Collagen: What the Science Says

What is collagen?

The word “collagen” is derived from Greek words meaning “gum producing”. (32) Collagen is essentially the “glue” that holds our bodies together. Making up 25-30% of all protein content in the body, it is our primary structural protein and can be found in the extracellular matrix (ECM) and connective tissues, including bones, muscles, tendons, ligaments, cartilage, skin, the intestinal lining, blood vessels, dentin of teeth, and corneas. (31, 32, 33) In addition to providing structural integrity to the body (31, 32), collagen provides strength and elasticity to the skin and supports biological cell functions, tissues and organ development, healing of bones and blood vessels, and formation of the extracellular matrix. (32)

Collagen is made up of three polypeptide chains, each composed of 1050 amino acids, primarily glycine, proline, and hydroxyproline. (32) Currently, 28 different types of collagen exist. The five most common types include:

Type I collagen found in skin, bones, tendons, ligaments, teeth, and vascular ligature

Type II collagen found in cartilage, eyes (vitreous body), and vertebral discs (nucleus pulposus)

Type III collagen found in skin, muscles, blood vessels, and reticular fibres

Type IV collagen found in the basal lamina and the basement membrane (epithelium-secreted layer)

Type V collagen found in hair, placenta, corneas, bones, placenta, and cell surfaces (31, 32)

The main component of human skin and prevalent in most connective tissues, type I collagen makes up 90% of collagen in the body, followed by type II and type III. (31, 32)

What factors affect collagen levels in the body?

Several factors impacting collagen levels in the body have been identified. The following factors have been shown to impair collagen synthesis and/or accelerate its degradation.

  • Age
  • Excess stress
  • Autoimmune conditions (31)
  • Smoking (16)
  • Excess sun exposure (29)
  • High sugar intake (6)
  • Nutrient deficiencies (i.e., Vitamin C) (27)

What are the benefits of collagen?

Collagen has been shown to have anti-inflammatory and antioxidant properties. In addition to its’ own antioxidant activities, collagen hydrolysates may support the activities of other antioxidant enzymes, such as superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and chloramphenicol acetyltransferase (CAT). There is also a significant body of research supporting the use of collagen in a number of different conditions. Collagen helps to support skin, nail, bone, joint, and cardiometabolic health. (33) Collagen peptides may also support weight loss and maintenance of a healthy weight. (31)

Skin & Nail Health

Skin aging

Skin, the largest organ is the body, is primarily composed of collagen, elastin, and hyaluronic acid. These components help to maintain skin structure and hydration. Studies have shown that collagen peptides, which can be absorbed into the dermis of the skin, can improve skin health and aging by increasing the number and diameter of collagen and elastin fibres, stimulating fibroblast proliferation and motility, and increasing production of hyaluronic acid. (1, 31) Several studies have noted improvements in the signs and symptoms of skin aging following collagen supplementation, including improvements in skin hydration, elasticity, wrinkling, and dermal collagen density. (4) A double-blind, placebo-controlled study found that administration of 2.5 g daily of bioactive collagen peptides (BCP) reduced eye wrinkle volume. BCP also increased procollagen type I by 65% and elastin by 18% after eight weeks. (23) Another study found that 1000 mg of low-molecular-weight collagen peptide composed of 3% Gly-Pro-Hyp administered daily over 12 weeks improved skin hydration, elasticity, and wrinkling. (13) Furthermore, it appears that composition of peptides may impact the beneficial effects of collagen supplementation. A randomised double-blind, placebo-controlled study compared the effects of two forms of collagen hydrolysates with different compositions of bioactive dipeptides Pro-Hyp and Hyp-Gly. While results were significant in both treatment groups, greater improvements in skin wrinkles, hydration, and elasticity were seen with the higher content of Pro-Hyp and Hyp-Gly. (12)

Pressure ulcers

Collagen supplementation has been shown to be an effective treatment for pressure ulcers, also known as bedsores, which generally occur over bony prominences as a result of long periods of pressure. An eight-week randomized, prospective, controlled, multicenter trial found that long-term care residents receiving collagen protein hydrolysate demonstrated better Pressure Ulcer Scale for Healing (PUSH) scores compared to residents receiving standard care. (17) Another study noted that healing of ulcers treated with topical collagen over eight weeks was comparable to topical hydrocolloid treatment. (9)

Cellulite

Collagen may also be effective in improving cellulite. A double blind, placebo-controlled study examined the effects of specific bioactive collagen peptides (BCP) on cellulite in 105 women aged 24 to 50 years. Over the course of six months, subjects received 2.5 g of BCP daily or a placebo. BCP treatment resulted in significant improvements in cellulite, skin waviness on thighs, dermal density, and length of subcutaneous borderline in both normal and overweight women, however, the results were more pronounced in normal weight women. (28)

Brittle nail syndrome

Commonly occuring in women, brittle nail syndrome is characterized by rough, ragged, and peeling nails. Collagen may improve these symptoms and accelerate growth of nails. One study examined the effects of 2.5 g daily of specific bioactive collagen peptides (BCP) for 24 weeks. Treatment with BCP decreased the frequency of broken nails by 42% and accelerated growth rate by 12%, (11) indicating that collagen peptide supplementation may be an effective treatment for brittle nail syndrome.

Bone & Joint Health

Bone density and osteoporosis

A systematic review on the therapeutic effects of collagen hydrolysate noted positive effects on both osteoporosis and osteoarthritis. Collagen hydrolysate was found to offer protective effects on articular cartilage, improve bone mineral density, and relieve pain. (21) A placebo-controlled study examined the effects of collagen supplementation in postmenopausal women with primary, age-related bone mineral density reductions. A 5 g dosage of specific collagen peptides administered daily over 12 months improved bone mineral density as a result of increased formation and reduced degradation of bones. (14)

Osteoarthritis (OA)

Several other studies have shown that collagen supplementation is effective in improving symptoms of osteoarthritis. (8) A randomized, double-blind, placebo-controlled study of 250 subjects with primary knee osteoarthritis examined the effects of 10 g of collagen hydrolysates per day over six months. Improvements in joint comfort were noted. The most significant results were noted in individuals with the greatest joint deterioration and those with lower intakes of meat. (2) Another study compared the use of undenatured type II collagen (UC-II) with glucosamine and chondroitin in knee osteoarthritis treatment. After 90 days, UC-II was determined a more effective treatment demonstrated by significantly greater improvements in a number of osteoarthritic measures, including WOMAC, VAS, and Lequesne’s functional index scores. (5)

Rheumatoid arthritis (RA)

Collagen has also been found to improve rheumatoid arthritis-related joint pain. A study compared the effects and safety of chicken-derived type II collagen with methotrexate, an immunosuppressant drug often used in the treatment of rheumatoid arthritis. Results demonstrated that both collagen and methotrexate treatment groups showed statistically significant improvements in pain, stiffness, and swelling. The research also notes the added benefit of collagen treatment due to the lower incidence of adverse events compared to methotrexate. (34) Furthermore, studies also suggest that the therapeutic effect of collagen supplementation involves immune system regulation in individuals with RA. Clinical trials have demonstrated reductions in anti-collagen antibody titres , rheumatoid factor, and TNF-alpha (7) following administration of bovine type II collagen.

Joint pain & exercise

Various forms of collagen supplementation has been found not only to improve joint pain in individuals with osteoarthritis and rheumatoid arthritis, but also in healthy individuals without history of arthritis or joint pain. In one study, 60 healthy, postmenopausal women were given 500 mg of natural eggshell membrane (NEM) daily or a placebo to determine the effects on exercise-induced joint pain or stiffness and cartilage turnover. The study found that NEM improved joint pain and stiffness following exercise. Decreases in cartilage degradation was also noted, indicating a chondroprotective effect. (25) Similarly, another randomized, double-blind, placebo-controlled study found that 40 mg of UC-II administered daily improved knee extension and joint discomfort during exercise in healthy individuals. (19) Collagen supplementation may also improve collagen synthesis, contributing to tissue repair and injury prevention. In a randomized, double-blind trial, vitamin C–enriched gelatin taken before exercise increased synthesis of collagen demonstrated by higher circulating levels the amino acids glycine, proline, hydroxyproline, and hydroxylysine. (30)

Cardiometabolic Health

Type II diabetes  

Studies have shown that marine collagen peptide supplementation may be effective in improving metabolic markers in patients with type II diabetes. A randomized, placebo-controlled study of 100 type II diabetic patients examined the effects of marine collagen peptides (MCPs) on glucose and lipid metabolism. Results demonstrated reductions in fasting blood glucose and blood insulin, human glycated hemoglobin A1c, low-density lipoprotein (LDL), total triglycerides, total cholesterol, free fatty acids, high-sensitivity C-reactive protein (hs-CRP), and nitric oxide (NO). Increased insulin sensitivity index, high-density lipoprotein (HDL), bradykinin, prostaglandin I2 (PGI2), and adiponectin were also noted. (36) Another similar study found that MCP treatment in diabetics decreased free fatty acid, hs-CRP, resistin, leptin, NO, and prostacyclin, while the treatment increased adiponectin and bradykinin. The study concluded that MCPs may offer protective effects against both type II diabetes and hypertension. (35)

Hypertension

Studies examining the effects of chicken collagen hydrolysate (CCH) supplementation have demonstrated anti-hypertensive effects. A study of fifteen mildly hypertensive patients found that CCH significantly improved blood pressure and reduced plasma renin activity after four weeks. (26) A second placebo-controlled study found that CCH supplementation had modulatory effects on circulation, marked by improvements in arterial stiffness, vascular damage, and blood pressure. (15)

For more information on the clinical applications of collagen, including dosing and administration, see the collagen reference sheet.

How can we increase collagen levels in the body?

Bone broth

Rich in collagen and many other beneficial nutrients, bone broth may be one of the best ways to get more collagen through the diet. It can be made at home from bones of your choice, such as beef, chicken, turkey, and fish. Simmering bones over a long period of time extracts collagen in the form of gelatin. If you’ve ever made homemade bone broth, you may have noticed that, as the broth cools, a layer of gelatin forms at the top. For instructions and helpful tips on how to make homemade bone broth, download a guide to collagen.

Collagen-boosting nutrients

Another way to increase collagen in the body is by increasing intake of collagen-boosting nutrients. There are several nutrients that provide the building blocks and support the synthesis of collagen in the body. The top nutrients for collagen formation are summarized below.

Dietary supplements

Research has shown that supplemental collagen can be beneficial for several different health conditions, as summarized above. Collagen supplements may be derived from a number of different animal sources, including beef, chicken, pork (32), and eggshell membrane. (25) Marine-derived collagen has become increasingly popular for environmental, ethical, and health reasons. Marine-derived collagen is considered less allergenic, therefore less likely to trigger an inflammatory response, and there are no concerns over potential contamination with zoonoses such as BSE, TSE and FMD as there are with bovine and porcine sources. (32) Look for “sustainable”, “grass-fed”, “pasture-raised”, and/or “free-range” to ensure supplements come from the best quality sources.

The quality of collagen supplements may also depend on its form, which affects its molecular size and ability to be absorbed. (31) During the manufacturing process, collagen can be extracted from materials like skin, bones, tendons, ligaments, and cartilage using hot water to form gelatin. Gelatin is then broken down by a process called hydrolyzation, which converts gelatin to collagen hydrolysate, a form of collagen often seen in dietary supplements. (33) Collagen hydrolysate is composed of small collagen peptides with low molecular weight, increasing absorption and bioavailability. (31) When it comes to prescribing supplemental collagen, be sure to consider quality and form to ensure optimal absorption and results.

More collagen resources

For more information on the clinical applications of collagen, including dosing and administration, see the collagen reference sheet.

For an overview of collagen and instructions to make homemade bone broth, download a patient guide to collagen.

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