Collagen is the most abundant protein in the human body—it makes up about a third of all the body's proteins. Found in skin, cartilage, bones, tendons, and ligaments, it ensures their cohesion, strength, and elasticity. But starting at age 25, its production decreases by about 1% per year. By age 40, this decline accelerates. Wrinkles, loss of firmness, and joint stiffness are the visible consequences of a progressive collagen deficiency. Here's what science says about supplementation.
How does collagen work in the body?
There are several types of collagen, each with distinct functions. Type I collagen is the most abundant in the body: found primarily in the skin, tendons, and bones, it contributes to skin firmness and elasticity. Type II collagen is mainly located in articular cartilage, where it provides flexibility and shock absorption to the joints.
When collagen is taken as a dietary supplement, the hydrolyzed collagen peptides—small fragments—are absorbed by the intestines and transported to target tissues. There, they stimulate specialized cells (fibroblasts in the skin, chondrocytes in cartilage) to produce new endogenous collagen, thus improving tissue structure from within. To understand how skin structures and renews itself, our article "Understanding Skin" explains these mechanisms in detail.
Marine, animal or plant collagen: which source to choose?
Marine collagen (derived from fish cartilage or skin) has the highest bioavailability of all sources. Its low molecular weight allows it to be absorbed more efficiently by the intestines, requiring lower doses (1 to 2 g/day) for an equivalent effect. Rich in glycine, proline, and hydroxyproline—the amino acids that form the structure of collagen—it benefits both skin and joints.
Animal collagen (bovine or porcine) is predominantly type I. Effective on the skin, it requires higher doses (5 to 10 g/day) and sometimes raises traceability issues depending on the origin of the farms.
The term "plant collagen" is a misnomer: plants do not synthesize collagen. These are plant-based complexes (algae, legumes) that provide precursors (amino acids, vitamin C) to stimulate endogenous production. This is a suitable option for vegetarians and vegans, but it lacks the direct structural action comparable to animal or marine collagen.
The benefits of collagen documented by science
Skin: wrinkles, firmness and hydration
This is the most studied benefit. Several double-blind clinical trials show that supplementation with hydrolyzed collagen peptides improves skin elasticity, reduces wrinkle depth, and increases skin hydration after 8 to 12 weeks. A meta-analysis published in the Journal of Cosmetic Dermatology (2021) confirmed these effects in 1,125 participants. The results are even more pronounced after age 40, when natural collagen production has significantly decreased. For a comprehensive guide on maintaining healthy skin, our article "5 Tips for Beautiful Skin" complements these approaches. And to specifically target wrinkles, our article "How to Prevent Wrinkles" presents all the available strategies.
Joints: mobility and comfort
Type II collagen supports articular cartilage. Clinical studies have shown that supplementation reduces joint pain and improves mobility in people with osteoarthritis or activity-related joint discomfort. A 2018 review published in Nutrients confirms a significant reduction in pain after three months of supplementation. To complement this approach, our article on natural remedies for joint pain offers other well-documented suggestions.
Bones, tendons and side effects
Collagen contributes to bone strength (it makes up 90% of the organic matrix of bones) and tendon resistance. Users report beneficial side effects such as stronger nails and thicker hair. Since collagen synthesis also plays a role in intestinal integrity, some studies are exploring its impact on intestinal permeability, but the data remains preliminary.
How to optimize your collagen treatment
Vitamin C is an essential cofactor for the body's own collagen synthesis: without it, the enzymes responsible for collagen production cannot function properly. Combine your supplementation with a diet rich in vitamin C (kiwi, citrus fruits, bell peppers) or with a targeted supplement to enhance its effects.
Consistency is more important than dosage : moderate daily doses (1 to 2 g of highly bioavailable marine collagen) for 3 months are more effective than large doses taken irregularly. The body needs time to remodel its tissues—the first joint effects generally appear after 4 weeks, and skin effects after 8 to 12 weeks.
A healthy lifestyle amplifies the results: sufficient sleep (during which the skin regenerates), hydration (1.5 to 2 liters of water per day), moderate physical activity (which stimulates cartilage renewal) and limiting tobacco and alcohol (which degrade existing collagen fibers).
To choose a quality supplement, check the traceability of the source, the hydrolysis process (enzymatic, solvent-free), and the presence of published clinical studies on the active ingredient. Cartidyss® collagen, derived from Breton skate cartilage, is one of the few marine ingredients with double-blind clinical studies demonstrating its effects at low doses (500 mg to 1 g/day) on the skin and joints.
Precautions and contraindications
Collagen is well tolerated in the vast majority of cases. People allergic to fish or shellfish should avoid marine collagen. As a precaution, pregnant or breastfeeding women and children under 18 should seek medical advice before taking any supplements. If you are taking medication (anticoagulants, anti-inflammatories), consult your doctor. Mild digestive upset is rarely reported in some sensitive individuals.
Frequently Asked Questions about Collagen
At what age is it beneficial to take collagen?
Collagen production begins to decline as early as age 25, but the effects are generally only noticeable from age 35-40. Preventive supplementation can be considered from age 30 for people exposed to factors that accelerate collagen breakdown (smoking, intense sun exposure, a diet low in protein). For most people, age 40 is when supplementation becomes most relevant.
Is collagen powder as effective as collagen capsules?
The form (powder, capsules, liquid) does not significantly influence the bioavailability of collagen—what matters is the quality of the hydrolyzed collagen and its molecular weight. Capsules offer precise dosing and greater convenience. Powders can be incorporated into smoothies or drinks, but often require larger doses and use less bioavailable sources.
Can dietary collagen (bone broth, fish) replace supplementation?
Foods rich in native collagen (bone broth, chicken skin, fish, organ meats) provide precursor amino acids but not directly the active peptides found in hydrolyzed supplements. Diet remains the foundation, but for a clinically documented effect on skin and joints, supplementation with highly bioavailable hydrolyzed collagen remains the best-studied approach.