Collagen labels throw around Roman numerals — Type I, II, III — as though everyone knows what they mean. Here is the plain version, and why it matters less than the marketing suggests.
The three types you will actually see
| Type | Where it is in the body | Usually marketed for |
|---|---|---|
| Type I | Skin, bone, tendon — the most abundant | Skin, hair, nails |
| Type II | Cartilage | Joints |
| Type III | Skin, blood vessels, organs | Usually alongside Type I |
Sources map to types
Bovine collagen is mostly Types I and III. Marine (fish) collagen is mostly Type I. Chicken collagen is the usual source of Type II. So “marine collagen for skin” is not marketing nonsense — it does reflect what is in it.
The part the labels skip
Here is the honest complication: hydrolyzed collagen is broken into peptides during digestion, and those peptides do not travel to a specific body part according to their original type. The idea that swallowing Type II collagen sends it straight to your knees is a simplification. What research suggests is that collagen peptides may act as building blocks and signals more generally.
One meaningful distinction does exist: undenatured Type II collagen (UC-II) is used at very small doses (around 40 mg) and is thought to work through a different, immune-mediated mechanism — not as a building block. That is a genuinely different product from bulk collagen peptides.
Hydrolyzed Collagen Peptides (e.g. Vital Proteins, Sports Research)
- Bovine peptides supply Types I and III; marine is mostly Type I
- Around 10 g per day is the amount used in most studies
- Look for third-party testing such as NSF or Informed Sport
Widely available · usually unflavored
Check Price →So which should you buy?
For general use, standard hydrolyzed peptides are fine and usually the best value — do not pay a premium for an elaborate type blend. If your interest is specifically joints, either standard peptides at around 10 g or a low-dose UC-II product are reasonable, and they work differently enough that it is worth choosing deliberately rather than assuming more types means better.
More on the evidence in collagen for joints, or compare options in the best joint supplements guide.