Thinking Nutrition

Tendon troubles: can collagen supplements help with tendon repair?

• Dr Tim Crowe • Episode 120

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Tendons play a vital part in helping us move. They are a collagen-infused super-strong bridge that connects muscles to bones allowing you to move your limbs. When overused, overloaded or damaged, these same tendons can cause us a lot of pain and movement impairment. Outside of the well-defined medical treatments and physiotherapy rehabilitation programs that assist with recovering from tendon injuries, there has been growing interest in the role of specialised tendon-targeted nutritional supplements in aiding repair and recovery. And for good reason, hydrolysed collagen is a key component of many of these supplements. In this podcast, I’ll look at where the evidence stands for nutritional supplements helping with tendon healing.

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Tendons play a vital part in helping us move. They are a collagen-infused super-strong bridge that connects muscles to bones allowing you to move your limbs. When overused, overloaded or damaged, these same tendons can cause us a lot of pain and movement impairment. Outside of the well-defined medical treatments and physiotherapy rehabilitation programs that assist with recovering from tendon injuries, there has been growing interest in the role of specialised tendon-targeted nutritional supplements in aiding repair and recovery. And for good reason, hydrolysed collagen is a key component of many of these supplements. In this podcast, I’ll look at where the evidence stands for nutritional supplements helping with tendon healing.

Today the podcast theme is all about tendons. So what are they? Tendons are strong rope-like bands of connective tissue that attach muscle to bone so they are essential in helping limbs move as they provide the bridge linking the force generated by the muscle to the bone. Tendons also help reduce the risk of muscle injury by absorbing some of the impact force your muscles experience when you run or jump.

Tendons are mostly composed of collagen which make up about three-quarters of the dry weight of the tendon. You’ll also find elastin in tendons which, as its name suggests, is a protein that gives tissues some degree of stretch and recoil ability.

Tendons do a lot of work. And in cases of overuse and injury, this can cause pain, swelling and reduced performance. The two most common conditions affecting tendons are inflammation which is called tendonitis and the other condition, called tendinosis, is more associated with the breakdown of the collagen fibres that make up most of the tendon. Collectively, these types of conditions come under an umbrella term called tendinopathy.

Overuse is a common cause of tendinopathy where the tendon is repeatedly strained until tiny tears form. Shoulder, wrist, knee, shin and heel are the common places it appears. Sports people represent a high-risk group for tendinopathy and in runners, for example, some estimates put the incidence of tendinopathy at 10 percent of runners developing it each year. In athletes, common locations for tendinopathy include the Achilles and patellar knee caps. But tendinopathy is also common in people over the age of 40, those who do repetitive tasks, and in people with poor muscle strength.

Now this podcast has its focus on nutrition as that’s my expert area so I’m going to leave well alone the medical and physiotherapy management of tendinopathies – you can do your own reading on this area and seek out appropriate professional advice. And because the symptoms of tendinopathy can be similar to other conditions such as arthritis, it is important to seek medical advice when faced with joint pain that doesn’t resolve after a week or two of rest.

With tendinopathy such a common problem, there has been a lot of interest in the potential benefit that dietary interventions and nutritional supplements could play, especially interventions targeted towards inflammation, in treating tendinopathy in hand with currently recommended medical and physiotherapy approaches.

So, now we have a recently published review paper that attempted to collate the research field of nutritional supplements for treating tendinopathies to see what interventions have been tried and what were the outcomes. And I’ll link to the review in the show notes. https://pubmed.ncbi.nlm.nih.gov/37146985

Let’s get into what the review looked at. In all, 16 studies, 12 of which were randomised controlled trials, were identified that investigated a range of nutritional supplements in the clinical management of various tendinopathies. The tendinopathies were located in the Achilles, rotator cuff, patellar and plantar heel.

I’ll list the nutritional supplements used so you can appreciate the common themes.

There were two studies with a commercial supplement called TendoActive which contains mucopolysaccharides (which are found in joints), type I collagen and vitamin C.

Three studies used the commercial supplement Tendisulfur which contains mucopolysaccharides, hydrolysed collagen, arginine, lysine, vitamin C, bromelain (which is an enzyme found in pineapples and linked with reducing inflammation) along with chondroitin, glucosamine, the herb Boswellia and myrrh of the biblical “Three wise men” fame.

Two studies used the commercial supplement Tenosan which contains arginine, alpha-ketoglutarate, hydrolysed type I collagen, mucopolysaccharides, vitamin C, bromelain and vinitrox which is a mixture of polyphenols.

Collagen peptides alone were used in two studies. And the remaining studies used omega-3 fatty acids, turmeric, HMB, and vitamin C either in isolation or combined with gelatin. And finally one study used creatine.

That’s a real mixed bag, but the clear common ingredient was collagen. More about collagen shortly.

So what did the review uncover? Most of the studies found positive clinical outcomes, such as improvements in pain, function and tendon structure following nutritional supplementation. And there was evidence the benefit from supplementation was increased when combined with eccentric training (which corresponds to the downward lowering phase of weight lifting) or extracorporeal shockwave therapy known as EWST where high-frequency shock waves are delivered to an injured tendon to stimulate healing.

Many of the supplements used are known to have anti-inflammatory properties and may be capable of downregulating inflammatory processes in tendinopathy so this could be where some of the benefit on pain was being seen. Reducing pain is certainly of some benefit to a person, but there could be other effects going on related to collagen synthesis and tendon repair. And this is probably the area of greatest interest, but one that the review was less clear on giving direction on.

The review was not without limitations as it included a range of study designs so there was a lot of variability between the studies so treat the findings with some level of caution. And while nutritional supplements may seem safe and have fewer side effects than pain medications, they still carry risks and can be abused, especially by high-performing athletes who undergo drug testing for banned substances and where there can be a risk of supplement contamination. So for anyone considering trialling any supplements for tendon repair and recovery, it is important to be educated about their use and what exactly you are taking.

But back to collagen as that was the key common ingredient across the supplements studied in the review. Collagen makes up about three-quarters of the dry weight of tendons and its crosslinking strength aids the tendon structure to endure resistance from high-impact stresses and shear forces so it is no surprise that collagen supplements featured heavily in the studies outlined in the review.

And collagen itself has been looked at quite a lot for its health effects. Taking a more exercise recovery and joint injury perspective, a 2021 review looked specifically at the role of collagen peptide supplementation in this area. And the findings, albeit based on a small research field, were positive for collagen and indicated that collagen is beneficial in improving joint functionality and reducing joint pain. And I’ll link to the review in the show notes. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8521576

A possible reason that collagen supplementation may reduce joint pain is that it increases collagen levels in the cartilage while also increasing the production of proteoglycan (which is an important structural protein in connective tissue) as well as elastin – thereby reducing tissue damage and decreasing pain. It is also thought that collagen peptides may exhibit some level of anti-inflammatory effect, further decreasing pain and inflammation. Based on the studies collated from this second review, the authors concluded there was a benefit in improving joint pain and functionality, especially when complemented with a rehabilitation exercise protocol. And the type of doses we’re talking about is in the realm of 5 to 15 grams per day.

It is easy to dismiss most of what I’ve covered today as it is true the evidence base is still small. And if you see the common criticisms about collagen, many dismiss it out of hand for having no evidence for a benefit, and no plausible reason why it should have any effect different to any other protein source you may eat. And, all that research is funded by Big Collagen don’t you know? All three claims are completely wrong.

The best-researched area to do with collagen is to do with skin health. And we now have dozens of double-blinded randomised controlled trials showing a benefit on skin hydration, skin elasticity and wrinkles. I went into a deep dive into this area in previous podcasts and you can read the summary of all this in a detailed blog post of mine which I’ll link to in the show notes. https://www.thinkingnutrition.com.au/collagen-supplements-health

In the blog post, I outlined the findings from a systematic review of 19 clinical trials that was published in 2021 that looked at collagen supplements and skin health. Research never stands still and there has been more research since then - so much so, that only in the last few months, a new systematic review was published. And this could analyse 26 randomised controlled trials of oral collagen supplements that looked at skin hydration and skin elasticity. And again, the review showed a significant benefit with almost every study pointing in  the right direction for a benefit. And I’ll link to the study in the show notes. https://www.mdpi.com/2072-6643/15/9/2080

And sure, you can always find fault with any individual study, but for anyone to claim that there is ‘no evidence collagen supplements work’ is living in scientific denial. And many of those studies had no funding by the collagen industry or any conflict of interest reported by the authors.

And to top all this off there is a plausible and actual well-understood mechanism where collagen can have direct effects on collagen production in the body different to any other protein source. That’s because when collagen is eaten, it is digested and absorbed into the bloodstream where both single amino acids and unique dipeptides and tripeptides appear. These small peptides have a unique fingerprint because of the presence of the amino acid hydroxyproline. What’s special about hydroxyproline? It is unique to collagen and is made from the amino acid proline with the help of vitamin C. So these small peptide fragments only exist in the blood from collagen breakdown or from the collagen we eat.

Absorbed collagen peptides not only redistribute to the skin but can act as signalling molecules, binding to receptors on the surface of fibroblasts. Fibroblasts are skin cells that are major producers of collagen. This receptor binding stimulates fibroblasts to produce collagen, elastin (needed for skin elasticity) and hyaluronic acid (for water retention). This is a key point as it provides a plausible mechanism by which collagen consumption could directly affect our skin. And similar types of pathways exist in cells that produce collagen found in cartilage and tendons.

So, let’s wrap all this up. There certainly is a plausible use case for why collagen-containing nutritional supplements could support tendon injury repair and recovery when combined with best-practice medical and physiotherapy treatments. And the evidence so far looks positive and is supported by a solid use case for collagen in skin health and joint conditions such as osteoarthritis. If anything, I am more sceptical of people who dismiss collagen out of hand which was a valid position 5 to 10 years ago with a limited research base, but not today when faced with the growing evidence across multiple areas where it seems collagen supplements offer a benefit for many conditions. And coming from a career medical researcher of over 30 years, when I look at the evidence through my own critical analysis filter, it is strong enough for me that hydrolysed collagen is one of the few supplements I now take on a regular basis.

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, 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. 

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