Everything you need to know about collagen

From celebrity endorsements, to headlines and social media ads, collagen, and particularly collagen supplements, seem to be the hot topic of 2025. But what is collagen, and why the explosion in interest around collagen supplements? In this article, we delve into the world of collagen and seeks a more scientific understanding about the claims and headlines we are being bombarded with. Importantly, we will be considering collagen supplements and whether these are worth investing in.

What is collagen?

Collagen is a protein – in fact the most abundant protein in our bodies. Its fibrous structure plays a pivotal role in connective tissue, knitting together different types of tissues in the body. Found in bones, skin, muscles, tendons and cartilage, collagen ensures tissue strength, resilience and flexibility – an important function for tissues involved in movement and growth.

In our diet, collagen naturally occurs in animal-derived foods like meat and fish that are rich in connective tissues. However, protein is interesting because it is made up of smaller units called amino acids. Amino acids from diverse protein sources, including plants, can be used to form collagen in the human body. So even individuals following a plant-based diet can maintain a healthy collagen supply in the body.

The ageing process

Protein is the most important nutrient in our bodies for maintaining structure – we constantly break down proteins and build up new ones from the protein we get in our diets. The same is true for collagen. However, as we age our collagen production gradually diminishes, compounded by an increase in the enzyme that breaks down collagen. This helps to explain why our skin, in particular, starts to become less firm and potentially becomes more prone to developing wrinkles as we age.

It is tempting to correlate this decline in collagen production (and increase in its breakdown) with the changes we see in our skin as we age, and then think about ways that we could reverse this decline and get back to those youthful, wrinkle-free days! If collagen holds the key, then why not add more collagen to our diets and reap the benefits of firmer, younger-looking skin?

Although this would seem plausible, protein science is a bit more complicated than that – so it's not just a case of adding more collagen to the diet, there are a few steps in between.

Collagen in the diet

Considering this need for the amino acids from protein, you might consider whether consuming foods containing collagen is necessary, and which foods might be good sources? Tough cuts of meat such as brisket that contain a lot of connective tissue serve as a good source of collagen. Also, there has been a lot of interest in bone broth in recent years – with claims that this method of boiling down the bones results in a rich collagen ‘soup'. However, the science is pretty weak around the number of amino acids that are available after the boiling process.

Remember though that eating collagen-rich foods doesn't necessarily correlate with an increase of collagen forming in the body – the dietary collagen is broken down to its constituent amino acids, then those amino acids are used throughout the body wherever they're needed. Not just for collagen formation. Other protein sources in the diet can be used for those all important amino acids we need to make protein in the body, including collagen.

Protein digestion and absorption

There are 20 amino acids that join together in various combinations to make different proteins – these proteins are important for many different parts of our bodies including our bones, teeth, muscles, blood, hormones, and immune system. When we eat food that contains protein, it has to first be digested back into those individual amino acids, absorbed into the body, then the clever part – the amino acids are redirected around the body to wherever they are needed to build new proteins. Think of amino acids as beads, and protein as a chain of those beads in a necklace.

So whatever form of protein you eat – whether it's a steak, an egg, lentils, or a protein shake, the same process occurs. Breakdown of the protein to its amino acids, then the amino acids are used to make new proteins. It is the amino acids that are important, not necessarily the protein that was eaten in the first place.

What about collagen supplements?

There is a huge array of different collagen supplements available, all claiming to have positive effects on hair, skin, joints and other parts of the body. So what is the evidence for these?

There are some scientific studies looking at the impact of collagen supplements on skin elasticity, and there is some evidence that suggests that using supplements might work. In one study published in the Journal of Dermatology those who used collagen supplements saw an improvement in the firmness, suppleness, and moisture content of the skin, with wrinkles appearing less noticeable. That sounds promising, but it's unclear if these skin improvements were actually due to collagen. Most of the trials used commercially available supplements that contained more than collagen: vitamins, minerals, antioxidants, coenzyme Q10, hyaluronic acid, and chondroitin sulphate were among the additional ingredients.

There haven't been enough large-scale, good-quality clinical trials yet to show that collagen supplementation alone has a positive impact on skin health. It may be that the other nutrients are having an effect too.

As for nail and hair health, the evidence remains weak – in fact there are no good quality trials to show that collagen supplementation has any impact on nail strength or hair health. Currently, no medical evidence supports product claims that collagen supplements can improve hair shine, growth or thickness.

I am taking collagen supplements and can see benefits – why is it working for me?

Many people find that taking supplements can be a useful way to enhance their health, and to ensure that nothing is missing from the diet. This can absolutely be the right thing to do for some, and often seeing the impact of such supplementation is confirmation of this.

Collagen supplements are a rich source of protein and often have additional ingredients such as vitamin C, antioxidants, zinc or other important nutrients. We're not sure yet whether it's the collagen itself, the protein in general, or the additional nutrients that have an impact on skin health. However, it is proven that these elements do have an effect. Sometimes a deficiency in one nutrient impacts our ability to use another nutrient properly e.g. vitamin C is vital in collagen production – often with nutrition it can be trial and error to find out what works best for you.

Take-home message

As we age, the cells in our bodies do too. This is a natural process which can lead to changes in our skin, hair and nails. Choosing a healthy, balanced diet, being as active as you can, staying hydrated and looking after your skin from the outside can all help to slow down the ageing process.

Nutritional supplements may help to ensure you're not missing out on important nutrients, but remember that the science might not have caught up yet with the claims being made so do your homework before you buy.