Collagen: It’s the Sprinkles, Not the Cake
A client recently sent me an episode of Science Vs called “Collagen Peptides: Should You Take Them?” (If you’d rather read than listen, the show has posted a public transcript.)
I love it when clients do that. It gives me a reason to dig into a subject, then I can share what I learn with everyone.
Collagen supplements are everywhere. They're promoted for smoother skin, fewer wrinkles, healthier joints, stronger tendons, and better recovery from exercise. Some of the claims sound pretty impressive.
When people ask me about collagen, they’re most often interested in what it does for their skin, so let’s start there.
But the episode’s most interesting finding was about something else: exercise.
Eating collagen doesn’t necessarily put it where you want it
Collagen is the most abundant protein in your body, a key part of skin, tendons, ligaments, and bone. Most supplements are hydrolyzed, broken into small peptides, so they dissolve easily.
When you swallow collagen, it’s broken down into amino acids, and your body uses them wherever it needs them. They don’t leap straight to your face or your knees. It’s a lot as I think of glucosamine—how would it know to go to your knee instead of your elbow?
Skin: a small effect but control your expectations
We lose about 1% of our skin’s collagen each year, and sun exposure accelerates the breakdown.
Full disclosure: I’ve been adding collagen to my oatmeal for several years because…I don’t know, I guess I figured it couldn’t hurt. It is the one supplement I take that I know for certain does something, even if it wasn’t what I was looking for… my fingernails started needing to be trimmed twice as often!
The case for it.
When I looked at collagen research on ConsumerLab, one ingredient that caught my attention was VERISOL, a branded collagen peptide ingredient studied for its effects on skin. In placebo-controlled studies, collagen peptides have been linked to small improvements in skin hydration and elasticity, and sometimes in wrinkles. In astudyof women aged 45 to 65, 2.5 grams a day was linked to about a 7% reduction in eye-wrinkle volume after four weeks and about 20% after eight, compared with placebo. A 2025 study of 66 women, funded by the ingredient's maker, reported a similar result.
The case for caution.
The effect is small. Even in positive studies, the improvements are minimal and measured with precise instruments. They might not be enough to see in the mirror.
Many positive studies are funded by the manufacturer. A 2025 review of 23 trials found small gains in hydration and elasticity, but no significant benefit once it looked only at higher-quality or independent studies. Industry groups have criticized that review for errors in how it described some trials, so we might call the question not conclusive.
A moisturizer might get a similar effect. In a 12-week study of 85 women who all used the same moisturizer, collagen didn’t significantly improve wrinkle depth, elasticity, or how participants felt about their skin. Skin density and moisture did improve slightly.
The placebo effect is strong with skin. People taking dummy pills often report better skin, and some placebo groups’ measurements improve, too!
The dermatologist on the podcast doesn’t take collagen. Her recommendations were daily sunscreen and, for some people, prescription tretinoin, which you’d want to pursue with your dermatologist. Collagen creams and injections don’t help.
My take:if you’re curious, about 2.5 grams a day has the most research behind it, and it’s reasonable to try it for two to three months without expectations. Don’t use it to replace the practices with strong evidence behind them: using sunscreen and a good moisturizer, and, need I say it? not smoking!
A note on “Ozempic face”
Rapid weight loss from GLP-1 medications can leave facial skin looking thinner and more lined. Collagen is often marketed for it but ConsumerLab found no clinical studies testing collagen for this purpose. Collagen wouldn’t replace lost fat, the cause of the skin becoming slack. What does help during weight loss is protecting your muscle with resistance training and eating enough protein.
Tendons and joints: where exercise comes in
This gets interesting!
Strength training makes your body produce more collagen in muscles and tendons.
In one study, 10 young men drank a placebo, 15 grams of collagen, or 30 grams of collagen, each with vitamin C, an hour before squatting. Squats alone raised collagen production. The 30-gram dose raised it roughly another 20%.
The researcher said that collagen without the exercise probably wouldn’t do much, because the tissue has to be stressed first.
Promising: Small studies show that taking collagen peptides alongside rehab exercises helped runners with chronic Achilles tendinopathy and athletes with ankle instability return to sport faster than exercise alone.
The reality check: These studies were small and often funded by ingredient manufacturers, but the theory of pairing targeted loading (exercise) with collagen is promising.
The verdict: Collagen won't repair an injured tendon on its own, but pairing it with structured strength training might give you a slight edge during rehabilitation.
Dr. Dana Lis, a performance nutritionist who’s worked with pro athletes, used a birthday cake to explain it: Exercise is the cake, and collagen is the sprinkles.
Building muscle: skip it
Collagen is low in leucine and lacks some essential amino acids, so it isn’t a good muscle-building protein. Resistance training and getting enough total protein from complete sources do that job.
So, should you take it?
For skin: maybe, if you keep your expectations low and cover all the proven basics.
For a tendon or ligament you’re rehabbing: it might help a bit. Collagen with vitamin C, about an hour before a strength training session, has the most support. The podcast host did this for a knee injury and credited five months of squats as much as the powder.
For muscle: put your money into protein instead.
On a budget: you can get the same amino acids from food. Meat, fish, eggs, soy, legumes, seeds, and bone broth all contribute, and an orange adds vitamin C.
If you try a supplement,
Look for third-party testing. Heavy metals, like lead and arsenic, have been found in some products, particularly marine collagen. The research review found them safe at recommended doses, but who wants to take a chance?
Check the source: if you have a fish or other animal allergy.
Decide in advance what result would make it worth the price to you. A supplement can be well tolerated, yet offer too little benefit to justify the expense. It’s easy to keep buying it out of hope… ahem, to which I plead, “guilty”…
Start with the cake
As is the case with most supplements, the greatest results come from addressing the “big rocks” that have been proven to make a significant difference. No amount of collagen can deliver the impact you’ll get from lifting progressively heavy weights, meeting your protein requirements, protecting your skin from the sun, sleeping well, and minimizing stress as much as possible.
Those are the cake. A supplement is a little something on top.
