Updated: Nov 13
Two supplements for Achilles tendon repair are backed up by research: Vitamin C-enriched gelatine and hydrolysed collagen. This article takes a look at what the research found and provides indications of when and how much of the supplements to use. Remember, if you need help with an Achilles injury, you're welcome to consult one of our team via video call.
The terms tendinitis, tendonitis, tendinosis, and tendinopathy mean the same thing for all practical purposes, and we use these interchangeably in most of our articles.
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Collagen in the Achilles tendon
Your Achilles tendon consists mainly of collagen fibres. These fibres are strong and densely packed together in parallel – think of the sinewy white bits in meat that are difficult to chew. (Sorry, I don’t know how else to describe it!) Collagen, in turn, is made up of specific amino acids that are linked together.
When you have Achilles tendonitis, the collagen fibres in a part of your tendon are weakened and lose their parallel structure. The only way to restore the tendon’s former strength is by exercising it, which stimulates the production of new collagen fibres (collagen synthesis) and then aligns them in parallel.
The exercises are typically heel raises (going up on your toes) and in some cases, when the tendon is somewhat stronger, hopping and jumping exercises.
Supplements for Achilles tendon rehab – What does the research say?
The research into supplements that may support or speed up the healing process described above is patchy at this stage, but some promising pilot studies have been done, and we report on these below.
When the body digests gelatine or hydrolysed collagen, it breaks them down into the specific amino acids that collagen is made of. There’s evidence that supplementing with these substances can increase healthy tendon growth.
Keep in mind that your injured Achilles tendon will never heal completely if you just chug the supplements … and then sit back and wait. The supplements are meant to increase the benefits of a rehab exercise programme, as the studies discussed below also indicate.
Vitamin C-enriched gelatine
An Australia-based research team led by Gregory Shaw reported in The American Journal of Clinical Nutrition that taking a gelatine supplement an hour before exercising the Achilles tendon increased collagen production. (Gelatine is a derivative of collagen that is used in food.)
The study involved three groups of people (none of whom had an Achilles injury). One group was given a placebo, one group took 5 grams of gelatine, and one took 15 grams of gelatine, each of which was dissolved in a low-calorie drink containing 48 grams of Vitamin C. The participants had to wait for an hour after taking the supplement and then skip rope for 6 minutes to stimulate collagen production in their tendons and ligaments. They had to do this three times a day for three days.
Blood samples were taken at various intervals during the experiment and analysed. The blood of the group who took 15 grams of gelatine indicated a greater increase in collagen synthesis than the other two groups.
Lab-grown ligaments were also treated for six days with serum from the blood of the three groups. The ligaments treated with the serum from the higher dosages of gelatine were found to have produced more collagen and to be stronger.
Shaw and his colleagues concluded: “The current data strongly support the hypothesis that starting an exercise bout 1 h after consuming 15 g gelatin results in greater collagen synthesis in the recovery period after exercise.”
These products are similar to the ones used in the studies:
Another Australian study, this time on athletes with mid-portion Achilles tendonitis, found that participants recovered more quickly from their injury when they used a hydrolysed collagen supplement (also called specific collagen peptides) in combination with a strength training programme versus those that followed only the strength training programme.
As reported in the scientific journal Nutrients, Stephan Praet and his team did a six-month study in which two groups of participants took either 2.5 grams of hydrolysed collagen or a placebo twice a day, half an hour before they did their Achilles tendon strengthening exercises.
In the first three months one group took the placebo and the other the collagen, and in the next three months they switched around.
In both time frames the group who took the collagen had a bigger improvement in tendon strength and pain levels than the placebo group.
Another sign of an injured Achilles tendon is that it has blood vessels growing into it. Healthy tendons don’t have blood vessels. The collagen-taking group in each time frame had a bigger decrease in blood vessels, which is considered a sign of healing.
“We conclude that oral supplementation of specific collagen peptides may accelerate the clinical benefits of a well-structured calf-strengthening and return-to-running program in Achilles tendinopathy patients,” wrote Praet el al.
They also note that the USA’s FDA has found specific collagen peptides to be “generally recognized as safe”.
What’s the difference between gelatine and hydrolysed collagen?
They contain the same amino acids, but hydrolysed collagen can dissolve in cold and hot water and appears to be easier to digest. This may explain why the study that used gelatine used 15 grams vs. the 2.5 grams in the hydrolysed collagen study. Another difference is that gelatine coagulates when prepared, while hydrolysed collagen does not.
How much supplement do you need?
There isn’t enough large-scale research available yet to give you a definitive answer. Different dosages and times than in the pilot studies discussed above may well give you better (or worse!) results, and people are different in so many ways, but for now it may be better to stick to what the researchers did.
Please note that I’m not a dietitian and that these recommendations may not be right for you.
Based on the research, my recommendations are:
Don’t use both gelatine and hydrolysed collagen – choose one!
Vitamin C-enriched gelatine: Take 48 grams of Vitamin C with 15 grams of gelatine in a low-calorie drink an hour before your rehab exercises. The low-calorie drink might already contain some Vitamin C, so check that.
Hydrolysed collagen: Take 2.5 grams, dissolved in a glass of cold water, half an hour before your rehab exercises.
The active ingredients in the hydrolysed collagen option available on Amazon below are made by the manufacturer of the stuff they used in the research study above. We couldn’t find the manufacturer used in the study on gelatine on Amazon, but gelatine is a fairly generic food product, so we chose another one.
We went for the powder options rather than for capsules or tablets, because it’s easier to measure out the correct dosage that way, and capsule or tablet ingredients may not be absorbed by your body in the same time frames as in the studies.
How we can help
Need help with your Achilles injury? You’re welcome to consult one of the team at TMA online via video call for an assessment of your injury and a tailored treatment plan.
We're all UK Chartered Physiotherapists with Master’s Degrees related to Sports & Exercise Medicine. But at Treat My Achilles we don't just value qualifications; all of us also have a wealth of experience working with athletes across a broad variety of sports, ranging from recreationally active people to professional athletes. You can meet the team here.
About the Author:
DePhillipo NN, Aman ZS, Kennedy MI, et al. Efficacy of Vitamin C Supplementation on Collagen Synthesis and Oxidative Stress After Musculoskeletal Injuries: A Systematic Review. Orthopaedic Journal of Sports Medicine 2018;6(10):2325967118804544.
Maughan RJ, Burke LM, Dvorak J, et al. IOC consensus statement: dietary supplements and the high-performance athlete. International Journal of Sport Nutrition and Exercise Metabolism 2018;28(2):104-25.
Praet S, Purdam C, Welvaert M, et al. Oral Supplementation of Specific Collagen Peptides Combined with Calf-Strengthening Exercises Enhances Function and Reduces Pain in Achilles Tendinopathy Patients. Nutrients 2019;11(1):76.
Shaw G, Lee-Barthel A, Ross ML, et al. Vitamin C–enriched gelatin supplementation before intermittent activity augments collagen synthesis. The American Journal of Clinical Nutrition 2016;105(1):136-43.