Your knees ache after five-a-side, your Achilles complains on the first run of the week, and every second ad promises that a scoop of collagen will fix it. Collagen for joints is one of the most heavily marketed supplements aimed at men over 35. Here is what the research actually shows, what doses studies used, and why how you load your tendons matters more than what you stir into your coffee.
Key takeaways
- Collagen research for joints and tendons is promising but thin: mostly small, short trials, many funded by supplement makers.
- The best-known protocol (Shaw 2017) used 15 g of gelatin with vitamin C about an hour before a short bout of exercise. It raised a blood marker of collagen synthesis in eight young men.
- Tendon studies used roughly 5–30 g a day for weeks to months, combined with exercise; the clearer results came at 15 g or more.
- Collagen is an incomplete protein. It should not replace the high-quality protein you need for muscle.
- Progressive tendon loading is the proven treatment for tendon problems. Collagen, at best, is a small add-on.
What collagen is and why people take it
Collagen is the main structural protein in tendons, ligaments, cartilage, bone and skin. Your tendons are mostly collagen fibres, arranged like ropes that transmit force from muscle to bone.
Collagen supplements are made from animal hides, bones or fish skin and come in two main forms. Gelatin is partially broken-down collagen (it sets into jelly). Hydrolysed collagen, or collagen peptides, is broken down further so it dissolves in cold liquid.
When you swallow either, digestion breaks them into amino acids and small peptides. The theory is that these building blocks, especially glycine, proline and hydroxyproline, reach connective tissue and give it raw material, or that certain peptides signal cells to make more collagen. That theory is plausible. The question is whether it makes a noticeable difference to your joints.
What the evidence shows
The Shaw 2017 gelatin and vitamin C study
This is the study behind most “collagen before training” advice. Researchers at UC Davis and the Australian Institute of Sport, publishing in the American Journal of Clinical Nutrition, gave eight healthy young men (average age 27) a drink with 0, 5 or 15 g of gelatin plus 48 mg of vitamin C. One hour later they did six minutes of rope skipping, three times a day for three days.
With 15 g, a blood marker of collagen production (PINP) rose more than with placebo or 5 g; the authors described it as roughly doubling. They also took blood from participants and applied it to lab-grown ligaments, which then produced more collagen.
Before you get excited, note the limits:
- Only eight participants, all young men.
- PINP mainly reflects bone turnover, so the authors acknowledge it may not directly measure tendon or ligament collagen.
- The ligament results come from a lab model, not from human tendons.
- It measured a short-term marker, not injury rates, pain or performance.
It is a clever mechanistic study, not proof that collagen prevents injuries.
Tendon trials
A 2026 systematic review in the Journal of Functional Morphology and Kinesiology pooled eight randomised trials (257 participants aged 18–52) in which collagen was combined with strength or jump training for 3 to 15 weeks. Three of four trials that measured tendon size found greater increases with collagen than placebo. Trials using 15–30 g a day showed improvements in tendon stiffness versus placebo, while trials using around 5 g a day did not show clear between-group differences.
The authors still flagged small samples, varied protocols and short durations. Bigger, stiffer tendons on a scan are also not the same as fewer injuries or less pain.
For people with existing tendon problems, a small Australian pilot trial gave 20 people with chronic Achilles tendinopathy specific collagen peptides alongside a calf-strengthening programme for six months, in a crossover design. Function scores improved more during the collagen phases. It is encouraging, but 20 people is very small, and the collagen was a branded product.
Joint pain and osteoarthritis
A 2019 meta-analysis of randomised placebo-controlled trials in International Orthopaedics found that collagen reduced total osteoarthritis symptom scores (WOMAC) and visual pain scores. But when the WOMAC was broken down, the pain and function subscores were not significantly different from placebo; only stiffness improved.
A 2021 systematic review of 15 trials combining collagen peptides with exercise concluded collagen was most beneficial for joint function and joint pain, with 15 g a day linked to higher collagen synthesis. Most participants were recreational athletes.
The funding problem
Much of this research is funded by, or involves authors working for, collagen manufacturers. That does not make it wrong, but it raises the risk of bias. In an NPR report on collagen, Boston University rheumatologist David Felson noted that many joint studies were industry funded and called for large independent trials. For skin, a meta-analysis found that the positive results came mostly from industry-funded trials, while independent, higher-quality trials did not show a significant benefit.
Doses used in studies
| Goal studied | Form and dose | Timing | Strength of evidence |
|---|---|---|---|
| Collagen synthesis marker (Shaw 2017) | 15 g gelatin + 48 mg vitamin C | About 1 hour before 6 minutes of loading | Very small, short-term, mechanistic |
| Tendon size and stiffness | 15–30 g/day collagen peptides; ~5 g/day showed weaker results | With 3–15 weeks of strength or jump training | Small RCTs; promising but limited |
| Achilles tendinopathy | Specific collagen peptides, daily | With twice-daily calf exercises, 3–6 months | One small pilot trial |
| Joint pain and osteoarthritis | Varies widely between trials and collagen types; 15 g/day was the dose most linked to higher collagen synthesis | Daily for several months | Mixed; effects on pain subscores not consistent |
No official body sets a recommended intake for collagen. If you decide to try it, the doses above reflect what was tested in research, not a proven therapeutic dose. Check with your doctor first.
Collagen vs simply eating enough protein
Here is the part the ads skip: collagen is a low-quality protein for muscle. It contains no tryptophan, one of the essential amino acids, so it is classified as an incomplete protein. It is also low in leucine, the amino acid that most strongly switches on muscle building.
In a McMaster University study of adults aged 65–80, people taking whey regained more muscle after a period of inactivity than people taking collagen. A 2021 review likewise found collagen did not stimulate muscle protein synthesis as well as higher-quality proteins.
So collagen should not count as your main protein source. The International Society of Sports Nutrition recommends 1.4–2.0 g of protein per kg of body weight per day for people who train, spread across meals of roughly 20–40 g. Hit that first with foods like dal, chana, rajma, tofu, paneer, Greek yoghurt, eggs, milk, fish or chicken. Our guide to protein after 35 shows you how.
Two other points matter for connective tissue:
- Vitamin C is required to build collagen. Fruit (guava, oranges, kiwi), peppers and tomatoes cover you easily.
- Total protein supplies glycine and proline anyway; your body also makes glycine itself.
A note for vegetarians
All collagen and gelatin supplements are made from animals (cow, pig or fish). There is no plant collagen. Products labelled “vegan collagen” are usually blends of amino acids and vitamin C meant to support your own collagen production; they are not the same thing that was tested in trials. If you are vegetarian, focus on total protein from varied plant and dairy sources, enough vitamin C, and the loading programme below.
Why tendon loading matters more
Tendons adapt to load, just as muscles do, only more slowly. The proven treatment for most tendon pain is a progressive strengthening programme, not a supplement.
In a 2021 randomised trial in the American Journal of Sports Medicine, 44 adults with chronic patellar tendinopathy did slow resistance training at either moderate (55% of max) or heavy (90% of max) loads. Both groups improved pain and function at 12 weeks and kept the gains at one year. Heavy loading was not better than moderate, which is good news if you are cautious about heavy weights.
Physiologist Keith Baar, a co-author of the Shaw study, summarised lab findings in Sports Medicine in 2017: tendon cells respond to short bouts of loading (around 10 minutes), then become less responsive and need roughly six hours to reset. He suggests short connective-tissue sessions spaced through the day. Much of this comes from lab-grown tissue, so treat it as a sensible idea rather than settled science.
How to load your tendons
- Train two to three times a week with slow, controlled lifts: squats, split squats, Romanian deadlifts, calf raises (straight and bent knee).
- Use a slow tempo, around three seconds down and three seconds up, for tendon-focused work.
- Progress gradually. Tendons take months to adapt. Add load in small steps.
- Avoid sudden spikes in running mileage, jumping or sprinting, which is when most weekend-warrior tendon problems start.
- Accept mild discomfort (around 3 out of 10) during rehab if it settles by the next morning; back off if it lingers.
Building a base of strength is the best injury insurance there is. Start with our strength training after 35 guide and, if you are returning after a long break, starting to work out after 40.
So, is collagen worth it after 35?
If your protein intake is already adequate, you are lifting consistently, and you want to try collagen alongside a tendon-loading programme, it is unlikely to harm most healthy people and might help a little. A reasonable experiment is the research protocol: about 15 g with a vitamin C source, roughly an hour before a short loading session, for a few months, after checking with your doctor.
If you are not lifting, not eating enough protein, or ramping up running mileage too fast, collagen will not save you. Fix those first. Your money is usually better spent on food and a few sessions with a good physiotherapist.
Safety note: Collagen is generally well tolerated, but some people get bloating or an upset stomach. Avoid fish-based collagen if you have a fish allergy, and check the source if you avoid beef or pork for religious or dietary reasons. Supplements are not tightly regulated, so quality varies. If you have kidney disease, are on a protein-restricted diet, take medications, or have significant joint swelling, locking or pain after an injury, see a doctor or physiotherapist before self-treating.
FAQ
Does collagen rebuild cartilage?
There is no good evidence that collagen supplements rebuild worn cartilage in human joints. Some trials show modest improvements in symptoms like stiffness, but results on pain are inconsistent.
Is gelatin as good as collagen peptides?
Both are made from the same raw material and break down into similar amino acids. The Shaw study used plain gelatin. Peptides are more convenient because they dissolve in cold drinks.
Can I count collagen toward my daily protein target?
Partly, as part of a mixed diet, but it is a poor protein for building muscle because it lacks tryptophan and is low in leucine. Hit your protein target mainly with complete proteins.
How long until I notice anything?
Tendon and joint studies ran from a few weeks to six months. Tendons adapt slowly, so judge any change over months, not weeks, and pair it with a loading programme.
Are there vegetarian alternatives to collagen?
No plant food contains collagen. Your best options are enough total protein from dairy, legumes, soy and grains, plenty of vitamin C, and regular tendon loading.
Free tool: make sure your total protein is covered with the protein calculator.
Sources
- Shaw G, et al. Vitamin C–enriched gelatin supplementation before intermittent activity augments collagen synthesis. Am J Clin Nutr. 2017.
- Buchalski A, et al. Collagen supplementation on tendon-related structural and performance outcomes: a systematic review. J Funct Morphol Kinesiol. 2026.
- Praet SFE, et al. Oral collagen peptides combined with calf-strengthening exercises in Achilles tendinopathy. Nutrients. 2019.
- GarcÃa-Coronado JM, et al. Effect of collagen supplementation on osteoarthritis symptoms: a meta-analysis of RCTs. Int Orthop. 2019.
- Khatri M, et al. Collagen peptide supplementation on body composition, collagen synthesis and recovery: a systematic review. Amino Acids. 2021.
- NPR – Can collagen supplements improve your skin? Here’s what the research shows (2025)
- Paul C, et al. Significant amounts of functional collagen peptides can be incorporated in the diet while maintaining indispensable amino acid balance. Nutrients. 2019.
- McMaster University – Whey vs collagen for rebuilding muscle in older adults (Am J Clin Nutr, 2018)
- Jäger R, et al. ISSN position stand: protein and exercise. J Int Soc Sports Nutr. 2017.
- Agergaard AS, et al. Clinical outcomes, structure and function improve with both heavy and moderate loads in patellar tendinopathy. Am J Sports Med. 2021.
- Baar K. Minimizing injury and maximizing return to play: lessons from engineered ligaments. Sports Med. 2017.
This article is for general education and is not medical advice. Check with your doctor before starting a new training or nutrition plan, especially if you have a health condition.
