A couple weeks ago, I answered 20 of your burning questions about collagen. Today I’m back for part two of this series with 20 MORE questions.
Before starting, let me make a general disclaimer so I don’t have to sound like a broken record: To offer an optimal supplementation strategy with any confidence, you need a fairly substantial body of evidence to draw upon. While collagen is a hot topic, there really isn’t a ton of research on collagen supplementation yet, particularly not studies done in humans. That’s not to say we’re shooting blind here. We know that collagen used to be abundant in the human diet, and we need collagen to balance out the methionine we get from meat. Plus, there is a growing (but not yet extensive) literature on collagen supplementation, as well as a fair number of studies aimed at understanding the effects of specific amino acids—glycine in particular—that are found in collagen.
All this is to say, while I can provide my educated opinion about best practices, some of the nitty-gritty questions you submitted require data we simply don’t have yet. I’m hopeful that it’s forthcoming. In the meantime, here’s what I’ve been able to glean from the available science.
What types of collagen are best for joints and skin?
Skin contains mostly type I and type III collagen. Cartilage is type II. However, collagen supplements all contain the same basic amino acid building blocks. There’s no evidence that one formulation is better than another for achieving specific goals. You probably don’t need to worry about micromanaging.
How does collagen supplementation relate to the use of glucosamine and chondroitin for joint health? Do we need both?
They serve different functions. Glucosamine and chondroitin are used to prevent cartilage breakdown and relieve joint pain, though evidence regarding their effectiveness is mixed. Collagen provides amino acids necessary to build collagen in the body. I don’t know if you need both, but you can take them together.1
Does topical collagen work?
Collagen peptides are too large to penetrate the skin effectively, and there’s virtually no evidence that topical collagen products have anti-aging or other cosmetic benefits.2 Some medical applications are quite promising, though. Specifically, I’m keeping my eye on research into collagen-based biomaterials to help speed wound healing. 3
Is collagen good for gut health? Does collagen “heal the gut?”
“Heals the gut” may be too strong a promise, but the available data suggests that collagen does support gut health. In particular, studies show that glycine—the primary amino acid in collagen peptides—exerts anti-inflammatory and cytoprotective effects in the gut. Glycine protects against endotoxemia and ulcers as well.456
For joint health, is there a specific collagen supplementation protocol you recommend? How much do I have to take, how often, and in what form to support joint health?
As I said up top, we don’t have the fine-grained studies we’d need to answer this question. The few available human studies suggest that 10 grams of collagen peptides or 10 mg of undenatured type II collagen can be enough to yield some benefits.78
Does collagen supplementation help when doing prolotherapy?
I like this hypothesis, but I don’t know that anyone has tested it. With prolotherapy, doctors inject an irritant around injured connective tissue, supposedly triggering the deposition of new collagen tissue. It seems like you’d want as many available amino acids as possible in this situation. Why not try?
Do collagen peptides speed wound healing, and if yes, in what quantity?
Based on available evidence, I’m fairly confident the answer is yes. However, a 2019 review found only eight studies of collagen peptides worth considering—not nearly enough to answer the second part of this question.9 Topical collagen treatments continue to show promise as well, but they’re still experimental at this point.10
Can collagen speed recovery time for broken bones, cancer metastases, or other major injuries?
Another good hypothesis that needs to be tested. Here’s what we know: Bone is predominantly type I collagen. Collagen supplementation appears to improve bone mineral density and protect against age-related bone loss.11 Vitamin C, an important cofactor for collagen production, helps bones heal after injury.12 I’d try it, personally.
Can pregnant women take collagen? Should they?
I see no reason why not, nor do any of the major (American) medical associations seem to have any issue with it. Some sources recommend avoiding marine collagen during pregnancy due to potential sensitivities, but this may be an abundance of caution. Talk to your doctor if you’re concerned.
Can women who are breastfeeding use collagen supplements?
Same as above. Pregnant and breastfeeding women need those amino acids. Moreover, collagenous bone broth, soups, and stews made from meat on the bone are traditional postpartum foods around the globe. Ancestral wisdom at its finest! Always select reputable brands that test their collagen for contaminants. (Yes, Primal Kitchen does.)
Should you take more collagen as you get older? Are different forms of collagen better for people of certain ages?
Older folks require more protein to stimulate muscle protein synthesis. Specifically, they need more of the amino acid leucine. Although collagen contains some, meat is a better source.13 That said, older folks should consider adding collagen for bone health. Any collagen peptides will do.
Benefits for endurance athletes to support ultra running and other endurance events? Are there other benefits for endurance beyond joint health?
This is a slam dunk, in my opinion. Check out the “Collagen for Performance” section in this post. Besides joint and connective tissue health, collagen supplementation may positively influence body composition and, according to one study, improve muscular strength and endurance.1415 Glycine also supports sleep, which is critical for recovery.16
I believe collagen powder is rather high in oxalates. For those of us who have to minimize our oxalate intake, is there a decent alternative?
The amino acid hydroxyproline is a precursor to oxalate production in the liver.17 All collagen supplements (and bone broth) contain hydroxyproline. Talk to your doctor before supplementing if you’re prone to calcium oxalate kidney stones. You might be ok taking smaller servings. Standalone glycine supplements are another option (see below).
Can you be allergic to collagen? My 16-year-old daughter gets an itchy throat when she uses collagen powder.
That certainly sounds like an allergic reaction. There have been a couple documented cases of collagen allergies, though they seem quite rare. Folks with fish and shellfish allergies should steer clear of marine collagen. Does the powder in question contain other ingredients? In any case, she should stop taking it.
Do I need to worry about heavy metals like lead in collagen supplements?
With any supplements, you want to make sure you buy from a trustworthy source that follows best safety practices. At Primal Kitchen, our quality standards include testing each lot of collagen produced for compliance with regulatory standards for heavy metals.
Does adding collagen to your coffee (but nothing else) officially break your fast? Does it matter?
I have a whole post about what supplements do and do not break a fast. To quote myself: I’m going to say “technically yes,” but “realistically no, collagen doesn’t break the fast.” There’s a small possibility that glycine might inhibit autophagy, but I’m not overly concerned about it.
If I’m tracking macros, should I track collagen peptides toward my total protein?
No. Collagen is considered an incomplete protein because it lacks tryptophan, one of the essential amino acids. It’s also a relatively poor source of leucine compared to meat or whey protein. Your food tracking app will count collagen toward your daily protein total, so you’ll need to mentally subtract it.
I’ve heard that collagen can lower serotonin levels and cause increased anxiety in some people. Any truth to that?
Collagen peptides lack tryptophan, a precursor of serotonin. If you don’t consume enough complete protein sources, it’s true you could end up deficient in tryptophan. Collagen doesn’t deplete tryptophan, though, so supplementing collagen shouldn’t cause low serotonin. Just don’t replace other protein sources with collagen.
Glycine powder is much more cost-effective than collagen, and is actually quite tasty (naturally sweet). Do you think supplementing 10-15g of glycine can approximate most of the benefits of collagen supplementation?
I have a post on this, too. The short answer is: I’m all for supplementing glycine if you want, but it won’t net you all the benefits of collagen. Consider that collagen is the only meaningful dietary source of hydroxyproline, which is crucial for collagen synthesis in the body.
Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.