Thinking Nutrition
Thinking Nutrition is all about presenting the latest nutrition research in plain language and then translating this into what it means for your health. Dr Tim Crowe is a career nutrition research scientist and an Advanced Accredited Practising Dietitian. Tim has over 30 years of research and teaching experience in the university and public health sectors, covering areas of basic laboratory research, clinical nutrition trials and public health nutrition. He now works chiefly as a freelance health and medical writer and science communicator.
Thinking Nutrition
Collagen supplements: an update on the evidence for health benefits
It was back in episode 55 that I first tackled the topic of collagen supplements. It proved to be one of my most popular episodes ever. And for good reason as there is a growing evidence base to support many of the health claims made about collagen: from improving skin health to perhaps even helping with sports injury recovery and osteoarthritis. In this podcast, I give an update on the growing scientific evidence for the use of collagen supplements. I’ll also explain how there is certainly a plausible biological mechanism to explain how this particular dietary protein source can have a targeted benefit even after digestion.
Links referred to in the podcast
- Meta-analysis of effects of hydrolysed collagen on skin ageing https://pubmed.ncbi.nlm.nih.gov/33742704
Episode transcript
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It was back in episode 55 that I first tackled the topic of collagen supplements. It proved to be one of my most popular episodes ever. And for good reason as there is a growing evidence base to support many of the health claims made about collagen: from improving skin health to perhaps even helping with sports injury recovery and osteoarthritis. In this podcast, I give an update on the growing scientific evidence for the use of collagen supplements. I’ll also explain how there is certainly a plausible biological mechanism to explain how this particular dietary protein source can have a targeted benefit even after digestion.
So, if you haven’t caught my previous podcast on collagen supplements, let’s do a quick refresh about collagen itself. Collagen’s key role is as a major structural protein in numerous tissues of the body including tendons, ligaments, cartilage, blood vessels and skin. It is so abundant in the body, that it makes up almost 30 percent of our total protein mass.
The structure of collagen is characterised by a triple helix arrangement of chains of 1014 amino acids which forms a very strong structure – think of collagen like a rope with many fibres intertwined to make it strong. No wonder then its key role is in forming a scaffold for the structure and strength of tissues such as skin and bones.
Collagen though is not one molecule, but at least 28 distinct types. But it is Types 1, 2 and 3 collagens that are the most abundant in your body. You’ll find type I collagen in the connective tissue of tendons, ligaments, corneas, bones and skin. Type III collagen usually is found along with type I collagen in the skin and blood vessels. While type II collagen is primarily found within cartilage.
Now when it comes to oral collagen supplements, it is hydrolysed collagen that dominates the market. Hydrolysed simply means the breaking down of a molecule with water. Hydrolysed proteins are smaller in length compared to undenatured whole proteins, so they’re generally absorbed faster and more efficiently. Hydrolysed collagen is also much more soluble than its precursor of gelatin so it is much more convenient to put into drinks. The collagen that is used in supplements can be derived from numerous sources including cattle, pigs, chicken, and marine sources. It is a nice use of what would essentially be a waste product in the processing of these animals and fish for human consumption.
Collagen metabolism 101
But why even bother with taking a collagen supplement? Surely all protein just becomes an amino acid soup in our body after digestion? It’s a common criticism I read about collagen supplements in the popular press for articles that completely dismiss any benefit of it because of this digestion issue. If it was completely digested, then such criticism would be valid. The thing is, that isn’t the case. And when you appreciate that there is a valid mechanism to explain how collagen can be specifically utilised by the body, then that forms the basis of giving credibility to any clinical trials that follow.
One plausible physiological mechanism is hydrolysed collagen, in the form of small collagen peptides, can increase significantly in the blood after ingestion. Peptides are short chains of amino acids, and in the case of collagen, these are unique of either two or three amino acids long – called dipeptides and tripeptides. It is to do with the structure of collagen that is heavily made up of three specific amino acids called glycine, proline and hydroxyproline that exist in repeating sequences. Fun fact, the amino acid hydroxyproline requires vitamin C for its production and it is why vitamin C deficiency leads to poor wound healing and bleeding gums because the collagen is too weak.
After ingesting collagen, it is actually possible to measure levels of these unique collagen peptides in the blood so they certainly can pass through the digestion and absorption process. These collagen peptides and free amino acids are then distributed in the body, in particular to the skin, where it has been shown, at least in rat studies, that they can remain in place for up to 2 weeks.
It gets more interesting when you know that these collagen peptides can also act as signalling molecules that bind to receptors on the surface of fibroblasts. Fibroblasts are skin cells that are major factories for….collagen. And guess what the binding of the collagen peptides to fibroblast receptors does? It stimulates them to produce collagen as well as elastin and hyaluronic acid. One theory is that collagen peptides in the blood are a marker for collagen breakdown so are acting to signal the body that it needs to produce more collagen.
So, we have here clear evidence that collagen protein can produce by-products after digestion that are quite unique, the peptides can be specifically stored in the skin, and can stimulate skin protein production such as collagen as well as molecules involved in water retention such as hyaluronic acid.
Now for an update on the evidence base for what clinical trials in humans have to say. Back in podcast episode 55 when I covered collagen, I said how surprised I was when I went digging into the evidence for just how much there was. At the time, I could count 12 RCTs showing a favourable benefit of supplementation with hydrolysed collagen on skin health on markers of skin elasticity, hydration and wrinkles. And there was even a 2019 review that looked at eleven studies involving over 800 people and with doses of collagen hydrolysate ranging from 2.5 to 10 grams per day that supported a benefit. And with every study showing some type of positive outcome. All with no reported adverse events.
Well, since then, a more in-depth systematic review and meta-analysis has been published. In the paper published in the International Journal of Dermatology which I’ll link to in the show notes, 19 clinical trials were included and all of them were randomised controlled trials where both the people taking the supplements and the researchers were blinded to if a person got the collagen or a placebo. And the results: a clear and consistent benefit of hydrolysed collagen on skin hydration, skin elasticity and wrinkles. https://pubmed.ncbi.nlm.nih.gov/33742704
The analysis also reported not being able to see any evidence of a publication bias in the field. A publication bias is an indication that only more positive studies are published, and perhaps less favourable research buried so this can be an issue. This is a really important point as another criticism I see of collagen supplements in dismissing any benefit they can have is that somehow the positive evidence is just a sign of industry-sponsored research and it can’t be trusted.
Firstly, that is an absolute lazy form of argument when it comes to critiquing scientific evidence. Research should be evaluated on the merits of the study, not who funded it. While it can be true that industry-funded research is more likely to report a positive finding, that can be because less favourable research is not published. The review I’ve covered here could not find evidence of that.
And do you know what else? Among all those 19 clinical trials covered in the review, many of them were not funded by a manufacturer of collagen supplements nor did any of the research team have any conflicts of interest to declare - and those studies were just as likely to report a positive benefit as studies funded by industry. And the people who put this latest review together also had no COI to report or a funding source tied to makers of these hydrolysed collagen supplements.
Other benefits of collagen
I’ve focussed this update on the benefits of hydrolysed collagen on skin health, but the research evidence in other areas such as osteoarthritis and injury repair is growing. And the research looks promising so far and why such supplements are now being recommended for athletes as part of soft-tissue injury recovery.
And it’s not all about skin and joints. There is some really interesting preliminary work showing that hydrolysed collagen may be effective at improving insulin sensitivity, glucose and lipid metabolism, and reducing hypertension in people with type 2 diabetes. So, certainly, watch this space as the research develops.
Summary
For hydrolysed collagen, it reads like a shopping list of health benefits that sound too good to be true. But for those who are regular listeners of this podcast, you would know that I have a high evidence threshold for making claims, and at least with collagen, there definitely appears to be something to the story – especially for skin health. All for something that is naturally part of foods and has little evidence of any adverse problems.
If you want to trial it yourself, look past all the glossy promotion of expensive powdered supplements touted by Insta influencers and just evaluate a supplement based on price. For that, just look at how much actual collagen is in it and work out the price per gram as that is the best way to shop around to make valid comparisons. And you only need a few grams per day. Some supplements may contain a long list of other ingredients such as vitamins, minerals and herbals, but it is the collagen that is the star of the show here so just focus on that rather than pay for over-priced collagen.
So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.
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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.
