Collagen is the most abundant protein in our body: it accounts for nearly 30% of total protein.
A true “glue” for the body, it provides structure and strength to the skin, bones, tendons, muscles, and even blood vessels. Collagen is also found in the liver’s extracellular matrix.
Because collagen is a protein, and the liver plays an active role in protein metabolism, the link between the two may seem obvious. But as I delved into the scientific literature, I quickly realized that the subject is much more nuanced than it appears.
It is important to distinguish between the collagen naturally present in the liver’s structure and the collagen that accumulates there in certain liver diseases such as fibrosis.
This therefore raises questions: is collagen in supplement form harmful to the liver…or potentially protective? I looked into the topic and the current scientific answers.
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Collagen, an indispensable ally of the liver?
An indispensable ally… up to a certain point
In a healthy liver, collagen has its place. Along with other proteins such as elastin or glycoproteins, it helps maintain the liver’s proper architecture and facilitates exchanges between the blood and hepatocytes.
I find this point important to emphasize. When we hear about collagen and liver disease, we might think that this protein is necessarily harmful. But it is exactly the opposite: it is essential… as long as it remains present in normal amounts.
When collagen builds up: hepatic fibrosis
When the liver is chronically damaged (excessive alcohol consumption, chronic hepatitis, toxic substances, metabolic dysfunction-associated steatosis), it triggers a repair mechanism.
Hepatic stellate cells become activated and begin to produce more extracellular matrix, including collagen types I and III. At first, this response is beneficial because it helps the liver repair damaged tissue.
But if the injury persists over the long term, collagen fibers accumulate between liver cells. The liver then becomes stiffer and works less efficiently: this is what is known as hepatic fibrosis.
These mechanisms are now well known. And described in this recent review dedicated to the role of collagen in hepatic fibrosis.
If it is not detected in time, it can progress to cirrhosis.
Is collagen dangerous for the liver?
To date, no scientific data can state that collagen is harmful to the liver in healthy people. It does not appear to have any particular toxicity.
Collagen is simply digested like any other dietary protein. Once ingested, it is broken down into peptides and then amino acids. They will be used by the body according to its needs. There is currently no evidence that this process places excessive strain on the liver.
However, you may experience some digestive side effects if you are sensitive. Bloating, discomfort, heaviness, especially at the start of supplementation.
However, I strongly recommend turning to quality brands that use patented collagen and are manufactured in France.
Collagen, glycine, and liver “detox”: what does the science say?
Glycine, a promising avenue
Collagen is particularly rich in glycine, an amino acid that makes up nearly one-third of its composition. As a precursor to a powerful antioxidant, glutathione, this amino acid is of interest to researchers.
In animals, several studies from the 2000s suggest that a high intake of glycine could slow the progression of liver fibrosis.
A study conducted in rats with liver fibrosis induced by carbon tetrachloride (CCl₄) showed that a diet enriched with glycine reduced collagen deposition in the liver. And it slowed the development of fibrosis. Similar results were observed in a model of alcoholic liver disease in rats.
These results remain preclinical, however. To my knowledge, no clinical trial has shown that collagen or glycine supplementation can slow liver fibrosis in humans.
Collagen does not “detoxify” the liver
Collagen does not “detoxify” or “clean” the liver. This claim is not scientifically supported.
In general, the term “detox” is a marketing argument. The liver itself carries out the transformation and elimination of its waste products.
So we can say that collagen provides amino acids, including glycine, which are of interest to research on liver diseases. On the other hand, we cannot claim that a course of collagen “detoxifies” or regenerates the liver.
Conclusion: collagen, a protein with a dual role
On the one hand, collagen is an essential component of the liver’s structure. On the other hand, when it is produced in excess in response to chronic injury, it becomes scar tissue that characterizes liver fibrosis.
As for hydrolyzed collagen peptide dietary supplements, they do not currently appear to pose a risk to the liver. When they are of good quality and used according to the manufacturer’s instructions.
However, they have not proven any benefit in “detoxifying” the liver. While the glycine it contains is an interesting avenue of research, the available results come mainly from preclinical studies.
Sources and scientific studies
- Arriazu E, Ruiz de Galarreta M, Cubero FJ, Varela-Rey M, Pérez de Obanos MP, Leung TM, Lopategi A, Benedicto A, Abraham-Enachescu I, Nieto N. (2014) Extracellular matrix and liver disease.
- Rivera CA, Bradford BU, Hunt KJ, et al. (2001) Attenuation of CCl4-induced hepatic fibrosis by GdCl3 treatment or dietary glycine. Am J Physiol Gastrointest Liver Physiol.
- Senthilkumar R, Nalini N. (2004) Glycine prevents hepatic fibrosis by preventing the accumulation of collagen in rats with alcoholic liver injury.
