Collagen Supplements: What They Are, Types, Sources and Evidence

Overview

Collagen is a structural protein found throughout the body. A collagen supplement is usually a powder, drink or capsule made from animal collagen that has been broken into small pieces, called hydrolyzed collagen or collagen peptides. It is a different product from creatine, which is a separate compound with a separate evidence base (see Creatine). Nothing here suggests the two are interchangeable.

Collagen is the most abundant protein in the human body, about 30% of its dry weight, and is part of skin, tendons, bones and cartilage. [1] The research below asks a practical question: do people who take it, compared with people who take a placebo, see measurable changes?

How the evidence is labeled

This page uses plain labels: established nutritional role (a proven job in the body), promising but limited, mixed, insufficient evidence, and marketing claim. Where I looked and found nothing usable, the page says Proper evidence not found and what was checked.

What the research shows

For the full picture on skin, joints and bone, see Collagen for skin, joints and bone. For the beauty-supplement claims overall, see collagen, biotin and beauty supplement claims.

Is collagen a complete protein?

No. Collagen protein lacks one essential amino acid, tryptophan, so under the standard scoring method it is classed as an incomplete protein. [10] It is not a substitute for your main protein foods. For the head-to-head, see Collagen vs protein powder.

Forms and sources

Hydrolyzed collagen and gelatin are made from the same raw materials, commonly pig or cow skin, with marine and poultry sources also used. [11] Undenatured type II collagen is a different product, taken in milligrams rather than grams (see Gelatin and undenatured type II collagen). Types and animal sources are covered in Collagen types and sources.

Amounts used in studies

These are study amounts, not recommendations. One review reported that effective amounts in the literature ran from 2.5 to 15 g a day. [10] Another summarized a 12 g daily dose in osteoarthritis and bone studies. [11] One skin meta-analysis drew its conclusion from use over 90 days. [2]

Side effects and who should be careful

• Tolerability: reviews of randomized trials describe collagen as generally well tolerated, with a low rate of side effects. [4] In the knee osteoarthritis review, adverse events did not differ significantly from placebo. [5]
• Fish allergy: marine collagen comes from fish. In a Japanese study, half of people with fish allergy had antibodies to fish collagen. [12] If you have a fish allergy, ask a clinician before using a marine product.
• Pregnancy, breastfeeding, children, kidney disease, medicines: the sources I read did not cover these groups for collagen. That is a gap in the evidence, not a sign of safety. See Pregnancy and breastfeeding and How interactions work.

Reading the label

Look for the animal source, the type of collagen, the grams per serving, any allergen statement, and whether a third party tests the product. See Reading supplement labels. "Vegan collagen" products are a separate question, covered on the types and sources page.