Collagen: how it works in the body, its types, and how effects differ by source

Collagen is among the most frequently supplemented substances and at the same time the most abundant protein in the human body. Yet many simplifications and myths surround it. Do bovine and marine collagen truly differ in their effects? What types of collagen exist and how is it absorbed? And why does its production decline with age? In this article we look at collagen “from the ground up” – from its composition and types, through the differences between sources, to the real mechanisms of absorption, the age-related decline, and who supplementation is suitable for.

What will you learn in this article?

1. Collagen up close
2. Types of collagen
3. Amino acid spectrum as a key factor
4. Bovine vs. marine collagen
5. How collagen absorption works
6. Myths vs. reality: do effects differ by source?
7. Collagen, aging, and lifestyle
8. Who is collagen supplementation suitable for?
9. Key takeaways

Collagen up close

Collagen is a structurally specific protein whose biological function is closely linked to its amino acid composition. In the human body it is the most abundant protein, accounting for approximately 30% of all proteins, and it provides tissues with strength, elasticity, and resilience against mechanical stress. Its presence is crucial in bones, cartilage, tendons, ligaments, and skin, but it also plays an important role in the walls of blood vessels, in the cornea, and in other organs. [1]

The structure of collagen consists of a triple helix (known as tropocollagen) 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.

The synthesis of collagen depends on a key cofactor – vitamin C. Without sufficient amounts, the body cannot produce stable, fully functional collagen. For this reason, adequate vitamin C intake is important even when using supplemented collagen.

Types of collagen

Although collagen is often perceived as a single substance, in reality it is an entire family of proteins. In the human body there are at least 28 different types of collagen, which differ in their molecular structure, organization, and tissue distribution. Despite this diversity, only a few main types – primarily types I, II, and III – make up approximately 80–90% of all collagen in the human body. [2]

• Type I collagen: This is the most common type, accounting for up to 90% of total collagen in the body. It is made of very dense, strong fibers and is a fundamental structural component of the skin, bones, tendons, ligaments, and teeth. Its primary function is to provide tissues with strength and resistance to tension. In the skin, it forms a dense network that ensures firmness and elasticity. In bones, it creates an organic matrix into which minerals such as calcium are deposited. This type is most often the target of dietary supplements aimed at improving the appearance of the skin, hair, and nails.

• Type II collagen: This type is the dominant component of joint cartilage, where it makes up to 70% of its dry weight, and it is also found in the vitreous body of the eye. Unlike type I, its fibers are arranged more loosely and form a fine mesh. This structure enables cartilage to withstand high pressure and act as a shock absorber in joints. A decline in type II collagen is linked to degenerative joint diseases such as osteoarthritis. This type of collagen is most often a key ingredient in dietary supplements designed to support the musculoskeletal system.

• Type III collagen: It is the second most abundant type in the body and often occurs together with type I collagen, especially in the skin and blood vessels. It consists of thinner fibers and is key to the structure and elasticity of hollow organs, such as muscles, the uterus, and the walls of large blood vessels. It also plays a crucial role in the process of wound healing. In the early stages of healing, type III collagen creates a kind of “scaffold” that is gradually replaced by stronger, more resilient type I collagen.

For overall connective tissue support, the key factors are collagen quality, processing form, and bioavailability, not strict classification by type.

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. [3]

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. marine 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. [4]

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). [5]

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. Bioactive peptides, meanwhile, function as signaling molecules and 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. [6] [7]

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 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, so 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.

Collagen, aging, and lifestyle

The need for collagen supplementation is a direct response to the age-related decline in the body’s own production, as well as accelerated degradation driven by factors of modern lifestyle. While aging is an inevitable biological process, many external factors that speed up collagen loss in the body can be influenced.

Natural age-related decline in collagen

The human body has the ability to synthesize its own collagen, but this capacity decreases with age. Collagen production naturally begins to decline around the age of 25. After this point, the rate of decrease is estimated at approximately 1 to 1.5% per year. Although this may seem like a negligible number, over decades it becomes a cumulative loss that begins to show, both visibly and subjectively.

After the age of 40, this decline becomes very noticeable, and after 60 the drop in production is so dramatic that it becomes one of the main factors contributing to the signs of aging.

The impact of lifestyle and external factors

In addition to inevitable biological aging, there are a number of external factors that can significantly accelerate collagen loss. These factors act as aging accelerators, and their impact is often more significant than age itself.

• UV radiation: Excessive and unprotected exposure to sunlight is considered one of collagen’s main enemies. Ultraviolet (UV) rays penetrate the skin, where they generate reactive oxygen species, so-called free radicals. These unstable molecules trigger a cascade of damage, including direct breakdown of collagen and elastin fibers, while also stimulating the production of enzymes that actively degrade collagen. The result is premature skin aging.

• Excessive consumption of refined sugars and simple carbohydrates leads to a process called glycation. Sugar molecules in the bloodstream bind uncontrollably to proteins, including collagen, forming so-called advanced glycation end-products (AGEs). These AGEs cause collagen fibers to stiffen, become brittle, and lose their natural elasticity and function.

• Smoking: Toxic substances in cigarette smoke damage collagen in several ways. Nicotine causes vasoconstriction (narrowing of blood vessels), which reduces the supply of oxygen and key nutrients to tissues, including the skin. This disrupts the body’s ability to naturally synthesize new collagen. Smoking also increases levels of enzymes that degrade collagen and lowers vitamin C levels, which are essential for collagen formation.

• Stress: Chronic stress (physical and psychological) leads to increased production of the stress hormone cortisol. Cortisol not only reduces the synthesis of new collagen, but also promotes its degradation.

Who is collagen supplementation suitable for?

Collagen supplementation is often recommended when the body’s natural production is no longer sufficient to meet its needs. Increased collagen intake is therefore especially beneficial for people over the age of 25, when collagen synthesis naturally declines, as well as for athletes who put stress on their joints and muscles, women in menopause, and seniors dealing with loss of bone mass and reduced tissue elasticity. Collagen supplementation can be relevant both from an aesthetic perspective and in terms of supporting vitality and overall condition.

• Individuals who want to improve the appearance of their skin and the condition of their hair and nails:

  Collagen supplementation is a popular part of a “beauty” routine. According to studies, hydrolyzed collagen improves skin hydration and elasticity and supports wrinkle reduction. [8]

• Older adults:

  As we age, natural collagen production declines, which can manifest as faster skin aging, loss of bone mass, and reduced tissue elasticity. Collagen supplementation may help maintain a more youthful appearance and support mobility and tissue strength.

• Athletes and physically active individuals:

  Higher physical load places greater demands on connective tissue recovery. Collagen can support faster repair of tendons, ligaments, and joints with regular training. [9] [10]

• People with joint pain, osteoarthritis, or recovering from injuries:

  Collagen is a major component of cartilage, tendons, and ligaments, and supplementing it supports the regeneration of these tissues. Studies show that in people with osteoarthritis, collagen supplementation leads to a significant reduction in pain, improved mobility, and overall quality of life. [11] [12]

• People with digestive issues (“leaky gut”):

  Collagen contains amino acids such as glycine, proline, and glutamine, which are key for gut lining health and may help restore its integrity. [13]

• Women in menopause:

  Estrogen supports collagen synthesis, which improves skin hydration, firmness, and elasticity. After menopause, estrogen production drops sharply and collagen production can decrease by up to 30% within the first 5 years. This leads to thinner skin, reduced elasticity, dryness, and the formation of wrinkles.

  However, the decline in estrogen and collagen does not affect only the skin. In bones, the collagen matrix becomes thinner, increasing the risk of osteoporosis. In joints and ligaments, decreasing collagen levels manifest as reduced tissue elasticity and strength. Blood vessel walls also lose flexibility, which may contribute to arterial stiffening and the development of atherosclerosis.

  Collagen deficiency therefore does not affect only aesthetics, but significantly impacts musculoskeletal health as well as the cardiovascular system.

Key takeaways

• Collagen is a key structural protein – it makes up approximately 30% of all proteins in the body and provides strength, elasticity, and mechanical resilience to tissues, including bones, joints, skin, blood vessels, and tendons.

• Vitamin C is essential for its production, including when using collagen supplements.

• There are at least 28 types of collagen in the body; the main ones are type I (skin, bones, tendons), type II (joint cartilage), and type III (skin, blood vessels, hollow organs). For supplementation, however, quality, processing form, and bioavailability matter more than strict classification by type.

• Collagen is composed of amino acids crucial for its function – glycine, proline, and hydroxyproline dominate.

• The differences between bovine and fish collagen lie mainly in molecular weight and solubility, not in fundamentally different compositions.

• After ingestion, collagen is not deposited directly into tissues but is broken down into amino acids and bioactive peptides; some of these act as signaling molecules and 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 production declines as early as around age 25; UV radiation, smoking, excessive sugar intake, and stress accelerate its loss further.

• Supplementation is especially beneficial for people over 25, older adults, athletes, people with joint pain, individuals with “leaky gut,” and women in menopause.

Sources:

[1] Collagen. NCBI Bookshelf (StatPearls), NBK507709. https://www.ncbi.nlm.nih.gov/books/NBK507709/

[2] Ricard-Blum S. The collagen family. Cold Spring Harb Perspect Biol. 2011 Jan 1;3(1):a004978. doi: 10.1101/cshperspect.a004978. PMID: 21421911; PMCID: PMC3003457.

[3] CB Supplements. Collagen amino acids profile. https://cbsupplements.com/cc/collagen-amino-acids-profile/

[4] International Journal of Food Science and Technology. https://academic.oup.com/ijfst/article/54/6/1976/7805934

[5] Journal of Agricultural and Food Chemistry. https://pubs.acs.org/doi/10.1021/jf050206p

[6] PubMed Central, PMC2846778. https://pmc.ncbi.nlm.nih.gov/articles/PMC2846778/

[7] Journal of Medicinal Food. https://journals.sagepub.com/doi/10.1089/jmf.2022.K.0149

[8] Lupu MA, Gradisteanu Pircalabioru G, Chifiriuc MC, Albulescu R, Tanase C. Beneficial effects of food supplements based on hydrolyzed collagen for skin care (Review). Exp Ther Med. 2020 Jul;20(1):12-17. doi: 10.3892/etm.2019.8342. PMID: 32508986; PMCID: PMC7271718.

[9] Clark KL, Sebastianelli W, Flechsenhar KR, et al. 24-Week study on the use of collagen hydrolysate as a dietary supplement in athletes with activity-related joint pain. Curr Med Res Opin. 2008 May;24(5):1485-96. doi: 10.1185/030079908x291967. PMID: 18416885.

[10] Brueckheimer PJ, Costa Silva T, Rodrigues L, Zague V, Isaia Filho C. The Effects of Type I Collagen Hydrolysate Supplementation on Bones, Muscles, and Joints: A Systematic Review. Orthopedic Reviews. 2025;17. doi:10.52965/001c.129086. PMID: 39980497.

[11] Genç AS, Yılmaz AK, Anıl B, et al. Effect of supplementation with type 1 and type 3 collagen peptide and type 2 hydrolyzed collagen on osteoarthritis-related pain, quality of life, and physical function: A double-blind, randomized, placebo-controlled study. Jt Dis Relat Surg. 2025;36(1):85-96. doi:10.52312/jdrs.2025.1965.

[12] Martínez-Puig D, Costa-Larrión E, Rubio-Rodríguez N, Gálvez-Martín P. Collagen Supplementation for Joint Health: The Link between Composition and Scientific Knowledge. Nutrients. 2023 Mar 8;15(6):1332. doi: 10.3390/nu15061332. PMID: 36986062; PMCID: PMC10058045.

[13] Chen Q, Chen O, Martins IM, Hou H, Zhao X, Blumberg JB, Li B. Collagen peptides ameliorate intestinal epithelial barrier dysfunction in immunostimulatory Caco-2 cell monolayers via enhancing tight junctions. Food Funct. 2017 Mar 22;8(3):1144-1151. doi: 10.1039/c6fo01347c. PMID: 28174772.