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1. Collagen is the 'scaffolding of our skin'

Collagen is one of the main structural proteins in our body and it makes up the largest part of our 'extracellular matrix', or what Dr Wedgeworth describes as "the scaffolding of our skin".

When we get older, even as early as our mid-twenties, depending on genetics and skin type, our collagen depletes and degrades. Less collagen leads to thinner skin and is a major factor in wrinkling.

A major factor for this change is exposure to the sun. "External UV exposure causes quite significant damage to the deeper layers of our skin," says Dr Wedgeworth.

2. There is no collagen in plants

Collagen is an animal and fish-based protein. Most supplements, especially those with often the biggest dose, use 'marine' collagen, and it's thought that marine may be absorbed more readily than bovine sources (cow bones being a typical source).

Plant-based, vegan or vegetarian 'collagen' isn't actually collagen, it's a mix of the amino acids that make up collagen protein, along with the likes of vitamin C and zinc which help us make collagen.

3. Collagen has to be broken down for us… and then it goes everywhere

Our stomachs aren't able to absorb large collagen protein molecules in their original, whole form so supplements are made with 'hydrolised collagen – shorter 'peptides' – strands of the amino acids that make them up.

There is evidence that collagen peptides make it through the stomach and into the blood, after which they likely go everywhere in the body. "The skin is a very, very dynamic organ," notes Dr Wedgeworth, "so it could potentially use the collagen more than other organs."

4. Supplements 'kick-start cells' to produce collagen

Once consumed, the collagen peptides don't directly add to the body's reserves of it. The 'hypothesis', as Pupinder Ghatora, co-founder of Ingenious Beauty, describes it, is that "if you can get the body to absorb a collagen peptide, through the gut into the small intestine and then into the blood, your body senses them floating around the bloodstream and thinks, 'oh gosh, we've got a lot of collagen breakdown going on, what should we do?’ That kick-starts your own cells to produce more."

5. Collagen doesn't actually break down in stomach acid

There are various ways that collagen supplements can be delivered: pills, powders and liquids. Which is best hinges around the question of whether collagen breaks down in the stomach.

Co-founder of Absolute Collagen Darcy Laceby says her company is doing research with the University of Birmingham which aims to show that collagen doesn't actually break down in the stomach. If proven, this would change the current thinking around how collagen is absorbed.

At the moment Absolute Collagen claim on their website that their liquid sachets allow collagen to be absorbed at a rate of 90 to 95% compared to 40 to 45% via pills or capsules. To support this, she cites the general principle of liquids being better absorbed than tablets But, thinks Dr Wedgworth: "You probably can absorb similar from liquid to tablets to powders. It really depends on the individual formulation. But you pick a formulation actually that's suitable for you, because some people just hate tablets."

Meanwhile, Ingenious Beauty's supplements use a smaller amount of collagen inside a plant cellulose capsule "which shields the collagen peptides as they travel through the stomach". Pupinder Ghatora says this more directed approach contrasts with the liquids and powders that are "like throwing mud at a wall". He references a carbon isotope test carried out by his company that showed collagen peptides in their capsules travelling to various parts of the body.

6. Studies show a link between collagen consumption and reduced wrinkles, but no absolute proof of increased collagen production

Ingenious Beauty are the only company in the UK to have carried out independent, double-blind trials on their own product. Although not yet published, co-founder Pupinder Ghatora says the study shows that taking their collagen product leads to increases in skin hydration, elasticity and a reduction of wrinkles.

However, no study has yet been able to prove that taking supplements leads directly to increased collagen production in the skin (that would require skin biopsies to be taken). Ghatora is clear that the results speak for themselves though.

"What would be the reason for your skin to become more elastic?" responds Ghatora. "Why would the wrinkles reduce? Why are you holding more moisture in the skin? It's all going to be down to an increase in collagen production."

7. Diet is among factors that can make a difference to ageing skin

So, crucially, will taking collagen supplements help reduce the effects of ageing? There's a lot ultimately to weigh up. Consultant dermatologist Dr Wedgeworth believes that there isn't enough evidence to support taking supplements daily. But she recognises that there may be a small benefit, so if people want to continue spending their money on them they should go for it, as they are unlikely to cause harm.

There are other things that have more evidence behind their positive effect on your skin though, like topical vitamin A or retinols. Dr Wedgeworth also reminds us that being careful in the sun, a sensible diet and not smoking will also all contribute positively to the health of our skin.

Find out more about Greg's findings, and if Jo will continue to spend £53.98 a month on her supplements, by listening here.

The information contained in this article was correct at the time of broadcast on 24 November, 2022.