Recenlty, I have seen a real lack of clarity surrounding collagen protein, so I wanted to put together an article to give you a good read on the subject and what you should know.

Today, let me tell you the complete story on collagen protein and what you can do about it.

A Message From A Viewer…

Dear Dr. C,

Thanks for your great videos! It is obvious that you really care and you do lots of research.

I’m a week into the Metabolism Reset Challenge and it doesn’t seem to be working for me. I’ve lost zero inches and my appetite is worse than ever. The only thing I’m doing differently from your instructions is that I’m using collagen protein instead of pea protein. Could that matter?

Your fan,


Collagen & Bone Broth Supplements

First and foremost, thank you for writing in Alycia.

I appreciate you taking the time to send me that message, and this has been an article that I have been planning for quite some time.

In the recent past, I have seen plenty of folks unclear on this subject. This is a great place to start for today’s discussion.

The short answer is that using collagen/bone broth supplements instead of a complete protein could lead to the Metabolism Reset Challenge not working for you.

If you did everything else, as per the guidelines, that might just be the only change you need. (Read: How you can boost your metabolism)

“Protein” Supplements

That said, the truth is that collagen “protein” supplements drive me nuts! They are not even protein by our usual definition.

Let me be clear, though, I do not have anything against them. I love a good chicken or beef broth for culinary purposes. Early on during this bone broth fad, there was data suggesting they were high in lead.

This concern did not pan out when more detailed studies were performed.

I can understand the thought process, though, where folks have been led to speculate and believe in collagen’s potential healing properties.

Here is where I have to differ – speculation is just a starting point, not a conclusion. Once you speculate, you need to look at the evidence. Did it actually work, as advertised, when studied?

Let me walk you through why collagen does not work as a protein source. After that, I will address the next logical follow-up question: isn’t it good for other things?

How Do We Define Quality Protein Sources?

Overall, the most respected marker out there today is the Protein Digestibility Corrected Amino Acid Score (PDCAAS for short).

What this score does is it takes into account the presence and proportion of essential amino acids and the digestibility of food.

Key Insight: Proteins are composed of amino acids. Of the amino acids, 9 are essential. Our bodies are unable to make them naturally – yet we need them.

Non-essential amino acids are ones we can make on our own. In the case of some uncommon nutrient deficiencies or diseases, we cannot make a few of the non-essential amino acids. But, we can never make the essential amino acids on our own.

In fact, if a food contains amino acids but lacks essential amino acids, it has no protein value. Even “incomplete” plant proteins, as found in grains or legumes, do not lack any of the essential amino acids. They just have lower amounts of some than others.

Amino Acids Used by Humans

Essential Non-Essential
Histidine Arginine Glutamic Acid
Isoleucine Cysteine Serine
Leucine Glutamine
Lysine Glycine
Methionine Proline
Phenylalanine Tyrosine
Threonine Alanine
Tryptophan Aspartic acid
Valine Asparagine

Here are some common foods that contain protein and their PDCAAS scores1:

Where Are Collagen and Bone Broth?

Notice anything missing? Collagen and bone broth are nowhere to be found.

To quote Dr. Stuart Philips from McMaster University:

“PDCAAS score of collagen is zero due to the fact that it is lacking in tryptophan”2

Key Insight: Besides the fact that collagen completely lacks tryptophan, it is also nearly devoid of the branched-chain amino acids (especially valine).

I’ve had discussions with proponents of collagen as a source of protein. Their argument was that people with diets already high in essential amino acids could utilize collagen for up to about 15 grams of protein daily. They often cited this WHO report.3

The problem is that those who are not at optimal protein status or on low-fuel diets are those who can benefit from protein supplementation. Collagen does not help anyone with their protein needs, but those who already have enough or too much can use a fraction of their protein from collagen and do no worse.

That really says nothing. They could also not consume collagen and do no worse. They did no better from it either.

There is also evidence suggesting that consuming incomplete proteins when lacking protein is even worse than just going without. That said, consuming large amounts of non-essential amino acids can further tax a system that is lacking in some of the essential amino acids.

This problem emerged with the liquid protein diets of the late 70s/early 80s. Some proteins used liquid collagen as the sole source of protein on low-calorie diets.

Tragically, death was such a common side effect that diets like these are no longer commercially available. Fasting is safer than consuming a low-calorie diet with collagen as the sole protein.4

Are Collagen and Bone Broth Good for Anything?

The top claims by supplement manufacturers are that collagen supplements help with:

  • Chronic pain
  • Skin health
  • Muscle growth and fat burning
  • Cellulite
  • Digestive health

If I wanted to provide you with a detailed breakdown, I needed to dive into the research. Given all these potential benefits, I did a full review of the available medical literature. Here are the studies and what they say:

Chronic Pain

There have been studies which linked collagen to easing joint pain, but let’s do a little bit of digging to understand them better.

The collagen used in these studies is called “undenatured type 2 collage ovine collagen” – typical collagen supplements are bovine type 1 and type 3.

Key Insight: This is not the same compound as bone broth or collagen “protein” used in the supplements that you are likely to come across.

After 90 days of treatment, respondents had pain scores in their knees down 33%. While this is good news, it is not the same as the collagen protein or bone broth that you would typically find in stores.

Bottom Line: There is no evidence that collagen/bone broth helps joint pain, only that a certain type of collagen you would never see in these supplements has shown positive effects when studied.

Skin Health

From a recent study, younger women (under the age of 50) did worse than the placebo on a moderate dose of collagen.5

Older women, though, did 0.1% better with high dose. However, the margin of error for the cutometer was 4-6% for non-sun exposed skin (this study used the inner forearm).

To take this study at face value, collagen may worsen collagen levels. However, the changes good or bad were so minuscule that they were not measurable within the known randomness of the tool used.

Overall, they would hardly be noticeable.

Muscle Growth and Fat Burning

One study performed on elderly men enjoying 16% protein diets and 1800 calories overall. The addition of 15g of collagen and strength training resulted in more muscle mass and more fat loss than placebo.

A pitfall here was that the placebo was not specified – and was likely not a protein. Ultimately, this means that collagen was not proven to help as much as protein from a quality food source or a complete protein supplement might have.


There have been no studies to prove this point, as per the last meta-analysis.6 A sponsored study did show that collagen reduced cellulite more than placebo, but the difference between placebo and no treatment was much greater than the difference between placebo and collagen.

Digestive Health

With IBD serum levels of laminin and type-four human collagen are lower. These are disease markers that include the word collagen but have no relationship to collagen supplementation. This does not mean that collagen supplementation reverses the disease.

Understanding Bone Broth & Collagen

What we have seen from the latest available research is that collagen and bone broth really are not suitable protein sources, and their list of benefits may not be as trustworthy as they seem.

Ultimately, if you are on the Metabolism Reset Diet, I would not recommend subbing either of these for pea protein – you may miss out on the effects of the diet, in general.

Interested in learning more about the Metabolism Reset Diet and getting started on living your best life? If so, please start by clicking this link. It can give you everything that you need to know so that you can take the next step in your journey to better health.


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P.S. Whenever you are ready, here is how I can help you now:

1. Schedule a Thyroid Second Opinion with me, Dr. C, Click Here for Details
2. Download and use my Favorite Recipes Cookbook Here
3. Check out my podcast Medical Myths, Legends, and Fairytales Here

Dr. Alan Glen Christianson (Dr. C) is a Naturopathic Endocrinologist and the author of The NY Times bestselling Adrenal Reset Diet, The Metabolism Reset Diet and The Thyroid Reset Diet.

Dr. C’s gift for figuring out what really works has helped hundreds of thousands of people reverse thyroid disease, lose weight, diabetes, and regain energy. Learn more about the surprising story that started his quest.