Collagen peptides: what the trials show, and who paid for them

What exactly do collagen peptides do?

Collagen is the most abundant protein in the human body⁶ and a key structural protein of the skin⁵. How the supplement is made, and from which animals, is covered in our guide to what peptides are.

Researchers divide collagen products into undenatured collagen, gelatin and collagen hydrolysate⁷. Collagen peptide supplements are the hydrolysate, which is a group of peptides¹. Undenatured type II collagen, sold as UC-II, is a different supplement made from chicken breastbone cartilage⁸.

After a dose, amino acids and short collagen fragments appear in the blood⁹¹⁰. In a 1-week trial in 25 young men, 15 g twice a day raised blood glycine, proline and hydroxyproline more than placebo⁹. Which fragments reach the blood, and how much, depends on the gelatin source¹⁰. In a crossover study, 5 healthy men each took gelatin hydrolysate from fish scale, fish skin and pig skin in turn¹⁰. Total blood levels over 24 hours were higher after the fish-scale product than the pig-skin one¹⁰. That study came from a company lab at Meiji Seika Kaisha¹⁰.

Food supplies collagen too: the meat in one serving of most Japanese dishes held 0.2 to 2.5 g¹¹. Beef tendon, eel with skin and skinned shark tail held 7.6 to 13.3 g¹¹. After cooked shark meat, total blood levels of most collagen fragments were about 30% of those after hydrolysate with the same collagen content¹¹.

Much of the case for how the peptides might work comes from animal studies and skin samples kept alive in the lab¹²¹³. In mice, 95% of a radioactively labeled gelatin hydrolysate was absorbed within the first 12 hours¹². Their cartilage held more than twice as much radioactivity as in mice given labeled proline, an amino acid¹². In human skin samples, collagen peptides raised collagen and glycosaminoglycan production¹³. Hyaluronic acid is a glycosaminoglycan with a unique capacity to hold water³. That skin paper’s affiliations include Rousselot, which makes the collagen peptide brand Peptan¹³¹⁴.

Two trials looked for changes inside human tissue¹⁵¹⁶. A 2014 trial in 114 women took skin samples from a subgroup¹⁵. After 8 weeks, they held 65% more procollagen type I and 18% more elastin than with placebo¹⁵. In a pilot trial of 30 people with mild knee osteoarthritis, an MRI measure of cartilage rose in two regions after 24 weeks¹⁶. It fell with placebo, and there were no significant differences in the other four regions or in clinical outcomes¹⁶.

Do collagen supplements really work for skin?

A 2021 meta-analysis, a grouped analysis of 19 trials, concluded that 90 days of hydrolyzed collagen reduces skin aging¹⁷. A 2023 meta-analysis of 26 trials found that trials lasted 2 to 12 weeks, with significant benefits after 8 weeks or more³. Among its limitations, its authors noted that some trials enrolled fewer than 40 people³.

A 2025 meta-analysis of 23 trials, searching studies up to 14 June 2024, split them by who paid². Trials funded by pharmaceutical companies showed significant gains in hydration, elasticity and wrinkles, while the others showed no effect². High-quality trials showed no significant effect in any category, while low-quality trials showed better elasticity².

A 2026 review searched studies up to 1 April 2023 and described 25 trials one by one, without pooling them¹⁸. The trials had 13 to 236 people each¹⁸. Hydration improved in 10 of 15 trials that measured it, elasticity in 10 of 13 and wrinkles in 9 of 10¹⁸. Results for transepidermal water loss, the water that evaporates through the skin, were less consistent¹⁸. The review rated most trials at high risk of bias, meaning their design could skew results¹⁸. Its authors reported no external funding¹⁸.

The four trials below show the size, length and backing of individual studies^15192021. The 2019 trial measured hydration and elasticity with instruments, by methods called corneometry and cutometry²⁰.

• A 2014 trial gave 69 women aged 35 to 55 either 2.5 g or 5.0 g of collagen hydrolysate, or placebo, daily for 8 weeks¹⁹. Elasticity improved in both collagen groups compared with placebo, moisture changes were not significant, and no side effects were noted¹⁹.
• A second 2014 trial gave 114 women aged 45 to 65 a branded peptide, VERISOL, or placebo, at 2.5 g a day¹⁵. Eye wrinkle volume fell compared with placebo, by 20% at 8 weeks¹⁵.
• A 2019 trial gave 72 healthy women aged 35 or older a drinkable product, ELASTEN, or placebo for 12 weeks²⁰. Its ampoules combined 2.5 g of collagen peptides with acerola fruit extract, vitamin C, zinc, biotin and vitamin E²⁰. Hydration, elasticity, roughness and density all improved more than with placebo²⁰. Its maker, Quiris Healthcare, funded the trial, and the paper states the sponsor had no influence on the analysis²⁰.
• A 2024 trial gave 85 East Asian women aged 43 to 65 either 5 g of collagen peptides or placebo²¹. Both groups used the same face cream²¹. By day 84, dermis density and skin moisture had improved more with collagen²¹. Elasticity, wrinkles and nail color improved by day 28 with collagen, but the placebo group showed the same effects by day 84²¹. Its author affiliations include Rousselot²¹.

A 2026 review lists multi-ingredient formulas, short trials and industry funding among the limits of the skin evidence⁵. Our skin goal page covers the other peptides marketed for skin, and our guide to peptides in skincare covers creams and serums.

Do collagen peptides help joint pain and osteoarthritis?

Osteoarthritis is one of the most common diseases of the muscles, bones and joints⁷. A 2024 meta-analysis pooled 35 trials of collagen products with 3,165 patients, searching up to June 2023⁴. It found small-to-moderate benefits for pain and function, with moderate certainty for pain and high certainty for function⁴. Collagen products did not raise the risk of withdrawal or side effects compared with control groups⁴. Its authors wrote that “strong evidence supports the efficacy and safety” of these products for osteoarthritis⁴.

That analysis covered “collagen derivatives”, a term that spans undenatured collagen, gelatin and hydrolysate⁴⁷. A 2025 meta-analysis limited to knee osteoarthritis pooled 11 trials with 870 people and also found better pain and function scores²². A 2012 review of 8 studies rated the evidence moderate to very low⁷. It found too little evidence to recommend routine use and called for “more independent high-quality studies”⁷.

• A 2009 trial gave 250 people with knee osteoarthritis 10 g a day for 6 months²³. It reported a “significant improvement in knee joint comfort” on pain scales²³. People with the most joint deterioration and the least meat protein in their diets benefited most²³.
• A 2012 trial gave 200 people aged 50 or older with joint pain 1,200 mg a day or placebo for 6 months²⁴. At 6 months, 51.6% on collagen had at least 20% less pain in their worst joint, against 36.5% on placebo²⁴. At 3 months, the groups did not differ significantly²⁴.
• Two University of Freiburg trials gave young, active adults with knee pain during sport 5 g a day or placebo for 12 weeks²⁵²⁶. The 2017 trial had 139 athletes, and 180 people aged 18 to 30 completed the 2021 trial²⁵²⁶. Pain during activity fell more than with placebo in both²⁵²⁶. The 2017 paper lists a Collagen Research Institute affiliation, and GELITA partly funded the 2021 trial and supplied its FORTIGEL peptides²⁵²⁶.
• A 2023 trial enrolled 86 adults aged 40 to 65 who exercised more than 4 hours a week and had ongoing joint or muscle pain⁶. They took placebo, 10 g or 20 g a day⁶. Over 6 months, 10 g improved daily activities, but improved pain only in people exercising more than 180 minutes a week⁶. PB Leiner, part of the Tessenderlo Group, funded it and supplied the collagen⁶.
• A 2020 trial gave 167 healthy, active people with self-reported knee pain 10 g a day or placebo for 12 weeks²⁷. Pain fell by a similar amount in both groups²⁷.

UC-II has its own evidence⁸. In a trial that randomized 191 people with knee osteoarthritis, 40 mg a day for 180 days lowered the WOMAC score more than placebo⁸. WOMAC is a standard measure of knee pain, stiffness and function, and UC-II also beat glucosamine with chondroitin on it⁸. Its sponsor, InterHealth Nutraceuticals, employed authors who helped design the study, and an Indian drug company ran it independently⁸.

Can collagen peptides improve bone density after menopause?

A 2018 German trial enrolled 131 postmenopausal women with low bone density²⁸. They took 5 g a day of FORTIBONE, a GELITA collagen peptide product, or placebo for 12 months, and 102 finished²⁸. Bone density at the spine and the femoral neck, the top of the thighbone, rose compared with placebo²⁸. Bone density scores, called T-scores, changed by +0.1 at the spine and +0.09 at the femoral neck, against −0.03 and −0.01 with placebo²⁸. GELITA financially supported part of the study²⁸.

A later report followed some of these women in an open-label way, meaning everyone knew they were taking the peptides²⁹. In it, 31 women completed a total of 4 years, and their spine density rose²⁹. It recorded fractures but had no comparison group²⁹. GELITA is its listed funder and supplied the FORTIBONE peptides²⁹.

One trial’s registry entry defines osteopenia, or low bone density, as a T-score between −1 and −2.5³⁰. That Greek trial, in 51 women with osteopenia, compared calcium and vitamin D with or without 5 g of collagen peptides³¹. Its registry entry lists no masking, meaning no one was blinded to who took what³⁰. It was first submitted to the registry on 25 June 2019, after its listed completion date of 20 November 2018³⁰.

After 3 months, the collagen group’s P1NP, a bone-formation marker, fell 13.1%³¹. CTX, a bone-breakdown marker, dropped 11.4%, but that change was not statistically significant³¹. In the German trial P1NP rose instead, yet both teams read their marker results as good for bone²⁸³¹. A 12-month report from the same Athens hospital, also in 51 women, found higher spine density with collagen³². Vivapharm SA supported the 3-month study and supplied its Colabone sachets, which contained FORTIBONE³¹.

A 2025 meta-analysis found higher bone density with collagen, but results varied widely between trials (I² = 80.1%)³³. Chinese national and provincial science foundations, a city program and a hospital program funded it³³. We found no randomized trial testing whether collagen peptides prevent fractures, in a PubMed search on 8 October 2026³⁴. By contrast, the prescription peptide Forteo cut new spine fractures from 14.3% to 5.0% in 1,637 postmenopausal women with osteoporosis³⁵. That trial ran for a median of 19 months³⁵. Forteo and other approved options are covered in peptides for women.

Does collagen build muscle, and is it a complete protein?

Collagen is not a complete protein: it is missing at least one indispensable amino acid, so it scores zero on the standard protein-quality score³⁶. In all six collagen peptide samples tested, tryptophan was the indispensable amino acid in shortest supply³⁶. A 2019 analysis found collagen peptides could supply up to 36% of protein in a standard American diet while still meeting indispensable amino acid needs³⁶. The trials it cited gave 2.5 to 15 g a day, for 3 to 18 months³⁶. Its author affiliations include the Collagen Research Institute and GELITA, and it reported no external funding³⁶. One author also provides research services for the company Designs For Health³⁶.

With strength training, several trials found more fat-free mass, meaning everything except body fat, with collagen than with placebo³⁷³⁸³⁹.

• A 2015 trial gave 53 older men with sarcopenia, or age-related muscle loss, 15 g a day or placebo during 12 weeks of training³⁷. Fat-free mass rose 4.2 kg with collagen and 2.9 kg with placebo³⁷. Gelita AG paid part of the costs³⁷.
• In a 2019 trial, 77 premenopausal women gained more fat-free mass and grip strength with 15 g a day during 12 weeks of training³⁸. The paper says GELITA partly funded it, but its funding note says it received no external funding³⁸.
• In a 2019 trial in 57 young men, 15 g a day during 12 weeks of training raised fat-free mass more than placebo³⁹. Type II muscle fibers grew no more than with placebo³⁹. The Collagen Research Institute funded it, and funders were allowed “to make suggestions in phrasing”³⁹.
• A 2023 trial gave young men 15 g a day or placebo during 15 weeks of training, with 19 on collagen and 20 on placebo⁴⁰. Strength gains did not differ, but quadriceps volume grew more with collagen: 15.2%, against 10.3% with placebo⁴⁰. The Collagen Research Institute funded it⁴⁰.

Against other proteins, collagen falls short on muscle protein synthesis, the rate at which the body builds muscle protein⁴¹⁴². In 22 older women, 30 g of whey twice a day for 6 days raised longer-term synthesis, while the same amount of collagen did not⁴¹. The Canadian Institutes of Health Research funded that trial⁴¹.

A 2024 trial gave 31 men aged 65 to 80 an extra 25 g of whey, pea or collagen protein twice a day⁴². Over days 8 to 15, when the extra protein was given, synthesis rose with whey and pea but not collagen⁴². Roquette Frères, which made the pea protein, funded that trial through a research contract⁴². In a 1-year trial in 208 adults over 65, daily collagen or whey changed no measured outcome compared with a carbohydrate supplement⁴³. Its author affiliations include Arla Foods Ingredients⁴³.

Collagen has been suggested as the preferred protein source for building the connective tissue inside muscle⁹. But 15 g twice a day for 1 week did not raise that building rate in 25 young men⁹. A single 30 g dose did not raise it either, in a 2025 trial of 45 young adults⁴⁴. A public-private partnership between Maastricht University and the Tessenderlo Group, which produces collagen, funded that trial⁴⁴.

Does collagen help hair, nails or gut health?

A 2017 nail study was open-label, with no placebo group⁴⁵. In it, 25 people took 2.5 g a day for 24 weeks⁴⁵. Nail growth rose 12% and broken nails fell 42%⁴⁵. Its listed affiliations include the Collagen Research Institute in Kiel, Germany⁴⁵.

Two placebo-controlled trials measured hair⁴⁶⁴⁷.

• A 12-week trial in 2024 tested an Absolute Collagen supplement with 8,000 mg of hydrolyzed marine collagen and 60 mg of vitamin C⁴⁶. The company funded it, and all but one author work there⁴⁶. Of 138 people randomized, hair was examined in only 11 on the daily supplement and 13 in each other group⁴⁶. Hair counts rose 27.6% more than with placebo, but the difference was not statistically significant⁴⁶. Expert-graded hair appearance improved 31.9% with the daily supplement, against 9.4% with daily placebo⁴⁶.
• A 2026 trial gave 114 women aged 20 to 50 either 1,000 mg a day of fish collagen peptides or placebo for 24 weeks⁴⁷. All had thigh cellulite and self-reported thinning hair, and hair diameter rose significantly by week 24⁴⁷. The authors declared no competing interests, but their affiliations include the Korean companies UKON Solutions and NEWTREE⁴⁷.

A 2026 review linked collagen with thicker, stronger hair and modestly faster nail growth⁵. It said “independently funded trials” are still required⁵. A 2022 review compared Instagram, YouTube and company claims with the research⁴⁸. It found that dermatologic claims in the media “surpass any evidence currently supported by the literature”⁴⁸.

We found no placebo-controlled trial of collagen peptides as a treatment for bloating or other digestive complaints, in a PubMed search on 8 October 2026⁴⁹. In a 2025 crossover trial, 15 healthy, active women took 15 g a day of collagen peptides or a taste-matched placebo for 7 days⁵⁰. Gut symptoms did not differ between collagen and placebo⁵⁰. Rousselot supported that trial, made the peptides tested and employs some of its authors⁵⁰.

A 2022 gut study funded by Rousselot, which makes the Peptan peptides it tested, had no placebo group¹⁴. It recruited 40 women, and 14 finished 8 weeks of 20 g a day¹⁴. Of those 14, 13 reported fewer digestive symptoms, including bloating¹⁴.

Is there a downside to taking collagen peptides?

Trials report few problems⁴⁷¹⁸. A 2012 review found mild to moderate digestive complaints were the most reported side effects⁷. A 2026 review called collagen supplements “generally well-tolerated”¹⁸. Another 2026 review lists short study durations among the evidence’s limits⁵.

Collagen supplements are made from cattle, pigs or fish¹. Under US food law, fish, crustacean shellfish and milk are major food allergens, and labels must name the food source of a major allergen⁵¹. Alpha-gal syndrome, a meat allergy linked to tick bites, can involve reactions to gelatin and other products from mammals⁵².

As of its 30 September 2026 update, FDA’s openFDA database held 28 recall records for products described as collagen⁵³. openFDA warns users to assume all its results are unvalidated⁵³. The records include undeclared fish, shellfish or milk, whey protein sold as collagen in 2018, and Listeria in collagen bars in 2017⁵³.

• In 2023, 59,701 canisters of collagen peptides were recalled because pieces of a broken blue lid might be inside⁵³.
• In 2024, 25,500 kg of bovine collagen powder made in China was recalled for possible Salmonella⁵³.
• In 2025, a collagen product was recalled after testing by NSF found less manganese than its label stated⁵³.

On 10 February 2026, FDA sent a warning letter to Hearthy Foods, a Los Angeles firm that makes collagen supplements⁵⁴. The letter said the firm had no product specifications for its collagen products and performed no quality control operations⁵⁴. FDA also observed what appeared to be rodent droppings in storage areas⁵⁴. The labels also failed to identify the products as dietary supplements⁵⁴.

FDA does not approve dietary supplements before they are marketed and does not test them before they are sold⁵⁵. A firm making a structure/function claim, about effects on the body’s structure or function, must have substantiation that it is truthful⁵⁵. FDA does not pre-approve these claims, but the firm must notify FDA no later than 30 days after marketing⁵⁶. The label must also say that FDA has not evaluated the claim⁵⁶.

No law limits how much of an ingredient a serving may contain; the manufacturer decides⁵⁵. FDA is generally responsible for safety, quality and labeling, and the Federal Trade Commission for advertising⁵⁵.

Who pays for collagen research?

A 2026 review lists industry funding among the limits of the collagen evidence⁵. These companies and institutes funded, sponsored or supplied trials on this page, or employed their authors^{681420283139424657}.

• GELITA: paid part of the 2015 muscle and 2018 bone trials, partly funded the 2021 knee trial and funded the bone follow-up^26282937.
• Collagen Research Institute: funded the 2019 and 2023 muscle trials³⁹⁴⁰.
• Rousselot, maker of Peptan: funded the 2022 gut study and supported the 2025 appetite trial¹⁴⁵⁰. It is also an affiliation on the 2015 and 2024 skin papers¹³²¹.
• PB Leiner, part of the Tessenderlo Group: funded the 2023 joint trial, and Tessenderlo co-funded the 2025 muscle study⁶⁴⁴.
• Quiris Healthcare: funded the 2019 trial of its own skin product²⁰.
• Vivapharm SA: supported the 3-month Greek bone study and supplied its sachets³¹.
• Absolute Collagen: funded the 2024 trial of its supplement⁴⁶.
• InterHealth Nutraceuticals: sponsored the 2016 UC-II trial⁸.
• Viscofan: funds the research center that ran a 2024 weight trial and employs some of its authors⁵⁷. The paper names the Center for Industrial Technological Development (CDTI) as funder⁵⁷.
• Roquette Frères, a pea protein maker: funded the 2024 trial comparing whey, pea and collagen⁴².

Several of these papers state that the funders had no role in the study design or analysis¹⁴²⁶⁴². In the 2019 trial in young men, funders could “make suggestions in phrasing”, but the authors made the final decision³⁹. Company money has also produced null results, such as the 2025 muscle study co-funded by Tessenderlo⁴⁴. A 2019 skate collagen trial reported no external funding, but its author affiliations include Yeong San Skate⁵⁸. Studies here without company funding include the Canadian whey trial, the 2025 bone meta-analysis and a 2019 whey-versus-collagen trial in women³³⁴¹⁵⁹.

The evidence at a glance

A tier grades the best human evidence for any use, not whether a compound is safe. Whether each one works for the use people take it for, and its legal status: the evidence table. How we grade: our method.

Questions people ask

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• Are peptides legal? The legal tracker
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• The 2026 gray-market briefing

Sources

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55. 55Questions and Answers on Dietary Supplements U.S. Food and Drug Administration, 27 Aug 2026. fda.gov
56. 56Structure/Function Claims U.S. Food and Drug Administration, 28 Mar 2024. fda.gov
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