Collagen

What is collagen?

Collagen is the most abundant protein in the body and the main structural material of connective tissue; researchers sum up its job as holding the body together. More than twenty types have been identified, and type I is the major one in most tissues, all of it part of the extracellular matrix, the scaffolding that sits between cells. Supplements are made by extracting collagen from animals, usually cattle or fish, then hydrolysing it: breaking the long strands into short peptides that dissolve in water. It is sold as hydrolysed collagen, also labelled collagen peptides, or as undenatured type II collagen, which is left whole.

Why do people take collagen?

What does collagen do in the body?

Collagen is hydrolysed before it is sold: the long strands are broken into short peptides, some products down to tripeptides three amino acids long. What is swallowed is fragments rather than whole collagen, and reviewers note that absorption is still poorly measured. Collagen is made largely of non-essential amino acids, so the interest is less in its quality as a protein than in what those fragments do.

Reviews of the skin research set out three possible routes. The peptides may act directly on fibroblasts, the cells that build the scaffolding around them; they may act through immune cells in the tissue; or they may work through oral tolerance, the way meeting a protein in the gut quietens the immune reaction to it elsewhere. In skin samples and in the trials, collagen peptides were followed by more collagen, more of the sugar chains that go with it, and more procollagen and elastin. Meanwhile the body is constantly taking its own collagen apart with enzymes called matrix metalloproteinases.

What do people say about taking collagen?

These are anecdotes people have shared, not evidence.

What forms of collagen are there?

What else is worth knowing about collagen?

• Labels give the collagen per serving, and a serving is often more than one capsule or scoop. Skin trials mostly used one to ten grams a day, around four being commonest; the training trials fifteen grams, the bone trial five.
• Every form on sale is extracted from an animal — cattle, fish or chicken — so none of it is suitable for vegetarians or vegans.
• Reviews describe it as generally well tolerated, with few adverse events and several trials recording none. One review of joint trials was the exception, reporting high rates of side effects in some studies it gathered.
• Nearly everyone in the skin trials was a woman aged twenty to seventy. The joint trials were in adults with osteoarthritis, the training trials in adults who exercise, and the bone trial in postmenopausal women.

If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.