Collagen 101: Everything You Need to Know About the Vital Protein

Whether it has made an appearance in your evening moisturizer, popped up in your favorite line of face masks, been recommended as a way to supercharge your workout, or simply called out to you in the vitamin aisle of your grocery store, there is no denying that collagen has been taking center stage in the wellness world.

But even with the rising prevalence of collagen in the mainstream nutritional milieu, there are plenty of us who are still left wondering: what even is collagen, anyway, and why do we suddenly want it in everything from our skincare to our smoothies?

To answer all of your burning collagen questions, the following post will dive a little deeper into the up-and-coming protein, including answering things like:

What is collagen?
What are the benefits of collagen?
Why do we lose collagen over time?
How is collagen made, and what is it made up of?
What are the different types of collagen?
What are the main sources of collagen?

Collagen powder on a picnic blanket

What is collagen?

Plain and simple, collagen is a protein. But more than that, it is basically the most vital protein in our bodies, found in the skin, as well as bones and tendons, cartilage, blood vessels, muscles, and the digestive system. In some cases, collagen actually amounts for the majority of the tissue. In the case of skin and tendons, for example, collagen comprises about 75 percent and 80 percent, respectively, of those bodily components, on average (1).

While collagen makes up a particular percentage of different tissues in your body on a more granular scale, a more zoomed out look at the protein in our overly bodily compositions demonstrates that collagen is concentrated in a single crucial structure: the extracellular matrix, or ECM (2). The ECM, in simple terms, is just the structure that holds all of your cells together and helps keep the network of cells in your body functioning properly and smoothly.

What are the benefits of collagen?

Because of its abundance in the body, collagen is the protein that you can credit for a myriad of regular processes and functions in your system. This includes:

Binding joints and tendons

Collagen is a major component of connective tissue, which means that it acts kind of like the glue that keeps your body together. To that end, it is crucial to maintaining the integrity of your skin, bones, joints, and muscle tissue.

Playing a key role in cell signaling

Collagen plays an important role in sending messages to your brain that essentially determine cellular shape or behavior in different cases (3). For example, collagen may help cue the repairing of damaged cells, or might help fend off inflammation.

Promoting skin health and elasticity

And as far as skin goes, collagen is a key component to maintaining skin’s natural strength and elasticity as you age, meaning that its a key component in maintaining skin firmness and smoothness (4). Improved skin elasticity also results in a reduction in visible cellulite and stretch marks, thanks, again, to its role in keeping skin firm and strong. In addition to skin elasticity, collagen can also improve skin moisture and play a part in replacing dead skin cells with healthy ones.

Promoting brain and cognitive health

Research has shown that collagen – particularly collagen IV – may play an important role in preventing cognitive disease, like Alzheimer’s (5). Specifically, collagen can help protect the brain against neuron-attacking proteins and peptides (in the case of Alzheimer’s, collagen protects against what are known as amyloid-beta proteins), making it an important neuroprotective agent in your body.

Healing the gut

When your body has a low supply of collagen, you become more likely to experience issues with digestive health, including irritable bowel syndrome (IBS) and leaky gut syndrome (6). This, in turn, means that maintaining healthy collagen levels helps reduce the risk of harmful toxins leaking into your bloodstream.

Easing joint and knee pain

Whether it’s a natural product of aging or it’s an accelerated process linked to athletics or a physically demanding job, joint pain is something that most people are (or will be) familiar with at some time or other. Collagen not only helps support joint health, but may also slow the process of joint deterioration often linked to athletics, physically-taxing activities, or conditions like arthritis (7).

Older woman looking out the window

Why do we lose collagen over time?

There are several different factors that may contribute to a loss of collagen over time. Some, like aging, are natural and inevitable. Others, like consuming too much sugar, are more tied to habits and may be somewhat preventable in that sense. Here are a few of the key causes of collagen loss over time.


Perhaps the most drastic cause of collagen depletion over time, if for no reason other than that it is unavoidable, is aging (8). As we get older, the body naturally begins to produce less collagen, which is why aging goes hand in hand with wrinkles, weaker bones and joints, thinning of hair, etc. Again, while there isn’t necessarily a way to reverse or halt the natural loss of collagen with age, tapping into collagen supplementation is one way to make up for the decrease in natural collagen production and keep your levels healthy.

High sugar consumption

Maybe you already try to take it easy on the sugar because of the implications that high sugar consumption typically has on a waistline, but here’s one more reason to keep it in check: too much sugar can seriously damage your body’s natural collagen supply. Basically, when you consume too much sugar, all of the excess sugars go through a process called glycation, by which they bind to fats and proteins in your skin (9). This process results in the production of enzymes that weaken your natural collagen, resulting in rougher, more discolored skin.


It’s hardly a secret that collagen is bad news for your health. When it comes to collagen, the chemicals present in tobacco may be responsible for decreasing the synthesis of particular types of collagen (10). Even just coming into contact with cigarette smoke could slow the production of collagen, since it could lead to skin congestion and blood vessel constriction that ultimately make it harder for your body to produce and replace lost collagen effectively.

Exposure to UV rays

When enjoyed healthily (read: in the company of SPF 30), sunlight has a multitude of health benefits. However, excessive exposure to UV rays without the proper skin protection could lead to the absorption of free radicals into your skin, which ultimately leads to the degradation of collagen over time (11).

Genetic changes

Similar to aging in that this cause of collagen loss is more linked to natural shifts in your body composition as opposed to ones instigated by your habits, it’s possible for changes in your genetic makeup to throw off the natural production of collagen in your body. A group of enzymes known as matrix metalloproteinases (MMPs), for example, may degrade the collagen in your system by splitting and breaking down collagen proteins (12).

How is collagen made, and what is it made up of?

The fact that you lose collagen over time, both naturally and a result of different habits that may expedite the process, makes it so that collagen supplementation is crucial, particularly as you age. However, before understanding how to incorporate collagen supplementation into your usual routine, it’s essential to first understand the basic composition of collagen, the differences between major categories of collagen, and how collagen is made.

Collagen composition

When it comes to the composition of collagen, you can think of amino acids as the key building blocks, as is the case with any protein. While natural collagen isn’t a complete protein source – i.e. it doesn’t contain all nine essential amino acids – it is a tremendously strong source of amino acids at large, providing about 18-20 amino acids to that your body requires to create proteins. With collagen in particular, the triple-helical structure of the protein is characterized by especially high levels of three specific amino acids: glycine, proline, and hydroxyproline (13).

Glycine: An amino acid with natural anti-inflammatory, nervous system-improving qualities, glycine is largely instrumental in allowing collagen to form and maintain its unique helical structure (14). The amino acid accounts for one-third of the total composition of collagen.

Proline: A conditionally essential amino acid, proline is a key precursor for the production of hydroxyproline. Together with hydroxyproline, proline comprises about 23% of the collagen molecule (15).

Hydroxyproline: Hydrogen bonds between hydroxyproline residues are essential to maintaining the stability of the collagen helix, particularly when it comes to resisting thermal denaturation (16).

What are the different types of collagen?

Although there are 28 different types of collagen that have been identified by science so far, there are five types that are most common: types I, II, III, IV, and V. When it comes to the concentration of different forms of collagen in your body, about 90 percent of all collagen found in the human body is just from one category: type I collagen.

Type I

Type I collagen is found all throughout the human body, including the skin, tendons, bones, and vasculature (the components of the vascular system that carries blood across the body). Type I collagen is the most abundant type by far. The fibrils, or smaller sections of a fiber, are incredibly strong and can resist a ton of pressure without breaking; gram for gram, these fibrils are stronger than steel (17). Type I collagen can also be found in the GI tract and improve gut health by sealing leaky spots. As it helps make skin stretchy and elastic as well as holds together tissues to prevent tearing, type I collagen is super Important for wound healing.

Type II

Type II collagen is mostly found in cartilage, and is important for joint health because cartilage is what keeps your bones from grinding against each other when you move.

Type III

Type III collagen is often found next to type I within the human body. It usually appears in muscles, organs, arteries, and a type of connective tissue called a reticular fiber, which makes up part of the liver, adipose tissue, bone marrow, spleen, and more. Type III is also associated with skin firmness, an important ingredient in maintaining youthful-looking skin. A deficiency in type III collagen has been linked to higher risk of rupturing blood vessels (18).

Type IV

Type IV collagen forms the basal lamina, which is a layer of the extracellular matrix (the supportive outer layer of individual cells) that lives next to the epithelium. Its most important function is to give external support to skin cells and provide cushion and padding for the tissue beneath it.

Type V

Type V collagen is most commonly found in cell surfaces, hair, bone matrix, the cornea, and the connective tissue between the cells of muscles, liver, lungs, and placenta, also referred to as the interstitial matrix.

Type X

Though not one of the five most prominent types of collagen, Type X collagen is worth noting for its importance in helping form articular cartilage, a white tissue that covers bones in joints. It’s also an important part of new bone formation and the creation of bone tissue, known as endochondral ossification. Because of this bone-building power, type X collagen is beneficial to healing bone fractures and repairing synovial joints, which are the most common type of joints in the human body (think elbow, wrist, and knee joints).

Cows standing in a field.

What are the main sources of collagen?

Collagen that is consumed by humans comes from animal products and, to a lesser extent, by-products. The type of collagen found in ingestible supplements is directly determined by the source it is produced from. The major sources of collagen available to consumers now come from bovine, porcine, chicken, marine, fish, and eggshell membrane sources.

Bovine Collagen

Components used in production: hide, bones, tendons, cartilage, and placenta of cows.

Types produced: I, III, and IV.

This is the most popular form of collagen used in the food and supplement industry because of the well-rounded array of collagen types it contains, supporting all the tissues in your body at once. It’s especially good at improving skin and bone health. However, the quality of the collagen can be significantly impacted by the health of the cows, so you’ll want to opt for grass-fed collagen supplements whenever possible. Bovine collagen is rich in glycine, which is needed to build healthy DNA and RNA strands and to form creatine (essential for muscle-building), as well as proline, which is used to synthesize proteins. Bovine collagen also encourages the body to make its own collagen.

Porcine Collagen

Components used in production: skin and bones of pigs.

Types produced: I and III.

The collagen produced from pigs is similar to beef, but lacks type IV collagen. It’s used more often in the biomedical industry than supplement because it is the most closely related to human collagen.

Chicken Collagen

Components used in production: feet, cartilage, skin, and neck of chickens.

Types produced: I, II, III, IV, V, and IX.

Chicken feet are eaten as a popular snack in some countries (China, Indonesia, Romania, Jamaica, and more) and are often used to make gelatin and stock for cooking. The types of collagen found in a finished product vary depending on the parts of the chicken used to make it. Chicken collagen also provides chondroitin sulfate and glucosamine sulfate, which have anti-aging effects. Chicken collagen is less popular than bovine because of a much higher risk of contamination through aviary diseases.

Marine Collagen

Components used in production: tissues, skin, cranial cartilage, cornea, and embryonic organs of various marine creatures.

Types produced: I.

Source animals include fish, starfish, jellyfish, sponges, sea urchin, octopus, squid, cuttlefish, anemone, and prawn. Marine collagen has several advantages over other types of collagen, including a higher yield during extraction, environmentally-friendly processing, and easier absorption thanks to its lighter molecules. One caveat with marine collagen, however, is that it’s pretty limited to type I collagen, and is only in the beginning stages of research and development as an industry.

Fish Collagen

Components used in production: bones, skins, fins, and scales of fresh or saltwater fish.

Types produced: I.

The most common species used in collagen production are: Atlantic cod, silver carp, Japanese sea-bass, chub mackerel, bullhead shark, bigeye tuna, skipjack tuna, yellow sea bream, horse mackerel, Nile tilapia, and others. Production of fish collagen uses discarded materials from fish that have already been harvested, so it helps to reduce pollution and environmental damage. Both marine and fish collagen are newer sources that are still in the early stages of research, so they are less available and popular on the market.

Egg Shell Membrane

Components used in production: the shells and whites of eggs.

Types produced: contains types III, IV, and X, but by far mostly type I, just like the human body. This form of collagen contains glucosamine sulfate, chondroitin sulfate, hyaluronic acid, and other amino acids that help build connective tissues, heal wounds, build muscle mass, and reduce pain and stiffness.