal of Nutrition in 2019 examined 5 trials in osteoarthritis and found significant improvements in pain and function, though the authors noted that study quality was variable.
Vitamin C: The Essential Co-Factor
Collagen synthesis requires vitamin C as a cofactor for the enzymes prolyl hydroxylase and lysyl hydroxylase, which add the hydroxyl groups to proline and lysine that give collagen its unique triple-helix structure. Taking collagen peptides without adequate vitamin C is significantly less effective. Research by Keith Baar at the University of California Davis found that taking hydrolysed collagen with 48 mg of vitamin C 60 minutes before exercise significantly increased blood amino acid levels and stimulated collagen synthesis markers compared to collagen without vitamin C, or placebo.
Practical Guidance
- Dose: 10 grams daily of hydrolysed collagen peptides is the dose used in most positive trials; lower doses of 2.5 grams may be sufficient for skin effects in less depleted individuals
- Timing: taking collagen with vitamin C 30 to 60 minutes before activity or physical rehabilitation produces the largest acute increases in circulation of collagen-building amino acids
- Type: type I and type III collagen peptides are most relevant for skin, tendon, and ligament; type II collagen peptides are most relevant for cartilage health; many supplements contain a mixture
- Source: marine collagen peptides have slightly higher bioavailability than bovine; both are well studied; plant-based alternatives do not exist as collagen is an animal protein, but plant-based diets providing adequate vitamin C, proline, glycine, and copper support endogenous collagen synthesis
- Bone broth: a traditional food source of collagen peptides; the collagen content of bone broth varies widely depending on preparation; supplementation provides a more consistent and quantifiable dose
Sources
- Choi, F.D., et al. (2019). Oral collagen supplementation: a systematic review of dermatological applications. Journal of Drugs in Dermatology, 18(1), 9-16.
- Clark, K.L., et al. (2008). 24-week study on the use of collagen hydrolysate as a dietary supplement in athletes. Current Medical Research and Opinion, 24(5), 1485-1496.
- Shaw, G., et al. (2017). Vitamin C-enriched gelatin supplementation before intermittent activity augments collagen synthesis. American Journal of Clinical Nutrition, 105(1), 136-143.
- Proksch, E., et al. (2014). Oral supplementation of specific collagen peptides has beneficial effects on human skin physiology. Skin Pharmacology and Physiology, 27(1), 47-55.
- Bello, A.E., & Oesser, S. (2006). Collagen hydrolysate for the treatment of osteoarthritis and other joint disorders. Current Medical Research and Opinion, 22(11), 2221-2232.