Collagen makes your skin younger. But could it make you younger too?



Most of the research on collagen supports its benefits for improving skin appearance and elasticity, reducing joint pain, and even regulating glucose and lipid metabolism in people with type 2 diabetes.



There's also plenty of research on what collagen doesn't do well; for example, it’s no better (and maybe even worse) for stimulating muscle protein synthesis than standard protein supplementation. Collagen won't really help you build muscle.



New research has uncovered an intriguing potential benefit of collagen, or more specifically its primary constituent amino acids—glycine, proline, and hydroxyproline.



Researchers identified a simple ratio of these three amino acids as the key bioactive component of collagen. When given to worms and mice, this ratio—3 glycine to 1 proline to 1 hydroxyproline—produced synergistic benefits on healthspan and lifespan that were greater than the sum of the individual amino acids, suggesting their combination in this precise ratio functions as a conserved recognition signal. In humans, a special collagen supplement with this amino acid mixture lowered biological age by nearly 2 years.



Should we start to think about collagen as a "longevity supplement"? Today's newsletter will attempt to provide an answer.



A collagen supplement lower biological age in humans


The study was really 3 studies in 1: with worm (C. elegans), mouse, and human components, all of which were different but together, allowed an in-depth investigation into collagen peptide's mechanism of action and biological effects.



Because you’re likely more interested in the human component, we'll start there.



A total of 66 participants (47 years old on average with 67% being women) were supplemented for 3 months with a proprietary "Collagen Activator" supplement. Each serving contained a patented mix of 5,000 mg glycine, 1,700 mg proline, and 1,700 mg hydroxyproline (in a 3:1:1 ratio shown to be maximally beneficial in preclinical studies described below). The supplement also contained 1,000 mg of alpha-ketoglutarate (included for its synergistic longevity effects observed in C. elegans), 4 mg astaxanthin (an antioxidant shown to enhance collagen homeostasis), and 48 mg of vitamin C from acerola fruit juice.



After 3 months, objective measurements of skin parameters showed significant improvements, including a 5% improvement in skin texture, a 12% improvement in cheek hydration, a ~4% improvement in cheek skin elasticity, and a 4% (but non-significant) decrease in wrinkle severity.



But the novel finding was that the collagen supplement reduced the participants' biological age by 1.4 years on average, from 47.07 at baseline to 45.7 when measured 6 months after starting supplementation. The result was consistent across genders—biological age decreased 1.33 years and 1.48 years for women and men, respectively, and the greatest improvements were seen in participants with a higher biological age at baseline and were independent of other supplements the participants were taking.



Interestingly, alcohol consumption modulated the supplement's effects. Participants who consumed more than 1 alcoholic drink per week had fewer improvements than non-drinkers, suggesting a negative interaction between alcohol and the collagen supplement that's probably worth consideration.


Skin characteristics in participants supplementing with the Collagen Activator.

Collagen amino acids extend healthspan & lifespan


Before testing its validation in humans, the study rigorously tested the 3:1:1 amino acid ratio across multiple biological systems to assess its efficacy and understand its mechanisms.



Supplementing C. elegans worms with the amino acid mixture increased their average and maximum lifespan by 6–27% across five independent trials, remarkably outperforming whole collagen supplementation, which produced only a mild increase in average (but not maximal) lifespan. The supplemented worms also remained more active at very old ages compared to unsupplemented worms. Stacking collagen with alpha-ketoglutarate had additive effects on longevity, hence why it was included in the "Collagen Activator" supplement in the human trial.



In addition to the worm study, a 6-month study was conducted on old male mice. After 6 months, mice receiving the collagen amino acid mixture had less visceral fat than the control group and maintained their grip strength; collagen counteracted the typical age-related decline in muscle function.



To test the efficacy in a more "people-relevant" context, researchers exposed human skin cells to the amino acid mixture. Collagen-related genes were significantly enriched after 8 and 24 hours of exposure, confirming that this specific ratio of amino acids promotes extracellular matrix and collagen homeostasis in human cells, mirroring the effects seen in C. elegans.



Collectively, these studies provide compelling evidence that a specific 3:1:1 ratio of glycine, proline, and hydroxyproline (the "collagen amino acids") is a key driver of collagen's benefits which are remarkably conserved across several species (including humans). They point to an ancient and fundamental biological mechanism driving collagen's effects in the body.


Body composition, frailty measures, and grip strength in mice supplemented with collagen amino acids and the placebo.

Can collagen help you build muscle?


Collagen is considered a low-quality protein source due to its limited amino acid spectrum necessary for maximizing muscle protein synthesis. It's highly concentrated in glycine and proline (about 50% of its content) but deficient in key amino acids like leucine, lysine, and methionine. Furthermore, collagen is a structural protein prevalent in cartilage, bones, tendons, and ligaments—skeletal muscle contains very little (less than ~2%) collagen. This explains why collagen does not significantly enhance muscle protein synthesis or muscle connective tissue protein synthesis after exercise, and why consuming collagen has a much bigger impact on strengthening connective tissues than muscle fibers.



Thus, for people engaging in resistance exercise training and looking to build lean body mass or strength, experts like Dr. Luc van Loon (who appeared on episode #93 of the FoundMyFitness podcast), relying on collagen as one's sole supplemental protein source is likely to compromise muscle protein synthesis and by consequence, long-term muscle growth.



The research supports this: In a study of young men engaging in 1 week of resistance training, those taking 15 grams of collagen peptides twice daily saw no greater increase in muscle protein synthesis or connective-tissue protein synthesis than those taking a placebo, despite higher levels of collagen peptides in their blood, suggesting that collagen doesn't enhance muscle growth or repair beyond what exercise alone achieves.



However, the "jury is out" regarding collagen's benefits for structures that are almost purely collagen-based, such as tendons, ligaments, bones, and cartilage. Some evidence suggests that combining collagen with exercise training can benefit these structures. For example:



12 weeks of resistance training with collagen supplementation (20 grams of hydrolyzed collagen after training) increased patellar tendon cross-sectional area, tendon stiffness and measures of tendon strength in middle-aged men.

Soccer players who supplemented with hydrolyzed collagen and vitamin C three times per week for 10 weeks (alongside a training regimen designed to strengthen their knee and thigh muscles) experienced an 18% increase in knee tendon stiffness.

A randomized controlled study involving 27 healthy men found that supplementing with 5 grams of collagen peptides during a 14-week resistance training program increased the size of the Achilles tendon by ~7% and the strength of surrounding muscles by ~5% compared to a placebo.



There may also be utility in using collagen protein during injury recovery, especially in collagen-based structures (e.g., the knee, hips, or other tendons and ligaments). In this scenario, it may be wise to consume a protein supplement that also has a little bit of collagen (but perhaps not one that only comprises collagen protein).


For more on collagen, check out our Hydrolyzed Collagen topic page, where you'll find answers to questions like:



Is bone broth a significant source of hydrolyzed collagen?
Is hydrolyzed collagen better absorbed than other types of collagen?
How does aging affect collagen production in the skin?

Can collagen benefit bone health?

Does collagen have benefits for people with type 2 diabetes?

And more!

Collagen shines for skin and join health


In contrast to the dearth of collagen in skeletal muscle, it comprises about 70% of our skin's dry weight. But we lose about 1% of our skin's collagen content per year, and by age 80, it may be 75% less compared to young adulthood, leading to thinner, less elastic skin and wrinkle formation.



For this reason, many collagen-containing skin creams and lotions are marketed as "anti-aging" remedies, but the science on topical (applied to the skin) collagen is weak—intact collagen molecules are too large to penetrate deeply into the skin. While hydrolyzed collagen in lotions could aid in surface hydration, it won't rebuild deeper skin layers. Oral collagen can.



Oral collagen supplementation improves skin elasticity, decreases facial lines and wrinkles, and increases skin hydration, especially when combined with other nutrients like hyaluronic acid, biotin, and vitamins C & E. It also reduces premature skin aging due to UV light exposure (a process called photoaging), at least in rodents.



Collagen supplementation may also be promising for osteoarthritis. Not as a cure, but for symptom relief.



Arthritis is fundamentally a “joint tissue problem”: pain, stiffness, and reduced mobility often track with progressive cartilage breakdown. And cartilage is collagen-rich—type II collagen makes up ~60% of cartilage dry weight.

The strongest human evidence is on osteoarthritis or OA (age- and/or injury-related cartilage degeneration). Multiple trials suggest oral hydrolyzed collagen (collagen peptides) can reduce pain and improve function.



The story is more mixed for rheumatoid arthritis or RA. RA is autoimmune-driven, and a “low-dose type II collagen” approach (microgram dosing) may work via immune tolerance rather than simply supplying building blocks. Studies report improvements versus placebo in some symptom/activity measures, but when directly compared, methotrexate (an immune system suppressant) outperforms collagen across key outcomes—so collagen is not a replacement for standard RA therapy.



So, collagen looks most promising as an adjunct for OA symptom management—especially pain and function—while RA evidence is preliminary and should be viewed as “interesting but not definitive.”

Final thoughts


Collagen is a complex molecule. Whether it “works” or not is highly context specific. If you’re looking to build muscle, then it’s no better than standard protein. But if you’re looking for healthier skin aging, it may be worth a shot.



If you aren’t enthused about the research on collagen in either of these areas, then perhaps the study we covered today perked up your ears. While it doesn’t suggest that plain old collagen could be a longevity supplement, the specific collagen amino acids administered in the precise ratio did show preliminary yet promising effects on biological age and skin health in humans, in addition to the lifespan- and healthspan-extending effects in worms and mice.



So, maybe we should start to reframe the way we think about the biological effects of collagen. It’s not merely building blocks for muscle, cartilage, or skin, but rather, collagen and its constituent amino acids may be providing valuable biological signals to our body.



As for me, I supplement with hydrolyzed collagen for the purposes of skin aging. And if the results of today’s study hold up, I may also be contributing to my longevity and healthspan.


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Premium members get exclusive access to live AMA sessions and the full-length recordings once they're released, plus exclusive access to all episodes of The Aliquot. A few of my previous member Q&A sessions have covered the topic of collagen:



Q&A #33: Does collagen reduce wrinkles?
Q&A #37: What brand of hydrolyzed collagen does Rhonda supplement with?
Q&A #40: Does combining collagen with vitamin D and calcium improve bone health in women?
Q&A #41: Can collagen protect against UV damage to the skin?


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