This page shows what was measured, who it was measured in, and what that does not settle.
What Collagen peptides does in the body
Taken for skin, joints, hair and nails
Collagen in a tub is animal connective tissue that has been boiled and then cut up by enzymes into short fragments. Swallowed, it meets the same digestion as steak: acid and proteases break it down to individual amino acids and very short peptides, and it is those that cross into the blood. Your body then builds its own collagen from scratch, using whichever amino acids happen to be available, in a process that needs vitamin C and does not care where the raw material came from. The only part of the story that is unusual is that a few two-and-three-letter fragments containing hydroxyproline survive intact, and there is a real hypothesis that these act as a chemical message rather than as material.
What happened in people
Pro-Hyp and related hydroxyproline dipeptides survive digestion and reach plasma at 20 to 60 nmol/mL, peaking at one to two hours
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The recorded finding that sits closest to something a person would notice. Written into the record, not signed off, and it carries no population or interval.
No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.
Shown as the opening line on this page.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 153 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Stand-in result
A stand-in result is a number measured because the real result takes too long.
A picture of it, and where the picture fails
It is like judging a journey by the speedometer rather than by arriving.
Where that stops being true. Speed does predict arrival. Many stand-in results do not predict the real one.
What people get wrong. A stand-in result is often reported as the result itself.
A surrogate endpoint substituted for a clinical endpoint, valid only where the substitution has been shown to hold.
Randomisation
Randomisation means chance decides who gets which treatment.
A picture of it, and where the picture fails
It is like a coin toss deciding the groups.
Where that stops being true. A coin toss is fair once. Fairness here comes from doing it for everyone.
What people get wrong. It is thought to make groups identical. It makes them similar on average, including on things nobody measured.
Allocation of participants to arms by a chance process, so that unmeasured factors are balanced in expectation.
Receptor
A receptor is a part of a cell that a signal fits into.
A picture of it, and where the picture fails
A receptor is like a lock waiting for one key.
Where that stops being true. A lock either opens or does not. A receptor can be half-triggered, or worn out.
What people get wrong. Fitting a receptor is read as causing a benefit. It causes a step, and nothing more.
A protein that binds a specific ligand and converts that binding into a cellular response.
Pathway
A pathway is a chain of steps inside a cell, each one setting off the next.
A picture of it, and where the picture fails
A pathway is like a row of dominoes.
Where that stops being true. Dominoes fall one way. Pathways loop back and can switch themselves off.
What people get wrong. Changing one step is read as changing the outcome. Other steps often absorb it.
An ordered series of molecular interactions producing a defined cellular change.
What happened in people◇Read from sources, not yet reviewed
What was measured, goal by goal
One row for each goal a registered study measured something for. One column for each kind of thing that could be measured.
Registered studies list 2 outcome measures that RNAWiki could read. A registered study says what someone planned to measure. It does not say what they found. 0 of the matched studies tested this substance, and 0 posted a result.
There is no single score. A strong test result and a weak life result are different facts.
Goals down the side, kinds of measurement across the top. Each cell says what kind of thing was registered, not what was found.
Goal
Life outcome
What a body can do
How a person feels
A test result
A step in the body
Harms
How long
Who was studied
Muscle
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
∅Nothing in the sources checkedNo registered study lists a symptom measure for this goal.
△Only a number moved1 registered test measure.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Which registered measures put each goal on this table
Muscle
muscle mass
Sorted by fixed word lists, version v1. A name the rules do not recognise stays unsorted rather than moving to the nearest column.
What each mark on this table means
∅ Nothing in the sources checked
No registered study lists a life outcome for this goal.
△ Only a number moved
1 registered test measure.
— Not recorded
Harms were not a registered measure for this goal.
… Waiting for a reviewer
Who was studied is listed further down the page.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
Skin hydration, elasticity, firmness and wrinkles versus placebo
✓ The study showed what it set out to show
Who was studied
de Miranda 2021 meta-analysis of hydrolysed collagen and skin ageing
How many people
1125
Study design
Systematic review and meta-analysis of 19 randomised double-blind controlled trials
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Favourable grouped results for hydration, elasticity and wrinkles; hydration and elasticity confirmed in subgroup meta-analysis
Repeated elsewhere
Partially Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. Ninety-five percent of participants were women, so the result is effectively untested in men. Outcomes are instrument-measured surrogates over short durations, and manufacturer affiliation is not corrected for in the pooling.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral powder, capsule or liquid; bovine, porcine or marine hydrolysate
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Circulating amino acids, serum P1NP, and mechanics of engineered ligaments treated with subject serum
✓ The study showed what it set out to show
Who was studied
Shaw 2017 — vitamin C-enriched gelatin and collagen synthesis
How many people
8
Study design
Randomised double-blinded crossover with an in vitro tissue arm
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Circulating glycine, proline, hydroxyproline and hydroxylysine rose, peaking 1 h after supplementation
Repeated elsewhere
Unreplicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. Eight healthy men, three days of exposure, and the mechanical outcome measured on engineered constructs rather than human tendon. No human tendon or ligament was tested.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral powder, capsule or liquid; bovine, porcine or marine hydrolysate
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Change in spine and femoral neck bone mineral density T-score at 12 months
✓ The study showed what it set out to show
Who was studied
Konig 2018 — specific collagen peptides and bone mineral density
How many people
131
Study design
Randomised double-blind placebo-controlled
Compared against
A dummy treatment
Kind of result
A number that stands in for health
What was found
Spine T-score +0.1 +/- 0.26 versus -0.03 +/- 0.18 (ANCOVA P = 0.030); femoral neck +0.09 +/- 0.24 versus -0.01 +/- 0.19 (P = 0.003)
Repeated elsewhere
Unreplicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. Standard deviations exceed the mean changes, and a 0.1 T-score shift sits within the repeat-measurement precision error of most DXA systems. The corresponding author is affiliated with the Collagen Research Institute GmbH.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral powder, capsule or liquid; bovine, porcine or marine hydrolysate
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Reported improvement in visual analogue parameters; only 97 of 147 randomised subjects could be statistically evaluated
Repeated elsewhere
Partially Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. A third of the randomised sample was lost before analysis, which removes the protection randomisation provides. The primary outcome is a subjective pain scale in a population aware it was in a supplement trial.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral powder, capsule or liquid; bovine, porcine or marine hydrolysate
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 5 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What happened in people◇Read from sources, not yet reviewed
How close this is to real life
The top step is something a person would feel or care about. The bottom is a guess from software. Filled steps are where evidence exists for this substance.
□Living longer, or avoiding a major eventNo evidence recorded. Death, a heart attack, a stroke, a hospital stay.No registered study measures this.
□What a body can do day to dayNo evidence recorded. Walking, dressing, breathing, recovering.No registered study measures this.
□Measured performanceNo evidence recorded. How much was lifted, how far was run, how fast.No registered study measures this.
□Symptoms and quality of lifeNo evidence recorded. Pain, tiredness, mood, sleep, as the person rated it.No registered study measures this.
■A number that stands in for healthEvidence recorded. Cholesterol, blood sugar, bone density. A stand-in, not the thing itself.1 registered measure of this kind.
■A step measured inside a personEvidence recorded. Something measured in human tissue or human cells.A human record sits on the stored organism ladder.
■AnimalsEvidence recorded. Mice, rats, dogs. Useful for ideas, not proof about people.Stored records in C. elegans (roundworm), Mouse. A result in animals says what to test next. It does not say what happens in people.
■Cells in a dishEvidence recorded. Cells or chemistry on a bench, far from a whole body.Stored mechanism abstracts describe steps measured in cells or tissue.
□A guess from softwareNo evidence recorded. Nobody measured it. RNAWiki never publishes one as a finding.RNAWiki stores no prediction for this record. Software can suggest a link. RNAWiki does not publish one as a finding.
Higher on these steps means closer to something a person would feel. It does not mean better done.
What it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Start
Collagen peptides
What a person takes: Oral powder, capsule or liquid; bovine, porcine or marine hydrolysate.
The measurement behind this step
Sold in the United States as a dietary supplement under DSHEA, so no agency reviewed efficacy, safety or content before sale. Species of origin is a real variable — it changes the amino acid profile, the allergen profile and the religious-dietary status — and is often absent from the label. Molecular weight distribution decides how much of a product is free amino acid and how much is the intact dipeptide the mechanism depends on, and is essentially never disclosed. Branded ingredients such as Verisol and Fortigel are specific hydrolysates whose trial evidence does not transfer to unbranded hydrolysate.
Getting in
It is digested exactly like any other protein
Stomach acid and gut enzymes take the collagen fragments apart. Nothing about being collagen protects it from this, and nothing about it addresses it to skin.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Pepsin, trypsin, chymotrypsin and brush-border peptidases reduce collagen hydrolysate to free amino acids and di- and tripeptides, which cross the enterocyte through PepT1 and amino acid transporters into the portal circulation. There is no tissue-addressing mechanism at any point. The released amino acids join the free pool and are used according to whatever the body is synthesising.
One small class of fragments does get through whole. Pro-Hyp is the main one, and it appears in blood within an hour of a dose.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Iwai et al. measured peptide-form hydroxyproline rising from negligible to 20 to 60 nmol/mL of plasma at one to two hours, falling to half by four hours, with Pro-Hyp the dominant species and Ala-Hyp, Ala-Hyp-Gly, Pro-Hyp-Gly, Leu-Hyp, Ile-Hyp and Phe-Hyp also detected. The bond adjacent to hydroxyproline is relatively resistant to prolidase, which is the accepted explanation for the survival.
The live hypothesis is that these fragments act as a signal to the cells that build collagen, telling them to get to work, rather than being used as bricks.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Pro-Hyp has been reported to act on dermal fibroblasts and chondrocytes as a chemotactic and proliferative stimulus. The critical unresolved question is concentration: the plasma level achieved is 20 to 60 nmol/mL peptide-form hydroxyproline, and much of the supportive in vitro work has used concentrations well above that. An effect at a concentration humans do not reach is not a mechanism.
The fibroblast builds collagen from scratch, needing vitamin C
Whatever the signal, the actual construction uses ordinary amino acids and cannot proceed without vitamin C, which is what the hydroxylating enzymes require.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Procollagen chains are assembled from glycine, proline and lysine, then hydroxylated at proline and lysine residues by Fe(II)- and 2-oxoglutarate-dependent dioxygenases that require ascorbate to maintain the active-site iron. This is why Shaw et al. supplemented gelatin with vitamin C rather than alone, and why the deficiency that stops collagen synthesis is a vitamin C deficiency, not a collagen deficiency.
What the positive trials measure is skin hydration and elasticity by probe, a blood marker of collagen turnover, and pain scores — not the collagen content of anyone's skin.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
The pooled skin analysis of 19 trials in 1,125 participants used corneometer hydration, cutometer elasticity and wrinkle measurement. Shaw used serum P1NP and engineered ligament mechanics. Konig used DXA T-score changes of about 0.1. No trial in this literature has biopsied human skin and shown increased collagen content after oral collagen.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 5 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What it would be like to take◇Read from sources, not yet reviewed
Felt, measured, or meaningful
Three different things that get called the same word. Registered studies measured all three, and mixing them is how a blood test becomes a health claim.
Felt
Things a person could notice without a test.
No registered study measured anything of this kind.
Measured
Things only a test, a scale or a device shows.
muscle mass
Meaningful
Things that change how a life goes, not only a number.
No registered study measured anything of this kind.
A registered study says what someone planned to measure. It does not say what they found. A number moving is not the same as a life going better. The two are shown apart here.
Felt, but not shown to help. A person notices a change. No study showed it leads anywhere good.
Measured, but not felt. A number moves. The person notices nothing. Both can be true.
Measured, but not shown to matter. A number moves in the good direction. Nobody showed that lives went better.
Matters, but takes years. The result that counts may take longer than anyone would keep watching.
Names that fit none of the three (1)
telomere length
These are harms, study-process measures, or names the rules did not recognise. They are shown rather than dropped.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
Overwhelmingly women — 95% of participants in the pooled skin-ageing trials were female. Also athletes taking gelatin for tendon and ligament, older adults for joints and bone, and a large market taking it in coffee for no defined endpoint.
Who is missing from the studies
Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
Where the result stopped carrying
The building-block account of how collagen supplements work, which digestion and the amino acid profile both refute
The Clark joint-pain trial's randomisation, which did not survive losing a third of its subjects before analysis
This is a scope explorer, not a diagnosis engine.
It shows who was studied so you can see whether people similar to you were included.
RNAWiki cannot tell whether a study fits you. It can show who was in it.
What it would be like to take◇Read from sources, not yet reviewed
Why it might seem to do nothing
A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.
It was studied for a different goal
The studies measured something else entirely.
On this record: Some registered studies measured things that match no goal on this page.
It was studied in different people
The people in the studies were not much like the reader.
On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
The evidence may simply be wrong
Small early studies often do not hold up.
On this record: RNAWiki has not yet published a reviewed conclusion for this use.
The product may not be what it says
Contents of a sold product are not always what the label states.
On this record: This is sold as a supplement, so no agency checked what is in a given tub before it was sold.
Other reasons RNAWiki checked and found nothing for (9)
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
There was nothing to correct
Where a level is already normal, topping it up may change nothing. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.
None of these is a reason to take more. Taking more is not a step this page ever suggests.
What it would be like to take◇Read from sources, not yet reviewed
What taking it involves
The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.
How it is supplied
Varies by country
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Read from the recorded approval status.
No source is stored against this line.
Form and route
Oral powder, capsule or liquid; bovine, porcine or marine hydrolysate
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
Not usually supervised: sold as a supplement or food ingredient where recorded. That is a legal category, not a safety judgement.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
The identity record classes it as a supplement ingredient; no medicines register records an approval.
No source is stored against this line.
What is in the pack
Sold in the United States as a dietary supplement under DSHEA, so no agency reviewed efficacy, safety or content before sale. Species of origin is a real variable — it changes the amino acid profile, the allergen profile and the religious-dietary status — and is often absent from the label. Molecular weight distribution decides how much of a product is free amino acid and how much is the intact dipeptide the mechanism depends on, and is essentially never disclosed. Branded ingredients such as Verisol and Fortigel are specific hydrolysates whose trial evidence does not transfer to unbranded hydrolysate.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold and what that means for what is in the pack.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
Generally well tolerated, with mild gastrointestinal complaints and an unpleasant taste the commonest reports. Marine collagen carries genuine fish allergen risk. As an animal by-product it is not vegetarian regardless of how the tub is styled. The substantive risk is nutritional rather than toxicological: collagen lacks tryptophan, so replacing complete protein with it degrades dietary protein quality, and the industry's own analysis puts the substitution ceiling at 36% of daily protein. Independent testing of protein powders as a category has repeatedly found arsenic, cadmium, mercury and lead.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.
Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What is missing or unclear◇Read from sources, not yet reviewed
Does the exact form matter?
Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.
The form that was studied
Oral powder, capsule or liquid; bovine, porcine or marine hydrolysate
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
Species of origin is a real variable — it changes the amino acid profile, the allergen profile and the religious-dietary status — and is often absent from the label. Molecular weight distribution decides how much of a product is free amino acid and how much is the intact dipeptide the mechanism depends on, and is essentially never disclosed. Branded ingredients such as Verisol and Fortigel are specific hydrolysates whose trial evidence does not transfer to unbranded hydrolysate.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on which forms are sold and how they compare.
No source is stored against this line.
What is recorded as being sold
3723 marketed supplement labels list this ingredient, classed as amino acid/protein, botanical with nutrients, other combinations and protein.
Those labels carry all other, nutrient and structure/function claims. A claim of that kind is written by the manufacturer and is not assessed by any regulator, so its presence says nothing about whether it is true.
Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.
What it would be like to take◇Read from sources, not yet reviewed
What you could measure
Watching one thing carefully can tell you whether it moved. It cannot tell you what moved it.
This is sold without a prescription, so a person can sensibly watch one thing and see whether it moves.
Pick one goal. One goal only. Two at once cannot be told apart afterwards.
Pick one thing to watch. Registered studies measured things like: muscle mass.
Measure before you start. Take the same measurement several times first. One reading is not a starting point.
Know the swing. Write down how much it moves on its own across a normal week.
Change one thing. Change nothing else at the same time, including training and sleep.
Give it the study length. No finished study window is recorded, so no length is suggested here.
Track whether you took it. Missed days are the most common reason a home test shows nothing.
Read the trend. Look at the line across weeks. A single reading tells you almost nothing.
What not to measure
Anything that swings more day to day than the change you are looking for.
A wearable estimate of sleep stages, which is an estimate and not a measurement.
Weight on one morning, which mostly records water.
A feeling you did not write down before starting.
When to stop
Stop if something new and unpleasant starts, and ask a pharmacist or doctor.
Stop if you cannot keep everything else steady, because the result will not mean anything.
Stop at the end of the window you set, and read the trend then.
Tracking can show whether something changed for you. It cannot show what caused it.
RNAWiki does not work out an amount for anyone.
What is missing or unclear◇Read from sources, not yet reviewed
Claims that go past the evidence
Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.
✗Goes past the evidence
That swallowed collagen is delivered to skin, joints or bone as collagen — digestion rules this out
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That an increase in a serum collagen-synthesis marker demonstrates stronger tendon in a person
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That a 0.1 T-score change in one manufacturer-affiliated trial establishes a bone density intervention
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That collagen can substitute for complete protein in a daily total
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
What is missing or unclear◇Read from sources, not yet reviewed
What nobody knows yet
Open questions, each with why it is open and what would close it.
How much did people take in the studies?
The sources RNAWiki checked hold nothing for this field.
Why it matters. A result belongs to an amount. Without the amount the result floats free.
What would answer it
A stored source that records it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
How fast does the body clear it?
The sources RNAWiki checked hold nothing for this field.
Why it matters. Without this, nothing on this page can say how long anything lasts.
What would answer it
A stored source that records it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing populations
Which groups were under-represented in the studies has not been recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing long-term data
No completed tested study window is recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
No reviewed conclusion
RNAWiki has not yet published a reviewed conclusion for this use.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing interaction studies
No interaction was found in the registers checked. Not finding one is not the same as showing there is none.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Formulation uncertainty
Several salts, forms or products of Collagen peptides are recorded. Results from one form may not transfer to another.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Mechanism not reviewed
No reviewed mechanism story exists for this substance.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
What happened in people◇Read from sources, not yet reviewed
Check any of this yourself
Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.
Every line above can be traced to the study named beside it. Follow the link and read it.
The industry's own paper: collagen has no tryptophan and is an incomplete protein
In plain words
A paper written by authors at a collagen manufacturer and a collagen research institute states plainly that collagen protein lacks an essential amino acid and is therefore incomplete.
What was measured
That collagen peptides are a protein supplement comparable to whey or dairy protein, when the manufacturer-authored analysis classifies them as an incomplete protein source
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Paul, Leser and Oesser — affiliated with the Collagen Research Institute GmbH in Kiel and GELITA AG, a collagen manufacturer — wrote that "according to the current protein quality evaluation method PDCAAS, collagen protein lacks one indispensable amino acid (tryptophan) and is therefore categorized as an incomplete protein source" and that it "displays a low indispensable amino acid profile." Their iterative PDCAAS calculation concluded that up to 36% of daily dietary protein could be replaced by collagen peptides while still meeting indispensable amino acid requirements, and that the effective doses in the literature, 2.5 to 15 g per day, fall below that ceiling. Read carefully, this is a paper establishing an upper safe substitution limit, published by the people who sell the product, and it concedes the central nutritional fact: collagen is a poor protein. Any consumer counting a collagen scoop toward a daily protein target is substituting an incomplete protein for a complete one.
Written into the record, not signed off as a reviewed claim
Pro-Hyp really does survive digestion and reach the blood
In plain words
The one part of the collagen story that holds up mechanically: specific two- and three-amino-acid fragments containing hydroxyproline appear intact in human blood after a dose, peaking at one to two hours.
What was measured
Plasma concentration of peptide-form hydroxyproline and identity of the surviving peptides after gelatin hydrolysate ingestion
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Iwai and colleagues had healthy volunteers ingest 9.4 to 23 g of gelatin hydrolysate from porcine skin, chicken feet or cartilage after a 12-hour fast. Peptide-form hydroxyproline was negligible in blood before ingestion, rose significantly afterward to a maximum of 20 to 60 nanomoles per millilitre of plasma at one to two hours, and fell to half that by four hours. The major constituent identified in serum and plasma was Pro-Hyp, with smaller but significant amounts of Ala-Hyp, Ala-Hyp-Gly, Pro-Hyp-Gly, Leu-Hyp, Ile-Hyp and Phe-Hyp. This is a real, cleanly measured pharmacokinetic finding and it is the only credible foundation for any collagen mechanism. What it demonstrates is that small peptides survive, not that collagen is delivered. The step from "Pro-Hyp is in the blood at 20 to 60 nmol/mL" to "therefore skin collagen increases" is not measured anywhere in this literature.
Written into the record, not signed off as a reviewed claim
Nineteen skin trials, 1,125 people, favourable — and 95% were women
In plain words
Pooling nineteen randomised double-blind trials, collagen supplementation improved skin hydration, elasticity and wrinkles compared with placebo. Almost every participant was a woman.
What was measured
Instrument-measured skin hydration, elasticity and wrinkle outcomes versus placebo across 19 randomised trials
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
De Miranda and colleagues searched Medline, Embase, Cochrane, LILACS and the Journal of Negative Results in BioMedicine, restricting inclusion to randomised, double-blind, controlled trials of oral hydrolysed collagen reporting skin wrinkles, hydration, elasticity or firmness. Nineteen studies with 1,125 participants aged 20 to 70 were included, of whom 95% were women. Grouped analysis showed favourable results for hydrolysed collagen against placebo on skin hydration, elasticity and wrinkles, and the hydration and elasticity findings were confirmed in subgroup meta-analysis. That is a genuinely positive pooled result and this page records it as such. Three qualifications belong beside it: the outcomes are instrument-measured surrogates rather than clinical endpoints, the trials are short relative to skin ageing, and the collagen trial literature is unusually concentrated among manufacturer-affiliated investigators, which the pooled analysis does not correct for.
Written into the record, not signed off as a reviewed claim
The tendon result is eight men, and the tissue tested was engineered in a dish
In plain words
The most-cited study behind "collagen for tendons" had eight subjects. The strengthening was measured not in their tendons but in laboratory-grown ligaments soaked in their blood serum.
What was measured
Plasma amino acid response, serum P1NP, and mechanical properties of engineered ligaments treated with subject serum
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Shaw and colleagues ran a randomised, double-blinded crossover in eight healthy male subjects consuming 5 g or 15 g of vitamin-C-enriched gelatin or placebo, three times daily with at least six hours between exercise bouts, over three days, each dose followed an hour later by six minutes of rope-skipping. Circulating glycine, proline, hydroxyproline and hydroxylysine all rose, peaking one hour after the supplement. Serum drawn before and one hour after gelatin was then used to treat engineered ligaments in culture, and amino-terminal propeptide of collagen I was measured in blood at 4, 24, 48 and 72 hours after the first exercise bout. The design is elegant and the finding is interesting. It is also eight men, a three-day exposure, a surrogate blood marker of collagen synthesis, and a mechanical measurement performed on tissue constructs rather than on any human tendon. The gap between that and "collagen strengthens your tendons" is the whole of this audit.
Written into the record, not signed off as a reviewed claim
The bone trial moved a T-score by one tenth, and was co-authored at the manufacturer's institute
In plain words
A twelve-month trial in postmenopausal women reported a statistically significant increase in bone density on collagen peptides. The size of the change was about a tenth of a T-score point.
What was measured
Change in spine and femoral neck bone mineral density T-score and in P1NP over 12 months
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Konig and colleagues randomised 131 postmenopausal women with age-related reduction in bone mineral density to 5 g of specific collagen peptides or placebo daily for 12 months; 102 completed and all were included in the intention-to-treat analysis (mean age 64.3 +/- 7.2 years, spine T-score -2.4 +/- 0.6, femoral neck T-score -1.4 +/- 0.5). Spine T-score changed by +0.1 +/- 0.26 on collagen peptides against -0.03 +/- 0.18 on control (ANCOVA P = 0.030) and femoral neck by +0.09 +/- 0.24 against -0.01 +/- 0.19 (P = 0.003). P1NP rose significantly in the treated group (P = 0.007). The statistics are real and the effect is at the edge of what densitometry resolves: the standard deviations exceed the mean changes, and a tenth of a T-score is well inside the precision error of most DXA scanners for repeat measurement. The corresponding author is affiliated with the Collagen Research Institute GmbH, and this is the single trial on which the bone claim rests.
Written into the record, not signed off as a reviewed claim
The joint-pain trial lost a third of its subjects before analysis
In plain words
A widely cited 24-week study of collagen for joint pain in athletes recruited 147 people. Only 97 could be statistically evaluated.
What was measured
Change in visual analogue scale scores for joint pain, mobility and inflammation over 24 weeks
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Clark and colleagues at Penn State ran a prospective, randomised, placebo-controlled, double-blind study in 147 varsity and club-sport athletes with activity-related joint pain and no evidence of joint disease, comparing 25 mL of a liquid containing 10 g of collagen hydrolysate against a xanthan-containing placebo over 24 weeks, with visual analogue scales as the primary efficacy parameter. Data from only 97 of the 147 subjects could be statistically evaluated. Losing a third of a randomised sample before analysis breaks the protection randomisation provides, because the people who drop out of a study of joint pain are not a random subset of people with joint pain. A visual analogue pain score is also the outcome most responsive to expectation, in a population that knew it was in a supplement trial. The trial is cited throughout the category as establishing a joint benefit; what it establishes is that a large attrition-affected trial reported a subjective improvement.
Written into the record, not signed off as a reviewed claim
The mechanism moved from building block to signal, and the marketing did not
In plain words
The original idea was that eating collagen supplies collagen to skin. That is not what happens. The surviving scientific hypothesis is that small fragments act as chemical messages, which is a different claim with far less support.
What was measured
That eating collagen supplies collagen to skin, joints or bone, which digestion rules out
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Two facts closed the building-block account. First, dietary protein of any kind is hydrolysed to free amino acids and small peptides before absorption, and collagen has no exemption; the amino acids released enter the general pool and are used for whatever the body is synthesising. Second, collagen is a poor source of those amino acids in the first place, lacking tryptophan entirely, as the manufacturer-affiliated PDCAAS analysis states. What replaced it is the signalling hypothesis: Iwai's measured Pro-Hyp in plasma at 20 to 60 nmol/mL, acting as a ligand or a chemotactic signal to fibroblasts and chondrocytes rather than as material. That hypothesis is legitimate, is being actively tested, and is a much weaker claim than the one on the packaging. It also predicts something the marketing does not: if the active entity is a specific dipeptide, then hydrolysate composition and molecular weight distribution matter enormously and products are not interchangeable.
This order is fixed in code and does not count clicks or time on the page.
What is not here
5 questions this page could not answer
These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.
How long anything takes — found nothing in the sources checked.
What it may clash with — found nothing in the sources checked.
Other ways to the same goal — found nothing in the sources checked.
How this medicine reached us — found nothing in the sources checked.
What changed on this page — found nothing in the sources checked.
The record as stored
The full record, for auditing
Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.
The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
Swallowed collagen is digested like any other protein and, by the admission of a paper written at a collagen manufacturer, lacks tryptophan entirely and is an incomplete protein; a pooled analysis of 19 trials in 1,125 people does find favourable skin hydration, elasticity and wrinkle results, and the mechanism that could explain it is a dipeptide signal rather than any delivery of collagen to skin.
Recorded evidence blocks (8)
Q1
What did Collagen peptides's largest trial (125 people) and its longest (2.3 years) measure?
125 people in Collagen peptides's largest registered study, 2.3 years in its longest registered window, measuring Peak plasma concentration after administration (Cmax) for hydroxyproline after single dose of the different collagen peptides. ClinicalTrials.gov · 2026-09-01
6 na; NCT07456449; 2028-08. Last human test completed 2025, NCT07195396.
Interpretation These counts include studies where Collagen peptides was a comparison treatment, a background treatment or an exposure in an observational study, and the longest window may be a planned end date. Trial roles have not yet been classified for this record.
Show the evidence
na
6
Last recorded human testNCT07195396
2025-12-22
recorded 2026-09-01 · last checked 2026-09-04
Q2
From C. elegans to human: where has Collagen peptides shown lifespan?
Interpretation Peak plasma concentration after administration (Cmax) for hydroxyproline after single dose of the different collagen peptides — the recorded outcome words.
Show the evidence
C. elegans
lifespan
mouse
mechanism-only
humanNCT04097808
biomarker; Peak plasma concentration after administration (Cmax) for hydroxyproline after single dose of the different collagen peptides; 6
recorded 2026-09-01 · last checked 2026-09-04
Q3
Could one person measure Collagen peptides's effect on muscle mass?
Muscle mass: measured in Collagen peptides's trials.
Interpretation muscle mass is the recorded endpoint.
Show the evidence
biomarkers
muscle mass; 2026-09-01
telomere length; 2026-09-01
human trials at or under30
4
Not recorded for this substance
a recorded half-life
smallest human trial
3; NCT07195396; NA; the smallest recorded human enrolment at or below 30; the registry states no direction of its result; COMPLETED
Q4
What will the one ongoing trial of Collagen peptides report, and when?
"Collagen Peptides and Cellular Aging"; n 125; "Telomere length"; 2028-08
recorded 2026-09-01 · last checked 2026-09-04
Q5
Which 4 trials of Collagen peptides posted no result?
Posted no result
4 of 4 completed trials
Registrations
NCT03994198, NCT04097808, NCT05252962 and NCT07171411
Completion dates
oldest 2018-08-30; newest 2024-04-10
Show the evidence
Trial
NCT03994198
2018-08-30
NCT04097808
2019-10-25
NCT05252962
2023-05-17
NCT07171411
2024-04-10
Q6
At the median, Collagen peptides's trials enrolled 12.5 people — anything larger?
Median enrolment
12.5
Largest enrolment
125
Registered trials counted
6
Q7
Was Collagen peptides studied with exercise?
exercise is named in Collagen peptides's label sentences: "The current findings revealed a significantly higher upregulation of key anabolic pathways (PI3K-Akt, MAPK) in human skeletal muscle 4 h following an acute resistance training combined with intake of 15 g of specific collagen peptides compared to placebo." openfda-label+europepmc · 2022-04-05
1 recorded statement; exercise
Show the evidence
exercise
The current findings revealed a significantly higher upregulation of key anabolic pathways (PI3K-Akt, MAPK) in human skeletal muscle 4 h following an acute resistance training combined with intake of 15 g of specific collagen peptides compared to placebo.
recorded 2022-04-05 · last checked 2026-09-04
Q8
What is recorded about Collagen peptides and NAD+?
"This review examines the validity of an integrative "In and Out" approach, combining topical treatments, such as retinoids, peptides, antioxidants, and exosome-based formulations, with internal nutraceuticals including NAD<sup>+</sup> precursors, collagen peptides, polyphenols, and microbiome modulators." — where Collagen peptides and NAD+ appear together. Europe PMC · pathway abstract search · 2026-04-02
NAD+, IGF-1; PMID 41926038, 37888466
Show the evidence
NAD+PMID 41926038
"This review examines the validity of an integrative "In and Out" approach, combining topical treatments, such as retinoids, peptides, antioxidants, and exosome-based formulations, with internal nutraceuticals including NAD<sup>+</sup> precursors, collagen peptides, polyphenols, and microbiome modulators."
IGF-1PMID 37888466
"The present study clearly shows that fish collagen peptides (FCPs) stimulate activities of thymic epithelial cells (TECs), including cell proliferation, thymocyte adhesion, and the gene expression of thymopoietic factors such as FGF-7, IGF-1, BMP-4, VEGF-A, IL-7, IL-21, RANKL, LTβ, IL-22R, RANK, LTβR, SDF-1, CCL21, CCL25, CXCL5, Dll1, Dll4, Wnt4, CD40, CD80, CD86, ICAM-1, VCAM-1, FoxN1, leptin,…"
recorded 2026-04-02 · last checked 2026-09-04
Where it is registeredIdentifiers, relations and other names
Trade name
Sold as hydrolysed collagen, collagen hydrolysate, gelatin hydrolysate or "specific collagen peptides"; brand ingredients include Verisol, Fortigel and CH-Alpha
Sources (7)
Sources
ClinicalTrials.govClinicalTrials.gov API v2 snapshot 2026-09-01T09:00:05 ·
ClinicalTrials.gov — US Government work · Europe PMC — metadata only, under the recorded legal gate · derived from this page's own recorded fields; no external licence · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
✗ required summary fields resolved: 4 required field(s) not terminal: Why people use it, Best-supported result, Biggest unanswered question, Human evidence
✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 7 source rows
✓ no critical contamination: no quarantine open
✓ canonical metadata passed: slug and display name present
✓ no raw internal fields: enforced by the copy-contract test over the rendered page
This is a record of evidence. It is not medical advice, and it does not say this substance suits you. Nothing here says any substance on RNAWiki is appropriate for a child.