What Happens to Collagen With Age?

Key Takeaways:

• Collagen is the most abundant protein in the body, making up three quarters of the dry weight of human skin.
• Collagen self-assembles into fibers and networks, supports cell growth and tissue development, and is responsible for the mechanical and structural properties of skin.
• Age-related collagen decline can be slowed with proper nutrition, lifestyle choices, sunscreen, topicals, and supplements.

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Imagine a material with greater tensile strength than steel wire, that can support more than ten thousand times its own weight, and that interacts with its environment intelligently. It’s not some futuristic biotechnology you’ll read about in MIT Technology Review. It’s collagen, a protein woven into the biology of the animal kingdom, from sponges, the simplest known multicellular organisms, to complex vertebrates (that’s you). Collagen makes up roughly one quarter of all the protein in the human body and three quarters of the dry weight of human skin. Collagen is elastic, strong, and resilient. It gives your skin its mechanical and structural properties, and when it’s abundant, it’s responsible for the plump, youthful look of our faces. Because collagen is such an essential component of skin, our largest organ, age-related changes to collagen impact how our skin looks and functions. The changes to our skin are meaningful to our appearance and to our overall health. 

This article explains what collagen is, how it changes with age in the skin, and what you can do about age-related collagen changes.

What is collagen?

To understand the importance of collagen, go right to the etymology of the word: from the Greek kólla (“glue”) and genḗs (“forming”). That which forms glue. It was once considered a sort of biological glue that holds cells in place. It’s a loose metaphor for what we now know about the structure and function of collagen in the body, but it’s a good start.

Image: Collagen distribution in the body.

Collagen is the most abundant protein in the body, making up, as we said above, three quarters of the dry weight of human skin. It’s also an essential component of other tissues, including the tendon, cornea, blood vessel, cartilage, ligament, organs, intestinal lining, and bone. A modern definition of collagen, according to researchers, “is the major extracellular matrix (ECM) molecule that self-assembles into cross-striated fibrils, provides support for cell growth, and is responsible for the mechanical resilience of connective tissues.” Collagen is produced by a special type of cell called a fibroblast. 

The ECM mentioned in the definition is what gives tissues their mechanical and biomechanical properties—their structure and integrity. Inside the ECM you’ll find water, collagen, elastin, glycosaminoglycans such as hyaluronic acid. This dynamic network of molecules is essential for the homeostasis of the skin, wound healing, and healthy aging. 

There are 28 types of collagen, with collagen types I, II, and III making up most of the collagen in the body and in the skin. Eighty percent of collagen in the skin is type I, while type III makes up 15 percent. Collagen is a glycoprotein with three distinct features: 1) The amino acid repeating sequence [Gly–X–Y]n, with and without interruptions; 2) the occupation of the X and Y positions by proline and hydroxyproline, respectively; 3) it’s composed of three chains wound together to form a triple helix, which is tight because glycine is the smallest of all the amino acids. 

What role does collagen play in skin?

The skin is your largest organ, and along with your hair, nails, oil glands, and sweat glands, it makes up the integumentary system. Our skin is a barrier and interface with the outside world and much more. It plays a role in regulating body temperature, storing water and fat, sensing temperature and pressure, producing hormones, and protecting us from harmful aspects of the environment. In these capacities, it’s involved with the nervous, immune, and endocrine systems. And let’s be real: Our skin is also much of what we see physically in the mirror, and so many of us are concerned about the role it plays in our appearance.

Collagen plays a primary role in our skin. The skin has three layers: the epidermis, dermis, and hypodermis. The epidermis is the outermost layer of the skin, a protective layer made mostly of keratinocytes. The dermis is the middle layer of the skin and also the thickest layer; it’s held together mostly by collagen with the support of elastin. The hypodermis is also known as the subcutis or subcutaneous fat layer, and as the name suggests, it consists mainly of fat (adipocytes), as well as collagen and elastin.

The dermis is especially rich in collagen fibers and consists of two layers, the papillary (upper) dermis and the reticular (deep) dermis. The collagen in the upper dermis is characterized by thinner fibers, while dense fibers make up the deep dermis. Within this middle layer of skin are many essential cells and structures, including blood vessels, lymph vessels, hair follicles, sweat glands, sebaceous (oil) glands, nerve endings, connective tissue, and fat cells. These components of the dermis participate in sensing pain, temperature, and pressure; sweating; keeping the skin moist; flexibility and protection from injury; regulating body temperature; and protecting from infection or invasive organisms.

In that context, it would be an oversimplification to say that collagen gives the skin its structure and elasticity—but it does that exceptionally. Elasticity is the property of a substance that allows it to change length, volume, and shape in response to force and to regain its original form. Another important property of collagen in the skin is viscoelasticity, which includes the quality of viscosity. In fluid dynamics, viscosity describes a resistance to flow when a shearing force is applied. Think here motor oil, which can circulate through the engine of a car while also providing lubrication. Viscoelasticity in the skin, thanks to collagen, allows an additional degree of movement away from and back to baseline without breaking and causing injury. This has obvious value in the skin as well as all the other places in the body where collagen is present. 

It’s additionally the unique structure of collagen and the way multiple collagen fibers assemble into sheets and cables that lend these properties. Collagen assembles into what are called “supramolecular complexes,” such as fibrils and networks. Collagen also interacts with other components like elastin to offer unique properties when it’s in the skin and when it’s in bone or tendon. In the skin, elastin interacts with collagen to provide the recoil after repeated stretch.

Image: Scanning electron microscopy image of a collagen bundle (HaefnerP, CC BY-SA 4.0, via Wikimedia Commons)

Beyond structural and mechanical properties, collagen in the skin also regulates cell adhesion (how cells interact and attach to neighboring cells), chemotaxis (the migration of cells in response to chemical stimulus, such as from growth factors), and directs tissue development. And so, yes, collagen does give your skin its plump, youthful look—and so much more.

What happens to collagen with age?

Changes to collagen in the skin are part of the broader process of skin aging, which happens as a result of intrinsic factors and environmental, or extrinsic, factors. Intrinsic causes are related to genetics and chronological aging, while the primary extrinsic factor is ultraviolet radiation from the sun, along with exposure to air pollutants, nutrition, sleep quality, and toxins. All of these processes result in connective tissue breaking down, repair and regeneration declining, and the overall functionality of our skin as a barrier to the outside world degrading. The outward appearance of this is thinner and more translucent skin, with wrinkles, sagging, pigmentation, and dryness. Functionally, skin may be more easily bruised, more prone to skin disorders and cancer, less effective at regulating heat, and less efficient at healing wounds. 

With collagen making up a significant portion of the skin, its changes are meaningful to our appearance and overall health. And collagen does change with age. A reduction in collagen types I and III in the skin is a result of both aging and sun exposure. Research has shown that collagen production in sun-protected skin of individuals over the age of 80 is 75% less than young adults aged 18-29. The loss of collagen is a result of degradation of collagen and a reduction in the synthesis of collagen. The causes are manifold.

• Reactive oxygen species

ROS play a role in skin aging as a result of intrinsic aging, photoaging, and pollution. They are the byproducts of normal cellular activity, but they also increase with age. What makes ROS dangerous is that they consist of atoms or molecules with an unpaired electron, making them reactive and unstable—prone to stealing electrons from other molecules. In skin aging, ROS impact many cellular components, including proteins, lipids, and DNA, leading to cellular dysfunction. ROS also lead to the overexpression of matrix metalloproteinases (MMPs), which degrade collagen and inhibit their synthesis.

• Cellular senescence

Cellular senescence is a hallmark of aging, and researchers hypothesize that it plays a role in skin aging as well. One downstream effect of senescent fibroblasts is an impaired ability to synthesize collagen. Senescent fibroblasts also impact the integrity and function of the skin more broadly through the release of a senescence-associated secretory phenotype, or SASP, which includes proinflammatory factors. This degrades the ECM more broadly and also activates the same MMPs that degrade collagen and inhibit their synthesis.

• Advanced glycation end products

AGEs are aging-related defects that happen in collagen that’s exposed over time to ribose and glucose sugars. The collagen forms crosslinks and dehydrates, resulting in reduced elasticity, increased stiffness, wrinkles, and discoloration of the skin. AGEs are also associated with high-sugar diets.

• Hormonal changes

Hormonal changes occur with age, in particular among women during and after menopause. The decrease in estrogen is associated with multiple aspects of skin aging, including a reduction in collagen by roughly 2% per post-menopausal year.

• Sun exposure 

Nothing leads to the degradation of skin quite like sun exposure. It leads to the loss of collagen in multiple ways. One is that sun exposure creates ROS. The creation of UV-induced ROS sets in motion several cellular processes that cause harm to the skin and promote aging: Excessive ROS activate the NF-kB pathway, which plays a role in inflammation; this increases levels of tumor necrosis factor alpha (TNF-α), a regulator of the inflammatory response; the end product is an increase in matrix metalloproteinases (MMPs), which degrade the extracellular matrix, degrade collagen, and prematurely age the skin.

• Sleep loss

Sleep is essential for healthy skin aging, with studies finding that sleep loss is associated with looking less healthy, less attractive, more wrinkled, as well as other signs of aging. Some researchers also hypothesize that a compromised immune system from sleep loss is associated with impaired collagen production.

• Smoking

Smoking accelerates skin aging and causes facial wrinkling, facial pigmentation, changes to hue and radiance, and increased tissue laxity. Research shows that smoking increases MMPs and decreases the synthesis of types I and III collagen substantially.

• Stress

Stress impacts the skin and collagen in particular. Chronic stress increases the release of glucocorticoids, which can increase MMPs and decrease the synthesis of collagen.

What can you do about collagen aging?

The reality is we’re all going to experience some degree of collagen loss with age. That said, much can be done simply by avoiding some of the pitfalls described in the section above: practice sun protection, limit refined carbohydrates and sugar, get adequate sleep, don’t smoke, and limit stress when possible. That said, if you’re looking to be proactive about maintaining collagen with age, there’s more you can do.

• Eat colorful fruits and vegetables

• Get the right nutrients—including vitamin C

To synthesize collagen your body needs the right combination of ingredients, which include vitamin C, copper, and zinc, as well as the amino acids glycine and proline. 

• Use retinol

Retinol is a derivative of vitamin A that’s available widely in topical form. Studies show that retinol can increase collagen in the skin and decrease MMPs, improving skin texture and pigmentation, increasing epidermal thickness, decreasing wrinkling, and generally mitigating the impact of photoaging.

• Try laser resurfacing

Carbon dioxide laser resurfacing is a technique that uses heat from a laser to resurface photodamaged skin. It works by thickening collagen fibers and generating new collagen and fibroblasts in the period following the treatment. Several studies have shown the procedure to be effective.

What about supplementing with collagen directly?

You’re probably familiar with collagen supplements that go by the name collagen peptides or hydrolyzed collagen. Both names refer to the same thing: collagen that’s been broken down into smaller peptides with a low molecular weight, through enzymatic reaction. Hydrolyzed collagen comes mainly from cows, fish, and pigs. The quality of hydrolyzed collagen depends on the source and method used to extract it. So, do these widely available powders improve your skin?

A review and meta-analysis published in the International Journal of Dermatology looked at 19 studies, with a total of 1,125 participants between the ages of 20 and 70. The review concluded that collagen supplementation over the course of 90 days led to improvements in skin hydration, elasticity, and wrinkles. While the results are promising, two dermatologists at Harvard have questioned the findings: most of the collagen supplements contained additional ingredients such as hyaluronic acid, coenzyme Q10, chondroitin sulfate, vitamins, minerals, and antioxidants, which could have contributed to some of the improvements. 

In order for hydrolyzed collagen to reach the deeper layers of the skin, it must first cross the intestinal barrier and then enter the blood circulation. Hydrolyzed collagen is likely broken down into smaller forms and free amino acids during digestion, which may provide building blocks for forming collagen. The smaller collagen peptides may also act as signaling molecules to stimulate collagen production. It is unclear, however, if ingested collagen actually reaches the target tissue—the skin—in humans, and additional research is needed to confirm the benefits and to understand their mechanism of action.