Collagen Types Compared: I vs II vs III, Marine vs Bovine
Not medical advice. This summarizes published trials and the labels manufacturers file with the NIH. Talk to a clinician before starting a supplement, especially for joint disease.
Quick answer
There are only two collagen products the trials support, and they are not interchangeable. For skin, bone, nails and body composition: hydrolyzed Type I/III peptides at 2.5–10 g/day (bovine or marine; no head-to-head trial separates them). For joints: undenatured Type II at 40 mg/day, a different molecule with a different mechanism, where milligrams are the right dose and grams of peptides do not substitute.
Everything else on the tub is sourcing or marketing. We read 746 collagen labels filed with the NIH. Only 43.2% declare a type at all. 12.3% sell “multi-collagen” blends that are bovine and fish peptides by weight, and of the multi-type blends that claim Type II, only 2.2% use the undenatured form the knee trials tested. See the census →
Already know your type? See the ranked collagen picks →
On this page
Why one collagen is dosed in grams and the other in milligrams
The confusion on this shelf comes from one word, “collagen”, covering two products that do different things in the body.
Hydrolyzed peptides are a nutrient. Your gut breaks most of a 10 g scoop into free amino acids, but a measurable fraction survives as short collagen-specific peptides, prolyl-hydroxyproline (Pro-Hyp) and hydroxyprolyl-glycine (Hyp-Gly), that have been identified in human blood after ingestion (PMID 16076145, 25212331) and confirmed in a 2024 randomized crossover (PMID 39149544). Those peptides are thought to signal fibroblasts and chondrocytes. The trials use grams because the body needs both the raw material and the signal, and the outcome is slow: 8–12 weeks for skin, 12 months for bone.
Undenatured Type II is an immune signal. Kept in its native folded shape, the intact triple helix is recognized by immune tissue in the gut and induces oral tolerance, the same effect first shown when patients with rheumatoid arthritis were fed small amounts of Type II collagen in a 1993 Science trial (PMID 8378772), and later characterized for the UC-II ingredient (PMID 12837047). A signal needs only a tiny dose, which is why 40 mg works, and why heating or hydrolyzing Type II destroys the structure that makes it work.
Most label claims sort themselves once you know which of the two you are looking at.
Every collagen type on a label, compared
| Type | Source & form | Sold for | What the trials show | Studied dose | Verdict |
|---|---|---|---|---|---|
| Type I | Bovine hide; fish skin and scales Hydrolyzed peptides (grams) | Skin, hair, nails, bone | Best-supported use. A placebo-controlled trial of 2.5 g or 5 g/day of specific peptides improved skin elasticity in 69 women aged 35–55 over 8 weeks; a 12-week trial of 2.5 g in a blend with vitamin C, zinc and biotin improved hydration, elasticity, roughness and density. Meta-analyses of 19 and 26 RCTs (1,125 and 1,721 participants) confirm modest hydration and elasticity gains; the 2023 analysis flags bias in the included trials. A 12-month RCT of 5 g/day raised spine and femoral-neck bone density in 131 postmenopausal women. (PMID 23949208, PMID 31627309, PMID 33742704, PMID 37432180, PMID 29337906) | 2.5–10 g/day (skin), 5 g/day (bone) | The product the skin and bone evidence is about. Bovine hide supplies it with Type III; fish supplies it nearly alone. |
| Type II — undenatured (UC-II) | Chicken sternal cartilage Native, unhydrolyzed (milligrams) | Joints, knee comfort | Works by oral tolerance — the intact triple helix is an immune signal, not a building block. 40 mg/day beat placebo and glucosamine 1,500 mg + chondroitin 1,200 mg on total WOMAC in 191 people with knee osteoarthritis over 180 days, and improved knee extension in healthy adults with activity-related discomfort. (PMID 26822714, PMID 19847319, PMID 24153020, PMID 8378772, PMID 12837047) | 40 mg/day | A different product with a different mechanism. Milligrams are the correct dose, not an underdose. Grams of hydrolyzed collagen do not substitute for it. |
| Type II — hydrolyzed | Chicken cartilage Hydrolyzed peptides (grams) | Joints | No trial isolates hydrolyzed Type II. The gram-dose joint trials (10 g/day for 24 weeks in athletes; 5 g/day in physically active adults) used Type I/III-dominant collagen hydrolysate, not Type II. (PMID 18416885, PMID 28177710, PMID 33562729) | 5–10 g/day (as generic hydrolysate) | Buy it as generic collagen peptides. The "Type II" on the label is not what the joint evidence tested. |
| Type III | Bovine hide, alongside Type I Hydrolyzed peptides (grams) | Skin, gut, blood vessels | Arrives with Type I in every bovine-hide hydrolysate; the skin and bone trials above used Type I/III mixtures. No trial isolates Type III or shows it adds anything to Type I. (PMID 23949208, PMID 29337906) | Not separately studied | A word on the label, not a product. "Type I & III" and "Type I" bovine peptides are the same thing. |
| Type V and Type X | Eggshell membrane (V, X); chicken cartilage (X) Hydrolyzed, inside "multi-collagen" blends | "All five types" / "complete collagen" | No human outcome trial of Type V or Type X as a supplement. They appear in trace amounts inside eggshell-membrane and cartilage ingredients; the blends that list them are, by weight, bovine and fish Type I/III peptides. | None | Marketing. Pay for the grams of Type I/III in the blend, not for the count of types on the front. |
“Type II” is two different products. The undenatured form (branded UC-II, from chicken sternal cartilage) is what the knee-osteoarthritis trials used: 40 mg/day for 180 days beat both placebo and glucosamine 1,500 mg plus chondroitin 1,200 mg on the total WOMAC score in 191 people (PMID 26822714), and improved knee extension in 55 healthy adults with activity-related knee pain over 120 days (PMID 24153020). Hydrolyzed “Type II” powder sold in grams has no trial of its own; the gram-dose joint studies used Type I/III-dominant hydrolysates: 10 g/day for 24 weeks in athletes (147 randomized, 97 evaluable; PMID 18416885) and 5 g/day in physically active adults (PMID 28177710, 33562729).
Type III is not a decision you get to make. Bovine hide contains Type I and Type III together, so every “Type I & III” bovine peptide is chemically the same product as a bovine “Type I” peptide. The 8-week skin trial that improved elasticity at 2.5 and 5 g/day (PMID 23949208) and the 12-month trial that raised spine and femoral-neck bone density in postmenopausal women at 5 g/day (PMID 29337906) both used that mixture. Nothing isolates Type III.
Bovine vs marine vs chicken vs eggshell: what the source actually changes
Source decides which types you get and what the product costs; it does not, on current evidence, decide whether it works.
| Source | Types | Form | Evidence specific to the source | Practical |
|---|---|---|---|---|
| Bovine (hide) | I and III | Hydrolyzed peptides, gelatin | The most-studied source: the 2.5–5 g skin trials and the 5 g bone trial used bovine-derived peptides. (PMID 23949208, PMID 29337906) | Cheapest per gram; not suitable for pescatarians, kosher/halal buyers need a certified product. |
| Marine (fish skin, scales) | Mostly I | Hydrolyzed, often low molecular weight | Positive skin RCT at 1 g/day of a low-molecular-weight fish peptide over 12 weeks in 64 people. In a 5-man crossover, fish-scale hydrolysate produced more hydroxyproline peptides in blood than porcine skin — a pharmacokinetic signal, not an outcome, and bovine was not tested. The 26-trial meta-analysis found no significant difference between collagen sources on skin elasticity (p = 0.21). No head-to-head outcome trial against bovine exists; the 2025 marine-collagen review is a narrative summary of mostly preclinical (cell and animal) work, not human trial evidence. (PMID 29949889, PMID 17253720, PMID 37432180, PMID 41393269) | Fish allergy excludes it; pescatarian-compatible; usually costs more per gram; heavy-metal testing matters more here. |
| Chicken (sternal cartilage) | II | Undenatured (UC-II) or hydrolyzed | The only source of the undenatured Type II used in the 40 mg knee-osteoarthritis trials. (PMID 26822714, PMID 19847319) | Buy it undenatured and in milligrams; hydrolyzed chicken collagen is a generic peptide. |
| Eggshell membrane | I, V, X (with elastin, hyaluronic acid) | Whole membrane powder | A different ingredient with its own small trials at 500 mg/day for joint pain and stiffness; it is not a collagen peptide supplement. (PMID 19554094) | Egg allergy excludes it. Its presence is what lets a blend print "Type V and X". |
“Marine absorbs better” rests on five men. In a single-blind crossover, fish-scale gelatin hydrolysate produced a higher blood concentration of hydroxyproline-containing peptides than porcine-skin hydrolysate, and some peptides appeared only with fish sources (PMID 17253720). That is a pharmacokinetic finding in five people, it compared fish with pork rather than beef, and it measured blood, not skin. The 26-trial meta-analysis of hydrolyzed collagen for skin found no significant difference between collagen sources on elasticity (p = 0.21) (PMID 37432180). Marine has its own positive skin trial, 1 g/day of a low-molecular-weight fish peptide for 12 weeks in 64 people (PMID 29949889), and so does bovine. Marine makes sense for a fish-only diet or for kosher/halal reasons and is ruled out by a fish allergy. Expect to pay more per gram for the same evidence.
Eggshell membrane is a different supplement wearing a collagen label. It is a whole membrane powder (collagen types I, V and X with elastin and hyaluronic acid) with its own two small open-label trials at 500 mg/day for joint pain and stiffness (PMID 19554094). Its presence in a blend is what lets the front of the tub say “Type V and X”.
Peptides vs gelatin vs undenatured: the form does the work
| Form | What it is | Evidence |
|---|---|---|
| Hydrolyzed collagen / collagen peptides | Collagen broken by enzymes into short peptides (typically under 3,000 Da) that dissolve in cold water. | The form in every skin, bone and body-composition trial. Specific peptides (Pro-Hyp, Hyp-Gly) are detectable in blood after ingestion; a further enzymatic hydrolysis step raised the absorption rate of glycine, proline and hydroxyproline in a 10-man crossover. (PMID 16076145, PMID 25212331, PMID 39149544, PMID 31086034) |
| Gelatin | Partially hydrolyzed collagen that gels when cooled; the same amino acids in longer chains. | In an 8-man crossover, 15 g of vitamin-C-enriched gelatin taken an hour before six minutes of rope-skipping doubled the blood marker of collagen-I synthesis (P1NP). A mechanism study for tendon and ligament, not the evidence base peptides have for skin. (PMID 27852613) |
| Undenatured (native) Type II | Collagen kept in its folded triple-helix shape by low-temperature processing. | Acts through oral tolerance in gut-associated immune tissue — the mechanism first shown with oral Type II collagen in rheumatoid arthritis. Dosed at 40 mg because it is a signal, not a nutrient. (PMID 8378772, PMID 12837047, PMID 26822714) |
| "Molecular weight" claims (e.g. 2,000 Da, 500 Da) | Peptide size printed on the label. | Trials used low-molecular-weight hydrolysates, and brand-specific "bioactive collagen peptide" products ran their own trials. No study shows that a lower stated Dalton number predicts a better outcome. (PMID 29949889, PMID 31086034) |
Hydrolysis is not a marketing flourish: in a 10-man crossover, an extra enzymatic hydrolysis step raised the absorption rate and availability of glycine, proline and hydroxyproline from the same 35 g of collagen protein (PMID 31086034). Vitamin C shows up next to gelatin in the tendon literature: 15 g of vitamin-C-enriched gelatin an hour before exercise doubled a blood marker of collagen-I synthesis (PMID 27852613). Keep that in mind when you get to the census figure on vitamin C pairing.
We read 746 collagen labels: what “type” means on the shelf
Original research Every collagen label filed with the NIH Dietary Supplement Label Database that we could read (851 labels in total: 746 from the general collagen shelf plus 105 matching “type II collagen”), classified by the type, source and form the label itself declares, and the daily dose its own directions add up to. 46,040 collagen-containing labels are on the market; 611 of the ones we read carried a parseable collagen dose.
Most collagen products do not say which type they are. On the general shelf, 43.2% of labels declare any collagen type. Among those that do, 86.3% list Type I, 77.3% Type III, 44.7% Type II, and 18% and 17.1% list Types V and X respectively, almost always together as a five-type blend.
| Item | Value (%) |
|---|---|
| Type I | 86.3% |
| Type III | 77.3% |
| Type II | 44.7% |
| Type V | 18% |
| Type X | 17.1% |
“Multi-collagen” is 12.3% of the shelf, and it is not what the joint trials tested. 92 labels claim three or more types. Their sources are bovine hide, chicken cartilage, fish and eggshell membrane in various combinations, and their form is overwhelmingly hydrolyzed: of the multi-type labels that claim Type II, only 2.2% use the undenatured form. A five-type blend is, by weight, a bovine-and-fish Type I/III peptide with a pinch of cartilage and membrane. That is a reasonable peptide product. It is not a joint product in the UC-II sense.
One label, read against the table. A representative multi-type label in the corpus (NaturesPlus Collagen Peptides, DSLD 249656, filed 2021) states: These 6 major Collagen Types (I, II, II, IV, V & X) provide a powerful profile delivering exceptional whole body benefits.
Its Supplement Facts panel names the ingredient as hydrolyzed grass-fed beef collagen, fish collagen, chicken collagen and eggshell membrane concentrate, 20 g per two scoops. Against the trial table: the beef and fish peptides are the Type I/III the skin and bone evidence is about; the chicken collagen is hydrolyzed, so it is not UC-II and carries no oral-tolerance evidence; and Types IV, V and X have no supplement trial at all. It is a perfectly good 20 g peptide powder sold on a count of types. (The label also lists Type II twice.)
The 50-fold gap. Across both populations, 247 labels name Type II. Products sold as undenatured Type II direct a median of 40 mg/day, the trial dose, while labels selling hydrolyzed “Type II” direct a median of 2 g. Same words on the label, 50× the dose, two different mechanisms, and only one of them has a knee trial behind it.
| Item | Value ( mg) |
|---|---|
| Undenatured (UC-II) | 40 mg |
| Hydrolyzed "Type II" | 2 g |
Source is declared far more often than type. 89% of shelf labels name a source. Of those, 72% name bovine, 61% marine or fish, 24.4% chicken and 16.4% eggshell membrane (labels naming more than one are counted under each). Single-source products differ sharply in how much collagen a day’s directions deliver: a median of 11 g for bovine-only labels against 5 g for marine-only; chicken-only labels run far lower because chicken collagen is mostly sold as a joint ingredient, in milligrams, inside capsules (their median moved too much between the two halves of our read to print).
Vitamin C is co-formulated on 30% of labels; hyaluronic acid on 17.4%. Your body needs vitamin C to hydroxylate proline when it builds its own collagen, and the gelatin trial above paired the two. If you buy a peptide without it, your diet supplies the cofactor, which most Western diets do comfortably. The pairing is fine. It is not worth paying extra for.
Form. 84% of shelf labels describe themselves as hydrolyzed or as peptides, 1.7% as undenatured, and 14.2% say neither. Our earlier format census of 465 labels found that 70.8% of capsule products direct less than the 2.5 g studied for skin, against 3.1% of powders. A capsule of peptides is the wrong tool for a gram-scale dose and the right tool for a 40 mg one.
Method: 851 collagen labels retrieved from the NIH Dietary Supplement Label Database (DSLD) v9 on 2026-09-14, in two populations (the general collagen shelf, 746, and every on-market label matching “type II collagen”, 105); 611 carried a parseable collagen dose. Types, sources and forms are read from the product name, the label’s own statements and the Supplement Facts ingredient names; allergen disclaimers (“no fish”) are excluded from source counts. Daily dose is the collagen row multiplied by the label’s maximum daily servings. Every figure above was recomputed in both halves of the read order: 22 of 26 findings held within tolerance; the 4 that did not (the share of multi-type blends drawing on all three of bovine, chicken and fish, the undenatured share of all Type II labels, the multi-collagen median dose and the chicken-only median) are described in words above and not printed as numbers. The type table and the census are published as open data at /collagen/types-compared.json (CC BY 4.0). What it cannot tell you: how many tubs of each type are sold, whether a label’s claimed type matches what is in the powder, or anything about brands that have not filed with the NIH.
Which collagen to buy, by goal
| Goal | Type & form | Studied dose | Picks |
|---|---|---|---|
| Skin elasticity, hydration | Type I/III hydrolyzed peptides (bovine or marine) | 2.5–5 g/day, 8–12 weeks | Best collagen for skin |
| Bone density (postmenopausal) | Type I/III hydrolyzed peptides | 5 g/day, 12 months | Best overall |
| Muscle with resistance training | Type I/III hydrolyzed peptides | 15 g/day, 12 weeks | Dosage guide |
| Knee osteoarthritis, joint comfort | Undenatured Type II (UC-II) | 40 mg/day, 90–180 days | Not in our ranked catalog yet; look for “undenatured” and 40 mg on the panel |
| Tendon, ligament (with exercise) | Gelatin + vitamin C | 15 g one hour before training | Any plain gelatin; pair with 50 mg vitamin C |
Product links below go to Amazon and we may earn a commission if you buy. It never changes which product we pick or what we say about it. How we choose.
Third-party-tested collagen peptides we track
All three are hydrolyzed Type I/III bovine peptides — the form the skin and bone trials used — ranked by cost per day.
| Product | Dose/Serving | Servings | Price | Cost/Day | Certification (as labelled) | Buy |
|---|---|---|---|---|---|---|
| Sports Research Collagen Peptides (Unflavored) Best Value | 11g collagen | 41 | $32.95 | $0.80 | Informed Sport, Non-GMO Verified | Buy on Amazon |
| Garden of Life Grass Fed Collagen Beauty (Cranberry Pomegranate) | 12g collagen | 20 | $25.89 | $1.29 | Non-GMO Verified | Buy on Amazon |
| Vital Proteins Collagen Peptides (Unflavored) Quality Pick | 20g collagen | 28 | $38.99 | $1.39 | NSF Certified for Sport | Buy on Amazon |
Safety and sourcing, briefly
Hydrolyzed collagen is well tolerated at trial doses, with mild digestive complaints the most common report; undenatured Type II showed no safety difference from placebo or glucosamine-chondroitin over 180 days (PMID 26822714). Collagen is an incomplete protein (it is low in tryptophan), so it does not count toward a protein target. The real purchasing check is contamination: hide, scale and cartilage concentrate whatever the animal was exposed to, so a current third-party certificate matters more here than on most shelves. The collagen hub covers the heavy-metal question and how to read a certificate of analysis.
Frequently asked questions
Is Type I or Type III collagen better?
They are not a choice you can make. Bovine hide contains both, so every "Type I & III" peptide product is the same thing as a bovine "Type I" product, and no trial has isolated Type III. The skin and bone trials used Type I/III hydrolysates dosed at 2.5–10 g/day. Pick by dose and third-party testing, not by which types the label lists.
Does "5 types of collagen" work better than one?
There is no human trial of Type V or Type X as supplements, and no trial showing a five-type blend beats plain Type I/III peptides. On the 746 labels we read, 12.3% claim three or more types; by weight those blends are bovine and fish peptides with chicken cartilage and eggshell membrane added, and only 2.2% of the ones claiming Type II use the undenatured form the joint trials tested.
Is marine collagen absorbed better than bovine?
Not proven. The only human source comparison is a 5-man crossover in which fish-scale hydrolysate produced more hydroxyproline peptides in blood than porcine (not bovine) skin — a blood-level signal, not a skin or joint outcome. A 26-trial meta-analysis found no significant difference between collagen sources on skin elasticity. Both marine and bovine peptides have positive skin trials; choose on diet, allergy, price and testing.
Is 40 mg of Type II collagen really enough?
Yes, for undenatured Type II. It works through oral tolerance — an immune signal, not a building block — so it is dosed in milligrams. In a 180-day trial of 191 people with knee osteoarthritis, 40 mg/day beat both placebo and glucosamine plus chondroitin on the WOMAC score. On the shelf, undenatured products direct a median of 40 mg/day while hydrolyzed "Type II" products direct 2 g — a 50-fold gap between two things sold under the same name.
Is it safe to take more than 40 mg of Type II collagen?
The knee trials used 40 mg/day and did not test higher doses, so there is no evidence that more helps — and no reason to expect it to, because undenatured Type II works as an immune signal rather than a nutrient that scales with the dose. Taking hydrolyzed collagen peptides alongside it is a different product for a different purpose (skin, bone), not a top-up of the same one.
Can vegans get collagen?
No. Collagen is an animal protein; "vegan collagen" products contain the amino acids and cofactors (glycine, proline, vitamin C) that your body uses to make its own, but no collagen and no collagen peptides. None of the trials on this page apply to them.
Related guides
- Collagen: does it work, and what to buy
- Collagen dosage guide: type and dose by goal
- Best collagen supplement, ranked
- Best collagen for skin
- Collagen products: prices and certifications
Sources
- Iwai K, et al. "Identification of food-derived collagen peptides in human blood after oral ingestion of gelatin hydrolysates." J Agric Food Chem. 2005. PMID: 16076145
- Shigemura Y, et al. "Identification of a novel food-derived collagen peptide, hydroxyprolyl-glycine, in human peripheral blood." Food Chem. 2011. PMID: 25212331
- Virgilio N, et al. "Absorption of bioactive peptides following collagen hydrolysate intake: a randomized, double-blind crossover study." Front Nutr. 2024. PMID: 39149544
- Trentham DE, et al. "Effects of oral administration of type II collagen on rheumatoid arthritis." Science. 1993. PMID: 8378772
- Bagchi D, et al. "Effects of orally administered undenatured type II collagen against arthritic inflammatory diseases: a mechanistic exploration." Int J Clin Pharmacol Res. 2002. PMID: 12837047
- Lugo JP, et al. "Efficacy and tolerability of an undenatured type II collagen supplement in modulating knee osteoarthritis symptoms: a multicenter randomized, double-blind, placebo-controlled study." Nutr J. 2016. PMID: 26822714
- Crowley DC, et al. "Safety and efficacy of undenatured type II collagen in the treatment of osteoarthritis of the knee: a clinical trial." Int J Med Sci. 2009. PMID: 19847319
- Lugo JP, et al. "Undenatured type II collagen (UC-II) for joint support: a randomized, double-blind, placebo-controlled study in healthy volunteers." J Int Soc Sports Nutr. 2013. PMID: 24153020
- Clark KL, et al. "24-Week study on the use of collagen hydrolysate as a dietary supplement in athletes with activity-related joint pain." Curr Med Res Opin. 2008. PMID: 18416885
- Zdzieblik D, et al. "Improvement of activity-related knee joint discomfort following supplementation of specific collagen peptides." Appl Physiol Nutr Metab. 2017. PMID: 28177710
- Zdzieblik D, et al. "The Influence of Specific Bioactive Collagen Peptides on Knee Joint Discomfort in Young Physically Active Adults: A Randomized Controlled Trial." Nutrients. 2021. PMID: 33562729
- Proksch E, et al. "Oral supplementation of specific collagen peptides has beneficial effects on human skin physiology: a double-blind, placebo-controlled study." Skin Pharmacol Physiol. 2014. PMID: 23949208
- Bolke L, et al. "A Collagen Supplement Improves Skin Hydration, Elasticity, Roughness, and Density: Results of a Randomized, Placebo-Controlled, Blind Study." Nutrients. 2019. PMID: 31627309
- de Miranda RB, et al. "Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis." Int J Dermatol. 2021. PMID: 33742704
- Pu SY, et al. "Effects of Oral Collagen for Skin Anti-Aging: A Systematic Review and Meta-Analysis." Nutrients. 2023. PMID: 37432180
- König D, et al. "Specific Collagen Peptides Improve Bone Mineral Density and Bone Markers in Postmenopausal Women — A Randomized Controlled Study." Nutrients. 2018. PMID: 29337906
- Ohara H, et al. "Comparison of quantity and structures of hydroxyproline-containing peptides in human blood after oral ingestion of gelatin hydrolysates from different sources." J Agric Food Chem. 2007. PMID: 17253720
- Kim DU, et al. "Oral Intake of Low-Molecular-Weight Collagen Peptide Improves Hydration, Elasticity, and Wrinkling in Human Skin: A Randomized, Double-Blind, Placebo-Controlled Study." Nutrients. 2018. PMID: 29949889
- Bartoletti E, et al. "Hydrolyzed Marine Collagen: Emerging Evidence of Benefits via the Oral Route — Review and Insights for Medical Practice." Clin Cosmet Investig Dermatol. 2025. PMID: 41393269
- Ruff KJ, et al. "Eggshell membrane: a possible new natural therapeutic for joint and connective tissue disorders. Results from two open-label human clinical studies." Clin Interv Aging. 2009. PMID: 19554094
- Skov K, et al. "Enzymatic Hydrolysis of a Collagen Hydrolysate Enhances Postprandial Absorption Rate — A Randomized Controlled Trial." Nutrients. 2019. PMID: 31086034
- Shaw G, et al. "Vitamin C-enriched gelatin supplementation before intermittent activity augments collagen synthesis." Am J Clin Nutr. 2017. PMID: 27852613
- NIH Office of Dietary Supplements. Dietary Supplement Label Database. dsld.od.nih.gov (labels retrieved 2026-09-14).