If you’ve had an even cursory thought about ageing, you’ll likely be familiar with collagen. The protein is abundant in humans, providing both strength and elasticity throughout our bodies, a fact that is most often brought up in relation to skin and its relative ‘youthfulness’. (Collagen also plays a role in supporting our bones, muscles, tendons and ligaments.)

While our body does continuously produce collagen, the amount starts to deteriorate from the age of 20 onwards, and that deterioration accelerates as we age.

Collagen in supplement form (powders, liquid, or capsules), is said to help combat that loss, promising firmer, more elastic skin, stronger nails and hair and a reduction in fine lines and wrinkles. Perhaps unsurprisingly then, the industry is booming: the global collagen supplements market was valued at $2.01bn in 2022, with projections of reaching $3.1bn by 2031, while Google Trends reports that searches for the supplements have accelerated since 2020 in the UK.

If supplements reversing ageing reads as too good to be true, that’s because it is… kind of.

Can collagen supplements reverse ageing?

Stewart Long is a former president of the Society of Cosmetic Scientists and CEO at Cutest, a company that specialises in testing beauty products. He tells i he has seen promising results from some collagen supplements but told me that “to be effective the collagen needs to enter the bloodstream and in order to do that it must be protected enough to survive the stomach and reach the small intestine.

“And, when it reaches the small intestine, the collagen must be of a low enough Dalton weight [the unit of measurement used to measure atoms] to pass through the intestinal wall. The lowest Dalton weight collagen is 2,000 Daltons or below. The industry standard used in most collagen supplements is 5,000 Daltons or above.” For improvements in skin the collagen needs to be 2,000-2,500 Daltons (or less) and for joints and cartilige 4,000-5,000 Daltons.

Vitamin C plays a big part too. Aesthetic doctor Dr Sophie Shotter explains that “your body needs the collagen to help build collagen in the skin, but it also needs other ingredients to do that, such as MSM (Methylsulfonylmethane, a form of sulphur) and vitamin C.”

But more importantly, evidence of collagen supplements actually working to improve skin or joints is quite scant.

Dr Thivi Maruthappu of the British Cosmetic Dermatology Group is the UK’s only dual-qualified dermatologist and nutritionist. She explains to i that the only thing you can really guarantee about collagen supplements is that they’ll be expensive.

“The data isn’t good enough to say that taking a collagen supplement prevents the decline of your existing collagen.” That said, she adds “people do observe an improvement in their skin smoothness, wrinkles and hydration. There are different types of collagen so if you choose one that benefits joints some people find it can help with joint pain.”

This is backed up by Harvard School of Public Health. While they refer to a couple of randomised control studies that have found some improvement in skin elasticity and joint mobility, they warn that potential conflicts of interest exist in this area: “Most if not all of the research on collagen supplements are funded or partially funded by related industries that could benefit from a positive study result, or one or more of the study authors have ties to those industries….this makes it difficult to determine how effective collagen supplements truly are and if they are worth their often hefty price,” they add.

Is it doing any harm to take them?

As collagen supplements are classed as a food supplement in the UK there are issues around regulation, with companies unable to make explicit medical or nutritional claims about efficacy – but they can couch their language in vague terms that can often be misleading.

Supplements can also vastly vary in source, dose, form and other ingredients. And the sourcing of the collagen used in supplements has been linked to devastating environmental effects, such as the collagen found in Nestlé-owned Vital Proteins being linked to vast deforestation and Indigenous land invasions in Brazil.

Positively, there are no perceivable ill effects from taking collagen supplements. As Dr Maruthappu puts it: “Studies have not observed any adverse effects – except that they’re pricey. Really the biggest side effect is on your budget.”

If you’re still intrigued, you should look for collagen peptides, also known as hydrolyzed collagen peptides – this means that the large structure of the collagen protein has been cut up, enabling it to be absorbed more readily.

Additionally Dr Maruthappu says, “you would go for either a marine or a bovine one (from either cows or fish), and you would need to take it every day for at least 12 weeks if you want to see if there’s an improvement. The usual dose is about 10g a day.”

On top of that, it’s worth noting that there are some dietary sources of collagen (such as fish and animal meat, particularly the skins and tendons) and like other vitamins and minerals, dietary sources are far better tolerated than supplementation.

So you’d probably be better off including the skin with your roast chicken rather than shelling out on some supplements.