Benefits
Skin elasticity, hydration, and wrinkle depth
Two pooled analyses of randomized trials, one of 19 trials with 1,125 people and one of 26 trials with 1,721 people, mostly women, found hydrolyzed collagen improved skin hydration and elasticity compared with placebo; the first also found fewer wrinkles after about 90 days. The second review noted several biases in the included trials, and many trials tested proprietary peptides.
Joint comfort in active adults and older adults with joint pain
In athletes, 10 g a day for 24 weeks reduced several self-rated measures of activity-related joint pain versus placebo, and 5 g a day for 12 weeks reduced knee pain during activity but not at rest. In 200 adults aged 50 or older with joint pain, 1.2 g a day gave more responders than placebo at 6 months (51.6 vs 36.5 percent) but not at 3 months.
Collagen production markers after gelatin and exercise
In a crossover study of 8 healthy men, 15 g of vitamin C-enriched gelatin taken 1 hour before brief rope-skipping doubled a blood marker of collagen production compared with placebo. Lab-grown ligaments treated with their blood serum gained collagen. No study cited here measured tendon injuries or recovery in people.
Bone mineral density in postmenopausal women
In a 12-month randomized, placebo-controlled trial of 131 postmenopausal women with age-related low bone density, 5 g a day of specific collagen peptides raised spine and hip bone density compared with placebo and shifted blood markers toward bone formation. This is a single trial of one proprietary peptide.
Nail growth and fewer broken nails; hair not studied
In an open-label study without a placebo group, 25 people with brittle nails took 2.5 g of specific collagen peptides daily for 24 weeks; nail growth rate rose 12 percent and broken nails fell 42 percent. None of the studies cited here measured hair.
Fat-free mass and strength with resistance training
In a 12-week randomized, placebo-controlled trial, 77 premenopausal women doing resistance training 3 days a week gained more fat-free mass and hand-grip strength and lost more body fat with 15 g a day of specific collagen peptides than with placebo. Leg strength rose in both groups, more in the collagen group. This is a single trial.
Thigh skin texture in women with cellulite
In a 6-month randomized, placebo-controlled trial of 105 women aged 24 to 50 with moderate cellulite, 2.5 g a day of specific collagen peptides reduced cellulite scores and skin waviness on the thighs in normal-weight women and improved dermal density. The effect was smaller in overweight women.
Mechanism of action
Peptide signaling to skin cells
In a trial with skin biopsies, women taking 2.5 g a day of specific collagen peptides for 8 weeks had 65 percent more procollagen type I and 18 percent more elastin in the skin than the placebo group; fibrillin rose 6 percent, which was not significant. This fits the idea that absorbed peptides prompt skin cells to make more matrix.
Collagen building blocks in the blood
After gelatin, blood levels of glycine, proline, hydroxyproline and hydroxylysine rise and peak about 1 hour later. Serum taken at that peak increased collagen content in lab-grown ligaments, which is the rationale for taking collagen before exercise.
Bone turnover
In postmenopausal women, a marker of bone formation (P1NP) rose with collagen peptides, while a marker of bone breakdown (CTX) rose in the placebo group, suggesting a shift toward bone building.
Clinical trials
Systematic review and meta-analysis of 19 randomized, double-blind, controlled trials of oral hydrolyzed collagen (de Miranda et al. 2021, Int J Dermatol)
1,125 participants aged 20 to 70, 95 percent women.
Pooled results favored collagen over placebo for skin hydration, elasticity and wrinkles, and subgroup analyses confirmed the hydration and elasticity results. The authors concluded that about 90 days of intake reduces signs of skin aging.
Systematic review and meta-analysis of 26 randomized controlled trials of hydrolyzed collagen (Pu et al. 2023, Nutrients)
1,721 participants across the pooled trials.
Collagen improved skin hydration and elasticity compared with placebo. Effects on hydration varied with collagen source and duration; source made no significant difference for elasticity. The authors identified several biases in the included trials and called for larger trials.
Double-blind, placebo-controlled trial of 2.5 g a day of specific bioactive collagen peptides (Verisol) for 8 weeks (Proksch et al. 2014, Skin Pharmacol Physiol)
114 women aged 45 to 65, 57 per group, with skin biopsies in a subgroup.
Eye wrinkle volume fell by 20 percent after 8 weeks, significantly more than with placebo, and the effect persisted 4 weeks after stopping. Skin procollagen type I was 65 percent and elastin 18 percent higher than with placebo; fibrillin did not differ significantly.
Randomized, placebo-controlled, blind trial of a drinkable blend of 2.5 g collagen peptides with acerola, vitamin C, zinc, biotin and vitamin E for 12 weeks (Bolke et al. 2019, Nutrients)
72 healthy women aged 35 or older, 36 per group.
Skin hydration, elasticity, roughness and density improved significantly more than with placebo, and the changes were largely retained 4 weeks after stopping. Because the product contained several nutrients, the effect of collagen alone cannot be separated.
Double-blind, placebo-controlled trial of 2.5 g a day of specific bioactive collagen peptides for 6 months (Schunck et al. 2015, J Med Food)
105 women aged 24 to 50 with moderate cellulite, normal weight or overweight.
In normal-weight women, cellulite scores and thigh skin waviness fell compared with placebo, and dermal density improved. Benefits were smaller in overweight women. The shortening of the subcutaneous border was not significant versus placebo.
Randomized, double-blind, placebo-controlled trial of 10 g a day of collagen hydrolysate for 24 weeks (Clark et al. 2008, Curr Med Res Opin)
147 varsity or club athletes without joint disease; 97 could be analysed.
Six joint pain measures improved more than with placebo, including physician-rated pain at rest and self-rated pain when walking, standing, carrying and lifting. Differences were larger in the 63 athletes with knee pain.
Randomized, placebo-controlled trial of 5 g a day of specific collagen peptides for 12 weeks (Zdzieblik et al. 2017, Appl Physiol Nutr Metab)
139 young athletes with knee pain during sport.
Pain during activity fell more than with placebo, by both participant (p = 0.046) and physician (p = 0.021) ratings, and use of other treatments dropped. Pain at rest and knee mobility did not differ significantly from placebo.
Randomized, double-blind, placebo-controlled multicenter trial of 1.2 g a day of collagen hydrolysate for 6 months (Bruyère et al. 2012, Complement Ther Med)
200 adults aged 50 or older with joint pain in the limbs or lower back.
At 6 months, 51.6 percent of the collagen group were responders (at least 20 percent less pain) versus 36.5 percent on placebo; at 3 months there was no significant difference. Tolerability was similar to placebo.
Randomized, placebo-controlled, double-blind trial of 5 g a day of specific collagen peptides for 12 months (König et al. 2018, Nutrients)
131 postmenopausal women with age-related reduction in bone density; 102 completed, all analysed.
Spine and femoral neck bone density rose compared with placebo. The bone formation marker P1NP increased with collagen, while the breakdown marker CTX increased in the placebo group.
Randomized, double-blind, placebo-controlled trial of 15 g a day of specific collagen peptides with 12 weeks of resistance training (Jendricke et al. 2019, Nutrients)
77 premenopausal women training 3 days a week.
Fat-free mass and hand-grip strength rose more, and body fat fell more, than with training plus placebo. Leg strength increased in both groups, more in the collagen group.
Randomized, double-blind crossover study of 5 or 15 g of vitamin C-enriched gelatin or placebo taken 1 hour before 6 minutes of rope-skipping (Shaw et al. 2017, Am J Clin Nutr)
8 healthy men.
Blood glycine, proline, hydroxyproline and hydroxylysine rose with gelatin. With 15 g, a blood marker of collagen production doubled, and serum from treated subjects increased collagen in lab-grown ligaments.
Open-label, single-center study of 2.5 g a day of specific bioactive collagen peptides for 24 weeks plus 4 weeks off (Hexsel et al. 2017, J Cosmet Dermatol)
25 participants with brittle nails.
Nail growth rate rose 12 percent and the frequency of broken nails fell 42 percent; 64 percent showed overall improvement. There was no placebo group.