Gelatin is collagen that heat has unwound and partly broken down: it dissolves in hot water and sets as it cools. Collagen peptides are cut much further, by enzymes, and dissolve without setting. Gram for gram the amino acids barely move: in one 2019 analysis, 20 g of gelatin carried 4,750 mg of glycine and 20 g of peptides 4,904 mg (Alcock and colleagues, Front Nutr 2019).
That makes this one of the few comparisons in the category with a short answer, and the more useful question sits underneath it. The study most collagen dosing advice traces back to used gelatin. A 15-week trial of the same dose used peptides. Which form did what matters more than the chemistry, and the two trials differ in far more than their form.
Is gelatin the same as collagen?
Not quite: gelatin is collagen that heat has changed. Intact collagen is three protein chains wound together, a molecule of about 300,000 daltons, and heating above about 40 degrees Celsius separates the chains (a 2019 review in Molecules). Partly broken down, they become gelatin, which melts and sets at temperatures below body temperature (Boran and Regenstein, Adv Food Nutr Res 2010). The amino acids are still collagen’s own.
What is the difference between collagen peptides and gelatin?
How far the chains have been cut. Gelatin’s chains are long enough to tangle into a gel as they cool. Collagen peptides are cut further by enzymes, typically to 3,000 to 6,000 daltons, which leaves a thin liquid that does not set; the 2019 review in Molecules lists hydrolysed collagen’s viscosity as low against intact collagen’s high. The four powders in a 2024 absorption study were all made by cutting gelatin with enzymes (Virgilio and colleagues, Front Nutr 2024).
| Property | Gelatin | Collagen peptides |
|---|---|---|
| What it is | Collagen unwound by heat and partly broken down | Gelatin cut further by enzymes |
| Molecular size | Long chains that tangle into a gel | About 3,000 to 6,000 daltons |
| In water | Dissolves warm, sets as it cools | Dissolves, does not set |
| Glycine in 20 g | 4,750 mg | 4,904 mg |
| Proline in 20 g | 2,664 mg | 2,722 mg |
| Peak blood glycine after 20 g | 674 micromoles per litre | 747 micromoles per litre |
| Time to that peak | 71 minutes | 48 minutes |
| Head-to-head marker trial, n = 10 | About 20% rise, not significant | About 20% rise, not significant |
| Tendon-question trial cited here | 2017: blood marker, 8 men | 2023: MRI, 39 men, no difference |
The amino acid and blood rows come from Alcock and colleagues, Front Nutr 2019, who gave 15 recreationally active men 20 g of each form, in random order at least 48 hours apart, after an overnight fast, and sampled their blood every 20 minutes for three hours. The marker row is from Lis and Baar, 2019, and the last row from Shaw and colleagues, 2017, and Balshaw and colleagues, 2023, all set out below. None of these measured a tissue.
Is hydrolyzed collagen the same as collagen peptides?
Yes. Hydrolysed collagen, collagen hydrolysate and collagen peptides are three names for one product: collagen, usually by way of gelatin, cut by enzymes into short chains. The 2019 review in Molecules describes it as a group of peptides of 3,000 to 6,000 daltons obtained by enzymatic action. A label that uses one name rather than another is making a word choice, not a chemical distinction; what differs between products is the raw material and how far it was cut.
Which is better, collagen peptides or gelatin?
Neither, on the evidence that exists. Lis and Baar gave ten men 15 g of vitamin-C-enriched gelatin or hydrolysed collagen an hour before six minutes of skipping; a blood marker of collagen synthesis tended to rise about 20% with both, and large variability left neither significant (Int J Sport Nutr Exerc Metab 2019). In Alcock’s 2019 trial, 20 g of each gave blood amino acid peaks of similar height, with glycine peaking later after gelatin.
The authors of the second trial put it plainly: “we did not find any difference in the bioavailability of gelatin compared to a hydrolysed peptide powder.” The one difference they did find was timing. Glycine peaked at 71 minutes after gelatin and 48 minutes after peptides, a gap of 23 minutes that reached significance in 15 men. Whether it matters anywhere beyond the blood was not examined.
The first trial carried a third arm worth knowing about: a gummy made of equal parts gelatin and hydrolysed collagen, which did not raise the marker at all. The trial was ten men, the marker was measured four hours after skipping, and amino acids were measured in only four of them. Its authors opened by noting that the scientific validity of such strategies “lags behind their hype.”
Did the best-known collagen dosing study use gelatin or collagen peptides?
Gelatin. Shaw and colleagues, Am J Clin Nutr 2017, gave eight healthy men 5 g or 15 g of vitamin-C-enriched gelatin, or a placebo, an hour before six minutes of rope-skipping, three times a day for three days. The 15 g dose roughly doubled PINP, a blood marker the authors read as collagen synthesis. That is eight men and a marker in blood, not a tendon; a later 15-week trial of 15 g of peptides that imaged the tendon by MRI found no difference from placebo.
That later trial is the one to set beside it. Balshaw and colleagues, Med Sci Sports Exerc 2023, randomised 39 young men to 15 g of collagen peptides or placebo a day through 15 weeks of lower-body resistance training, three sessions a week, and imaged the tendon by MRI: no between-group difference on any tendon measure. Tendon stiffness rose in both groups, by 17.3% with peptides and 20.9% with placebo, which is what the training did on its own.
Put those two side by side and the form is the smallest of the differences. Three days against 15 weeks. A blood marker against an MRI scan. Eight men against 39. Neither trial compared gelatin with peptides, so the null at 15 weeks cannot be blamed on the peptides any more than the rise in the marker can be credited to the gelatin. The trials that did compare the forms directly are the small ones above, and they found the forms alike.
Does collagen peptide powder mix better than gelatin?
Yes, for a drink. Gelatin melts and sets at temperatures below body temperature (Boran and Regenstein, 2010), so a 15 g dose has to go into warm liquid and be drunk before it sets, or be eaten as a set jelly. Peptides dissolve without setting, so the same dose can stand in a glass. In Alcock’s 2019 trial every protein, gelatin included, was served warm in 300 mL of fluid to keep the conditions identical.
Mixing is the main practical difference, and it is a kitchen difference rather than a physiological one. The volume question that changes what a person actually receives belongs to food sources, where the dose is not printed anywhere, and it is answered with measured amounts in collagen vs bone broth. How to read the serving line that makes a powder’s dose knowable is covered in the supplement label glossary.
What the research does not show
- A tissue-level head-to-head. The two direct comparisons measured a blood marker in ten men and blood amino acids in fifteen. No trial has compared gelatin with peptides on a tendon or any other tissue.
- Anything about form from the famous pair. The 2017 marker study used gelatin and the 15-week MRI trial used peptides, but they differ in length, measurement and size, so the form can be neither credited nor blamed.
- That blood levels translate. A higher or earlier peak in plasma is a fact about the blood. Whether 747 micromoles per litre of glycine does more than 674 anywhere else in the body was not measured.
- That smaller is better. In the 2024 comparison, the same cattle collagen cut to 2,000 or 5,000 daltons gave highly comparable fragment levels in blood, in six people, in a study funded by the company that made both powders.
Where Under Load sits
Under Load is collagen peptides, not gelatin: bovine, Type I and III, one ingredient, 350 g. The declared serving on its panel is 10 g, two 5 g scoops, 35 servings. The protocol on this site is a directions statement rather than a serving: 15 g, three scoops, 30 to 60 minutes before training, with 50 to 100 mg of vitamin C, which is 23 whole doses per tub. Its locked panel also says what peptides do in cold water: collagen does not mix well in it, so warm water first, ice after.
More in this cluster: bovine vs marine collagen, collagen types explained, how much collagen for tendons, how to choose a collagen supplement, the collagen research, summarised and every supplement form compared.
Sources
- Leon-Lopez A, Morales-Penaloza A, Martinez-Juarez VM, et al. Molecules 2019;24(22):4031. PubMed 31703345
- Boran G, Regenstein JM. Adv Food Nutr Res 2010;60:119-143. PubMed 20691955
- Virgilio N, et al. Front Nutr 2024;11:1416643. PubMed 39149544
- Alcock RD, Shaw GC, Tee N, Burke LM. Front Nutr 2019;6:163. PubMed 31681789
- Lis DM, Baar K. Int J Sport Nutr Exerc Metab 2019;29(5):526-531. PubMed 30859848
- Shaw G, Lee-Barthel A, Ross ML, et al. Am J Clin Nutr 2017;105(1):136-143. PubMed 27852613
- Balshaw TG, Funnell MP, McDermott EJ, et al. Med Sci Sports Exerc 2023;55(11):2083-2095. PubMed 37436929