Benefits
Dermal density and skin moisture in women aged 40 to 65
In 106 women in France, 10 g a day of fish Peptan F for 12 weeks raised dermal collagen density on ultrasound by 8.83 percent, with no change on placebo (p = 0.007). In 85 Chinese women, 5 g a day of porcine Peptan P for 84 days gave 6.3 percent higher dermal density and 8.4 percent higher clinician-scored skin moisture than placebo. Both trials used Rousselot products and Rousselot-employed authors; Rousselot funded the second.
Skin moisture measured by corneometer
In a small trial of 33 Japanese women with dry skin, 11 per group, 10 g a day of porcine Peptan P raised skin moisture by 28 percent after 8 weeks (p = 0.003 versus placebo). Fish Peptan F raised it 12 percent from baseline. Water loss through the skin did not differ from placebo. Groups were allocated by minimization, not randomization.
Skin elasticity, wrinkle depth and nail color
In the 85-woman trial, elasticity and crow's feet wrinkle depth improved in both groups by day 84, and no difference from placebo was reported at that point. The collagen group improved sooner: at day 28 elasticity had risen 18.9 percent with collagen (p = 0.001) and 11.8 percent with placebo (p = 0.063), and nails were less yellow than with placebo. Hair was not measured in people.
Jump recovery after strenuous exercise in active men
In 24 recreationally active men, 20 g a day of bovine Peptan for 7 days before and 2 days after 150 drop jumps did not significantly reduce muscle soreness (p = 0.071). Jump height recovered better at 48 hours (p = 0.050). Strength, inflammation and bone turnover markers did not differ from placebo.
Sleep measures in active men with sleep complaints
In a crossover study of 13 active men with sleep complaints, 15 g of collagen peptides 1 hour before bed for 7 nights did not change the main outcomes, time to fall asleep and sleep efficiency. Awakenings on the sleep recording were fewer than with placebo (21.3 versus 29.3, p = 0.028), a secondary result.
Energy intake at a meal after exercise in active women
In a crossover study of 15 active women, 15 g a day of collagen peptides for 7 days lowered intake at a test meal after cycling by about 10 percent (about 41 kcal) compared with a taste-matched placebo that had no protein or calories. Hunger ratings and digestive symptoms did not differ; GLP-1 and insulin were higher.
Mechanism of action
Hydroxyproline peptides reach the blood
In 6 healthy adults given single 10 g doses of fish, porcine and bovine Peptan in random order, free and peptide-bound hydroxyproline rose in the blood after every product, with no significant difference in free hydroxyproline between sources or average molecular weights (2,000 or 5,000 Da), although total hydroxyproline was higher after porcine than fish and after the 2,000 than the 5,000 Da bovine product. Separate analysis found that Pro-Hyp and Hyp-Gly carried much of the hydroxyproline after intake.
Matrix production in lab-grown skin samples
In human skin samples kept alive in the lab for 9 days, fish Peptan F added to the culture raised glycosaminoglycans in the lower epidermis (up to 18-fold) and collagen in the upper dermis (up to 9 percent). This is lab work that offers a possible explanation for the skin results, not a measurement in people.
Bone cell activity in lab and mouse work
Blood serum collected from people after they took collagen hydrolysate changed the behavior of bone-building and bone-resorbing cells in culture, unlike control proteins. In a mouse model of bone loss after menopause, collagen hydrolysate reduced bone loss compared with a control protein. No human bone trial of Peptan was found.
Clinical trials
One paper reporting two placebo-controlled, double-blind, single-center trials of 10 g a day of Peptan supplied by Rousselot: a pilot with minimized allocation (Japan, 8 weeks, dextrin placebo) and a randomized trial (France, 12 weeks, maltodextrin placebo); one author was a Rousselot employee; no registry number was reported (Asserin et al. 2015, J Cosmet Dermatol)
Pilot: 33 Japanese women aged 40 to 59 with low skin water content, 11 per group (Peptan F, Peptan P, placebo). Main trial: 106 Caucasian women aged 40 to 65 (54 Peptan F, 52 placebo); 99 analyzed for dermal measures.
Pilot: Peptan P raised corneometer skin moisture 28 percent at 8 weeks (p = 0.003 versus placebo) and Peptan F 12 percent; water loss through the skin did not differ. Main trial: dermal collagen density on ultrasound rose 8.83 percent with Peptan F versus no change on placebo (p = 0.007), and collagen fragmentation on confocal imaging fell 31.2 percent from baseline with no change on placebo. No adverse events were reported.
Randomized, double-blind, placebo-controlled parallel trial of 5 g a day of porcine Peptan P or maltodextrin for 84 days, with the same face cream for all participants; Rousselot provided funding and products, and four of the five authors were Rousselot employees; ethics approval E19098, no trial registry number reported (Vleminckx et al. 2024, J Cosmet Dermatol)
85 healthy Chinese women aged 43 to 65 with dry skin and crow's feet wrinkles (42 collagen, 43 placebo); no dropouts.
At day 84, dermal density on ultrasound was 6.3 percent higher and clinician-scored skin moisture 8.4 percent higher than placebo (p = 0.023 for moisture). At day 28, elasticity had risen 18.9 percent with collagen (p = 0.001) and 11.8 percent with placebo (p = 0.063); both groups improved by day 84. Wrinkle depth fell in both groups by day 84 without a reported difference between groups. Nails were less yellow than with placebo at day 28.
Randomized, double-blind, placebo-controlled parallel trial of 10 g of bovine Peptan twice a day or maltodextrin for 7 days before and 2 days after 150 drop jumps; funded by Rousselot, which supplied both products, and two authors were Rousselot employees (Clifford et al. 2019, Amino Acids)
24 recreationally active men.
Muscle soreness, a main outcome, did not differ significantly from placebo (p = 0.071), although it was lower at 48 hours. Countermovement jump height recovered better at 48 hours (p = 0.050). Maximal strength, pressure pain threshold, mood, inflammation markers and the bone turnover markers CTX and P1NP did not differ from placebo.
Randomized crossover trial with a rest condition and two exercise conditions: 10 g a day of bovine collagen peptides supplied by Rousselot or placebo for 7 days and 45 minutes before a 70-minute run; funded by Rousselot, two authors were Rousselot employees; registered retrospectively on the Open Science Framework (Taylor et al. 2023, Eur J Nutr)
20 volunteers, 16 of them men, with a high aerobic fitness level.
The main outcome, the gut injury marker I-FABP, did not differ between collagen and placebo, nor did gut permeability, inflammatory markers or digestive symptoms. Endotoxin rose 2 hours after exercise with placebo compared with the rest condition, but collagen and placebo did not differ significantly; this was not the main outcome.
Randomized crossover trial of 15 g of bovine collagen peptides supplied by Rousselot or a placebo 1 hour before bed for 7 nights; funded by Rousselot, two authors were Rousselot employees; preregistered on the Open Science Framework (Thomas et al. 2024, Eur J Nutr)
13 physically active men aged about 24 with self-reported sleep complaints.
The two main outcomes, time to fall asleep and sleep efficiency on polysomnography, did not change. As secondary results, awakenings were fewer than with placebo (21.3 versus 29.3, p = 0.028), diary awakenings were fewer, and accuracy on one cognitive test was higher the next morning. Core temperature, hormones, inflammation and sleepiness did not differ.
Randomized, double-blind crossover trial of 15 g a day of bovine collagen peptides from Rousselot or a taste-matched placebo without calories for 7 days, with a test meal after 45 minutes of cycling on day 7; supported by Rousselot, two authors were Rousselot employees; preregistered on the Open Science Framework (Reynolds et al. 2025, Br J Nutr)
15 healthy active women aged about 23.
Energy intake at the test meal, the main outcome, was about 10 percent (about 41 kcal) lower after collagen (p = 0.037). Hunger and fullness ratings and digestive symptoms did not differ. GLP-1 and insulin were higher after collagen. The placebo supplied no protein or calories, so the comparison was not matched for energy.
Randomized, double-blind crossover study of single 10 g doses of four Peptan products (fish, porcine and bovine at about 2,000 Da, and bovine at about 5,000 Da); funded by Rousselot, five authors were Rousselot employees; registered as NCT04097808 (Virgilio et al. 2024, Front Nutr)
6 healthy non-smoking adults, 3 women and 3 men, average age 25.
Free and peptide-bound hydroxyproline and selected collagen peptides rose in the blood after every product, with comparable uptake of free hydroxyproline across sources and molecular weights. No adverse events were reported. The study measured absorption only, not any health outcome.
Prospective, open-label, single-arm app-based study of 20 g a day of Peptan in two doses for 8 weeks, with no placebo group; the corresponding author was a Rousselot employee and the first author received consulting fees from Rousselot; registered as NCT04245254 (Abrahams et al. 2022, JMIR Form Res)
40 US women with a BMI above 25 recruited; 14 completed the full course.
Of the 14 completers, 13 reported fewer digestive symptoms, including bloating. With no comparison group and 65 percent not completing, the study mainly showed that a fully digital design was feasible.