Collagen supplements: the skin benefit fades when the sponsor leaves

Almost everything known about collagen comes from hydrolyzed collagen powders and peptides taken as supplements, and very little from food. A meta-analysis of 23 randomized trials in 1474 people found better skin hydration, elasticity and wrinkles when all trials were pooled. Split by who paid, the trials without pharmaceutical company funding showed no effect on any of the three, and the high-quality trials showed no significant effect either, while the abstract gives no effect sizes. A smaller meta-analysis of 10 trials in 646 people, mostly women, did report numbers, hydration SMD 1.25 (95% CI 0.77 to 1.74) and elasticity SMD 0.61 (0.21 to 1.02). Its typical dose was 4 g a day, its risk of bias was unclear, and publication bias was not assessed. For knee osteoarthritis, 11 trials in 870 people found pain scores fell by 13.63 points (95% CI -20.67 to -6.58) and function improved by 6.46 points, with very high variation between trials that used different forms of collagen. On a plate, collagen mostly arrives as gelatin, and a cup of gelatin dessert from the US survey holds 2.9 g of protein because the dessert is diluted with water and sugar.

Every statement here is tied to a source. The badge says what kind of evidence stands behind it: A is a meta-analysis or systematic review, E is the position of an expert body without its own analysis. How we verify →

We have no USDA entry for collagen itself in this cohort. The evidence below stands on published studies rather than on a composition table, and we would rather say that than show you a number for something else.

How much is actually in it

A cup of prepared gelatin dessert supplies only about 2.9 g of protein, so jello is a minor source of collagen protein. — US survey recipe, FNDDS Evidence C source
Protein 1.22 g per 3.5 oz (100 g); 1 cup 240 g = 2.9 g; snack cup 95 g = 1.2 g

What a real portion looks like

Across 10 RCTs with 646 people, collagen at a median 3.5 g a day raised skin hydration (SMD 1.25) and elasticity (SMD 0.61). — 10 RCTs, 646 participants, mostly women, studies 2010 to 2021 (n = 646) Evidence A source
Hydration SMD 1.25 (95% CI 0.77 to 1.74); elasticity SMD 0.61 (0.21 to 1.02); most common dose 4 g/day, median 3.5 g/day

What your body absorbs

NIH notes that the body needs vitamin C to make collagen, whatever the source of the protein building blocks. — general population, NIH ODS fact sheet Evidence E source
Vitamin C required for collagen biosynthesis

What cooking and storage change

After a single dose of bovine collagen hydrolysate in water, its signature amino acids peaked in blood within 60 to 120 minutes, and dissolving it in coffee did not change uptake of its key peptides. — healthy volunteers, single fasting dose in water or coffee, 360 min sampling Evidence B source
Free Hyp, Gly, Pro peak at 60-120 min; Pro-Hyp, Hyp-Gly, Gly-Pro-Hyp iAUC, Cmax and Tmax similar in water and coffee

What it does to your health

Pooling 19 double-blind RCTs with 1125 mostly female adults, about 90 days of hydrolyzed collagen improved skin hydration, elasticity and wrinkles against placebo. — 19 RCTs, 1125 participants aged 20 to 70, 95% women (n = 1125) Evidence A source
Favorable vs placebo for hydration, elasticity and wrinkles; effect sizes not in the abstract
In 19 trials with 768 training adults, collagen peptides for 8 weeks or more added a small gain in fat-free mass (SMD 0.48) and maximal strength (SMD 0.19). — healthy adults over 17 with exercise, 19 studies, mostly 8 weeks or more (n = 768) Evidence A source
Fat-free mass SMD 0.48; tendon morphology SMD 0.67; maximal strength SMD 0.19; GRADE moderate for body composition, low to very low for the rest
Across 12 placebo-controlled RCTs, collagen peptides cut fat mass by 2.6 lb (1.2 kg), LDL by 4.1 mg/dL and systolic pressure by 5 mmHg, the last two with very high variation between trials. — 12 randomized placebo-controlled trials to November 2021 Evidence A source
Fat mass -2.7 lb (95% CI -4.7 to -0.64; metric: -1.21 kg, -2.13 to -0.29); LDL -4.09 mg/dl (-8.13 to -0.04, I2 93.4%); SBP -5.04 mmHg (-9.22 to -0.85, I2 98.9%)
In 22 fit young men on 45 g protein a day for 3 weeks, swapping 20 g of whey for collagen peptides did not change muscle damage or recovery. — young fit males, 3-week eccentric training, whey 45 g vs whey 25 g plus collagen 20 g (n = 22) Evidence B source
No between-group difference in any outcome
A 2025 review and meta-analysis of 40 RCTs of supplements for sun-aged skin found collagen raised skin elasticity against placebo over trials of up to 24 weeks. — adults in randomized trials of oral supplements for skin photoaging (n = 40 trials) Evidence A source
Collagen improved skin elasticity (R2) or MED vs placebo; hyaluronic acid, lycopene and carotenoids did not
In an RCT of 114 women aged 20 to 50 with thigh cellulite and self-reported hair thinning, 1 g a day of fish collagen peptide for 24 weeks increased hair diameter against placebo. — women aged 20 to 50 with thigh cellulite and self-reported hair thinning; low-molecular-weight fish collagen peptide 1000 mg/day or placebo (n = 114) Evidence B source
Hair diameter increased significantly at week 24 vs placebo; size of change not in the abstract
In an open-label trial of 25 people with brittle nails, 2.5 g a day of collagen peptides for 24 weeks raised nail growth by 12% and cut broken nails by 42%. — participants with brittle nail syndrome, 2.5 g/day bioactive collagen peptides (n = 25) Evidence C source
Nail growth rate +12%; frequency of broken nails -42%; 64% global clinical improvement
A meta-analysis of 12 placebo-controlled RCTs found collagen peptides lowered fat mass by about 2.6 lb (1.2 kg) and raised fat-free mass by 1.5 percentage points. — adults in randomized placebo-controlled trials of collagen peptide supplementation (n = 12 trials) Evidence A source
Fat mass -2.7 lb (95% CI -4.7 to -0.64; I2 0%; metric: -1.21 kg, -2.13 to -0.29); fat-free mass +1.49% of body mass (95% CI 0.57 to 2.42)
In a crossover RCT of 15 active women, 15 g a day of collagen peptides cut food eaten at a meal after exercise by about 10%, or 41 calories, without changing hunger ratings. — healthy active females aged about 23, 15 g/day collagen peptides or taste-matched non-energy control for 7 days (n = 15) Evidence B source
Ad libitum energy intake about 10% (41 calories) lower; GLP-1 higher; subjective appetite unchanged
In a crossover RCT of 10 young women, a 40 g dose of collagen did not change hunger or food intake two hours later compared with whey protein. — healthy adult women, mean age 22.4, single 40 g dose of hydrolyzed collagen or whey protein (n = 10) Evidence B source
No difference in hunger (p = 0.983), desire to eat (p = 0.326), fullness (p = 0.567) or food intake (p = 0.168)
In a single-blind randomized crossover study of 24 adults, a breakfast of gelatin with added tryptophan cut energy eaten at lunch by about 20% compared with casein, soy or whey-GMP breakfasts. — healthy adults, mean BMI 24.8, mean age 25; custard breakfasts with different protein sources, including gelatin with added tryptophan (+TRP) (n = 24) Evidence B source
Lunch energy intake 2.5 vs 3.2 MJ (about 20% lower); appetite ratings about 40% different at 180 min
A 2024 Cochrane review found oral collagen supplements probably shrink pressure ulcers by 1.81 cm2 more than placebo, based on one trial of 74 people. — people with existing pressure ulcers, collagen supplement vs placebo (n = 74) Evidence A source
Mean change in ulcer area MD 1.81 cm2 smaller (95% CI 3.36 to 0.26 smaller); 1 study; moderate-certainty evidence
A 2022 meta-analysis of 11 randomized trials in 961 people with chronic wounds found collagen dressings raised complete healing to 53% versus 35% with standard care. — patients with chronic wounds (mostly diabetic foot and venous ulcers), collagen dressing plus standard care vs standard care (n = 961) Evidence A source
Complete healing 259/485 (53.4%) vs 164/476 (34.5%); RR 1.53 (95% CI 1.33 to 1.77); I2 28.2%

Safety, limits and interactions

A systematic review of 11 placebo-controlled RCTs with 805 people found collagen at 2.5 to 10 g a day for 8 to 24 weeks safe, with no adverse events reported. — randomized placebo-controlled trials of oral collagen in dermatology (n = 805) Evidence A source
No reported adverse events; skin elasticity, hydration and dermal collagen density improved
In 10 healthy adults, 30 g a day of gelatin raised urinary oxalate by 43% compared with whey protein, a concern for people prone to kidney stones. — healthy subjects with no history of nephrolithiasis, two 5-day controlled diets with 30 g gelatin or whey, washout of at least 1 week (n = 10) Evidence C source
Urinary oxalate +43%, glycolate 5.3-fold vs whey; changes seen at 5 and 10 g loads, not at 1 and 2 g
A case report describes anaphylaxis in a 20-year-old woman after a gelatin capsule, a reminder that gelatin allergy is rare but can be severe. — one 20-year-old woman with gelatin-specific IgE (n = 1) Evidence D source
Anaphylaxis within 5 minutes of a gelatin-containing capsule; no reactions after avoiding gelatin
In an RCT of 56 adults with overweight or obesity, 10 g a day of porcine collagen for 4 weeks did not change body measures and slightly raised fasting insulin and HOMA-IR. — men and women with overweight or obesity, 10 g/day porcine collagen hydrolysate or erythritol placebo for 4 weeks (n = 56) Evidence B source
Anthropometrics unchanged; fasting insulin (p = 0.005), HOMA-IR (p = 0.008) and post-meal glucose AUC rose; authors call changes small
In 10 healthy adults, 30 g a day of gelatin raised urinary oxalate by 43% compared with whey protein, a concern for people prone to kidney stones. — healthy subjects with no history of nephrolithiasis, two 5-day controlled diets with 30 g gelatin or whey (n = 10) Evidence C source
Urinary oxalate +43%, glycolate 5.3-fold vs whey
In the same meta-analysis, adverse events with collagen dressings were not more common than with standard care, across 7 trials and 556 cases. — patients with chronic wounds in 7 trials reporting adverse events (n = 556) Evidence A source
Adverse events RR 0.67 (95% CI 0.44 to 1.01)
A 2019 systematic review of 11 randomized placebo-controlled trials with 805 people found oral collagen generally safe, with no reported adverse events. — adults in RCTs of collagen hydrolysate 2.5 to 10 g a day for 8 to 24 weeks (pressure ulcers, xerosis, skin aging, cellulite) or collagen tripeptide (n = 805) Evidence A source
No adverse events reported; benefit results called preliminary; no pooled estimate
A 2026 systematic review of 25 randomized trials of hydrolyzed collagen found it was generally well tolerated with few adverse events, though most trials had a high risk of bias. — adults in RCTs of oral hydrolyzed collagen, 13 to 236 participants per trial (n = 25 RCTs) Evidence A source
Low incidence of adverse events; majority of trials high risk of bias
In 10 healthy adults, 30 g a day of gelatin raised urinary oxalate by 43% compared with whey protein, a concern for people prone to kidney stones. — healthy subjects with no history of nephrolithiasis, two 5-day controlled diets with 30 g gelatin or whey, washout of at least 1 week (n = 10) Evidence C source
Urinary oxalate +43%, glycolate 5.3-fold vs whey
A case report describes anaphylaxis in a 20-year-old woman after a gelatin capsule, a reminder that gelatin allergy is rare but can be severe. — one 20-year-old woman with gelatin-specific IgE (n = 1) Evidence D source
Anaphylaxis within 5 minutes of a gelatin-containing capsule
EU law lists fish and products made from it as an allergen that must be declared, with exemptions only for fish gelatine used as a carrier for vitamin or carotenoid preparations and for fining beer and wine. — foods sold in the EU Evidence E source
Fish and products thereof are a mandatory labeled allergen; only fish gelatine as a carrier for vitamin or carotenoid preparations and fish gelatine or isinglass as a fining agent in beer and wine are exempt
FDA lists fish among the nine major food allergens in the United States, and labels must name the species of fish. — US consumers with food allergy Evidence E source
Fish is one of the nine major food allergens; labels must name the species of fish
In a double-blind placebo-controlled challenge, none of 30 fish-allergic people aged 9 to 50 reacted to a cumulative 3.61 g of fish gelatin, and two reported mild subjective symptoms during the full challenge of up to 14.61 g. — fish-allergic patients aged 9 to 50 years diagnosed by EAACI guidelines (n = 30) Evidence B source
No adverse reaction to a cumulative 3.61 g of fish gelatin; 2 of 30 mild subjective reactions to active challenge (up to 14.61 g); skin prick test positive to fish gelatin in 3 of 30
Among 1,335 adults tested for suspected allergy, 30 of 40 people allergic to red meat were sensitized to gelatin and 12 were clinically allergic to it, and the alpha-gal sugar behind red meat allergy was found in bovine gelatin. — adults evaluated 1997-2011 for suspected allergy or anaphylaxis to medication, insect venom or food (n = 1335) Evidence C source
Positive gelatin test in 40 of 1335; in 30 of 40 with red meat allergy, 12 of them clinically allergic to gelatin; alpha-gal about 0.44 to 0.52 microgram/g in bovine gelatin

What people believe that the data does not support

A meta-analysis of 23 RCTs with 1474 people found collagen improved skin only in industry-funded and low-quality trials, with no effect in independent or high-quality ones. — 23 RCTs, 1474 participants, searched to June 2024 (n = 1474) Evidence A source
Pooled: better hydration, elasticity, wrinkles; non-industry-funded and high-quality subgroups: no significant effect
The EU did not authorize the claim that collagen contributes to healthy joint function. — EU health claims register Evidence E source
Status non-authorized
The EU did not authorize the claim that collagen helps skin keep its firmness and elasticity. — EU health claims register Evidence E source
Status non-authorized
The EU did not authorize claims that collagen hydrolysate rebuilds joint cartilage or improves joint mobility. — EU health claims register Evidence E source
Status non-authorized
A meta-analysis of 23 RCTs with 1,474 people found collagen improved skin overall, but showed no effect in high-quality trials or trials without industry funding. — adults in randomized trials of oral collagen for skin aging (n = 1,474) Evidence A source
Pooled: hydration, elasticity and wrinkles improved; independent and high-quality trials: no significant effect
The EU did not authorize the claim that a branded collagen peptide mixture maintains skin health by raising elasticity and reducing wrinkles. — foods and supplements sold in the EU Evidence E source
Claim status: non-authorized
The EU did not authorize the claim that a branded collagen peptide mixture maintains skin health by raising elasticity and reducing wrinkles. — foods and supplements sold in the EU Evidence E source
Claim status: non-authorized

Who this works differently for

In 11 RCTs with 870 people with knee osteoarthritis, oral collagen lowered pain scores by 13.6 points and improved function by 6.5 points against placebo. — 870 participants with knee osteoarthritis, 11 RCTs (n = 870) Evidence A source
Pain MD -13.63 (95% CI -20.67 to -6.58); function MD -6.46 (-9.52 to -3.40); I2 75-88%
An earlier meta-analysis of placebo-controlled trials in osteoarthritis found collagen lowered the total WOMAC score by 8 points, but not its pain subscore. — randomized placebo-controlled trials in osteoarthritis Evidence A source
WOMAC total WMD -8.00 (95% CI -13.04 to -2.95); pain subscore WMD -0.22 (-1.58 to 1.13); VAS WMD -16.57 (-26.24 to -6.89)
In 22 older women taking 30 g twice daily for 6 days, whey raised muscle protein synthesis while collagen protein did not lift longer-term synthesis above baseline. — 22 healthy older women, mean age 69, 30 g whey or collagen twice daily, 6 days (n = 22) Evidence B source
Longer-term MPS with exercise: whey +0.173%/d vs collagen +0.020%/d (not above baseline); P < 0.001 between groups
In 39 older adults after hip replacement, 15 g of collagen protein a day for 14 days did not change bone turnover markers against placebo. — 39 older adults aged about 71 after total hip arthroplasty, 15 g/day for 14 days (n = 39) Evidence B source
P1NP and CTX-1 no group differences (P-interaction 0.588 and 0.168); pain at rest fell only with collagen (P-interaction 0.007)
In 36 elite cyclists, 15 g of collagen before short jumping sessions for 18 weeks kept femoral neck bone density stable while it fell in controls. — 36 young elite road cyclists, 18 weeks, open-label (n = 36) Evidence B source
Femoral neck BMD 0.803 to 0.809 g/cm2 with intervention vs 0.789 to 0.774 in control (p < .01); other sites no difference
In 11 professional female footballers, 30 g of collagen with vitamin C before training for 10 weeks raised patellar tendon stiffness by 15.4% vs 4.6% on placebo. — 11 professional female soccer athletes, 10 weeks pre-season, 30 g collagen plus 500 mg vitamin C (n = 11) Evidence B source
Tendon stiffness +15.4% vs +4.6% (P = 0.002); Young's modulus +14.2% vs +3.4% (P = 0.004)
In an assessor-blinded RCT of 83 people with pattern hair loss or chronic shedding, a tablet with 300 mg collagen plus amino acids, iron and selenium added to drug treatment raised the global hair score. — adults with androgenetic alopecia or chronic telogen effluvium on drug treatment, mean age 41; 26 men, 57 women (n = 83) Evidence B source
GAS at 12 weeks 1.67 vs 0.66 (p < 0.001); GAS of 2 or more in 50% vs 23%
In an RCT of 85 East Asian women aged 43 to 65, 5 g a day of collagen peptides for 84 days improved dermis density and skin moisture against placebo. — healthy women aged 43 to 65, standardized face cream in both groups; collagen peptides 5 g or maltodextrin (n = 85) Evidence B source
Dermis density and skin moisture improved vs placebo at day 84; nail color improved earlier
A meta-analysis of 8 RCTs with 418 exercising adults found collagen peptides taken for at least 8 weeks with training added a moderate gain in fat-free mass. — healthy normal to overweight adults over 17 doing regular training, collagen peptides daily for at least 8 weeks (n = 418) Evidence A source
Fat-free mass SMD 0.48 (95% CI 0.22 to 0.74); GRADE moderate certainty for body composition
In an open-label RCT of 64 adults with overweight or obesity, two collagen bars a day (20 g collagen) for 12 weeks gave 6.6 lb (3.0 kg) weight loss against 3.3 lb (1.5 kg) on diet advice alone. — adults with overweight or obesity; healthy diet advice in both arms, plus two 90 calories bars with bovine collagen 45 min before lunch and dinner in the collagen arm (n = 64) Evidence B source
Weight -6.6 lb (-3.0 kg) vs -3.3 lb (-1.5 kg) (3.36% vs 1.80% of body weight, p = 0.045) at 12 weeks
In a double-blind RCT of 37 women with overweight, 26 g a day of protein as collagen for 8 weeks raised BMI slightly, while whey protein reduced android fat. — women with overweight, mean age 40.6, mean BMI 30.9; 38 g/day hydrolyzed collagen or 40 g/day whey concentrate (n = 37) Evidence B source
BMI +0.2 kg/m2 with collagen (p = 0.044); android fat -0.22 lb (-0.1 kg) with whey vs collagen (p = 0.031)
In a randomized trial of 89 nursing home residents with pressure ulcers, a fortified collagen protein supplement three times a day gave about twice the rate of healing at 8 weeks. — long-term-care residents with stage II to IV pressure ulcers, 23 facilities (n = 89) Evidence B source
Better PUSH scores at 8 weeks (P < .05); about twice the healing rate vs placebo; 71 completed
In a randomized trial of 66 patients with major burns, a drink with 40 g of collagen a day cut the time to complete healing to about 26 days versus 41 days on placebo. — patients with 20 to 45% deep partial or full-thickness burns, 4 weeks (n = 66) Evidence B source
Complete healing 26 ± 7.7 (collagen) and 27.4 ± 9.4 (collagen plus omega-3) vs 41.1 ± 16.6 days placebo; better scar scores
In a pilot randomized trial of 31 men with burns over 20 to 30% of the body, a collagen-based supplement made wound healing 3.7 times more likely at any time point than an isocaloric placebo. — men aged 18 to 60 with 20-30% total body surface area burn, 4 weeks (n = 31) Evidence B source
Hazard ratio of wound healing 3.7 (95% CI 1.434 to 9.519); hospital stay 9.4 vs 13.5 days (P = 0.063)

What is still unknown

A review of 25 RCTs found hydrolyzed collagen well tolerated with few side effects, but most of those trials carried a high risk of bias. — 25 RCTs, 13 to 236 participants each, adults Evidence A source
Low incidence of adverse events; majority of trials at high risk of bias
Collagen peptides reduced body mass in obese rodents across 19 studies, but the authors note the effect in humans remains largely unexplored. — rodents on high-fat or high-calorie diets, 19 studies, at least 3 weeks (n = 338) Evidence D source
Body mass SMD -1.87; very low certainty of evidence
A 2026 meta-analysis of 14 hair supplement studies with 967 people found gains in growing hairs for branded mixtures, none of them plain collagen, and no change in total hair count. — adults with alopecia or hair thinning taking commercial oral supplements (n = 967) Evidence B source
Anagen hair density MD +10.48 (95% CI 8.81 to 12.14); telogen density MD -5.91 (-6.74 to -5.08); total hair count not significant (p = 0.06)
A systematic review of 15 RCTs of collagen with exercise found only some improvements in body composition, with most trials in recreational athletes. — 12 trials in recreational athletes, 2 in older adults, 1 in untrained pre-menopausal women (n = 15 trials) Evidence A source
Certain improvements in body composition; strongest effect on joint pain; no pooled estimate
A meta-analysis of 19 rodent studies found collagen peptides lowered body mass on high-fat diets, but the certainty was very low and human effects remain largely unexplored. — rodents on high-fat or high-calorie diets given collagen peptides for at least 3 weeks (n = 339 animals) Evidence D source
Body mass SMD -1.87; food intake SMD -1.43; very low certainty of evidence
A 2026 systematic review of 18 randomized trials in 1231 people with pressure injuries found nutrition products, including collagen, appeared to help healing, but trials were small and of moderate quality. — people aged 38 to 83 with stage 2 to 4 pressure injuries (n = 1231) Evidence A source
Positive effects on prevention and healing reported; no pooled effect size
A 2025 meta-analysis of 23 skin trials with 1474 people found collagen worked only in industry-funded and low-quality trials, a warning about how collagen evidence is produced. — adults in RCTs of collagen supplements for skin aging (n = 1474) Evidence A source
Overall gains in hydration, elasticity, wrinkles; no effect in non-industry-funded or high-quality trials

The bottom line

Muscle is where collagen looks weakest next to other protein. In 22 healthy women around 69 years old taking 30 g twice a day for 6 days, whey raised muscle protein building by 0.173% a day with exercise. Collagen did not lift it above baseline at all, in a trial that was short and small. In 22 fit young men over 3 weeks of eccentric training, swapping 20 g of a 45 g whey dose for collagen improved neither muscle damage nor performance. Across 19 studies in 768 healthy exercising adults, collagen peptides raised fat-free mass (SMD 0.48) and maximal strength (SMD 0.19), with no intervals in the abstract and certainty rated moderate for body composition and low to very low for the rest. The tendon and bone results are small trials. In 11 professional female footballers over a 10-week pre-season, 30 g of collagen with 500 mg of vitamin C raised patellar tendon stiffness by 15.4% against 4.6% on placebo (P = 0.002). In 36 young elite cyclists over 18 weeks, an open-label program that combined collagen with jumping exercise held femoral neck bone density at 0.809 g/cm² while controls fell to 0.774, and the design cannot separate the collagen from the jumping. In 39 adults around 71 years old after hip replacement, 15 g a day for 14 days did not change bone turnover markers. Across 12 placebo-controlled trials, collagen peptides lowered fat mass by 2.7 lb (95% CI -4.7 to -0.64; metric: 1.21 kg, -2.13 to -0.29). The same pooling found LDL down 4.09 mg/dl and systolic pressure down 5.04 mmHg, both with very high variation between trials (I² 93% and 99%). Rodent studies suggest an anti-obesity effect, and the authors say it remains largely untested in humans. Who should take care. Collagen supplements and gelatin are made from fish, pig or cow tissue, so the source on the label matters. Fish is one of the nine major food allergens in the US, where labels must name the species, and EU law requires fish and fish products to be declared as an allergen. In a double-blind challenge, none of 30 fish-allergic people aged 9 to 50 reacted to a cumulative 3.61 g of fish gelatin, and two had mild subjective symptoms at up to 14.61 g. That is one small study of one product at a dose below the 5 to 10 g a day used in many collagen trials, so it does not show that marine collagen is safe for people with fish allergy. Gelatin itself can cause allergy. A case report describes anaphylaxis within 5 minutes of a gelatin capsule, and among 1,335 adults tested for suspected allergy, 30 of 40 people allergic to red meat were sensitized to gelatin and 12 were clinically allergic to it. In 10 healthy adults, 30 g a day of gelatin raised urinary oxalate by 43% compared with whey, which matters for people prone to kidney stones, although stone risk itself was not measured. A review of 25 randomized trials in adults found hydrolyzed collagen generally well tolerated with few adverse events, but most of those trials were at high risk of bias, there was no pooled analysis, and no trial looked at long-term safety. We have no card on pregnancy, breastfeeding, children or drug interactions for collagen supplements, so this page cannot tell you anything about those groups. Two things are often mixed up. According to the NIH, your body needs vitamin C to make its own collagen, which is a statement about synthesis and says nothing about collagen supplements. And the peptides are absorbed the same way whether the powder goes into water or coffee, judged by a single fasting dose in healthy volunteers. The EU refused three collagen claims, that it maintains skin firmness and elasticity, that it helps joint function, and that collagen hydrolysate rebuilds joint cartilage, and the register gives no reason for the refusals.

Questions about collagen, answered from the trials

Guides that discuss this food

Vitamin C: what it does, how much you need, and what it will not do

Sources

clgn-daily-r4-01 · USDA FNDDS
Gelatin dessert (FDC 2710310): Protein 1.22 G per 100 g; 1 cup 240 g 2.9 G; 1 snack size container 95 g 1.2 G
USDA FNDDS, Gelatin dessert, FDC 2710310 · checked 2026-10-03
clgn-daily-r4-06 · meta-analysis
The findings indicate that collagen supplements were statistically effective in increasing skin hydration (SMD 1.25 (CI: 0.77-1.74)) and elasticity (SMD 0.61 (CI: 0.21-1.02)). The most commonly administered dose was 4 g/day, with a median dose of 3.5 g/ day.
Indian J Dermatol Venereol Leprol, 2025 · checked 2026-10-03
clgn-daily-r4-03 · fact sheet
Vitamin C is required for the biosynthesis of collagen, L-carnitine, and certain neurotransmitters; vitamin C is also involved in protein metabolism [1,2].
NIH Office of Dietary Supplements, Vitamin C Fact Sheet for Health Professionals · checked 2026-10-03
clgn-daily-r4-02 · randomized crossover trial
The peak concentrations of the free signature AAs after intake of CH dissolved in water occurred between 60 and 120 min. ... However, when considering the uptake of BAPs, the pharmacokinetic endpoints iAUC, ΔCmax, and Tmax demonstrated similarity between water and coffee.
Food Res Int, 2025 · checked 2026-10-03
clgn-daily-r4-05 · meta-analysis
In the meta-analysis, a grouped analysis of studies showed favorable results of hydrolyzed collagen supplementation compared with placebo in terms of skin hydration, elasticity, and wrinkles.
Int J Dermatol, 2021 · checked 2026-10-03
clgn-daily-r4-09 · meta-analysis
Results indicate statistically significant effects in favor of long-term CP intake regarding fat-free mass (FFM) (SMD 0.48, p < 0.01), tendon morphology (SMD 0.67, p < 0.01), muscle architecture (SMD 0.39, p < 0.01), maximal strength (SMD 0.19, p < 0.01), and 48 h recovery in reactive strength following exercise-induced muscle damage (SMD 0.43, p = 0.045).
Sports Med, 2024 · checked 2026-10-03
clgn-daily-r4-10 · meta-analysis
Pooled data revealed that CPS significantly decreased fat mass (-1·21 kg; 95 % CI: -2·13, -0·29; I2 = 0·0 %; P = 0·010) and increased fat-free mass, based on body mass percentage (1·49 %; 95 % CI: 0·57, 2·42; I2 = 0·0 %; P = 0·002). Moreover, collagen peptide supplementation led to a significant decrease in serum LDL (-4·09 mg/dl; 95 % CI: -8·13, -0·04; I2 = 93·4 %; P = 0·048) and systolic blood pressure (SBP) (-5·04 mmHg; 95 % CI: -9·22, -0·85; I2 = 98·9 %; P = 0·018).
Br J Nutr, 2023 · checked 2026-10-03
clgn-daily-r4-12 · randomized controlled trial
In conclusion, substituting a portion of whey protein for collagen peptide, within a similar total protein dose, improved neither indices of eccentric muscle damage nor functional outcomes during eccentric training.
Int J Sport Nutr Exerc Metab, 2024 · checked 2026-10-03
ev-colh-02 · meta-analysis
Collagen, flavanols, and other polyphenol supplements have been found to alleviate skin photoaging and increase MED or overall skin elasticity (R2) when compared to a placebo.
Front Med (Lausanne), 2025 · checked 2026-10-06
ev-colh-05 · RCT
Hair diameter also increased significantly at week 24, with a larger proportion of participants in the LMWCP group exhibiting measurable hair thickening.
J Med Food, 2026 · checked 2026-10-06
ev-colh-08 · uncontrolled clinical trial
Bioactive collagen peptides treatment promoted an increase of 12% nail growth rate and a decrease of 42% in the frequency of broken nails.
J Cosmet Dermatol, 2017 · checked 2026-10-06
ev-colw-01 · meta-analysis
Pooled data revealed that CPS significantly decreased fat mass (-1·21 kg; 95 % CI: -2·13, -0·29; I2 = 0·0 %; P = 0·010) and increased fat-free mass, based on body mass percentage (1·49 %; 95 % CI: 0·57, 2·42; I2 = 0·0 %; P = 0·002).
Br J Nutr, 2023 · checked 2026-10-07
ev-colw-06 · RCT
Ad libitum energy intake was ∼10 % (∼41 kcal) lower in the CP trial (P = 0·037).
Br J Nutr, 2025 · checked 2026-10-07
ev-colw-07 · RCT
There was no difference between treatment groups in the perception of hunger (P = 0·983), desire to eat (P = 0·326), full stomach feeling (P = 0·567) or food consumption (P = 0·168).
Br J Nutr, 2022 · checked 2026-10-07
ev-colw-08 · RCT
Both at the level of 10 and 25 En% from protein, EI at lunch was approximately 20% lower after an alpha-lactalbumin or gelatin (+TRP) breakfast (2.5+/-0.2 MJ) compared with after a casein, soy, or whey-GMP breakfast (3.2+/-0.3 MJ, p<0.05).
Clin Nutr, 2009 · checked 2026-10-07
ev-cowh-01 · Cochrane systematic review
Compared to placebo, collagen supplements probably improve the mean change in pressure ulcer area (MD 1.81 cm² smaller, 95% CI 3.36 smaller to 0.26 smaller; 1 study, 74 participants, moderate-certainty evidence).
Cochrane Database Syst Rev, 2024 · checked 2026-10-07
ev-cowh-02 · meta-analysis
Statistical analysis indicated that the wound healing rate in the collagen group is significantly higher than that in the control group (RR = 1.53; 95% CI, 1.33–1.77) (Figure 4A).
Frontiers in Surgery · checked 2026-10-07
ev-colh-03 · systematic review
Collagen supplementation is generally safe with no reported adverse events.
J Drugs Dermatol, 2019 · checked 2026-10-06
ev-colh-09 · crossover study
Urinary glycolate excretion was 5.3-fold higher on the gelatin diet compared to the whey diet and urinary oxalate excretion was 43% higher.
Kidney International, 2006, Hydroxyproline ingestion and urinary oxalate and glycolate excretion · checked 2026-10-06
ev-colh-10 · case report
Allergic reactions to gelatin are comparatively rare, but according to the past reports, the reactions were severe.
Arerugi, 2014 · checked 2026-10-06
ev-colw-09 · RCT
Other parameters, anthropometrics, physical activity, and energy/nutrient intakes were not significantly changed.
Clin Nutr, 2025 · checked 2026-10-07
ev-colw-10 · crossover study
Urinary glycolate excretion was 5.3-fold higher on the gelatin diet compared to the whey diet and urinary oxalate excretion was 43% higher.
Kidney International, 2006, Hydroxyproline ingestion and urinary oxalate and glycolate excretion · checked 2026-10-07
ev-cowh-03 · meta-analysis
There was no difference in the risk of adverse events between the collagen group and SOC group (RR = 0.67; 95% CI, 0.44–1.01), as presented in Figure 7A.
Frontiers in Surgery · checked 2026-10-07
ev-cowh-05 · systematic review
Collagen supplementation is generally safe with no reported adverse events.
J Drugs Dermatol, 2019 · checked 2026-10-07
ev-cowh-06 · systematic review
HC supplementation was generally well-tolerated, with a low incidence of adverse events.
Eur J Clin Nutr, 2026 · checked 2026-10-07
ev-cowh-11 · crossover study
Urinary glycolate excretion was 5.3-fold higher on the gelatin diet compared to the whey diet and urinary oxalate excretion was 43% higher.
Kidney International, 2006, Hydroxyproline ingestion and urinary oxalate and glycolate excretion · checked 2026-10-07
ev-cowh-12 · case report
Allergic reactions to gelatin are comparatively rare, but according to the past reports, the reactions were severe.
Arerugi, 2014 · checked 2026-10-07
hf2-clgn-1 · regulation
SUBSTANCES OR PRODUCTS CAUSING ALLERGIES OR INTOLERANCES ... 4. Fish and products thereof, except: (a) fish gelatine used as carrier for vitamin or carotenoid preparations; (b) fish gelatine or Isinglass used as fining agent in beer and wine;
Regulation (EU) No 1169/2011 on the provision of food information to consumers, Annex II, consolidated text · checked 2026-10-08
hf2-clgn-2 · agency advice
The major food allergens are milk, eggs, fish, Crustacean shellfish, tree nuts, peanuts, wheat, soybeans, and sesame. ... the species of fish (for example, bass, flounder, cod)
US FDA, Food Allergies: What You Need to Know (updated 2026-03-11) · checked 2026-10-08
hf2-clgn-3 · randomized controlled trial
Thirty fish-allergic patients diagnosed according to the EAACI Guidelines were included (age 9-50 years). ... All patients underwent DBPCFC with a cumulative dose of 14.61 g fish gelatin. RESULTS: In all 30 patients SPT, HR, and specific IgE to codfish were positive. SPT and HR with fish gelatin were positive in 3/30 and 7/30, respectively. ... Two patients reported mild subjective reactions to active challenge. ... CONCLUSION: None of 30 fish allergic patients reacted adversely to the ingestion of 3.61 g cumulative dose of fish gelatin.
Food Chem Toxicol, 2004 · checked 2026-10-08
hf2-clgn-4 · prospective diagnostic series
Positive gelatin test results were observed in 40 of 1335 subjects: 30 of 40 patients with red meat allergy (12 also clinically allergic to gelatin) ... α-Gal was detected in bovine gelatin colloids at concentrations of approximately 0.44 to 0.52 μg/g gelatin by means of inhibition RIA. CONCLUSION: Most patients allergic to red meat were sensitized to gelatin, and a subset was clinically allergic to both.
J Allergy Clin Immunol, 2012 · checked 2026-10-08
clgn-daily-r4-04 · meta-analysis
However, in the subgroup meta-analysis by funding source, studies not receiving funding from pharmaceutical companies revealed no effect of collagen supplements for improving skin hydration, elasticity, and wrinkles, while those receiving funding from pharmaceutical companies did show significant effects. Similarly, high-quality studies revealed no significant effect in all categories, while low-quality studies revealed a significant improvement in elasticity.
Am J Med, 2025 · checked 2026-10-03
clgn-daily-r4-18 · EU claims register
POL-HC-6962 Collagen Collagen can/could contribute to the maintenance of the healthy function of joints. Non-authorised
EU Register on nutrition and health claims, claim POL-HC-6962, snapshot 2026-09-21 · checked 2026-10-03
clgn-daily-r4-19 · EU claims register
POL-HC-8291 Collagen Collagen is a natural component of the skin. Helps the skin to preserve its firmness and elasticity. Has beneficial effect in the maintenance of skin firmness and elasticity. Non-authorised
EU Register on nutrition and health claims, claim POL-HC-8291, snapshot 2026-09-21 · checked 2026-10-03
clgn-daily-r4-20 · EU claims register
POL-HC-6963 Collagen hydrolysate Contributes to the functioning of cartilage building cells. Supports the (natural) regeneration of joint cartilage. Stimulates the build-up of joint cartilage. Contributes to improved joint functioning and joint mobility. Contributes to joint comfort. Provides the building blocks (peptides) for the biosynthesis of cartilage. Provides strength, flexibility and support to skin connective tissues, ligaments, tendons, bones and other parts of the body. Non-authorised
EU Register on nutrition and health claims, claim POL-HC-6963, snapshot 2026-09-21 · checked 2026-10-03
ev-colh-01 · meta-analysis
However, in the subgroup meta-analysis by funding source, studies not receiving funding from pharmaceutical companies revealed no effect of collagen supplements for improving skin hydration, elasticity, and wrinkles, while those receiving funding from pharmaceutical companies did show significant effects.
Am J Med, 2025 · checked 2026-10-06
ev-colh-11 · regulatory register entry
POL-HC-8433 VeriSol®P Characteristic collagen peptide mixture (collagen hydrolysate) having a beneficial physiological effect on the maintenance of skin health, as indicated by an increased skin elasticity and a reduction of wrinkles volume, by contributing to a normal collagen and elastin synthesis. -/- Non-authorised
EU Register on nutrition and health claims, claim POL-HC-8433, snapshot 2026-09-21 · checked 2026-10-06
ev-cowh-13 · regulatory register entry
POL-HC-8433 VeriSol®P Characteristic collagen peptide mixture (collagen hydrolysate) having a beneficial physiological effect on the maintenance of skin health, as indicated by an increased skin elasticity and a reduction of wrinkles volume, by contributing to a normal collagen and elastin synthesis. -/- Non-authorised
EU Register on nutrition and health claims, claim POL-HC-8433, snapshot 2026-09-21 · checked 2026-10-07
clgn-daily-r4-07 · meta-analysis
The meta-analysis revealed an overall significant improvement of both function [MD, -6.46 (95% CI -9.52, -3.40); I2=75%; p=0.00001] and pain scores [MD, -13.63 (95% CI -20.67, -6.58); I2=88%; p=0.00001], favouring collagen supplementation.
Clin Exp Rheumatol, 2025 · checked 2026-10-03
clgn-daily-r4-08 · meta-analysis
Collagen treatment showed a significant reduction in the score of total WOMAC index (WMD - 8.00; 95% CI - 13.04, - 2.95; p = 0.002). After subgroup analysis of the WOMAC subscores, the collagen supplementation revealed a significant decrease in the stiffness subscore (WMD - 0.41; 95% CI - 0.74, - 0.08; p = 0.01), whereas the pain (WMD - 0.22; 95% CI - 1.58, 1.13; p = 0.75) and functional limitation (WMD - 0.62; 95% CI - 5.77, 4.52; p = 0.81) subscores did not have significant differences.
Int Orthop, 2019 · checked 2026-10-03
clgn-daily-r4-11 · randomized controlled trial
Longer-term MPS increased by 0.063 ± 0.059%/d in Rest and 0.173 ± 0.104%/d in Exercise (P < 0.0001) with WP; however, MPS was not significantly elevated above baseline in Rest (0.011 ± 0.042%/d) or Exercise (0.020 ± 0.034%/d) with CP.
Am J Clin Nutr, 2020 · checked 2026-10-03
clgn-daily-r4-13 · randomized controlled trial
Bone turnover markers greatly increase following total hip arthroplasty, but this is not modulated by daily collagen supplementation.
Clin Nutr ESPEN, 2026 · checked 2026-10-03
clgn-daily-r4-14 · randomized controlled trial
BMD of the femoral neck decreased in CON (from 0.789 ± 0.104 to 0.774 ± 0.095 g/cm2), while being preserved in INT (from 0.803 ± 0.058 to 0.809 ± 0.066 g/cm2; Time × Treatment, p < .01).
Int J Sport Nutr Exerc Metab, 2024 · checked 2026-10-03
clgn-daily-r4-15 · randomized controlled trial
The PT stiffness [COL, +15.4% ± 3.1% (d = 0.81) vs. PLA, +4.6% ± 3.0% (d = 0.32), P = 0.002] and Young's modulus [COL, +14.2% ± 4.0% (d = 0.65) vs. PLA, +3.4% ± 2.8% (d = 0.15), P = 0.004] increased more in COL than in PLA.
Exp Physiol, 2025 · checked 2026-10-03
ev-colh-06 · RCT
At week 12 the GAS score in Group A was statistically significant higher in comparison with Group B (1.67 ± 0.16 and 0.66 ± 0.20, p < 0.001; Mann-Whitney test).
Skin Res Technol, 2023 · checked 2026-10-06
ev-colh-07 · RCT
After 84 days, a significant improvement of dermis density and skin moisture was observed in the collagen peptides group compared to the placebo group.
J Cosmet Dermatol, 2024 · checked 2026-10-06
ev-colw-02 · meta-analysis
Eight studies including 418 subjects investigating fat-free mass changes following long-term CP supplementation (Fig. 2) revealed a significant pooled effect size (ES) of 0.48 [p < 0.01, confidence interval (CI) 0.22–0.74].
Sports Med, 2024 · checked 2026-10-07
ev-colw-04 · RCT
After three months (V3), a reduction in body weight of −3.0 ± 2.0 kg was observed in the group who consumed collagen compared to a reduction of −1.5 ± 1.3 kg in the control group (3.36% vs. 1.80% of weight loss, p = 0.045).
Nutrients, 2024 · checked 2026-10-07
ev-colw-05 · RCT
Additionally, our findings suggest that collagen may not be an effective supplement for overweight women who are attempting to alter body composition.
Nutrients, 2019 · checked 2026-10-07
ev-cowh-08 · randomized controlled trial
By week 8, PUSH tool scores-a measurement of pressure ulcer healing-showed approximately twice the rate of pressure ulcer healing in the treatment group compared with the control group.
Adv Skin Wound Care, 2006 · checked 2026-10-07
ev-cowh-09 · randomized controlled trial
The wound healing rate during the weeks post-burn (p = 0.006 and p = 0.01), and days of 95% (21.3 ± 6.8 and 22.9 ± 8.7 vs. 34.3 ± 14.8 days, p = 0.003 and p = 0.03) and complete (26 ± 7.7 and 27.4 ± 9.4 vs. 41.1 ± 16.6 days, p = 0.003 and p = 0.01) wound healing were significantly better with Collagen and Collagen.
Clin Nutr, 2023 · checked 2026-10-07
ev-cowh-10 · randomized controlled trial
The Hazard ratio of wound healing was 3.7 times in collagen compared to control group (95% CI: 1.434-9.519, P=0.007).
Burns, 2020 · checked 2026-10-07
clgn-daily-r4-16 · systematic review
HC supplementation was generally well-tolerated, with a low incidence of adverse events. ... The majority of included trials were rated as having a high risk of bias.
Eur J Clin Nutr, 2026 · checked 2026-10-03
clgn-daily-r4-17 · animal meta-analysis
However, CP's anti-obesity effects in humans remain largely unexplored, necessitating further research.
Int J Obes (Lond), 2026 · checked 2026-10-03
ev-colh-04 · meta-analysis
Supplements assessed included Ceramosides, Nutrafol, Nourkrin, Lambdapil, Viviscal, Forti5, GFM oral supplement, and Cynatine HNS.
J Cosmet Dermatol, 2026 · checked 2026-10-06
ev-colw-03 · systematic review
Certain improvements in body composition, strength and muscle recovery were present.
Amino Acids, 2021 · checked 2026-10-07
ev-colw-11 · animal meta-analysis
However, CP's anti-obesity effects in humans remain largely unexplored, necessitating further research.
Int J Obes (Lond), 2026 · checked 2026-10-07
ev-cowh-04 · systematic review
Overall, nutritional interventions appeared to enhance wound healing and reduce the incidence of new PIs. However, the strength of evidence was limited by small sample sizes, variability in interventions, and moderate methodological quality.
Adv Skin Wound Care, 2026 · checked 2026-10-07
ev-cowh-07 · meta-analysis
However, in the subgroup meta-analysis by funding source, studies not receiving funding from pharmaceutical companies revealed no effect of collagen supplements for improving skin hydration, elasticity, and wrinkles, while those receiving funding from pharmaceutical companies did show significant effects.
Am J Med, 2025 · checked 2026-10-07

Review. Reviewed on 2026-10-08 for evidence level, dose and population context, and claims a reader could misread. Bioma Learn has no human medical reviewer at this time, and we say so rather than invent one. Methodology. This is information, not medical advice.