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Collagen peptides
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In one pass Collagen is the scaffolding that holds the body up. Not this — Collagen peptides 'rebuild' your skin/joint collagen — Oral peptides are degraded to amino acids in the gut; this is the 'eat pork knuckle to feed your skin' fallacy.
Educational content, not medical advice — consult a clinician.
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Chapter 1
What collagen looks like
Collagen is the scaffolding that holds the body up. The structure of skin, bone, cartilage, tendons, ligaments, vessel walls and the white of the eye is mostly built from it. It is also the most abundant protein in the body, about 25–30% of all protein.
It is shaped like three strands of rope twisted together: three α chains wound into one right-handed helix. How firmly the rope holds depends on whether the prolines along the chain have had a hydroxyl group (-OH) added inside the cell, turning them into hydroxyproline. The enzyme that does this cannot work without vitamin C (the chapter Collagen needs vitamin C is about that step).
So this scaffolding is built by your own cells; eaten collagen is not bolted on directly. Eating collagen is not the same as growing collagen. The gelatin and collagen peptide powder on the shelf are both this rope cut into shorter pieces. They differ mainly in whether they dissolve easily and whether you can cook with them; their amino acid make-up is almost the same.
It is shaped like three strands of rope twisted together: three α chains wound into one right-handed helix. How firmly the rope holds depends on whether the prolines along the chain have had a hydroxyl group (-OH) added inside the cell, turning them into hydroxyproline. The enzyme that does this cannot work without vitamin C (the chapter Collagen needs vitamin C is about that step).
So this scaffolding is built by your own cells; eaten collagen is not bolted on directly. Eating collagen is not the same as growing collagen. The gelatin and collagen peptide powder on the shelf are both this rope cut into shorter pieces. They differ mainly in whether they dissolve easily and whether you can cook with them; their amino acid make-up is almost the same.
Mechanism · What is special about its amino acids
Collagen peptide ads love to talk about the amino acid make-up. It is unusual, but none of it is scarce:Glycine (Gly): about 33% of the residues. Eggs, meat, soy and gelatin all contain it, and the body can make its own.Proline (Pro): about 12%, and not in short supply either.Hydroxyproline (Hyp): about 10%. This one is a little special. Ready-made hydroxyproline only comes from animal collagen, and to make its own the body needs proline, vitamin C and an enzyme called prolyl 4-hydroxylase.
How the triple helix twists together
Each strand is a repeat of Gly-X-Y (textbook knowledge):
Glycine sits in every third position, because it has the smallest side chain and is the only amino acid that fits in the center of the helix.The X position is often proline.The Y position is often hydroxyproline. It is proline that had a hydroxyl group added after the chain was built, and that step needs vitamin C.
Where gelatin and collagen peptides come from
Gelatin: heating unwinds the triple helix and breaks it partly. The chains are still fairly long, and they set into a gel as they cool. You can make jelly or mousse with it, or simply eat it.Collagen peptide powder: enzymes cut it further. It dissolves in cold or hot water and no longer sets.
The two have almost the same amino acid make-up, and both are more than 90% protein. The marketing difference is easy to mix versus good for cooking, not better absorbed or better used.
Hydroxyproline you eat is not built straight into new collagen. When a cell makes protein, no codon stands for hydroxyproline, so the cell must first put in proline and then add the hydroxyl group on the chain (textbook knowledge). Dietary collagen mainly supplies raw material; the actual modification is done by your own fibroblasts (the cells that make collagen) with vitamin C.
The one line to keep: collagen peptides are not magic amino acids. They are a partly broken-down protein rich in glycine and proline and lacking tryptophan. If you already eat the 1.6–2.2 g/kg/day of total protein commonly used by people who train, collagen peptides add very few extra amino acids.
Chapter 2
Eating collagen doesn't build collagen
Eat it to grow it is the classic myth of the supplement aisle, and collagen is its poster child.
Every protein you eat, whether steak, egg or collagen peptides, goes down the same line. Stomach acid and the enzyme pepsin tear it into short peptides, enzymes from the pancreas cut those smaller, and the gut wall carries dipeptides and tripeptides into its cells. Most of them are split there into single amino acids, which travel through the portal vein into the body's shared pool. The body keeps no label saying this came from collagen. If you eat 20 g of collagen peptides, the glycine and proline in it go wherever they are needed at the moment, to build muscle, enzymes and heme, not only collagen.
The exception is a small share of short peptides. Studies in people can detect intact dipeptides and tripeptides in the blood for a short time. Whether cells in skin or tendon read them as a signal that collagen nearby has been broken down, and respond by making more, is a hypothesis not yet shown in people.
So collagen peptides do not deliver raw material straight to your skin. What they might add over an ordinary protein powder is, at most, this unproven signaling route; the marketing presents it as the raw-material story.
Every protein you eat, whether steak, egg or collagen peptides, goes down the same line. Stomach acid and the enzyme pepsin tear it into short peptides, enzymes from the pancreas cut those smaller, and the gut wall carries dipeptides and tripeptides into its cells. Most of them are split there into single amino acids, which travel through the portal vein into the body's shared pool. The body keeps no label saying this came from collagen. If you eat 20 g of collagen peptides, the glycine and proline in it go wherever they are needed at the moment, to build muscle, enzymes and heme, not only collagen.
The exception is a small share of short peptides. Studies in people can detect intact dipeptides and tripeptides in the blood for a short time. Whether cells in skin or tendon read them as a signal that collagen nearby has been broken down, and respond by making more, is a hypothesis not yet shown in people.
So collagen peptides do not deliver raw material straight to your skin. What they might add over an ordinary protein powder is, at most, this unproven signaling route; the marketing presents it as the raw-material story.
Mechanism · The intact-peptide hypothesis
Some collagen trials have seen an effect. One mechanism hypothesis tries to explain why:Short peptides in collagen that contain proline and hydroxyproline (such as Pro-Hyp and Gly-Pro-Hyp) are relatively hard for most protein-cutting enzymes to split.They are carried whole into gut cells by PEPT1 (the gut-wall transporter for dipeptides and tripeptides). Some escape being split there, pass into the portal vein and reach the blood.Pharmacokinetic studies, which track how blood levels change after a dose, such as Iwai 2005 and Shigemura 2018, can detect these peptides in human plasma for a short time.Hypothesis: they reach fibroblasts (the cells that make collagen) and are read as fragments of existing collagen that has been broken down, so the cells start making new collagen.
One experiment points the same way. Shaw 2017 took serum drawn from volunteers 1 hour after they ate gelatin and added it to engineered ligaments grown in the lab; those ligaments ended up with more collagen and better mechanical properties. That shows serum after a gelatin dose does something to cultured ligament, but it cannot tell whether the active part was the peptides or simply the extra amino acids.
Read the limits carefully: this is a plausible hypothesis, not a confirmed mechanism. It has not been measured directly in human tissue, and it does not explain every signal in the skin trials. Treat it as a research direction still in progress: one step above eat it to grow it, but far from the advertised feeds your skin directly.
iwai-2005-collagen-peptides-bloodshigemura-2018-collagen-peptides-blood
Mechanism · The four steps of protein digestion
The whole four-step line (textbook knowledge):1. Stomach acid and pepsin tear the triple helix into short peptides.
2. Trypsin, chymotrypsin and elastase from the pancreas cut those into smaller fragments of 2–6 amino acids.
3. Peptidases on the gut wall's brush border, together with the PEPT1 transporter, take dipeptides and tripeptides into the gut cells, where they are split into single amino acids.
4. The portal vein, then the liver: the amino acids join the body's shared pool.
The short-peptide exception happens at step 3. Some dipeptides and tripeptides are not fully split inside the gut cell and pass whole into the portal vein; that is where the hypothesis above begins.
The same line explains why expectations should stay modest. For the most part, the gut treats collagen exactly as it treats any other protein. Most collagen trials that saw an effect were small, and their endpoints were blood markers or self-rated pain, still some distance from a difference you would notice in clinic.
Chapter 3
Collagen needs vitamin C
When the body makes collagen, the cofactor that actually holds up the work is vitamin C, not collagen peptides.
The procollagen that fibroblasts (the cells that make collagen) produce first still carries ordinary proline. An enzyme called prolyl hydroxylase has to add a hydroxyl group to those prolines inside the endoplasmic reticulum before the three chains can twist into a stable rope, and that enzyme cannot work without vitamin C. When vitamin C is severely short for a long time, new collagen will not hold together while old collagen keeps being broken down. That is scurvy: bleeding gums and wounds that split open (textbook knowledge).
What this means for you: if you want your body to make collagen, first make sure you get enough vitamin C. The two small trials of gelatin before exercise also gave the gelatin together with about 50 mg of vitamin C; no trial has compared taking it with and without vitamin C.
Look at it the other way round. An orange, an egg and a piece of chicken breast already bring vitamin C, a complete set of amino acids and some glycine and proline. Counting raw material for collagen alone, that meal is about the same as collagen peptides plus a vitamin C capsule, and it fills you up more.
The procollagen that fibroblasts (the cells that make collagen) produce first still carries ordinary proline. An enzyme called prolyl hydroxylase has to add a hydroxyl group to those prolines inside the endoplasmic reticulum before the three chains can twist into a stable rope, and that enzyme cannot work without vitamin C. When vitamin C is severely short for a long time, new collagen will not hold together while old collagen keeps being broken down. That is scurvy: bleeding gums and wounds that split open (textbook knowledge).
What this means for you: if you want your body to make collagen, first make sure you get enough vitamin C. The two small trials of gelatin before exercise also gave the gelatin together with about 50 mg of vitamin C; no trial has compared taking it with and without vitamin C.
Look at it the other way round. An orange, an egg and a piece of chicken breast already bring vitamin C, a complete set of amino acids and some glycine and proline. Counting raw material for collagen alone, that meal is about the same as collagen peptides plus a vitamin C capsule, and it fills you up more.
In practice · The pre-exercise gelatin protocol
This routine comes from Keith Baar's lab at the University of California, Davis (the Shaw 2017 and Lis 2019 line of work) and is widely quoted in sports nutrition. First, what the two trials actually measured:Shaw 2017 (American Journal of Clinical Nutrition, AJCN)
8 healthy men in a randomized, double-blind crossover design: each man took a placebo, 5 g, or 15 g of vitamin C-enriched gelatin in turn.One hour after the drink they skipped rope for 6 minutes. They did this 3 times a day, at least 6 hours apart, for 3 days.Glycine, proline and hydroxyproline in the blood peaked 1 hour after the dose.After the 15 g dose, blood PINP (a short piece cut off when new type I collagen is made, used to track collagen synthesis) was 2 times the placebo level.Its limits: few people, only 3 days, and a blood marker as the endpoint, not the injury rate.
Lis 2019 (International Journal of Sport Nutrition and Exercise Metabolism, IJSNEM)
10 recreationally active men, again in a crossover design: placebo, 15 g of vitamin C-enriched gelatin, 15 g of hydrolyzed collagen, or a gummy made of half gelatin and half hydrolyzed collagen.PINP rose about 20% from before the dose with gelatin and with hydrolyzed collagen, but not with placebo or the gummy. Individual responses varied widely, and no treatment reached statistical significance.
The routine drawn from them (a recommendation from researchers and coaches; no trial has tested the long-term effect):
1. About 1 hour before exercise: 5–15 g of gelatin or collagen peptides with about 50 mg of vitamin C.
2. A few minutes of jumping, plyometric or isometric work to give tendons and ligaments a mechanical stimulus.
3. If you train again the same day, take another dose at least 6 hours later.
Who it might suit (reasoned from the mechanism; no trial has compared sports): sports that load tendons and ligaments heavily, such as jumping, sprinting, basketball, volleyball and tennis. During rehab from a tendon or ligament injury you can discuss it with your physiotherapist as an add-on; it does not replace physical therapy.
Not a muscle-building protein: collagen peptides lack tryptophan and are not a complete protein. In the Khatri 2021 systematic review, 15 g a day of collagen peptides raised collagen synthesis rates but gave no significant advantage for muscle protein synthesis (MPS) over the same amount of nitrogen from higher-quality protein. For building muscle, a complete protein such as whey remains the main choice.
One last word: this is a marginal adjustment for people whose training, sleep, total protein and vitamin C are already in place, not a foundation. While those are not in place, collagen peptides come last.
Mechanism · Why the hydroxylases need vitamin C
The hydroxylation step, one stage at a time (textbook knowledge):1. Fibroblasts first build procollagen, whose chains carry ordinary proline.
2. Prolyl 4-hydroxylase (P4H), inside the endoplasmic reticulum, adds a hydroxyl group at position 4 of proline, turning it into hydroxyproline.
3. Lysyl hydroxylase (LH) adds a hydroxyl group to lysine, turning it into hydroxylysine, which is needed later to form cross-links.
4. Both enzymes require ferrous iron (Fe²⁺), alpha-ketoglutarate and vitamin C (ascorbate) as cofactors.
5. Without vitamin C, prolyl hydroxylase stops working. The collagen ends up short of hydroxyproline, the triple helix cannot hold its twist at body temperature, and the new collagen is soon broken down.
Scurvy is what this broken link looks like. Sailors in the age of sail went long stretches without fresh fruit and vegetables and developed bleeding gums, loosening teeth and old wounds that reopened. Existing collagen kept being removed by normal turnover, while new collagen could not form a stable structure.
That is also why the value of vitamin C lies in turning this step from stuck to working. For someone who already gets enough, taking more does not make the hydroxylases work faster (reasoned from the mechanism).
Chapter 4
Trial results for joints and skin
The clinical evidence for collagen peptides stops at two narrow settings, and only at the level of symptom scores and instrument readings.
The first is athletes who already have exercise-related joint pain. In one 24-week , pain scores in the group taking 10 g of collagen hydrolysate a day fell a little more than in the placebo group; both groups improved. The second is skin elasticity in women aged 35–55. One 8-week trial measured a small improvement with an instrument. Pooled together, the skin trials lean favorable, but once they are split by funding source the effect shows up only in industry-funded studies; high-quality, independently funded studies did not see it.
Diagnosed osteoarthritis: when the trials are pooled, the total score on a symptom questionnaire and a separate visual analogue scale (VAS) score both fall, but the pain and function parts of the questionnaire show no significant difference. Preventing joint problems in healthy people: no trial has tested it.
Will it make you look 5 years younger? No. Will your skin be clearly better 10 years from now? The evidence does not support that. Can it make someone with exercise-related joint pain hurt a little less? One 24-week trial and several small ones say so, and the effect is modest.
The first is athletes who already have exercise-related joint pain. In one 24-week , pain scores in the group taking 10 g of collagen hydrolysate a day fell a little more than in the placebo group; both groups improved. The second is skin elasticity in women aged 35–55. One 8-week trial measured a small improvement with an instrument. Pooled together, the skin trials lean favorable, but once they are split by funding source the effect shows up only in industry-funded studies; high-quality, independently funded studies did not see it.
Diagnosed osteoarthritis: when the trials are pooled, the total score on a symptom questionnaire and a separate visual analogue scale (VAS) score both fall, but the pain and function parts of the questionnaire show no significant difference. Preventing joint problems in healthy people: no trial has tested it.
Will it make you look 5 years younger? No. Will your skin be clearly better 10 years from now? The evidence does not support that. Can it make someone with exercise-related joint pain hurt a little less? One 24-week trial and several small ones say so, and the effect is modest.
Evidence · How firm each marketing claim is
Collagen peptides have one of the widest gaps between marketing and evidence of any supplement. The table below grades each common claim by certainty of evidence (high / moderate / low / very low) and names the type of evidence in the same cell:| Marketing claim | Certainty of evidence |
|---|---|
| Fewer wrinkles, look 10 years younger | Very low: no significant effect on wrinkles in independently funded studies |
| Protects against photoaging and sun damage | Very low: none of the trials cited here measured it |
| Repairs or rebuilds joint cartilage | Very low: osteoarthritis trials measure only symptom scores; when pooled, the questionnaire total and a visual analogue scale (VAS) score fall, but the pain and function parts of the questionnaire are not significant |
| Thicker, longer hair and nails | Very low: personal experience and small studies |
| Eases athletes' joint pain | Moderate: one 24-week randomized trial (Clark 2008) plus a systematic review of 15 small trials; the endpoint is self-rated pain |
| Improves skin elasticity (women aged 35–55) | Low: a single trial (Proksch 2014) and pooled analyses lean favorable, but only in industry-funded studies |
| Special small peptides with remarkable activity (GHK and others) | Very low: lab studies, not verified in people |
Certainty of evidence in the table means how sure we can be, not how large the effect is. GHK is a small copper-binding peptide that often appears in skincare advertising.
What drives this category is mostly social media, influencer recommendations and "the celebrities drink it"; the clinical evidence trails far behind.
In practice: if the claim you hear sits in one of the very low rows, close your wallet. If your goal is exactly one of the moderate or low rows, you can try a course at the dose and length used in the trials (8–24 weeks) and stop if nothing changes.
Evidence · The joint and skin trials in numbers
1. Exercise-related joint painClark 2008 (Curr Med Res Opin), where this line of research starts:
147 university varsity or club athletes with no evidence of joint disease but with activity-related joint pain.Randomized, double-blind and placebo-controlled: 10 g of collagen hydrolysate a day, with a collagen-free liquid for the control group, for 24 weeks.Only 97 of the 147 people had data that entered the analysis.The endpoint was a visual analogue scale (VAS, where you mark on a line how much it hurts), scored by the participants themselves, plus one rating by a physician.Pain when walking fell by 1.11 with collagen and by 0.46 with placebo (p = 0.007). Pain at rest as rated by the physician fell by 1.37 versus 0.90 (p = 0.025).In the subgroup of 63 people with knee pain, the gap between groups was larger.
How to read it: both groups got better, and the collagen group's extra drop was a fraction of a point on the scale. A third of the participants were not analyzed, and the authors themselves wrote that further studies are needed to support the result. It is the most solid trial in this line, but it is still one trial.
Khatri 2021 (Amino Acids), a systematic review: it included 15 randomized trials (12 in recreational athletes, 2 in older adults, 1 in untrained premenopausal women) and concluded that collagen peptides taken with exercise helped most with joint function and joint pain. It did not pool the results statistically, and it calls for larger samples and more precise measures.
Diagnosed osteoarthritis (OA): García-Coronado 2019 pooled placebo-controlled trials. The total WOMAC score (a symptom questionnaire for osteoarthritis) was 8.00 points lower on average and the stiffness subscore improved, but the pain (P = 0.75) and functional-limitation (P = 0.81) subscores showed no significant difference; a visual analogue scale (VAS) score, pooled separately, was 16.57 points lower on average (P < 0.001), and the authors conclude that collagen improves osteoarthritis symptoms. Note what these endpoints are: WOMAC is a symptom score and cartilage thickness on X-ray is an imaging measure; neither is a such as joint replacement or disability.
2. Skin elasticity
Proksch 2014 (Skin Pharmacol Physiol):
69 women aged 35–55, randomized to 2.5 g or 5 g a day of specific collagen peptides or to placebo, 23 per group, for 8 weeks.Skin elasticity, moisture, water loss through the skin and roughness were measured objectively with instruments.Elasticity improved significantly versus placebo in both dose groups. Four weeks after stopping, older women still had higher elasticity.Moisture and water loss showed a positive trend only in a subgroup analysis and did not reach statistical significance.
Pooled results: de Miranda 2021 combined 19 trials with 1,125 people and found results favorable for skin hydration and elasticity. Myung 2025 split the studies by funding source: in studies not funded by industry, and in high-quality studies, there was no significant effect on hydration, elasticity or wrinkles; the effect appeared only in industry-funded studies.
So the certainty of evidence for skin is low: there is a signal, but it may come from who paid for the studies, and it is far from an anti-wrinkle miracle.
garcia-coronado-2019-collagen-oa-metade-miranda-2021-collagen-skin-metamyung-2025-collagen-skin-meta
Chapter 5
Who should buy it, and how to take it
Collagen peptides are broken down into amino acids and small peptides when you eat them; they do not land on your face intact. They lack tryptophan and cannot be your only protein source. What they can offer is a small signal for joint pain or skin elasticity in a few settings, provided your total protein is already enough and your goal matches.
Promises of fewer wrinkles or rebuilt cartilage have no reliable trials behind them. If you have exercise-related joint pain, or want a small gain in skin elasticity, you can try a course at the dose and length used in the trials, judge by how you feel at the end, and stop if nothing has changed. People allergic to fish, beef or pork protein should check the source on the label. If you have chronic kidney disease, ask your doctor before adding any protein supplement.
Promises of fewer wrinkles or rebuilt cartilage have no reliable trials behind them. If you have exercise-related joint pain, or want a small gain in skin elasticity, you can try a course at the dose and length used in the trials, judge by how you feel at the end, and stop if nothing has changed. People allergic to fish, beef or pork protein should check the source on the label. If you have chronic kidney disease, ask your doctor before adding any protein supplement.
In practice · Whether to buy it, by goal
Do you need collagen peptides?Q1: What is your goal?
Fewer wrinkles, looking 5 years younger: no reliable evidence, so not a priority. Sun protection and not smoking are the better first steps for skin aging.Repairing arthritis, rebuilding cartilage: osteoarthritis trials measured only symptom scores, with mixed results (the questionnaire total and a visual analogue scale score fell, while the pain and function parts of the questionnaire showed no significant difference). Exercise and weight control remain the first line.Active, with chronic joint pain or tendon discomfort: the certainty of evidence is moderate (one 24-week trial plus several small ones, with self-rated pain as the endpoint). You can try the trial routine for 8–24 weeks.Aged 35–55, skin elasticity declining, want a small improvement: the certainty of evidence is low (independently funded studies did not see an effect). If you want to try, use the Proksch dose.Not getting enough total protein (below 1.2 g/kg): fix total protein first with whey, protein powder or food. Collagen peptides are not the first choice.Recovering from a ligament or tendon injury: you can discuss it with your physiotherapist as an add-on to physical therapy. The evidence comes from small trials and does not replace rehab exercise.
Q2: Which form? Most trials used collagen peptide powder. A capsule holds only a few hundred milligrams, so reaching a trial dose takes many of them; liquid versions mainly cost more; and differences between patented peptide brands have not been properly tested.
Q3: How to take it?
Pre-exercise routine (the design of Shaw 2017 and Lis 2019): 5–15 g of gelatin or collagen peptides with about 50 mg of vitamin C, about 1 hour before exercise. Those two trials lasted only days.Skin routine (Proksch 2014): 2.5–5 g a day, and check skin elasticity after 8 weeks.Joint routine (Clark 2008): 10 g a day, and judge joint pain after 24 weeks.Key point: avoid blends that pack collagen, hyaluronic acid, chondroitin, glucosamine and quercetin together. You cannot see the dose of each, they cost more, and whether they interact is unknown.
Q4: When to be careful
As your only protein source: no, collagen peptides lack tryptophan.Pregnancy and breastfeeding: there are no dedicated trials. It is an ordinary animal protein and is not generally thought to carry special risk; you can ask your obstetrician before taking it.Gelatin allergy (uncommon): usually an allergy to pork or beef protein, so a fish source can replace it, unless you are allergic to fish.Chronic kidney disease (): it adds to your protein load, so ask your doctor first.
Myth · Does bone broth count as a collagen supplement
The most common claims made for bone broth:An ancestral superfoodNatural collagen plus mineralsHeals the gut and fights inflammation
What the chemistry says
Long-simmered bone broth does contain gelatin: the heat breaks the collagen out of bones, skin and sinew.But how much gelatin a bowl holds varies widely with the proportion of bone, how long it simmers and how hot; packaged broths usually do not state it. Reaching the 5–15 g of the pre-exercise routine often takes several bowls, along with a fair amount of fat and sodium.
Minerals?
Calcium, magnesium and phosphorus are in the bone, but they do not dissolve into the broth easily, and adding vinegar pulls out little more. A bowl usually supplies only a small fraction of a day's needs.
Anti-inflammatory? Gut healing?
These claims rest almost entirely on indirect extrapolation, amplified by influencers.No randomized trial has shown that drinking bone broth improves leaky gut, small intestinal bacterial overgrowth (SIBO) or autoimmune disease.
Conclusion: bone broth is soup. It is warm and tasty, has some protein and amino acids, and it has a place at family meals. But it is not a supplement-grade source of collagen, and it is not a superfood. If you really want 5–15 g of collagen, a weighed scoop of collagen peptide powder is more precise and cheaper.
If you enjoy the taste and ritual of bone broth, drinking it is fine. Just do not take "I drink a bowl of bone broth every day" as "I am supplementing collagen scientifically".
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In practice · Powder, gelatin or capsules
Q2: Which form?Collagen peptide powder (hydrolyzed collagen): dissolves in cold or hot water, does not set, and is easy to stir into coffee or oats. It is the form most randomized trials used.Gelatin: used in the two pre-exercise trials and good for cooking, but it sets as it cools, which makes it awkward to take every day.Liquid collagen peptides: a big marketing markup; in practice it is powder plus water plus flavoring.Collagen capsules: each holds only a few hundred milligrams, so reaching 5–15 g means swallowing a great many. Very poor value.Patented specific-peptide brands (Verisol, Peptan, TendoForte and others): trials such as Proksch's and Clark's each used one particular peptide product. Whether brands differ in effect has not been properly tested; the cautious choice is the product that a randomized trial has tested directly.
References · 5
- Khatri, M., Naughton, R. J., Clifford, T., Harper, L. D., & Corr, L. (2021). The effects of collagen peptide supplementation on body composition, collagen synthesis, and recovery from joint injury and exercise: a systematic review. Amino Acids, 53(10), 1493-1506. Systematic review of 15 RCTs (from 856 articles screened) combining collagen peptides with exercise: 12 in recreational athletes, 2 in elderly participants, 1 in untrained pre-menopausal women. Outcomes: joint pain and recovery from joint injury, body composition, muscle soreness and recovery, muscle protein and collagen synthesis; no skin endpoint, and the abstract reports no pooled effect estimate. Collagen synthesis rates were elevated with 15 g/day, with no significant effect on muscle protein synthesis vs isonitrogenous higher-quality protein (abstract, PMID 34491424; full text, PMC8521576). 10.1007/s00726-021-03072-x
- Shaw, G., Lee-Barthel, A., Ross, M. L. R., Wang, B., & Baar, K. (2017). Vitamin C-enriched gelatin supplementation before intermittent activity augments collagen synthesis. The American Journal of Clinical Nutrition, 105(1), 136-143. 8 healthy men, randomized double-blind crossover: 5 g or 15 g vitamin C-enriched gelatin or placebo 1 h before 6 min of rope-skipping, 3 times a day for 3 days. Blood glycine, proline, hydroxyproline and hydroxylysine peaked 1 h after the drink; with 15 g gelatin, blood amino-terminal propeptide of collagen I (PINP) doubled; serum drawn after gelatin raised collagen content of engineered ligaments in vitro. A collagen-synthesis marker; no injury or recovery outcome was measured (abstract, PMID 27852613). 10.3945/ajcn.116.138594
- Lis, D. M., & Baar, K. (2019). Effects of different vitamin C-enriched collagen derivatives on collagen synthesis. International Journal of Sport Nutrition and Exercise Metabolism, 29(5), 526-531. 10 recreationally active men, randomized double-blind crossover: placebo or 15 g vitamin C-enriched gelatin, hydrolyzed collagen, or a gummy with equal parts of both, 1 h before 6 min of jump rope. Blood amino acids rose similarly with all three; PINP tended to rise about 20% from baseline with gelatin and hydrolyzed collagen but not with placebo or gummy; large variability meant no treatment reached significance (abstract, PMID 30859848). 10.1123/ijsnem.2018-0385
- Clark, K. L., Sebastianelli, W., Flechsenhar, K. R., et al. (2008). 24-Week study on the use of collagen hydrolysate as a dietary supplement in athletes with activity-related joint pain. Current Medical Research and Opinion, 24(5), 1485-1496. 147 varsity or club athletes with activity-related joint pain and no joint disease (72 men, 75 women) randomized double-blind to 10 g collagen hydrolysate in 25 mL liquid (n = 73) or xanthan placebo (n = 74) for 24 weeks; only 97 of 147 could be evaluated. In those 97, physician-rated joint pain at rest fell 1.37 vs 0.90 VAS points (p = 0.025) and participant-rated pain when walking 1.11 vs 0.46 (p = 0.007); in the knee subgroup (n = 63) the differences were larger (physician-rated rest pain 1.67 vs 0.86, p = 0.001). The authors note the study's size and limitations (abstract, PMID 18416885). 10.1185/030079908X291967
- Proksch, E., Segger, D., Degwert, J., Schunck, M., Zague, V., & Oesser, S. (2014). Oral supplementation of specific collagen peptides has beneficial effects on human skin physiology: a double-blind, placebo-controlled study. Skin Pharmacology and Physiology, 27(1), 47-55. 69 women aged 35-55 randomized (23 per group) to 2.5 g or 5.0 g collagen hydrolysate or placebo daily for 8 weeks. Skin elasticity, the primary interest, improved significantly vs placebo in both dose groups; skin moisture and transepidermal water loss showed a positive influence only in a subgroup analysis and did not reach statistical significance (abstract, PMID 23949208). 10.1159/000351376