For decades, the health community had written off collagen as a “useless” protein. It wasn’t essential, in that it contained no amino acids you couldn’t make yourself. It didn’t contribute directly to muscle protein synthesis, so the bodybuilders weren’t interested. In all my years running marathons and then competing in triathlon at an elite level, no one talked about collagen. It was completely ignored, especially after the rash of collagen-based “liquid diets” ended up with a lot of people dead or in the hospital.1 
But you know my bias is to look at things from the perspective of human evolution and ancestral environments. And there is a ton of collagen on your average land animal. Close to half the weight of a cow is “other stuff”—bones, skin, tendons, cartilage, and other collagenous material. Most meat eaters these days might be throwing that stuff away, if they even encounter it, but humans for hundreds of thousands of years ate every last bit of that animal. Even as recent as your grandmother’s generation, utilizing every last collagenous bit of an animal to make soups, stocks, and stews was standard practice. This was the evolutionary environment of the ancient meat-eating human: rich in collagen.
There is strong evidence that humans are meant to eat the meat and the bones, skin, and sinew. That we function best when we eat the amino acids in muscle meat and the amino acids in collagenous materials. That the more muscle meat we eat, the more collagen we require. That we live longer, live healthier, and look and move better with plenty of collagen in our diets.
First, I’m going to tell you why collagen is so essential.
Then I’m going to tell you how to get it.
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Collagen Benefits: Why It’s Essential
The collagen question is a complicated one. The benefits are both “superficial” and deep. Most people know about its effects on skin and joints, but there are also “deeper” reasons to eat more collagen , including conferring longevity and protection from disease.
Glycine to Link Other Amino Acids
Collagen is the single greatest source of glycine in the human diet. Glycine is an interesting amino acid. It’s conditionally essential, meaning we can make it in-house but certain situations render it essential. What are these conditions and why is glycine so important?
Basic Physiological Requirements
We simply can’t make enough glycine to cover our basic daily needs. The average person needs 10 grams of glycine to cover all the physiological requirements. The average person makes 3 grams every day and gets 1.5-3 grams from their diet, leaving a glycine deficit of 4-5.5 grams per day.2  Collagen is about 1/3 glycine, so a 12 gram serving of collagen—about a heaping scoop of collagen peptides—will give you the glycine you need to fill the gap. Some people will need a bit more, some a bit less. But almost everyone needs some.
Further reading: What is the Difference Between Collagen and Whey Protein? 
High Meat Intakes
As I mentioned earlier, meat comes packaged with collagen in natural settings. You kill a deer, you get a lot of meat and a lot of skin, connective tissue, cartilage, tendons, and bones. And you eat all of it. These have different amino acid profiles. Meat contains a lot of methionine. Collagen contains a lot of glycine. Animal studies confirm that the more methionine an animal eats, the shorter their lifespan—unless they balance it out with glycine.3 
Human studies suggest this, too.
- In one study, the relationship between red meat and diabetes was abolished after controlling for low-glycine status. People with low glycine levels and high meat intakes were more likely to have diabetes, while people with higher glycine levels could have higher meat intakes without any issues.4 
- In another study, low circulating levels of glycine predicted diabetes risk.5 
- Meanwhile, high levels of glycine predict normal blood sugar control.6 
- In fact, low glycine comes before diabetes onset, suggesting causation.7 
- Low glycine levels are also common in patients with chronic kidney disease.8 
- High levels of glycine even predict higher physical activity in women.9 
These are observational studies and cannot prove causation. But the trend is consistent, with higher levels of glycine being linked to better health and lower levels being linked to worse health across a broad range of conditions.
Meat is incredibly healthy  and has been a vital part of the human diet  for hundreds of thousands of years, but it’s possible that the way most people eat meat in developed countries—eating chicken breasts over chicken wings and skin, lean steak over oxtails and shanks, muscle meat over bones, skin, and tendons—is unhealthy. Increasing your collagen, then, could balance out the meat intake by providing ample glycine.
Collagen to Support Sleep
A great sleep remedy  I’ll incorporate when I really want to knock out fast is a cup of bone broth with extra collagen or gelatin added. About midway through drinking it, I’ll start feeling sleepy. But why? What’s going on?
Once again, glycine is doing the lion’s share of the work here.
- It enhances production of serotonin, a necessary precursor for the sleep hormone melatonin.10 
- It drops body temperature when taken at night, which improves sleep quality.11 
- It improves subjective sleep quality; people feel like they get a better night’s sleep after taking 3 grams of glycine before bed.
- More importantly, it improves objective sleep quality; people perform better the next day after taking 3 grams of glycine the night before.12 
These studies used isolated glycine, but I much prefer using collagen .
Collagen and Skin Elasticity
Your skin is made of collagen. To maintain its elasticity and stave off wrinkling , we must provide the foundational substrates for collagen synthesis and deposition. That’s, well, collagen and two of its most prominent constituent amino acids: glycine and proline.
The beneficial effects of collagen supplementation on skin health are well-documented:
- 2.5 grams of collagen per day for 8 weeks reduced eye wrinkling by 20% and increased skin elastin (a skin protein that does exactly what it sounds like—provides elasticity) by 18%, an effect that persisted for one month following cessation of the supplement.13 
- 1 gram of a chicken sternum cartilage collagen extract per day reduced wrinkling by 13% and skin dryness by 76% while increasing collagen deposition by over 6%.14 
- 6 months of collagen supplementation even reduced the appearance of cellulite.15 
Now, in case you’re thinking skin appearance is a superficial benefit, consider that how old your face appears is one of the better predictors of your overall health.16  The quality of the collagen in your skin is a window to the quality of your internal collagen—your joints, your fascia, your other tissues. Improve one and the rest will follow.
Joints are Comprised of Collagen
Just like skin, your joints are made of collagen. Just like taking collagen can improve your skin, taking collagen can improve your joints—especially if there’s a problem.
In athletes complaining about joint pain, taking collagen hydrolysate supplements reduced pain.17 
In osteoarthritis patients, a collagen supplement reduced pain scores and improved walking ability.18 
Taking or eating collagen is low-hanging fruit for anyone with joint pain.
Collagen for Performance
Even the old claims about collagen being useless for muscle gain and gym performance are falling apart. Growing evidence shows that collagen can be protein-sparing ; by providing extra “non-essential” amino acids, it allows you to utilize the essential amino acids for more important, performance-related processes. For instance, in resistance training seniors, taking collagen supplements (and collagen alone; no whey or anything else) increases the anabolic response to lifting.19 
Taken pre-workout along with 50 mg of vitamin C, 15 grams of collagen can actually improve the performance of your tendons by increasing collagen deposition and remodeling. We usually think of building muscle from our training, but with collagen, you can build connective tissue too.20  I actually used this same protocol  to heal my own Achilles injury several years ago.
And if you use collagen to improve the quality of your sleep, your mental performance will also improve.
Accelerating Healing with Collagen
Most traumatic injuries involve damage to the connective tissue, skin, or fascia. Since we have good evidence that collagen supplementation speeds up healing time in ulcer patients and topical collagen can improve wound healing when added to dressings, and we know that pre-workout collagen can increase collagen deposition in tendons, it’s a safe bet that taking extra collagen can also speed up the healing time from any wound or trauma that requires the laying down of new collagen.21 22 
Best Collagen Sources: Foods and Supplements
Although getting hold of and consuming an entire animal is probably the ideal, optimal way to get the collagen you need, supplemental collagen is an easier alternative for most people that’s about as effective.
What are the best sources?
- Gelatinous meats: shanks, necks, feet, cheeks, oxtails, ribs
- Bones and cartilage
- Bone broth
- Powdered gelatin
- Collagen hydrolysate 
- Collagen bars 
Eat gelatinous meats. Many meats are low in collagen, but not all. Shanks, necks, feet, cheeks, oxtails, ribs, and all the other cuts that take extra time in the slow cooker to become tender are high in collagen. Favor these meats instead of yet another chicken breast.
Clean your bones. You know those crunchy caps at the end of chicken drumsticks? That’s cartilage, a big whopping dose of concentrated collagen. Eat it. Or those stringy tendons and sinew attached to the ends? Eat those too.
Eat skin. Skin is almost pure collagen. Chicharrones or pork rinds are the most widely available way to eat skin. If you ever get your hands on pork belly with the skin on, this is the way to cook it  so that the meat is fall-apart tender and the skin is crunchy and delectable (and full of collagen).
Drink bone broth. Bone broth is trendy right now, and for good reason; it’s a rich source of collagen. Bone broth is simple to make but takes valuable time. If you can’t do it yourself, there’s a budding bone broth industry more than willing to ship frozen or shelf-stable broth to your door.
Use powdered gelatin. I always keep a can around for cooking. My favorite use is a quick 10-minute Thai curry: toast the spices and curry powder in coconut oil, add coconut milk, reduce, and whisk in a couple tablespoons of gelatin powder to obtain the desired texture and mouth feel. Delicious and a huge dose of collagen. You can also add powdered gelatin to pan sauces to replicate the use of demi glace, or even make healthy jello out of herbal/green tea/coffee with non-caloric sweetener.
Use collagen hydrolysate. Several years back, I suffered an injury to my Achilles tendon. I’d already been eating gelatinous meats and drinking broth, but I really wanted to step up my collagen intake. I was moved to create my own collagen powder  with 20 grams of collagen protein (more collagen than 2 cups of bone broth) per serving. Eating 20-40 grams of supplemental collagen per day fixed my Achilles right up.
Eat Primal Kitchen bars. Each Primal Kitchen® collagen bar  contains 7.5 grams of pure collagen from grass-fed cows  (it’s what gives the bar its unctuous chewiness). With collagen being about 33% glycine, that’s almost 2.5 grams of glycine in each one—almost enough to satisfy those 3 grams used to improve sleep quality and reduce joint pain in studies.
Bone broth, chicharrones, tendon stew, gelatin, collagen powder —I don’t care how you get it, just get it. Collagen is non-negotiable.
That’s it for today, folks. How do you get your collagen? How much do you take or eat a day?
- https://charm.cs.uiuc.edu/users/jyelon/lowcarb.med/topic9.html 
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