Collagen
Collagen is the structural protein that forms the fibrous framework of skin, bone, tendon and cartilage in animals, and it is the most abundant protein in the human body. Supplements rarely contain the whole protein: they usually contain collagen peptides, the same protein broken down into short fragments so that it is easier to take and to absorb.
In nutritional terms collagen is classified as a protein, and specifically as an incomplete one, because it does not supply the full set of essential amino acids. Its amino acid make-up is distinctly unlike that of ordinary dietary protein: it is unusually rich in glycine, proline and hydroxyproline. Hydroxyproline is almost absent from other proteins, which is why laboratories use it as the marker for how much collagen a sample contains. The body also makes its own collagen, and vitamin C is required for that process.
About this ingredient
Collagen is not a single molecule but a family of related proteins, of which type I is the most abundant in skin, bone and tendon. Collagen makes up around 80 % of the dry weight of human skin, and roughly 90 % of that is type I. Collagen occurs only in animals — plants do not make it at all.
Dietary sources
Collagen is not an essential nutrient; the body makes its own. There is no Thai RDI for it, no EU nutrient reference value, and food composition tables generally do not list it as a separate entry. In an ordinary diet it comes from the connective-tissue parts of animals: pork skin and trotters, beef tendon, chicken skin and feet, fish skin and scales, dishes made by long-simmering bones, and the gelatin in desserts. How much a food contains therefore depends more on the cut and the cooking method than on the species. Plant foods contain none at all. Because tables do not report collagen directly, analytical work usually measures hydroxyproline instead and works back from it. Commercial raw material comes from hides, bones, and fish skin and scales: these are pre-treated, extracted with hot water to give gelatin, and then broken down further into collagen peptides.
Forms & absorption
Three things distinguish one collagen raw material from another: molecular size, collagen type, and source animal. Gelatin is collagen that has been broken down by heat, and collagen peptides are gelatin broken down further into much smaller pieces. Human studies that measure blood show that these smaller pieces are absorbed and can be detected within about one to two hours of being taken, and to a greater extent than gelatin. The source animals in common use are fish, cattle, pig and chicken, which is a dietary and religious consideration for many consumers in Thailand; type II collagen from chicken sternal cartilage is a separate item again. Collagen peptides are water-soluble, so they are sold as stick powders, ready-to-drink shots, tablets and jellies, and do not need to be taken with fat.
Research status
There is a substantial body of human research on collagen peptides, but most of it is short. A systematic review and meta-analysis published in Nutrients in 2023 pooled 26 randomised controlled trials with 1,721 participants, running from 2 to 12 weeks. The doses evaluated spanned a broad range, from less than 1 g to 12 g a day; 14 of the 26 used fish-derived collagen and 9 did not state the source at all, and almost all participants were women. The authors' own risk-of-bias assessment found missing outcome data in 13 of the trials, and they concluded that larger trials are still needed. In the European Union, two Article 13(5) applications on this raw material were assessed by EFSA and both failed: a 2011 opinion on collagen hydrolysate and maintenance of joints, and a 2013 opinion on VeriSol(R)P, a specific collagen peptide raw material, and a change in skin elasticity. On both occasions the Panel concluded that a cause-and-effect relationship had not been established. No health claim for collagen is therefore authorised in the EU, and none has been approved by the Thai FDA for the products on this site.
Safety & considerations
Thai FDA guidance on the use of key ingredients in dietary supplements, dated 8 July 2024, lists collagen, collagen peptide, collagen hydrolysate, collagen dipeptide and collagen tripeptide together as item 342, at not more than 10 g of total collagen per day, with fish, pig and bovine skin named as the sources. Abalone collagen (item 343) counts towards that same 10 g ceiling, while type II collagen from chicken sternum (item 344) is a separate item capped at not more than 1 g per day. Collagen is a protein, so whatever is taken also counts towards the day's protein intake. Anyone with a fish or shellfish allergy should read the source declaration, since fish-derived collagen is a labelled allergen. If you are pregnant or breastfeeding, take prescription medicines, or have been advised to limit your protein intake, speak to a doctor or pharmacist before starting any supplement, and always follow the amount printed on the label of the product in front of you. Dietary supplements are not intended to prevent, treat or cure any disease.
Quality markers
Five things are worth checking on a collagen label. First, the source animal and tissue: it should say fish skin, bovine hide, pig skin or chicken cartilage, not simply "collagen". Second, the word used for the raw material, because gelatin, collagen, and collagen peptides or hydrolysate describe different molecular sizes. Third, whether the weight printed on the pack refers to the collagen peptide alone or to the whole blended sachet including sugar and flavouring — a 5,000 mg sachet does not necessarily deliver 5,000 mg of peptide. Fourth, if the label states a peptide size, whether that figure is an average or a minimum, because brands express it in different ways. Fifth, a halal certification mark, which matters when the raw material is porcine. Every dietary supplement sold in Thailand also carries an FDA (อย.) registration number on the label, which can be checked against the Thai FDA public register.
- Article 13(5) (2011) ↗
- EFSA – Scientific Opinion on the substantiation of a health claim related to VeriSol(R)P and a change in skin elasticity, Article 13(5) (2013) ↗
- Nutrients (MDPI) – Systematic review and meta-analysis of 26 clinical trials of hydrolysed collagen (2023) ↗
- Thai FDA – Advice on the use of key ingredients in dietary supplements (8 July 2024), item 342 Collagen ↗
This page is general educational information about a nutrient — it describes the nutrient itself and is not a statement about any particular product. Dietary supplements are food, not medicine, and have no effect in preventing or treating disease. The references listed above are public-institution sources, not product claims.
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