The role of collagen in the human body

Collagen is a structural protein that is essential for the integrity, strength, and function of virtually all tissues in the body. Its importance ranges from providing mechanical support for bones and joints to maintaining the elasticity of the skin and blood vessels. Understanding its complex role is key to explaining why its age-related decline leads to such a wide spectrum of signs of aging—and why targeted supplementation has become a new trend.

What will you learn in this article?

1. What is collagen?
2. Types of collagen
3. Collagen, aging, and lifestyle
4. Who is collagen supplementation suitable for?
5. Key takeaways

What is collagen?

Collagen is the most abundant protein in the human body, making up approximately 30% of all proteins. 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.

The basic building block of collagen is a molecule called tropocollagen, which consists of three polypeptide chains twisted into a triple helix. These chains contain a high proportion of the amino acids glycine (approximately 33% of all amino acids), proline (about 10%), and hydroxyproline (about 10%). The synthesis of these amino acids, however, 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 for effective endogenous synthesis—and also 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. [1]

• 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 directly 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.

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. Hydrolyzed collagen improves skin hydration and elasticity and supports wrinkle reduction. [7]

• 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. [2] [3]

• 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. [4] [5]

• 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. [6]

• 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, tendons, and other organs.
    
    

  • Types of collagen:
    There are at least 28 types in the body, with the main ones being type I (skin, bones, tendons), type II (joint cartilage), and type III (skin, blood vessels, hollow organs). Each type has a specific role, but for supplementation, the most important factors are collagen quality, processing form, and bioavailability.
    
    

  • Age-related collagen loss and the impact of lifestyle:
    Collagen production begins to decline as early as around age 25; UV radiation, smoking, excessive sugar intake, and stress further accelerate collagen degradation.
    
    

  • Who collagen supplementation is suitable for:
    those who want to improve the condition of their skin, hair, and nails; older adults; athletes; people with joint pain; individuals with so-called “leaky gut” syndrome; women in menopause

  
  

Sources:

[1] 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.

[2] Clark KL, Sebastianelli W, Flechsenhar KR, Aukermann DF, Meza F, Millard RL, Deitch JR, Sherbondy PS, Albert A. 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. Epub 2008 Apr 15. PMID: 18416885.

[3] 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

[4] Genç AS, Yılmaz AK, Anıl B, Korkmaz Salkılıç E, Akdemir E, Sancaklı A, Mor A, Ermiş E, Saka Baraz L, Güzel N, Kehribar L. 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 PMCjointdrs.org.

[5] 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. PMC.

[6] 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.

[7] 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. Epub 2019 Dec 17. PMID: 32508986; PMCID: PMC7271718.