Collagen Under the Microscope

7.4.2026

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Collagen is among the most frequently supplemented substances, yet many simplifications and myths surround it. Do bovine and marine collagen truly differ in their effects? And how is collagen absorbed by the body? In this article, we look at collagen "from the ground up" – from its amino acid composition and source differences to the actual mechanisms of absorption and biological action.

What will you learn in this article?

Collagen up close
Amino acid spectrum as a key factor
Bovine vs. marine collagen
How collagen absorption works
Myths vs. reality: do effects differ by source?
Key takeaways from the article

Collagen up close

Collagen is a structurally specific protein whose biological function is closely linked to its amino acid composition. In the bodies of mammals and humans, it is the most abundant protein – accounting for roughly 25-30%. The structure of collagen consists of a triple helix made up of three polypeptide chains rich in glycine, proline, and hydroxyproline. These proteins, produced by fibroblasts (the main cells of connective tissue), spontaneously assemble into various triple helix structures (28 types) that provide strength to connective tissues such as skin, tendons, and bones.

Amino acid spectrum as a key factor

Amino acids represent the basic building blocks of proteins. Collagen contains a total of 19 amino acids, 8 of which are essential – meaning the body cannot produce them on its own and must obtain them through diet.

Collagen is characterized by a specific amino acid composition that differs significantly from most other proteins. This unique spectrum is tailored to its primary function – it allows for the creation of a strong, stable, and characteristically organized triple helix structure.

Collagen has a low content of essential amino acids such as tryptophan, cysteine, or methionine, but it is rich in specific non-essential amino acids such as glycine, proline, and hydroxyproline. This composition enables the stable and strong triple helix structure necessary for the mechanical function of connective tissues.

Main amino acids of collagen:

Glycine (~33%)

This is the simplest and most abundant amino acid in collagen. Due to its small size, it allows for the tight coiling of the triple helix structure. It is also the only one capable of binding to sites that other amino acids cannot reach due to spatial constraints. Thus, only glycine can be present inside the collagen helix, where it ensures the stability of the helix.

Glycine is an amino acid that is often lacking in the modern diet. In the past, people commonly consumed broths, skins, tendons, and other animal parts rich in collagen. Today, muscle meat predominates, which contains glycine only in limited amounts. Therefore, collagen (or broths) is one of the best ways to supplement glycine.

Additionally, glycine supports quality sleep and regeneration.

Proline (~12–15%)

The amino acid proline provides collagen with strength and stability. Together with hydroxyproline, it helps maintain the triple helix structure.

Proline is important for the health of skin, joints, and ligaments. Although the body can produce it, its demand may be higher during increased strain (stress, sports, need for healing). Its natural source is specifically collagen.

Hydroxyproline (~10%)

This is a key amino acid derived from proline that is essential for helix stability, as it enables the formation of hydrogen bonds between the chains. It is present in all types of collagen and ensures the stability of the collagen network.

Without its presence, collagen would not be able to "hold together." Hydroxyproline is specific to collagen, so its presence in the body reflects the state of collagenous tissues (skin, tendons, cartilage).

Alanine (~10%)

Helps maintain the collagen helix structure, though it does not have functions as significant as glycine or proline. Furthermore, alanine is commonly available from other protein sources, so its deficiency is usually not an issue.

Hydroxylysine (~1–2%)

It is formed from lysine and contributes to tissue strength and integrity. It is a key structural component of collagen, contributes to the stability of connective tissues, and occurs predominantly within them.

Other amino acids found in collagen:

Serine, arginine, threonine, glutamine, and asparagine are represented in smaller amounts.
Methionine, tryptophan, and phenylalanine are almost negligible or absent, reflecting the unique composition of collagen.

Bovine vs. Fish Collagen

Both bovine and fish collagen contain a very similar spectrum of amino acids:

Glycine (~30–33%)
Proline + hydroxyproline (~20–25%)
Low content of essential amino acids (e.g., tryptophan is practically absent)

The main difference is the higher hydroxyproline content in bovine collagen, which results in higher thermal stability and structural strength.

Conversely, the lower hydroxyproline content in fish collagen leads to lower helix stability and consequently higher solubility and faster digestibility.

Trime hydrolyzed Beef collagen originates from mammalian connective tissues, which are naturally and long-term exposed to mechanical stress. This is reflected in the collagen structure prior to its hydrolysis.

After hydrolysis, a specific spectrum of bioactive peptides is created, which can influence the strength and elasticity of joints, tendons, and fascia.

With a daily dose of 15g of collagen, one can naturally supplement approximately 3-3.5g of glycine per day. Therefore, when it comes to collagen, it is the most natural food source of glycine.

Due to its "composition," bovine collagen is designed as a supplement suitable for daily use and as a natural source of glycine. Higher dosages also allow for a higher intake of glycine and long-term functional support of connective tissues.

The source of Trime hydrolyzed Beauty Collagen is, on the other hand, the skin of wild-caught cod with MSC certification. These are tissues exposed to different mechanical conditions than the tissue structures of mammals. They are not primarily strained by gravitational force but rather require flexibility, elasticity, and adaptability in an aquatic environment.

After hydrolysis, this source of collagen creates a spectrum of peptides with a higher representation of "more flexible" collagen building blocks (Glycine–Proline–Y), which are typical for skin tissue. This amino acid profile then corresponds well to the needs of rapidly renewing tissues – primarily the skin, but also mucous membranes (e.g., in the gastrointestinal tract).

Typical dosages in clinical studies range around 5 g per day. The effect of collagen is not only related to the total intake of amino acids, but primarily to bioactive peptides that act as signaling molecules (ligands) and influence tissue metabolism.

How collagen absorption works

The differences in the absorption of individual types of collagen do not lie in the amino acid spectrum itself, but rather in their relative proportions and structure. After passing through the digestive tract, both bovine and fish collagen are broken down into amino acids and bioactive peptides. Therefore, the resulting effect depends primarily on the generated peptide profile, the dose, and the individual needs of the organism.

After ingesting collagen, most commonly in the form of hydrolyzed collagen peptides, a standard protein digestion process occurs. However, this leads to the formation of specific bioactive peptides that can have their own biological activity and influence cellular processes.

Collagen Digestion

In its natural form, collagen is a structurally very stable protein, which makes its native form more difficult to digest. Therefore, hydrolyzed collagen is used in dietary supplements, as it is already partially broken down into shorter peptides.

Absorption of Collagen Peptides

Unlike common proteins, a portion of collagen is absorbed not only as individual amino acids but also as "small packages" of di- and tripeptides, specifically prolyl-hydroxyproline (Pro-Hyp) and hydroxyprolyl-glycine (Hyp-Gly).

These peptides:

are transported across the intestinal wall using transporters
appear in the blood plasma as early as 30–60 minutes after ingestion
can persist in circulation for several hours

After absorption, collagen components follow two main pathways: Amino acids serve as building blocks for the synthesis of collagen and other proteins. Meanwhile, bioactive peptides function as signaling molecules but can also stimulate cells (fibroblasts, chondrocytes, and osteoblasts) to produce collagen.

Thus, collagen acts not only as a source of amino acids but also as a functional signaling substrate that stimulates collagen synthesis, supports the formation of the extracellular matrix, and can influence skin hydration and elasticity.

Myths vs. Reality: Do Effects Differ by Source?

Collagen supplements are often distinguished by their origin (bovine, marine, porcine), which is frequently linked to various claims about their effectiveness. However, the real difference must be understood in the context of digestion, absorption, and the biological action of collagen peptides.

The reason is that after ingestion, all types of collagen (regardless of the source) break down into the same amino acids and short peptide chains.

The organism does not distinguish the "origin" of collagen but works with its building blocks according to current needs. Distribution to tissues (skin, cartilage, bones) is determined not by the source, but by physiological processes and signaling mechanisms.

The lower hydroxyproline content in marine collagen leads to a less stable and more easily soluble structure, but after hydrolysis, the size of the peptides plays the main role in absorption, rather than the amino acid composition itself.

The lower hydroxyproline content in marine collagen results in a less stable and more easily soluble structure. While it is generally assumed that peptide size plays the primary role in absorption after hydrolysis—rather than the amino acid composition itself—this area is not entirely clear-cut. There is ongoing discussion regarding the possibility that specific collagen peptides (a so-called "fingerprint") may be absorbed in larger units and that their effect may also be related to the origin of the collagen.

Collagen breaks down during digestion - therefore, the body does not utilize a "finished type of collagen"
but rather its amino acids and bioactive peptides.

Certain specific peptides can influence specific tissues (e.g., cartilage), but it is not a direct delivery of a specific type of collagen to the target site.

Key takeaways from the article

Collagen is composed of amino acids that are crucial for its function – glycine, proline, and hydroxyproline dominate
The differences between bovine and fish collagen lie mainly in molecular weight, not in fundamentally different compositions
After ingestion, collagen is not deposited directly into tissues but is broken down into amino acids and bioactive peptides
Certain collagen peptides act as signaling molecules that stimulate the production of the body's own collagen
The source of collagen is not the primary factor of effectiveness – quality, absorbability, and consistency of use are more important
Collagen acts systemically and supports the body's natural regenerative processes, rather than a "targeted repair" of a specific tissue