What it is
Collagen is the most abundant protein in the body; type I makes up more than 90% of it and gives structure to skin, tendons, bones and ligaments. The supplement is animal collagen cut into small peptides, bought for skin, hair, nails and joints.
What the label does not say
- It is not a complete protein: collagen contains no tryptophan, an indispensable amino acid, so its PDCAAS score is zero, as authors with industry ties themselves write. The list of essential amino acids in the Canadian monograph in fact omits tryptophan. Its grams are not grams of complete protein.
- The positive skin trials have a funding problem: in the 2025 meta-analysis (23 trials, 1,474 participants), the studies not funded by industry show no effect on hydration, elasticity or wrinkles, and neither do the high-quality studies. The authors conclude that there are no clinical data to support collagen against skin aging.
- In Canada, the accepted claims target joints and amino acids, not skin: "helps to reduce joint pain associated with osteoarthritis" at 1.2 to 10 g per day, "use for at least 5 months". A skin promise does not come from this monograph.
- The vitamin C added to the bottle is not the argument you might think: the hydroxylases that assemble collagen need it as a cofactor, which explains scurvy, not an additional effect from a few milligrams in a powder. No trial comparing collagen with and without vitamin C was found.
The forms on the shelf
- Hydrolyzed (collagen peptides): Health Canada defines it by an average molecular weight of about 4 kDa (2 to 6 kDa), with no gelling power, soluble in cold water; accepted sources: bovine, porcine and fish skin and bone, chicken cartilage.
- Gelatin: the same collagen, less broken down, which gels. The trials cited here cover the hydrolyzed form.
- Marine versus bovine: in the 2023 meta-analysis, 14 of the 26 trials used fish collagen, with no difference in effect on elasticity by source (p = 0.21). "Type I", "II" or "III" refers to the tissue of origin; the Canadian monograph does not distinguish between types.
Published reference values
- Skin: from less than 1 g to 12 g per day in the 26 trials of the 2023 meta-analysis, most over 8 to 12 weeks; the literature cites functional doses of 2.5 to 15 g per day.
- Joints: 1.2 to 10 g per day according to Health Canada, for at least 5 months (20 weeks in the joint health products monograph).
- No upper limit: Health Canada asks you to consult in case of pregnancy or breastfeeding above 2.8 g per day and warns of possible digestive discomfort.
When
At any time. The time frame matters more: the skin trials measure at 8 and 12 weeks, the joint monograph asks for at least 5 months.
To mention to a professional
- Fish allergy (marine collagen comes from fish skin and bone), pregnancy and breastfeeding above 2.8 g per day: check with a health care professional.
What it is sold for, and what the data show
Collagen is sold to smooth skin, thicken hair, strengthen nails and protect joints. The meta-analyses that pool all the trials show gains in hydration and elasticity at 8 to 12 weeks, but the effect disappears in the trials independent of industry or of high quality. On the joint side, Health Canada accepts a claim on osteoarthritis pain after at least 5 months. For hair and nails, no meta-analysis was found.
From the plate first
Gelatin, simmered broths made from skin, bones and cartilage, pork rind and poultry skin provide collagen, with the same absence of tryptophan. A diet complete in protein provides the amino acids the body assembles into collagen on its own.
Sources
- Health Canada, natural health product monograph, Hydrolyzed Collagen
- Health Canada, product monograph, Joint Health Products, Multiple Ingredient
- Myung and Park, Effects of Collagen Supplements on Skin Aging: A Systematic Review and Meta-Analysis of Randomized Controlled Trials, American Journal of Medicine (2025)
- Pu et al., Effects of Oral Collagen for Skin Anti-Aging: A Systematic Review and Meta-Analysis, Nutrients (2023)
- Paul, Leser and Oesser, Significant Amounts of Functional Collagen Peptides Can Be Incorporated in the Diet While Maintaining Indispensable Amino Acid Balance, Nutrients (2019, authors with industry ties)
- StatPearls (NCBI Bookshelf), Biochemistry, Collagen Synthesis
- NIH Office of Dietary Supplements, Vitamin C (Health Professional)
Educational information, drawn from the sources above. It does not replace the advice of a health professional, who remains the reference for your situation, your medications, pregnancy or breastfeeding.