Collagen supplements: what the evidence says for skin and joints

Collagen is the most abundant protein in connective tissue, found in skin, tendon, bone and cartilage. A narrative review of joint-health products explains that the word covers very different ingredients: undenatured native collagen that keeps its triple-helix shape, gelatin (cooked, denatured collagen), and hydrolysed collagen or collagen peptides that have been enzymatically broken into short chains.

Most commercial material is extracted from animal by-products. Cattle and pig skin, hides and bones are the typical raw materials for type I collagen, cartilage is used for type II, and chicken, fish and even eggshell membrane are used by some manufacturers. Fish and poultry sources have grown in popularity partly because of religious restrictions on pork and concern about cattle-borne disease. For anyone who avoids a particular animal for faith, ethical or allergy reasons, the ingredient list therefore matters more than the front-of-pack wording.

Skin ageing involves gradual loss of collagen and elastin in the dermis, which shows up as dryness, laxity and wrinkles. A mini-review of hydrolysed collagen for skin care describes laboratory work suggesting that peptides from ingested collagen can reach the bloodstream and stimulate skin fibroblasts, the cells that make new connective tissue. It concludes that daily intake of hydrolysed collagen from several sources is associated with slower skin ageing.

That conclusion should be read as a summary of promising research rather than proof that a particular product will change how your skin looks. Published trials use different peptide mixtures, durations and ways of measuring skin, and the review itself notes that products can be combined with vitamins and other nutrients, making it hard to credit the collagen alone. Sun protection, not smoking and a varied diet remain the better-established ways to look after ageing skin.

Osteoarthritis is the most common joint condition, and there are no approved drugs that modify its course. That gap is why nutritional products attract attention. The 2023 narrative review of collagen for joint health reports that most tested ingredients seemed to give positive outcomes, but with huge variability in study design, effective dose and minimum treatment period, and it describes one randomised placebo-controlled study in which ten grams a day of bovine hydrolysed collagen for three months made no difference to joint pain or function.

It is also worth knowing that the review authors are employees of a company that makes a native type II collagen ingredient. That does not make the findings wrong, but it is a reason to look for independent trials. Meanwhile the NHS describes exercise and weight management as central to osteoarthritis care and states that GPs no longer prescribe glucosamine or chondroitin, with NICE recommending that supplements should not routinely be offered on the NHS.

• Strengthening and general fitness exercise is described by the NHS as one of the most important treatments for osteoarthritis.

• Weight loss, where relevant, reduces strain on weight-bearing joints.

• Pain relief options include paracetamol and anti-inflammatory medicines, chosen by a GP according to other health conditions.

The reviews report few safety concerns in the trials they cover, but those trials are short and not designed to find rare problems. The FSA advises reading the label, never exceeding the stated serving, and speaking to a GP or pharmacist before starting any food supplement if you are pregnant, breastfeeding, have a medical condition or take regular prescribed medicines. If you feel unwell after taking one, stop it and seek advice.

Because collagen is animal-derived, vegetarians and vegans will not find a true equivalent, and anyone with a food allergy to fish, egg or other source material should check carefully. Some products add vitamin C, biotin, hyaluronic acid or herbal extracts, so the label should be read for the whole formulation rather than assuming it is simply protein.

The FSA defines a food supplement as a concentrated source of a nutrient or other substance with a nutritional or physiological effect, sold in dose form. Because supplements are not medicines, they should not be marketed with claims that they prevent, treat or cure a medical condition, and any health claim on a pack should be an authorised one on the Great Britain nutrition and health claims register.

The FSA also warns that online marketplaces make it harder to know who is selling a product and where it came from, and that unusually cheap goods may be counterfeit. Concerns about safety, labelling or claims can be reported to the local authority or district council.

• Look for the type (hydrolysed peptides, gelatin or native type II) and the animal source.

• Be wary of promises that read like treatment claims for arthritis or wrinkles; supplements should not make them.

• Remember that protein from ordinary meals, fish, eggs, dairy and pulses also provides the amino acids the body uses to make its own collagen.

• Choose one product at a time and note any change, so you can tell whether it is making a difference.

• Tell your GP or pharmacist about every supplement you use, especially before surgery or when starting a new medicine.