Sometimes, being a beauty editor is a bit like being a doctor. Mention your job, and people start firing questions at you: should they take collagen? Which collagen is best? And are the health benefits of collagen really as good as they sound? This is similar, I imagine, to how a doctor might find themselves being shown any number of lumps, bumps and rashes while making polite small talk at a dinner party.

Occasionally people ask other things… perhaps about red light masks, or retinol, but for the most part these days, the questions are all about collagen. And for good reason. Collagen can help with everything from improving skin firmness to strengthening weak nails and supporting good gut health.

What is collagen?

“Collagen is the most abundant protein in the human body,” Hannah Alderson, BANT-registered nutritionist, hormone specialist and author of Everything I Know About Hormones: Six Steps to Optimal Health & Happiness, says. “But it’s not a ‘complete’ protein.” This means it doesn’t contain all nine essential amino acids that constitute a protein cell. But still, it’s not without its benefits.

How collagen works

“Collagen acts like scaffolding – giving structure, strength and elasticity to skin, bones, tendons, ligaments and connective tissues,” Alderson continues. “Think of it as the glue that holds everything together, from your complexion to your joints.” Nerds will appreciate that the word collagen actually comes from the Greek word for glue.

Are there different types of collagen?

Yes, there are different types of collagen both in the body and in the collagen supplements we consume. In the body, over 28 types of collagen have been identified, though there are five that we tend to concentrate on. These types of collagen appear in skin, nails, hair, bones, muscles, joints and organs.

Then, when it comes to collagen supplements, there are two main types of collagen: bovine collagen and marine collagen.

Bovine collagen

“Bovine collagen is derived from cows and typically contains Type I and Type III collagen,” Alderson tells British Vogue. “These types of collagen support skin, muscles, bones and connective tissue.” Bovine collagen is found in a cow’s connective tissue, bones and hide, and as with humans, it acts like a structure-supporting glue.

Marine collagen

“Marine collagen, on the other hand, is sourced from fish and is primarily Type I, making it particularly effective for skin health,” Alderson explains. Marine collagen can tend to be more bioavailable, meaning it’s more straightforward for the body to absorb, which can mean that it absorbs faster and more efficiently.

What are the benefits of collagen?

Whichever type you take, marine or bovine collagen, the list of benefits is long.

1. Skin hydration

“Collagen can help with skin hydration, elasticity and the appearance of fine lines,” says Alderson. An important thing to note, though, is that collagen can only do so much to mitigate certain lifestyle factors. Things like how much alcohol you drink, whether you smoke, if you wear sun protection and how hydrated you are can make a marked difference, too.

2. Improved bone density

Bones with high density are more resilient to cracks, breakages and fractures – all important things as you age. A 2018 study of post-menopausal women found that certain collagen peptides significantly increase bone mineral density. Other studies have shown that collagen can help increase bone density in people with diagnosed osteoporosis or osteopenia, both bone disorders caused by a loss of density.

3. Stronger nails

If weak, flaking nails are one of your biggest pet peeves, collagen could help restore them to their former glory. “As the most abundant protein in the body, collagen is essentially the building block that keeps skin firm and elastic and supports healthy hair and nails,” says Vida Glow founder Anna Lahey.

4. Gut-lining support

“Collagen can help support the integrity of the gut lining, though more research [in this area] is needed,” says Alderson. The gut lining is a semi-permeable layer that controls what passes through the gut and into the bloodstream.

For example, the nutrients from food, electrolytes and water are things that should pass through the gut lining and into the bloodstream. Things like bacteria and toxins, though, absolutely should not. When the integrity of the gut lining is compromised, it can become lax and let these harmful substances into the bloodstream, triggering inflammation. Collagen can help this mucus layer work as it should.

5. Joint comfort and mobility

Stiff, aching joints are something that collagen can help alleviate, says Alderson, particularly in “active or ageing individuals”. However, as with all collagen benefits, the only way to truly reap them is through consistency.