Collagen is the most abundant protein in the body and the main structural protein of connective tissue. Supplementing with collagen may improve arthritis symptoms and joint health, while some nutrients may help the body make more of its own collagen. Read on to learn more.
What is Collagen?
Collagen Superfamily and the Extracellular Matrix
Tissues are made of more than just cells. Most of the volume within a tissue is comprised of the extracellular matrix (ECM), a diverse mesh of proteins and sugars produced by certain cells, which acts as the mortar binding our cells together .
The ECM is composed of two components, proteoglycans, and fibrous proteins. Collagen, elastins, fibronectins, and laminins are all fibrous proteins making up the scaffolding in the ECM. The proteoglycans fill in space in between .
Collagen is one of the many proteins embedded in the ECM. In fact, it is the most abundant protein in animal tissues. Thirty percent of the total protein mass in mammals is comprised of collagen .
The term collagen stems back to the Greek word kólla, meaning “glue” .
Collagen proteins are produced by animal connective tissue cells called fibroblasts. For a protein to be classified as a collagen, it must form the collagen-like triple helix and provide structural support in the ECM .
Tropocollagen is the basic building block of collagen. It is made from three peptides (groups of amino acids) strands that are coiled together in the form of a helix. These strands are known as alpha chains (α-chains) [6, 7].
Collagenous region: This region is a series of three amino acids. The first amino acid, glycine, is the most important. The next two can be any amino acid but are usually proline and hydroxyproline. The repeating amino acid sequence is responsible for the helix structure of tropocollagen .
The three peptide strands of tropocollagen are glycine-rich. Foods containing lots of collagen also contain high glycine levels. Glycine helps to protect the vascular system, as it is able to decrease blood clots and inflammation .
Non-collagenous region: This region lacks the repeating amino acid sequence required for the helix structure. It contains binding sites for other ECM molecules to interact with . Multiple tropocollagens cross-link to form collagen fibrils .
Types of Collagen
Collagen is located throughout the body and has many known and unknown functions. Humans have 28 different types of collagen proteins and even more collagen-associated genes .
Some collagens are much more common than others. Over 80% of collagen is type I, II, or III, which are found mainly in the skin, bones, tendons, cartilage, lungs, intestines, and vascular system .
Type IV collagen is also very common, as it is a major component of the ECM produced by skin cells .
There are five major types of collagen:
- Type I
- Type II
- Type III
- Type IV
- Type V
Collagen Synthesis and Folding Requirements
The synthesis of collagen proteins within the body is a complex process. First, cells must properly read the genes in our DNA to produce the α chains. Three α chains then wrap around each other. Whether or not the α chains are identical depends on the type of collagen .
When these single α chains are produced within the cell, enzymes (prolyl hydroxylase and lysyl hydroxylase) modify the amino acids proline and lysine. These modifications are essential for forming a stable triple helix .
Folding of collagen generally occurs before it is exported out of the cell (from the Golgi apparatus) [13, 14].
Each type of collagen has specific ratios of glycine, proline, hydroxyproline, and hydroxylysine. Mutations affecting collagen can have negative health effects.
Genetic Disorders That Decrease Collagen Production
Brittle Bone Disease (Osteogenesis Imperfecta)
Osteogenesis Imperfecta (OI) is a collagen-related disease, which is both heritable and incurable. This is a painful disease characterized by fragile bones and abnormal tissues .
Depending on the mutation, an individual might be diagnosed with a mild, severe, or lethal OI condition, yet any form of the condition will increase the individual’s risk of bone fractures .
OI is an autosomal dominant disorder, meaning it only takes one of the two genes to be mutated in order to see the effect in the body. A single mutation in the COL1A1 gene can reduce the amount of type I collagen and cause a mild OI disorder .
The most common mutation is a substitution of the glycine amino acid in the triplet, which generally causes improper folding of the triple helix. Severe and lethal forms of OI are the result of mutations in either COL1A1 or COL1A2 genes that disrupt the triple helix [16, 17, 15].
Ehlers-Danlos Syndrome (EDS) is caused by a collagen deficiency or a defective collagen structure. Most commonly, EDS is linked to the mutations of COL1A1, COL1A2, COL3A1, COL5A1, COL5A2, which affects collagen type I, III, and V. These mutations all affect fibrillar collagen required in the skin, tendons, and vascular system .
Many mechanisms and mutations can reduce collagen production and lead to EDS. There are at least 10 different subtypes of EDS .
Generally, all EDS patients share the same features of highly elastic skin, fragile skin, flexible joints, and easy bruising. EDS patients usually have unstable joints and are more prone to dislocations and chronic pain. Some forms of EDS are far more life-threatening, as patients may have an increased risk of rupturing blood vessels [19, 20].
Potential Benefits of Supplementation
Collagen supplements have not been approved by the FDA for medical use and generally lack solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing.
Possibly Effective For
1) Rheumatoid Arthritis and Osteoarthritis
In 60 patients with severe rheumatoid arthritis (RA), three months of chicken type II collagen reduced the number of swollen and tender joints compared to placebo (DB-RCT). Four patients in the collagen group saw all symptoms disappear and a halt in the progression of the disease .
A larger study of 274 RA patients found that multiple doses (20, 100, 500, and 2,500 μg) reduced swollen and tender joint counts .
A study of 52 patients with osteoarthritis found that 90 days of chicken type II collagen reduced symptoms of their conditions, decreased pain, and improved their ability to complete daily activities including walking up and down stairs .
In dogs with arthritis, type II collagen for 90 days reduced pain and increased physical activity .
2) Joint Health
A study of 147 athletes with joint pain found that collagen hydrolysate for 24 weeks significantly reduced their pain .
In another study of 139 athletes with knee pain, five grams a day of collagen peptides for 12 weeks reduced activity-related pain .
Insufficient Evidence For
The following purported benefits are only supported by limited, low-quality clinical studies. There is insufficient evidence to support the use of collagen supplements for any of the below-listed uses. Remember to speak with a doctor before taking collagen, and never use it to replace something your doctor recommends or prescribes.
3) Skin Health
The skin is the largest organ on the body, and collagen is one of its main components. As we age, collagen content decreases by 1% per year (per unit area of the skin surface). This decrease can be seen in the form of wrinkling, loosening, and sagging skin .
One study in 69 women found that daily collagen supplementation for eight weeks increased skin elasticity, an indicator of increased collagen .
Another study in 85 women found that eight weeks of collagen hydrolysates improved skin moisture, elasticity, wrinkles, and roughness (all signs of increased collagen) .
4) Hair Growth
In a study of 15 women with thinning hair, 180 days of collagen supplementation resulted in improvements in hair volume, scalp coverage, shine, and thickness. Skin moisture and smoothness also improved .
Topical administration of collagen may be beneficial for hair growth, as it can attach and penetrate into the outer layer (cuticle) of hair follicles and increase their thickness .
In addition to supplementing with collagen, you can also look for hair and skin care products containing collagen hydrolysate.
5) Blood Sugar
Normal blood sugar levels are between 70-130 mg/dL between meals and no greater than 180 mg/dL two hours after eating.
Fifty individuals who took collagen supplements for three months had lower blood sugar, blood pressure, cholesterol, and creatinine levels .
In order to manage blood glucose levels, doctors generally recommend diet and exercise. Individuals can also supplement their diet with collagen to reduce blood sugar and increase insulin levels .
In a study of 89 patients with bedsores (pressure ulcers), collagen hydrolysate supplementation three times a day for eight weeks improved the healing of bedsores .
Animal Research (Lacking Evidence)
No clinical evidence supports the use of collagen for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
7) Bone Density
Collagen is also a major component of bones. As we age, collagen production decreases in our bones, which decreases bone density. Individuals over the age of 70 have lower bone density and increased risk of injury.
Patients suffering from osteoporosis and porous bone disease lose bone more rapidly than normal.
Hydrolyzed collagen increased bone density in rats .
Hydrolyzed collagen also increased type I collagen in the bones of rats with osteoporosis .
Hydrolyzed collagen stimulates human cartilage-producing cells (chondrocytes) to make more extracellular matrix molecules, including collagen itself .
Factors That Decrease Collagen Production
1) UV Radiation
UV radiation activates several cell growth factors and cytokine receptors, which increases MMP (matrix metalloproteinase) production and decreases collagen type I production .
Exposure to the sun disrupts ECM stability due to decreased collagen production and increased breakdown of the extracellular matrix .
2) Vitamin C Deficiency
Vitamin C is required for the proper formation of collagen. Vitamin C deficiency can lead to scurvy. Scurvy is the result of malformed collagen in the ECM. This leads to degraded tissues and may eventually cause death [38, 39].
Smoking tobacco can decrease collagen production. Smokers produce 18% less collagen type I and 22% less collagen type III in their skin than non-smokers .
Matrix metalloproteinases (MMPs) are responsible for degrading matrix proteins like collagen. MMP-8 levels 2x greater for smokers than non-smokers, meaning the matrix proteins are degraded at a faster rate .
The tissue inhibitor of matrix metalloproteinases (TIMP-1), normally stops MMPs from degrading collagen. TIMP-1 levels are 14% lower in the skin of smokers .
By decreasing collagen production, smoking accelerates skin aging and impairs our body’s ability to repair wounds [40, 41].
One reason why smoking decreases collagen production may be that smokers go through and require more vitamin C than non-smokers do .
4) Stress and Lack of Sleep
It is well known that stress negatively impacts our health. Stress can indirectly lead to accelerated skin aging and poor wound healing by decreasing collagen integrity .
Lack of sleep causes stress and increases cortisol levels [44, 45, 46, 47].
Cortisol decreases collagen production and its ability to fold. This reduces the stability of collagen .
5) High Blood Sugar and Diabetes
Collagen is a long-lived protein (has a low biological turnover). Amino acids in collagen-like lysine and hydroxylysyl can accumulate sugars as we age. High blood sugar (hyperglycemia) makes collagen more susceptible to glucose accumulation [4, 49].
As we age, collagen becomes stiffer. Researchers can predict a person’s age by how well their collagen is digested in the laboratory. Individuals with diabetes generally show stiffer collagen .
Patients with high blood sugar have less enzymatic crosslinks between collagen strands, resulting in less stable collagen formation .
Sugars block the LOX enzyme from properly forming collagen .
Diabetics have increased levels of homocysteine, which also decreases the activity of the LOX enzyme. High sugar and homocysteine levels reduce the quality of collagen .
Sugar can also block receptors on collagen. When these receptors are blocked, then this makes them unrecognizable to the receptors. Due to this fact, diabetes can alter collagen-associated cell signaling and gene expression and cause the release of pro-inflammatory molecules and free radicals .
Factors that Increase Collagen Production
Some foods, supplements, and lifestyle strategies have been found to increase collagen production in animal and human studies. Your doctor can help you determine whether any such strategies are appropriate for you; do not under any circumstances use these strategies to replace something your doctor recommends or prescribes.
Many types of collagen supplements exist, but oftentimes they require multiple doses throughout the day. In the interest of supporting the body’s ability to produce its own collagen, several nutrients interact with and influence production, including:
- Vitamin C – is found in many fruits and vegetables. It is required for enzymes to hydroxylate collagen and form healthy cross-linked fibrils [38, 39].
- Lysine and proline – are found in lean meats like chicken and fish. They are the amino acids required to build stable tropocollagen helices .
- Vitamin B3 (niacin) – is also known as niacinamide and nicotinamide. Found in high concentrations in lean meat, peanuts, and mushrooms. It is a precursor to NAD/NADH, which can help stimulate collagen synthesis .
- Vitamin A – also known as retinol, is found in liver, eggs, and dairy products. It can reduce the activity of matrix metalloproteinase (MMPs) and increase collagen production .
2) Orthosilicic Acid
Silicon is a trace nutrient that is likely involved in collagen production. Silicon increases collagen production and the amount of an enzyme needed to make collagen (prolyl hydroxylase) in cartilage and bone cells .
A form of silicon called orthosilicic acid (OSA) increased type 1 collagen production in bone cells .
Rats deprived of silicon have decreased collagen production in wounds and bones .
OSA increased collagen levels in the skin of calves .
A study of 134 women with low bone density (osteopenia) low bone density or osteoporosis found that OSA supplementation for 12 months increased markers for type 1 collagen synthesis and bone mineral density in the femur .
Another study in women with sun-damaged skin found that OSA increased skin smoothness and reduced hair and nail brittleness, indicating increased collagen production .
Insufficient Evidence For
After exercise, there is an increase in the mRNAs coding for collagen types I, III, and IV. This indicates collagen production may be increased after exercise [60, 61].
Studies conducted with mice and rats show that concentrations of hydroxyproline and healthy collagen increase after exercise [62, 63].
4) Aloe Vera
Aloe Vera is a plant that is widely used in skin and hair products like lotions, ointments, and shampoos. Traditionally, aloe is used for reducing skin irritations like sunburns or other types of chaffing.
Aloe vera supplements can improve the wrinkling of the skin by increasing collagen production and decreasing collagen degradation. Patients who used aloe vera for 90 days showed an increase in collagen production and a decrease in MMP-1 gene activity .
Animal Research (Lacking Evidence)
No clinical evidence supports the approaches listed below to increase collagen. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
5) Royal Jelly
Royal Jelly (RJ) is secreted by the glands of honeybees. It contains many proteins, sugars, fats, vitamins, and minerals. RJ also contains unsaturated fatty acids that increase collagen production and decrease collagen degradation in rats (lowers MMP activity) .
One study found that rats who were fed a 1% supplement of RJ produced more collagen in their skin .
Collagen supplements generally come from cows, pigs, or fish. Most of these supplements are hydrolyzed, meaning that the bonds holding collagen strands together are broken.
Collagen tripeptide, collagen hydrolysate, gelatin, gelatin hydrolysate, and hydrolyzed gelatine are other names for hydrolyzed collagen. Hydrolyzed collagen peptides are smaller than normal collagen structures, which is theorized to allow the body to better absorb and use them.
Gelatin and collagen hydrolysate come from the same sources: skin and bones. There are two main differences between the two collagen supplements.
Firstly, the peptides are much smaller in hydrolyzed collagen than non-hydrolyzed gelatin. Unhydrolyzed or partially hydrolyzed gelatins have longer collagen peptides and do not dissolve well in water .
Secondly, hydrolyzed collagen is more easily digested and absorbed into the body. Large unhydrolyzed collagen peptides can only bind to the peptide transporter, PEPT1. Small peptides are able to bind with both PEPT1 and PEPT2 transporters, allowing hydrolyzed collagen to be digested and absorbed easier [66, 67, 68].
Side Effects & Safety
Collagen is considered extremely safe to consume, especially given that it is a simple animal protein that is present in some foods. There are no reported side effects from taking collagen itself; however, collagen obtained from fish sources may have a higher concentration of calcium [69, 28, 70].
Rarely, some people may develop an allergy to bovine collagen [71, 72].
Most people who have taken collagen report a good experience. They noticed a significant decrease in joint pain, increased flexibility, and faster hair and nail growth. There are a few negative experiences, but more often than not, the bad reviews seem to be due to a lack of effect rather than adverse side effects.