What is the Truth About Collagen Supplements?

Thank you to the amazing team at Glowday for suggesting this topic.

Recently there has been a rise in so-called “nutricosmetics” or “nutraceuticals,” a trend that has been growing increasingly more popular and one that isn’t going anywhere soon. Essentially, the focus is on ingesting certain substances or supplements in order to improve the health or appearance of your skin or hair.

Of course your diet affects your overall health and appearance. But I will be the first person to put my hands up and say I naturally have a high, high skepticism of the whole field of dietary supplements.

From celebs on Instagram shilling gummy bears for your hair, to constant DMs from companies asking if I’d be interested in selling their health pills/detox supplements - let’s just say I’m not a fan!

In general, if you eat a well-balanced diet and have no health issues, you don’t need to spend money on extra vitamins, minerals, or dietary supplements.

There are exceptions to this, as many of us do need to supplement our Vitamin D - especially here in the UK - as recommended in current NICE (National Institute for Health and Care Excellence) guidelines. In the same vein, if a blood test from your GP objectively shows you have a deficiency needing to be corrected, then by all means take a supplement!

Knowing this, I am wary around these types of products. “Health” supplementation, after all, is a lucrative business.

Collagen supplements are the latest big seller, with inviting claims of improving the quality and youthfulness of your skin in a quick, easy, palatable way - and with the market size in collagen estimated to reach 7.5 billion USD by 2027!

The History of Ingesting Collagen

I say collagen supplementation is a new thing, but actually there is a long history of eating certain foods to improve health and appearance. It is thought that the habit of ingesting collagen-rich foods comes from China, the place of my own heritage, where foods like bone-broth, fish maw, and sea cucumbers are popular for beauty. Collagen is often served in the form of a gelatin, jelly, or liquid - derived from animal skin and bone.

In the west, we don’t tend to incorporate as much of this animal skin or bone into our diets. I’ve seen it written multiple times that Asian women have great youthful skin and collagen-rich diets, as proof that eating collagen is must work.

I think we know to take this kind of observation with a grain of salt - recognising it for the sweeping generalisation and loose correlation that it is. So let’s start getting down to the research.

What exactly is collagen?

As a reminder, collagen is a protein found in abundance in our hair, skin, bones, tendons, and nails. There are many different types of collagen, but they function similarly in providing a lot of the structure for these elements of our bodies.

As I’ve written previously, collagen is arguably one of the most important parts of the dermis where it is cross-linked into helices. When we are young, collagen fibres are abundant and can glide against one another easily, giving smooth and flexible skin. Aesthetic doctors are obsessed with protecting your collagen, to maintain this youthful, bouncy skin.

What is the evidence in favour of collagen supplementation?

[“Oral Collagen Supplementation: A Systematic Review of Dermatological Applications” by Choi et al was published in the Journal of Drugs in Dermatology (which can be accessed for free here). It is an excellent summary of the current data from clinical trials around this issue. You can find the original trials linked in the review, and a search of PubMed will give you more primary research. I always encourage people to read through studies themselves and never take anyone else’s word for anything, but I’ll summarise my take on the findings below.]

A systematic review published in 2019 looked specifically at the randomised control trials (the highest standard of evidence) that have been done on the effect of oral collagen supplementation versus a placebo on the skin, summarising the results of eleven trials encompassing the results of 805 patients. The authors concluded that collagen supplements were safe, and that they found evidence that collagen increased skin elasticity, hydration, and the density of collagen fibres.

So, it actually all sounds very promising, right?

Well…

Here are my problems with the body of evidence in favour of collagen supplements (a lot of which is also discussed in the above paper.)

Issue #1: Bias and Methodology

You can skip below to the summary if you don’t need this level of detail!

The Science: I’ve written systematic reviews before, and one of the most important things we must assess when we are trying to write a summary of the current research about a scientific question is the quality of any clinical trails or studies being examined.

One of the most important things to look for are issues in the methodology of the study and sources of bias, and whether it is appropriate to combine the results of different studies. These are some of the biases in the studies conducted on collagen supplements so far.

• Small sample size - many of these studies had a small number of participants, meaning it is harder to say that the results can be extrapolated to the wider population. They also mainly only looked at healthy women, which is obviously not a representative sample of the general population.

• Different interventions - many of these trials use different types of collagen of different sizes, meaning that even if a slightly positive effect was found for one type of collagen, it does not hold that this applies to another type of collagen. Eight of the studies examined collagen hydrolysate, two at collagen tripeptide, and one at collagen dipeptides. In addition to this, over-the-counter collagen supplements are quite unregulated, so you don’t always know what you’re getting when you buy them, what they’re mixed with, and what additives they contain. There also doesn’t appear to be an evidence-based consensus on how much collagen you actually should be consuming to see results.

• Inconsistent outcome measurements - when studies are measuring their outcomes in different ways, or indeed looking at different outcomes, it is difficult to pool their results together (like comparing apples to oranges!). For example, one trial was looking specifically at wound healing in pressure ulcers, one looked only at moisture in skin, one looked only at elasticity in skin, and so on. You can’t really combine or pool the results of those three studies, because they were looking at and measuring different things. Therefore we don’t have evidence from 805 patients consuming collagen all showing one, consistent thing - we have some evidence from small subgroups of patients saying slightly different things about collagen consumption.

• Funding bias - most of these studies were funded by the companies selling the supplements. This isn’t uncommon, of course, and we have to be realistic about the difficulty of finding funding in the research world. However, we must acknowledge that these companies are biased towards positive results, and would have no interest in publishing any negative or neutral results (which is why searching through the grey literature and unpublished trials is vital when doing reviews).

In summary: Basically there are a small number of trials with a small number of participants, many with different types of collagen consumed in different amounts, measuring different outcomes (some measurements also being subjective), and many funded by the company selling the supplements.

In other words, to really get to the bottom of things, we need further large-scale, well-designed, randomised control trials with consistent outcomes measures and interventions.

Issue # 2: You are what you eat…kind of?

There appears to be a popular misconception that when you eat collagen, it is somehow finding its way, intact, to your skin to replace any collagen you are missing. The science behind what happens to the food we ingest, how it is broken down by the body and used as fuel, is wonderful and amazingly, amazingly complicated.

Those collagen supplements you eat are broken down by enzymes in your stomach and intestines into amino acids (the basic building blocks of all proteins). Therefore, it would be a mistake to think that the collagen we eat is directly replacing missing collagen in our skin.

So that’s done and dusted then, right?

However, like everything in biology, the story is more complicated than that.

Collagen does have one unique amino acid - hydroxyproline - which is not found in other proteins. Studies have shown that this unique amino acid is detectable in the blood after collagen ingestion.

The amino acid hydroxyproline

Hydroxyproline is essential for stabilising our collagen, and it requires Vitamin C for its formation (that’s why a lack of Vitamin C famously gives you scurvy!). There is some evidence that the presence of hydroxyproline can act as a cell signal to stimulate the production of more collagen and more hyaluronic acid.

However the crucial distinction is that we don’t yet have the evidence that collagen ingestion raises the concentrations of hydroxyproline in the blood to a high enough level to accomplish this.

So do you need collagen supplements? What about diet?

If you know me, you know I’m a huge proponent of lifestyle medicine and good food as the first port-of-call.

I suppose the bottom line is this: the jury is still out on collagen ingestion and its benefits. But if you like the results of the research so far and want to ingest collagen, I would suggest you do it with real food, not spending extra hard-earned cash on buying something that may, or may not, work.

The other benefit of eating food over just taking a supplement is that your food is supplying you with more than just collagen - your food gives you many other vitamins and minerals.

For collagen-rich foods, you can make you own homemade stock using chicken, beef, or fish bones. You can find some collagen in chicken meat and fish, as well as egg whites.

If you do want to spend extra money on your skin, there are better methods of protecting your collagen and stimulating its growth - with much stronger evidence and years of research behind it:

SPF, Vitamin C, retinol, chemical peels

Final Thoughts about Collagen Supplementation (TL;DR)

• There is a long history of eating collagen-rich foods for beauty (from bovine, porcine, or seafood sources - their bones and skin).

• There is some evidence that ingesting collagen may lead to increased levels of one of its constituent amino acids (hydroxyproline) in the blood, but it is not yet proven that it is at a meaningful concentration to stimulate extra collagen growth.

• I think the science is too much in its infancy to either dismiss or substantially validate claims about eating collagen.

  (There are quite a few upcoming randomised control trials registered on clincaltrials.gov, and I am genuinely interested to see what the results are!)

• It doesn’t harm you to eat extra collagen if you like the idea, however I do not think the evidence is strong enough to be spending your money on collagen supplements that claim to work wonders on your skin.

• Instead, if you want to ingest collagen, look at incorporating collagen-rich foods into your diet as a less expensive (and more delicious!) way of increasing your collagen intake.

• And - if you really care about your collagen and want to spend money on your skin - I recommend spending your hard-earned cash on interventions that have much more convincing and proven evidence behind them: like SPF, Vitamin C, retinol, and chemical peels.