Everything You Need to Know About Collagen

Hey everyone, Chris Kresser here. Welcome to another episode of Revolution Health Radio. Today we’re going to dive deep into a topic that’s been everywhere lately– collagen. I imagine many of you listening are already taking a collagen supplement. If not, you’re almost certainly familiar with it from social media and even mainstream sources. But what exactly is collagen and why are so many people talking about it? In this episode, I’ll unpack the science behind collagen and its health benefits, and help you understand whether it’s worth incorporating into your own routine.

Collagen: What It Is and Why It Matters

I want to start by explaining what collagen is and why it matters. Collagen is the most abundant protein in the human body. It’s quite literally the stuff that holds us together. In fact, the word “collagen” comes from the Greek word kólla, meaning “glue,” because collagen was historically used to make glue by boiling animal skins and bones. It acts like a structural glue in our bodies providing strength and elasticity to our skin, hair, nails, bones, joints, and connective tissues. If you imagine your body as a house, collagen would be the framework and support beams. It’s what gives our tissues tensile strength. Some collagen fibers are gram for gram stronger than steel. Without collagen, we’d basically fall apart.

Collagen isn’t a new discovery by any means. Our ancestors were getting plenty of it through diets that included skin, cartilage, and bone broth. I often talk about an ancestral diet or nose-to-tail eating, and collagen is a big part of that. However, in the modern diet, we tend to eat a lot of lean muscle meats like chicken breasts or steak, and not as much of the other animal parts rich in collagen. As a result, many of us aren’t getting much collagen from food anymore. This might be one reason collagen supplementation has taken off. In the last decade, we’ve seen a rapid rise in the popularity of collagen supplements and powders. Collagen’s gone from something only your grandmother might have talked about, like a cup of bone broth or gelatin dessert, to a nearly $3 billion global “nutricosmetic” industry with powders and gummies and even collagen-infused lattes. It’s a booming trend, and for good reason. An accumulating body of research suggests that collagen has a range of potential health benefits.

So what are those key benefits? In today’s episode, we’ll cover four main areas where collagen makes a big difference. [The first one is] natural beauty, including skin, hair, and nails. This is perhaps the best known use of collagen. We’ll talk about how taking collagen can improve skin elasticity and hydration, reduce wrinkles, strengthen brittle nails, and even support hair growth. We’ll look at some human clinical trials (including RCTs, or randomized controlled trials) that back up these beauty claims.

The second is joint and bone health. Collagen’s a major component of our cartilage and bones. I’ll explain how supplemental collagen might help rebuild cartilage, reduce joint pain and stiffness in osteoarthritis and other conditions, and even improve bone density over time. This is about aging gracefully and keeping our joints resilient.

The third category is muscle recovery and performance. This one might surprise some people because collagen isn’t a typical muscle building protein like whey, but we’ll talk about how it can support muscle tissue and connective tissue recovery, aid post-exercise repair, and possibly improve muscle mass or strength when combined with resistance training, especially in older adults.

The fourth category is gut and sleep health. These are two more unexpected benefits of collagen because one of its key amino acids, glycine, can support a healthy gut lining and improve digestion and may promote better sleep quality. We’ll talk about how glycine works to heal the gut and how it acts as a calming neurotransmitter to help you sleep.

By the end of this episode, you should have a clear picture of what collagen can and can’t do. My goal is to give you a balanced, nuanced, and of course, evidence-based take. As always, I’ll avoid any hype or extreme claims. Collagen isn’t a miracle cure-all, although sometimes it can feel that way, and I’ll share a few personal anecdotes about that. But it’s a promising tool we can use as part of a holistic, functional medicine approach to health. I’ll also share some practical tips like how to choose a quality collagen supplement. For example, why grass-fed collagen might be better and what to look for on labels, how to take it for best absorption, how much to take, and any precautions to be aware of, which fortunately in the case of collagen are very few. I’ll also share some clinical anecdotes from my practice to illustrate how collagen can make a difference in real life.

So whether you’re considering collagen for smoother skin, stronger joints, or a healthier gut, stick around. Let’s jump into the fascinating world of collagen and see what the science really says.

Collagen for Natural Beauty: Skin, Hair, and Nails

Let’s jump right in with the benefit that put collagen on the map for a lot of people– its impact on our skin, hair, and nails. If you’ve seen beauty products touting “beauty from within,” collagen is often front and center in those products. This isn’t just marketing fluff. There’s real science suggesting that collagen can support skin elasticity and hydration, reduce wrinkles, strengthen nails, and perhaps even thicken hair. About 75 percent of the dry weight of our skin is collagen. It’s the protein that gives skin its structure and firmness. As we age, our bodies produce less collagen, and the collagen we do have breaks down. This loss of collagen is a big reason why we get wrinkles, sagging, and drier skin as we get older.

The idea behind taking collagen supplements is they provide the building blocks, and possibly signals, to help the body replenish or repair collagen in the skin. Quite a few randomized controlled trials, or RCTs, have been done on collagen supplements and skin aging. For example, studies have found that taking hydrolyzed collagen, usually in the range of 2.5 to 10 grams per day, for 8 to 12 weeks can lead to significant improvements in skin elasticity and hydration, and even a reduction in wrinkle depth. In one systematic review of 26 studies with over 1,700 participants, researchers concluded that collagen supplementation consistently improved skin hydration and elasticity, with the effects becoming significant after about eight weeks of daily use. In plainer terms, after two months of regular collagen use, people’s skin tended to be more hydrated.

Some studies also show wrinkle reduction. For instance, a trial might measure the depth of crow’s feet wrinkles before and after collagen supplementation and find that the collagen group’s wrinkles are notably shallower than the placebo groups after two to three months. That’s pretty remarkable, considering we’re talking about an oral supplement and not a topical cream or a procedure. And in fact, the theme of this podcast and the theme of the research is that internal supplements –oral supplements– actually are more effective than topical creams. If you think about it, this makes sense because true health comes from within. If we have a disrupted gut microbiome, for example, that is contributing to inflammation, that will show up in our skin because our skin is the largest organ system in the body. So no matter what you put on your skin, if you have that underlying root cause that’s driving inflammation in the skin, the topical stuff will have limited results. Whereas if you take something internally to address that root cause of inflammation, then it will lead to better, healthier skin, hair, and nails without even needing to put something on topically.

So let’s talk about the mechanisms for collagen and beauty from within. The collagen we ingest doesn’t just magically paste itself into our skin. When you ingest collagen peptides, [which are] basically collagen broken down into smaller pieces, those peptides and amino acids get absorbed into the bloodstream. Research suggests that some of those collagen fragments, especially dipeptides like proline-hydroxyproline, can travel to skin tissue and signal skin cells like fibroblasts to ramp up collagen production or repair. Think of these collagen peptides as messengers that tell your skin, “Hey, produce more collagen and hold on to moisture.” At the same time, the amino acids like glycine and proline serve as raw materials for building new collagen fibers. Collagen supplements have also been shown to increase the density of collagen fibers in the skin and the activity of fibroblasts, [which are] the cells that make collagen. This dual action, providing the building blocks on one hand and sending signals on the other hand, is likely why we see improvements in skin metrics like elasticity (skin bouncing back more readily) and hydration (skin holding more moisture so it looks plumper).

Another interesting thing here [is that] some research suggests that collagen supplements might help protect the skin from within. There’s evidence from animal studies and some human data that collagen peptides could enhance the skin’s natural barrier function, preventing leaky skin, and even offers some protection against UV-induced skin aging.

Collagen’s benefits aren’t just skin deep. Many people report stronger nails and better hair when taking collagen, and there’s definitely data to back this up, especially for nails. If you struggle with brittle nails that chip or peel easily, collagen could help. A small 2017 study on 25 women found that about six months of daily collagen supplementation led to significant improvements in nail growth and reduced brittleness. In fact, almost 90 percent of the participants reported that their nails were longer and less brittle after the treatment. Many of them saw their nails growing faster and breaking less. The researchers also noted that the benefits persisted for up to a month after they stopped taking the collagen, suggesting some lasting improvement in nail quality. Now this wasn’t a placebo-controlled trial, it was an open-label study, but it’s promising and it makes sense biologically– nails, like skin, contain collagen in the nail bed, and providing those extra amino acids could strengthen nail structure.

For hair, the evidence is more anecdotal at this point, but there are plausible reasons collagen could help. Hair is made of keratin (another protein), not collagen. But collagen may benefit the hair indirectly by supporting the skin and connective tissue that the hair grows from, since the hair follicles are in the dermal layer of the skin, which is rich in collagen. Some preliminary studies and lots of testimonials suggest collagen might lead to thicker or faster-growing hair, but we need more controlled research here. Still, given that collagen peptides provide amino acids like proline, which is used to produce keratin, it’s certainly possible that taking collagen supplies some of the nutrients needed for hair growth. In any case, skin and nail benefits are the most well-substantiated benefits so far.

Before moving on, let me share a quick personal anecdote. I’ve had patients in my practice, particularly middle-aged women, who started taking collagen primarily for joint pain or gut health. But then a few months later they’re saying something like, “Chris, my skin looks better and my hairstylist noticed my hair is thicker.” This has happened so many times, I’ve lost count. It’s great when a functional medicine intervention can address multiple issues at once. In my own life, I’ve noticed that when I’m regularly incorporating collagen, my skin doesn’t get as dried out in the winter. I live in a really dry, high desert winter climate and so my skin can get pretty dry in the winter months. And when I take collagen regularly, which I do, I notice this doesn’t happen as much.

Joint and Bone Health Benefits of Collagen

Let’s move on from beauty to joint and bone health, another big reason people turn to collagen. If you suffer from achy joints, osteoarthritis, or you’re concerned about osteoporosis or bone loss, collagen is definitely worth a look. This is an area I’m personally quite excited about because I had a significant injury last summer, as some of you know if you’ve been listening to my podcast for awhile or getting my emails, and I think that regular collagen in addition to omegas, curcumin, and other nutrients was a huge part of my ability to recover quickly. It was pretty shocking to the orthopedist that I saw. I was able to bounce back within a matter of weeks and fully recover prior to the ski season starting in November. My injury was in late August. I was able to avoid surgery and was fully recovered by the time ski season started, and I’ve skied probably 60 days this season already and have had no problems with my back. I really believe that collagen and some of the other nutrients that I took during that period were instrumental in my recovery process. And that has a huge impact on my quality of life and my happiness and daily well-being, to be able to recover that quickly from an injury and stay active.

Osteoarthritis, the wear-and-tear kind of arthritis, involves a breakdown of cartilage and joints, leading to pain and stiffness. Cartilage is the smooth, rubbery tissue that covers the end of bones in our joints, allowing them to glide over each other. And guess what? Cartilage is made mostly of collagen, specifically Type II collagen in articular cartilage. As cartilage degrades in osteoarthritis, some of those collagen fibers are lost or damaged. The idea of using collagen supplements for joint health is that providing those collagen peptides might give the cartilage forming cells, which are called chondrocytes, the building blocks to repair or maintain cartilage, and might also have an anti-inflammatory effect in the joint. Clinical studies have examined collagen, often in the form of collagen hydrolysate, for joint pain and a number of them have shown positive results, especially for knee osteoarthritis. A recent meta-analysis of studies in 2023 looked at multiple RCTs and concluded that collagen peptide supplementation led to significant pain relief in patients with knee osteoarthritis compared to a placebo. And what’s encouraging is that this came without significant side effects. The analysis found no difference in adverse events between collagen and the placebo groups, indicating that collagen was as safe as a dummy pill in those trials. That’s huge because so many of the medications like ibuprofen and other NSAIDs [used by] people who have arthritis have significant side effects and long-term risks.

Back to these trials, meta-analysis, some of the trials in the analysis used around 10 grams of collagen hydrolysate per day for a period of three to six months and saw pretty significant improvements in joint pain and function. Beyond pain, there’s evidence that collagen can improve joint function and mobility. Some trials have participants do things like the Stanford walking test or measure how far they can walk in six minutes. And collagen groups often perform better after the supplementation period.

There are also studies on younger athletic populations. For instance, one study on active athletes found that a specific collagen peptide supplement reduced joint discomfort with exercise and improved recovery. So this suggests collagen is not only for older adults with arthritis, it might help anyone whose joints are under a lot of stress. That’s where I characterize myself for now. I don’t have arthritis or any kind of bone degeneration, but I’m extremely active, skiing, mountain biking, strength training, paddle boarding, hiking, backcountry activities, all kinds of stuff that puts a lot of stress on my body. So I will take any advantage I can get that allows me to maintain that high activity level because it’s such a big part of my mental health and my enjoyment of life.

When we digest collagen, some peptides might accumulate in joint cartilage or stimulate cells in the joint. Collagen’s amino acids like proline and glycine are also used by the cells to build an extracellular matrix, which is a scaffold of cartilage, and collagen may have a mild anti-inflammatory effect. Glycine, for example, has been shown to reduce inflammation and oxidative stress. In the gelatin article I wrote a while back, I mentioned that gelatin, which has a lot of collagen in it, seems to have an effect that inhibits the breakdown of cartilage and even boosts cartilage metabolism. Collagen also contains lysine, an amino acid that helps your body absorb calcium and form collagen. Interestingly, lysine has been shown in animal studies to speed up fracture healing. So collagen is bringing a lot of helpful constituents to the table for joint integrity and bone health.

On a practical note, I’ve seen patients with mild osteoarthritis who start taking collagen and come back a few months later with less knee pain or less joint pain overall and better mobility. One patient of mine in his fifties was an avid tennis player. He said that after three months of daily collagen peptides, he could play longer matches with less knee stiffness the next day. As many of you know, I strained my pes anserine and medial collateral ligament last summer playing pickleball. I got the pickleball bug like so many others and went from not playing any court sports for 20 years to playing two hours a day, five or six days a week. I took 10 grams of collagen twice a day as part of my recovery, and I think it made a huge difference. I had a bit of a rough summer with that knee injury and back injury. Perhaps I was overdoing it a little bit, but collagen made a huge difference in my recovery because as we’ve discussed, it helps rebuild connective tissues like tendons and ligaments, which becomes increasingly harder for the body to do on its own as we age.

In fact, it’s not a bad idea to take collagen about an hour before rehab exercises or physical therapy to target those nutrients to the tissues that you’re working on. That’s a little bio hack that might increase collagen deposition in injured tendons or ligaments, based on preliminary research and the collective experience of a lot of really skilled physical therapists.

Let’s talk about bones now. It might surprise you, but bones are about one-third collagen by volume. Collagen forms the organic matrix of bone – imagine the rebar framework in a building – and then minerals like calcium and phosphorus stick to that matrix to make the bone strong and hard. As we age, or especially in postmenopausal women, bone density can decline. This is called osteopenia initially, and then it can progress to osteoporosis. While calcium, vitamin D, vitamin K2, and other minerals get a lot of attention for bone health, collagen is a critical and often overlooked component. If your collagen matrix is weak, adding more calcium is like packing concrete onto a crumbling mesh. You need to strengthen the mesh itself.

There’s compelling research indicating that collagen supplementation can improve bone mineral density. One notable study, an RCT published in Nutrients in 2018, involved post-menopausal women with age-related bone loss. They gave one group five grams of specific collagen peptides daily and the other group a placebo for 12 months. After a year, the collagen group had significant increases in bone mineral density in their spine and femoral neck, which is the hip, compared to the placebo group, which actually lost bone density as expected. To put this in perspective, the collagen group’s bone density went up while the control group’s went down. The women taking collagen also had favorable changes in their bone biomarkers. Blood tests showed an increase in a bone formation marker and a decrease in a bone degradation marker. This suggests that collagen was tipping the scale toward building new bone rather than losing it, which is exactly what the study results found. For a nutritional supplement to have that effect is pretty impressive. Typically you’d expect maybe a slowing of bone loss, but here we saw actual gains in bone mineral density.

Another study extended this kind of research over a longer period. In a follow-up, if I recall correctly, some researchers looked at collagen over four years and found continued benefit, implying that long-term use might keep adding up. And again, collagen is safe and well-tolerated, making it a nice adjunct to other bone health strategies. For someone concerned about osteoporosis, I consider collagen as a piece of the puzzle, along with resistance training, adequate calcium, vitamin D, K2, magnesium, and other nutrients. It’s not a replacement for those, but it addresses that collagen matrix aspect directly.

Essentially, collagen provides a support system for our musculoskeletal health. It keeps the cartilage and joints strong and less inflamed, and it helps bones stay dense and resilient. Collagen might not replace meds and other treatments if you have severe arthritis pain, but over the span of months, it could reduce your need for those meds by improving the underlying issue. And for bone, collagen isn’t going to be as potent as, say, prescription osteoporosis medications in someone with very low bone mineral density, but medications can have significant side effects and only address one aspect of bone health. Collagen, being nutritional, works more slowly but supports your body’s natural bone building processes and has virtually no downside. A balanced holistic approach might be using collagen to nourish the joints and bones, exercise to stimulate them, because bones and cartilage respond to the stress of exercise by getting stronger, and then including other nutrients and lifestyle factors to support tissue health like an anti-inflammatory, nutrient-dense diet, maintaining a healthy weight to reduce joint load, etc. And collagen fits really well into that kind of holistic approach.

Before moving on, I want to quickly mention [that] if you’re already eating a diet rich in connective tissue or bone broth, you are definitely getting some of these benefits of collagen without a supplement. For example, a long-simmered bone broth is essentially a collagen supplement in whole-food form because it’s rich in gelatin. I often encourage food as medicine first, as you know. But realistically, not everyone has the time or taste for bone broth daily and digesting gelatin can be difficult for some people, especially those with poor digestion or digestive conditions that limit absorption. So they may not be getting as much collagen from the gelatin as they wish, and supplementation can still really make sense in that context.

Collagen’s Role in Muscle Recovery and Athletic Performance

All right, let’s move on to the third category of collagen benefit which is muscle recovery and performance. This one’s really interesting because if you know nutrition, you know that collagen is not a complete protein. It’s actually low in essential amino acids like leucine and doesn’t contain any tryptophan at all. So you wouldn’t think of collagen as a muscle-building protein. And indeed, if you’re a bodybuilder or athlete that does a lot of strength training, collagen alone shouldn’t be your main protein source for muscle gains. You’d want whey and muscle meat, etc, to have the full spectrum of amino acids. However, collagen can still play a supportive role in muscle health and recovery, primarily by helping repair connective tissues like tendons, ligaments, and fascia, and possibly by maintaining lean muscle mass in older adults or during injury recovery. One key amino acid in collagen, glycine, is actually very important for muscle and metabolic health.

Glycine makes up roughly a third of collagen’s amino acid content. Research has shown glycine helps with the synthesis of creatine, for instance, and can prevent muscle wasting in certain conditions. In fact, one reason muscle meats alone can sometimes be problematic in excess is their high in methionine relative to glycine. Without enough glycine, you can get excess homocysteine and possibly more inflammation. Collagen helps balance that out by providing glycine. There’s evidence that glycine in the diet reduces age-related muscle loss, which is called sarcopenia. So think of collagen as an indirect helper. It’s not going to spike muscle protein synthesis like a whey shake, but it creates a metabolic environment that’s friendly to muscle maintenance and growth.

Now on to studies. A notable RCT published in 2015 looked at collagen peptide supplementation combined with resistance training in elderly men with sarcopenia. They had a group of older men do 12 weeks of strength training. Half of them got 15 grams of collagen protein after workouts, the other half got a placebo. By the end, all of the men gained muscle and lost fat from the exercise. No surprise there. But the collagen supplemented group did significantly better. They gained more fat-free muscle mass and strength than the placebo group. Specifically, the collagen group gained about 4.2 kilograms of lean mass versus 2.9 kilograms in the placebo group. They also had a greater increase in leg strength. That’s a pretty big difference attributable to just adding collagen peptides. The authors concluded that collagen can enhance the effects of exercise on body composition, helping increase muscle mass and decrease fat beyond exercise alone.

Why might that be? Well, there’s a few hypotheses. One, these older individuals might have been protein deficient to start, so any extra protein helps. Collagen in this case served as a supplemental protein source to fuel muscle building. Two, collagen’s glycine and arginine content could support creatine production and growth hormone release, aiding muscle recovery. Three, collagen could be strengthening the connective tissue in and around muscle, like tendons that attach muscle to bone. Stronger connective tissue might allow for better force transfer during workouts and reduce injury, indirectly helping muscle growth and performance. Also, if your joints and tendons feel good, you can push harder in training. So collagen might be fortifying the support system that your muscles rely on when you lift weights or run or do any activity.

There’s also research for athletes. For example, a small study looked at athletes with chronic ankle instability and found collagen supplementation improved ankle stability and reduced pain. Another area is injury recovery. There’s an emerging protocol where athletes with tendinopathies like Achilles tendon issues are given collagen plus vitamin C before doing their rehab exercises to stimulate healing in the tendon. The science behind this comes from both human and animal studies showing collagen intake can increase collagen synthesis in ligaments or tendons when paired with loading exercise. It’s a bit beyond the scope of this podcast to dive fully into, but the take-home is that collagen is increasingly used in sports nutrition for injury prevention and recovery. From a performance standpoint, while collagen won’t directly boost your VO2 max or something like that, it can contribute to faster recovery post-exercise. Many people report less soreness or joint pain after hard training when they include collagen, myself included, which means you might get back to training sooner or with more consistency. Also, if collagen helps you sleep better, which we’ll discuss shortly, that indirectly improves recovery, since sleep is when your body heals and builds muscle.

To summarize, collagen can aid muscle recovery and support performance indirectly by strengthening connective tissues and providing key amino acids for repair. It’s been shown to amplify muscle growth and strength gains in older adults when combined with exercise, likely by ensuring enough protein building blocks and by protecting against muscle breakdown. For younger folks or athletes, collagen might help keep joints and tendons healthy, [meaning] less injury [and] more consistent training, and possibly improve recovery so you can train hard again sooner. Just remember, collagen is not a standalone muscle fuel. Think of it as a specialized supplement that complements your main protein intake and training regimen.

Collagen and Gut Health: Healing from Within

The last set of benefits we’ll discuss are gut health and sleep quality. These might seem unrelated, but they share a common link through an amino acid I’ve mentioned several times in this podcast, glycine. Collagen is roughly glycine by composition, and glycine is a pretty remarkable amino acid. It has roles in digestive health and in the nervous system that affects sleep.

Many of you who follow my work know I often emphasize gut health as the foundation of overall health. Leaky gut, GERD, IBS, ulcers – these are common issues. It turns out that collagen and gelatin can be very soothing for the gut. Remember that collagen’s rich in glycine, proline, and glutamine, [which are] all amino acids that support the gut lining. Glycine and glutamine in particular are used by the cells of the gastrointestinal tract as fuel and as building blocks to regenerate the intestinal lining. Glycine also stimulates gastric acid secretion, which is interesting because having sufficient stomach acid is crucial for proper digestion. Low stomach acid can lead to heartburn, believe it or not, as well as poor protein digestion and dysbiosis.

Research suggests that collagen peptides can help restore the integrity of the gut lining. One way they do this is by enhancing the production of mucus in the stomach and improving the mucosal barrier that protects the gut wall. There was a study in rats showing gelatin could protect against ulcers by essentially coating and healing the stomach lining. In humans, there’s evidence, some of it indirect or clinical observations, but evidence nonetheless, that a diet rich in gelatin and collagen helps with conditions like leaky gut syndrome. In my own clinical practice, I would often see improvements in patients with IBS or intestinal permeability when we added bone broth or collagen supplements. And indeed, if you’re familiar with the GAPS diet, it’s heavily based on bone broth and it’s designed for people with significant digestive issues like Crohn’s disease or ulcerative colitis. These patients report less bloating, better stool consistency, and an overall calmer digestive system.

As a specific example, I had a patient with long-standing ulcerative colitis, which is an autoimmune inflammatory bowel condition. As part of her nutrition plan, we included daily collagen peptides, about 10 grams twice a day in her case, along with a nutrient-dense, anti-inflammatory diet with plenty of bone broth. Over a few months, her flare-ups reduced and her colonoscopy showed improved mucosal healing. Now again, we can’t credit collagen alone, because we did a lot of things, but given what we know about glycine’s role in modulating inflammation and helping tissue repair, I strongly suspect it was a major contributor to the healing environment in her gut.

It’s also worth noting that gelatin absorbs water and helps keep fluid in the digestive tract. This can improve intestinal transit and regularity. It’s similar to how soluble fiber works. Gelatin can bind to water and support that nice, healthy movement through the bowels. So if someone suffers from constipation, a bit of gelatin or collagen plus adequate hydration could help. In a nutshell, collagen is gut-friendly. It can increase gastric juices, improving digestion, help prepare the stomach and intestinal lining, and support healthy bowel function. If you have a leaky gut or are recovering from something like gastritis, incorporating collagen by a supplement or homemade bone broth is one of the first things I recommend. It’s gentle and nourishing, kind of like an internal bandage for your gut.

Improving Sleep Quality with Collagen

Now onto sleep, something we could all probably use a little more of. How does collagen come into play? Again, it’s mostly through glycine. Glycine is not just an amino acid for building proteins, it also acts as an inhibitory neurotransmitter in the brain. That means it can help calm the nervous system. In fact, glycine can cross the blood-brain barrier and has been shown to increase serotonin levels in certain brain areas and help regulate body temperature at night, both of which are related to sleep initiation.

There have been some pretty cool studies where they gave people with sleep problems a few grams of glycine before bedtime. The results showed measurable improvements in sleep quality. People fell asleep faster, had better sleep efficiency, and reported less daytime sleepiness after taking glycine at night. Typically, the effective dose is around three grams of glycine. Coincidentally, or maybe not so coincidentally, about two tablespoons of collagen or gelatin will give you roughly three grams of glycine. So taking a serving of collagen in the evening might mimic what those studies found. Glycine appears to help lower core body temperature a bit, which is a signal that facilitates sleep. Our bodies naturally cool down a couple degrees at night as we enter deep sleep. It may also reduce anxiety and promote a sense of calm. And some people even report that taking collagen or gelatin before bed gives them more vivid dreams or deeper sleep, likely because of glycine’s effects on sleep architecture.

To be clear, collagen, it’s not a sedative. It’s not like taking melatonin or a sleeping pill. Its effect is more subtle. It’s supportive. If you’re really wired or have major insomnia, you’ll need to address the root causes, whether that’s stress, blue light exposure late at night, etc. But as part of a wind-down routine, collagen can be a nice addition. For example, you could have a cup of warm herbal tea and stir in a scoop of collagen. Not only are you getting the glycine, you’re also giving your body some protein which can stabilize blood sugar through the night, which is another factor in sleeping soundly as blood sugar dips can wake you up. I often will take my collagen at night in a little bit of water or herbal tea about an hour before bed. And I do notice on nights that I do this, I tend to wake up less and feel a bit more refreshed. It’s anecdotal for sure, but it matches the study showing three grams of glycine can improve sleep continuity. Some of my patients with mild insomnia have also found this to be helpful, especially those who don’t want to take stronger sleep aids or who experience side effects when they do.

One more interesting angle is stress and the HPA axis. Glycine can help blunt cortisol output in response to stress. By calming the nervous system, it can indirectly support adrenal health and a more balanced stress response, which in turn helps sleep. It’s all connected – gut, brain, sleep, stress – and collagen, and glycine in particular, is one of those little leverage points that can positively influence multiple systems. So for gut and sleep, collagen supports a healthy gut lining and digestion, which can improve nutrient absorption and reduce GI issues. And collagen’s high glycine content helps promote relaxation and better sleep quality. If you have trouble with your gut or trouble sleeping, collagen can offer some relief for both – heal your gut and help your sleep through the night. It’s not often we find something that benefits so many different areas, but the human body is complex and these systems interrelate.

Choosing the Right Collagen Supplement: Quality, Sourcing, and Dosage

By now you’re hopefully convinced that collagen’s at least worth a try if you haven’t tried it already and you’re not already taking it, given its wide-ranging benefits. But as with any supplement, not all collagen supplements are created equal. Quality matters a lot. In this section, I want to guide you through what to look for in a collagen supplement, the importance of peptide size, or molecular weight, for absorption, how to dose it and how long to take it to see results, and why sourcing, especially choosing grass-fed collagen, can make a difference both for your health and for the planet. I’ll also highlight an ingredient called SOLUGEL® certified grass-fed collagen, which is unique in the industry.

Let’s start with bioavailability and talk a little bit about why peptide size matters when it comes to collagen. When you’re shopping around for collagen, you’ll often see the term “hydrolyzed collagen” or “collagen hydrolysate” or “collagen peptides.” This means the collagen, which is usually extracted from animal hides, bone, or fish scales, depending on the source, has been broken down with enzymes or other methods into smaller peptides.This process makes the collagen much more digestible and absorbable. Whole collagen or gelatin, like eating a piece of gristle, is a huge protein structure and your body would have a hard time absorbing it intact. But collagen peptides, typically with a molecular weight around two to three kilodaltons, which is very small, are easily absorbed in the small intestine. In fact, studies show these tiny peptides can be detected in the bloodstream within an hour after ingestion.

Why is two kilodaltons often cited? It’s because peptides of that size, roughly containing just a few amino acids, maybe two to 10 in length, can slip through the gut lining more readily than larger peptides. They also seem to have specific biological activity. For example, a dipeptide like hydroxyproline–glycine, which is common in hydrolyzed collagen, has been found to trigger cells in the skin, bones, and joints to ramp up collagen synthesis. You remember we talked about collagen as a signal earlier in the show, and this smaller collagen peptide is what provides that signaling. If the collagen was not broken down, say you just ate a massive intact collagen molecule, your digestive system would chop it up randomly and you might not get those beneficial little signaling peptides.

In essence, smaller peptides means better bioavailability and efficacy. One paper noted that when people take hydrolyzed collagen, about 10 percent of it is absorbed as these small intact peptides that travel in the bloodstream and act as messengers, while the rest is absorbed as free amino acids that provide building blocks. Both are useful. The intact collagen fragments are like a blueprint or a nudge to the body, like, “Hey, fix your collagen here.” and the free aminos are the raw materials, “Here are the bricks to build with.” This two-fold mechanism is something we already touched on with skin health, but it applies to collagen benefits generally.

When evaluating a collagen product, look for mentions of things like “hydrolyzed,” “peptides,” or even specifics like “average molecular weight of two kilodaltons or 2,000 daltons.” Most reputable collagen supplements have done the hydrolysis. If you see something like “gelatin,” like the kind you’d use to make Jell-O, that’s not fully hydrolyzed. It will still work, but it won’t dissolve in cold liquids and it’s not as easily absorbed unless you thoroughly heat it. Gelatin is great for making gummies or in cooking, but for daily supplementation, collagen peptides are more user-friendly. Also check if the brand provides any information on how they ensure quality. Do they test for heavy metals? Is it a trusted source? Collagen often comes from bovine sources, sometimes porcine, or marine sources like fish, or poultry sources. Each has its own amino acid profile, and allergen considerations of course. For example, if you have a fish allergy, you’d want to avoid marine collagen.

Everything you’ve wondered about collagen in one episode. How it affects skin, joints, gut health, muscle recovery, sleep, and how to choose the best supplement. It’s all here in this episode of Revolution Health Radio. #Collagen #Health #ChrisKresser #RHR

Bovine is the most common and tends to have types I and III collagen, which is good for skin, bones, and tendons. Marine collagen is usually type I, also good for skin, and sometimes touted for having smaller peptides, though that really depends on how it’s processed and the best, highest quality bovine collagen peptide supplements will have small molecular weight.

So here’s the bottom line. Most hydrolyzed collagen products from reputable brands should be relatively well-absorbed, but some collagen ingredients have lower molecular weight peptides like two kilodaltons or 2,000 daltons. This improves absorption and makes collagen peptides easier to digest, which can be important for folks with SIBO, IBS, and other gut issues. I’ve had quite a few patients in my practice that feel bloated after taking typical collagen supplements, but when they try a product with lower molecular weight peptides, they don’t experience that at all. Another benefit of low molecular weight is improved solubility. This is a fancy way of saying it mixes well with water and other beverages. No one wants to put collagen in their tea or coffee and have a bunch of clumps floating around. That’s gross. If your collagen doesn’t mix completely clear, it may mean the molecular weight of the peptides isn’t in that two kilodalton range.

So let’s talk practical recommendations – how much collagen to take, how often, and how long to stick with it to notice benefits. Based on the research and my experience, a typical dosage is around five to 10 grams of collagen peptides per day. Many studies on skin and joints have used 10 grams daily. If you’re targeting something specific like osteoarthritis or osteoporosis, or you’re dealing with an acute injury you’re trying to recover from, you might benefit from 20 grams a day, split into morning and evening doses. For example, when I had my knee and back injury, I took 20 grams a day. I would take 10 grams in the morning and then 10 grams in the evening before bed, and that had the added benefit of helping with my sleep. For general health or beauty, five grams might be sufficient. But of course, it just really depends on your goals and what you’re aiming for.

As a maintenance dose, personally, I take 10 grams a day. You can split this, maybe five grams in your morning coffee – a lot of people like to add gelatin to their coffee or tea – and then five grams in the evening, again, to promote healthy sleep. Collagen is not a stimulant or anything. As I said a few times, it can improve sleep, so timing isn’t critical. Here are another few tips to think about. You could take collagen around a workout, either before and after, so it can supply amino acids for recovery. And as we talked about before, if you’re rehabbing an injury, you can take it just before your [physical therapy]. That’s been shown to be beneficial. You could take it at night an hour before bed to support sleep. You can take it with meals to aid digestion. You could do all of the above. You can really spread it out throughout the day as much as you want. There’s not really a significant upper limit. I don’t know that people would benefit from much more than 20 to 30 grams a day, even when you have intensive acute injury, but there’s a pretty wide latitude to the amount that you can take.

An important thing to consider and remember with collagen is that consistency is key. It’s not like caffeine where you feel an immediate jolt or effect. It works gradually to repair and rebuild tissues and scaffolding. In most studies, benefits become noticeable around eight weeks or later. So you really have to stick with it. For example, skin elasticity improvements were significant after eight weeks and even more so after 12 weeks. For bones, we saw in that study that it took a year to really measure the biggest changes. And for joints, some RCTs showed joint pain reduction in three months while others needed up to six months. It’s not to say that you won’t experience some benefits earlier. Most people do. But you can’t really evaluate the full benefits that you’re going to get until at least eight weeks, and that’s for skin. For joints, it’s more like three months to six months. And for bones, it can be up to a year.

And that makes sense, right? The bones are the slowest growing tissues in the body. So they need more time to change. Whereas skin remodels itself much more quickly, so you can see the full changes earlier when it comes to skin health. I usually tell people [to] give collagen at least three months of daily use to assess its effects. Of course, you’re going to need a little bit longer than that if you’re working on bone health. You will see some positive changes earlier, maybe your nails grow faster after just four weeks, or your gut feels better after just a week. But [for] the full spectrum of benefits, three months is a fair trial period. One of the nice things about collagen is it’s essentially a protein food. So you don’t typically cycle it on and off like you might with certain herbs or high dose vitamins. You can take it indefinitely as part of your daily nutrition, and many people do.

Quick note on forms. Collagen powder is by far the most common and usually the most economical. There are also collagen capsules, but to get five to 10 grams a day, you’d have to swallow a lot of capsules since each capsule probably only has 500 milligrams. There’s also a growing number of collagen gummy products, but they usually have a bunch of artificial junk and flavors in them. I’m not a big fan of collagen gummies. And again, you have to eat a lot of them to get the full dose. So I really prefer powders. They can come unflavored and you can mix them in anything– water, coffee, smoothie, soup. There are also flavored collagens now. But again, you have to watch out for added sugar or artificial sweeteners or additives. To be honest, pure, unflavored, clean label collagen as the only ingredient is my go-to and what I recommend for most people. A good collagen product should be tasteless and odorless. As we talked about before, it should mix completely clear in water if it has a low molecular weight (or any other beverage). If a collagen powder tastes or smells kind of funky or has an “animal” aftertaste or smell, that definitely might be a quality issue or it’s not as hydrolyzed as it should be. Collagen peptides, again, should dissolve easily. If it’s clumping or not dissolving, try a different brand. A little trick is to sprinkle the powder on the surface of your liquid and let it sit for 30 seconds before stirring. That can help it dissolve without clumping.

Let’s discuss sourcing. This is a topic I’m passionate about because it intersects health, ethics, and environmental impact. Collagen supplements are derived from animal parts, typically the hides, bones, or scales that would otherwise be byproducts of the meat and fishing industries. Using these parts for collagen is a great way to reduce waste and utilize the whole animal because these parts would otherwise be thrown away. However, the quality of collagen will only be as good as the quality of the animal source. If the animals were unhealthy, exposed to a lot of pesticides or antibiotics, or raised inhumanely, that could potentially carry over into the product (or at least doesn’t align with the values of many of us in the ancestral health community). Grass-fed collagen comes from cattle that are raised on pasture, eating grass as their primary diet rather than in feedlots eating grain.

Why does this matter? For one, cows are ruminants and their natural diet is grass. When they eat grass, they tend to be healthier and leaner and their tissues might have a different composition. For example, we know that the omega-3 to omega-6 ratio is superior in grass-fed beef, and grass-fed beef also has higher amounts of other nutrients. With collagen, we’re mostly dealing with protein, so fatty acid content isn’t as relevant, but overall animal health could still influence the quality of the collagen. Just as importantly, grass-fed usually implies a better standard of animal welfare – the cows are free range, they’re not confined in crowded feedlots, and they’re not pumped with growth hormones or unnecessary antibiotics. From a human health perspective, choosing grass-fed ensures you’re not ingesting residues of things like antibiotics or growth promotants that might be present in feedlot cattle collagen. It can also reduce the risk of things like [bovine spongiform encephalopathy] (BSE), or mad cow disease. Although that risk is pretty low in modern supplements, as they source parts carefully and often from countries with no BSE. Grass-fed cattle also come from places where ranching practices can be regenerative. For example, a lot of grass-fed collagen on the market comes from South America, countries like Brazil, Argentina, or Colombia, or places like New Zealand where cattle can roam on pasture year-round. Well-managed grazing can support ecosystems, improve soil health, and sequester carbon. So there’s a potential environmental benefit when collagen is grass-fed and sustainably raised versus coming from industrial feedlot operations. So I think choosing a grass-fed option of collagen is critical.

But here is the really critical point. That is easier said than done when it comes to collagen supplements because there is no legal definition of the term “grass-fed” in supplements. It is completely unregulated. Dietary supplements, including collagen powders or capsules, are regulated by the FDA as a category of food, but “grass-fed” is not a legally defined term under FDA regulations. Unlike terms like “organic,” which have strict USDA definitions and certification, “grass-fed” is a voluntary marketing claim. There is no specific federal law or binding FDA rule that dictates what “grass-fed” must mean on a supplement label. In practice, this means that when a collagen is advertised as grass-fed, it is largely up to the manufacturer to ensure that the claim is truthful.

Government oversight is limited to general truth-in-advertising principles. The FTC prohibits misleading or false labels on products, and the FDA can take action if a label is blatantly deceptive. But there’s no pre-approval or standardized definition for “grass-fed” on supplements the way there is for certain nutrient content or health claims. Put more simply, any supplement company can say their collagen is grass-fed, and you have no way of knowing if that’s true. In fact, many supplement companies don’t even know themselves if it’s true. They might ask their contract manufacturer to source a grass-fed collagen ingredient, and the ingredient supplier tells the manufacturer their collagen is grass-fed. But what does that actually mean? Did the cows get exposure to grass for their entire life? Or was it just a few months? Or maybe a few days? There’s no way the manufacturer or supplement brand can know because the supply chain isn’t fully transparent or traceable in the vast majority of cases.

This is why certification is absolutely critical when it comes to grass-fed collagen. The American Grassfed Association sets standards for truly grass-fed animal products. For a collagen to be certified grass-fed, it means the cattle spent 100 percent, not 50 percent, not 70 percent, not 90 percent, [but] 100 percent of their lives on pasture, consuming a natural forage diet with no confinement for feeding or feedlot grain finishing. It also means no hormones or antibiotics were used. This is a high bar to meet.

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As of now, there is only one collagen ingredient I’m aware of that has achieved this. It’s called SOLUGEL® certified grass-fed collagen. This isn’t a brand of collagen that you can buy. This is an ingredient that supplement brands can use to make their collagen product. SOLUGEL® is an ingredient made by a company called PB Liner. This is a very reputable company in the supplement ingredient space and they worked with a third party certifier called LIAF Control in collaboration with the American Grassfed Association to certify their collagen peptides as grass-fed. Their cattle are raised in Latin America on family ranches and oftentimes these ranches have been in families for multiple generations. The cattle free-roam outdoors eating grass for their entire life, and they’re never confined or given growth hormones. The result is a collagen peptide product that can carry the “AGA Certified Grassfed” seal. And again, it’s currently the only bovine collagen in the world that I’m aware of at the time of this recording to have that 100 percent grass-fed certification. That’s a big deal if you care about the authenticity of the grass-fed claim.

So why might you choose a product with SOLUGEL® grass-fed collagen? Aside from the animal welfare and ethical aspects, you know you’re getting a pure and clean product. It’s free from hormones, antibiotics, and steroids, and it has a completely traceable supply chain. They know which farms the hides come from, and they have protocols in place to ensure quality at every step, from the pasture to the processing facility. For people like myself, and I imagine many of you listening to this show, who are concerned about where their food and supplements come from, that transparency and assurance are really valuable.

Environmentally, using hides from grass-fed operations supports those farms and ranches who are raising animals in a more sustainable way. It’s like voting with your dollar. You’re saying you support regenerative agriculture. Many grass-fed cattle, especially in places like Brazil or Argentina, are raised on land that’s been grassland for centuries. Ideally, if collagen demand can incentivize keeping land as pasture rather than plowing it for monocrops, that can be net positive ecologically. Now, I want to note here that non-grass-fed collagen isn’t inherently bad. A lot of collagen comes from mixed-feed cattle, and those products can still be high quality in terms of purity and amino acid profile. They also often source from hides that would be wasted otherwise, so it’s still a recycling of resources. But if you have the option and if it fits your budget, grass-fed is a really significant upgrade. I should also mention that not all products that claim to be grass-fed are not fully grass-fed. The problem is that you just don’t know, because there’s no certification process in place and there’s not a fully transparent supply chain as there is with the SOLUGEL® certified grass-fed collagen peptides. I should also mention that the SOLUGEL® ingredient has a low molecular weight, with an average peptide size of 2 kilodaltons or 2,000 daltons. As I mentioned earlier, this is important because the collagen peptides will be more bioavailable and effective, easier to mix with water and other liquids, and less likely to cause digestive issues.

One more quick note, there are also marine collagens for those who don’t want bovine or porcine sources for dietary or religious reasons. If you do go the marine route, look for wild-caught fish sources and testing for things like heavy metals because fish collagen often comes from fish skin and scales, typically of cod or snapper, and those species can contain significant mercury levels. Marine collagen is usually type I and can be a bit more expensive gram-for-gram than bovine, but it’s an option if you’re allergic to beef or don’t want to consume beef or porcine collagen sources.

Now that we’ve covered quality and sourcing, let’s address a few final points of caution and clarify any considerations when using collagen. The good news is collagen is a very safe supplement for most people. After all, it’s basically a food. But as with anything, there are a few things to keep in mind before you jump on the collagen train.

Cautions and Considerations

Let’s go over some potential concerns and how collagen differs from other protein supplements and ensure that we maintain a balanced perspective here. Collagen has an excellent safety profile in studies. Research trials, even at fairly high doses, show that the occurrence of side effects is no different than placebo. This makes sense – our body naturally metabolizes collagen peptides as it would any other protein, and they don’t tend to cause GI distress in most people, with the exception, as I mentioned, of people who have GI issues. Sometimes [they] don’t process larger amounts like 10 grams of collagen well, so that’s why it’s important to choose a product with a low molecular weight peptides. Collagen isn’t a stimulant as we discussed, so they won’t cause jitters or insomnia. Rather, the opposite, as we discussed with glycine. About the only minor side effect that’s occasionally reported is a feeling of fullness. But again, that can be averted with choosing a product with low molecular weight peptides.

One important consideration is allergies. If you have an allergy to beef or pork or fish, obviously you want to avoid that as a source of collagen. Beef allergy is not common, but there is something called alpha-gal syndrome from a tick bite that causes red meat allergy that’s been increasing in prevalence lately. But if you have that, you probably already know who you are and you would avoid beef collagen. Collagen is a protein, so if you have any medical condition where protein intake is restricted, like advanced kidney disease, you would need to count collagen toward your total protein intake and consult with your healthcare provider. Remember that collagen is not a complete protein. It’s low in some of the essential amino acids like leucine and tryptophan which are crucial for muscle protein synthesis, so you shouldn’t use collagen as your sole protein source. I think that would be very unlikely for someone to do, but I just want to call that out here.

When thinking about collagen versus gelatin versus bone broth, know that gelatin is just collagen that’s been partially broken down. It gels in deserts. Bone broth is a whole-food source containing gelatin plus minerals. If you’re consuming bone broth regularly and eating nose-to-tail, you might not need a collagen supplement on top of that. But again, those collagen proteins in gelatin are not as broken down as they would be in a high-quality, low molecular weight collagen supplement. So many people choose to use both, including myself. I use broth in cooking quite a bit. I will sometimes just drink bone broth. It’s a regular part of my diet. I eat nose-to-tail. I do enjoy steak, but I also eat other cuts of meat. For example, last night we had a slow-cooked brisket. You can have chuck roast, stew, oxtail, ribs, etc. You’re going to get gelatin and collagen that way. But I also take collagen peptides regularly, and I think that’s the best approach for most people. In terms of cost, collagen isn’t necessarily the cheapest supplement, but when you consider that it basically could be replacing or augmenting some of your food and protein budget, I think it’s reasonable, and especially given the depth and breadth of the health benefits that are associated with collagen.

One more key differentiation I want to make here is between collagen itself and nutrients that support collagen production. Nutrients like vitamin C, copper, zinc, and silica are important for collagen production. They’re necessary for our body to produce collagen on its own. However, studies have shown that taking these nutrients does not have the same impact as taking collagen itself. The benefits that we’ve discussed in this podcast were from taking collagen, not taking the nutrients that support collagen production. And this admittedly creates a little bit of a challenge for vegetarians and vegans, because all collagen sources are of animal origin, whether you’re talking about bovine source, porcine, or fish source. They all come from animals. So if you are a vegetarian or vegan, your only option at this point is to take these nutrients like vitamin C, copper, zinc, and silica. There are some companies now that are doing recombinant DNA sources of human collagen. I think there’s still some issues to be worked out there and safety questions and considerations and they’re not widely available on the market yet. That might be a route in the future that makes sense, but for now I think most vegans and vegetarians are going to be better off just taking these collagen-supportive nutrients.

We’ve covered a lot of ground today on collagen. Thanks for sticking with me. We’ve talked about what it is, why it’s important, [and] how it can benefit various aspects of your health. I hope this discussion has demystified collagen for you. It’s a wonderful example of a functional food, something that blurs the line between nutrition and medicine, helping to address root causes like rebuilding tissues rather than just masking symptoms. It aligns with what I often emphasize, [which is] a holistic approach to health that’s practical and based on our evolutionary needs. If you’re thinking about trying collagen, you now know what to look for and how to use it. It could be a simple addition to your morning routine or evening wind-down (or both) that yields subtle but meaningful improvements in how you look, feel, and move.

Personally, collagen has become a staple in my daily regimen and I’ve seen its benefits in both my own health and in many of my patients and listeners over the years. As always, I encourage you to pay attention to your own body. Some people may notice a big difference with collagen right off the bat. Others maybe less so. But again, you need to give it at least that three-month period to fully evaluate its effects. And if you’re taking it for bone health, those benefits will continue to accumulate for a year or more.

So thanks for joining me today on this deep dive on collagen. It’s been a pleasure to share this with you. I hope you find it helpful and that it empowers you to make informed decisions about your health. Remember, small steps like adding nutrient-dense foods or supplements can add up to significant improvements over time. Thanks for listening and see you next time.

Everything You Need to Know About Collagen

Collagen: What It Is and Why It Matters

Collagen for Natural Beauty: Skin, Hair, and Nails

Joint and Bone Health Benefits of Collagen

Collagen’s Role in Muscle Recovery and Athletic Performance

Collagen and Gut Health: Healing from Within

Improving Sleep Quality with Collagen

Choosing the Right Collagen Supplement: Quality, Sourcing, and Dosage

Cautions and Considerations

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Advocating For Critical Thinking Amid Social Tension – TeachThought

The Value of Accountable Talk

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Everything You Need to Know About Collagen

Collagen: What It Is and Why It Matters

Collagen for Natural Beauty: Skin, Hair, and Nails

Joint and Bone Health Benefits of Collagen

Collagen’s Role in Muscle Recovery and Athletic Performance

Collagen and Gut Health: Healing from Within

Improving Sleep Quality with Collagen

Choosing the Right Collagen Supplement: Quality, Sourcing, and Dosage

Cautions and Considerations

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