Collagen

What is collagen and why does it matter?

Collagen is the most abundant protein in the human body, making up about 30% of total protein mass. It forms the structural framework of skin, bones, tendons, ligaments, cartilage, and blood vessels. The name comes from the Greek word "kolla," meaning glue, and that's essentially what collagen does: it holds tissues together. Starting in your mid-twenties, collagen production drops by roughly 1-1.5% per year. After menopause, that decline accelerates sharply because estrogen directly stimulates collagen synthesis ^[1]. The visible consequences are familiar: thinner skin, stiffer joints, weaker bones, and slower wound healing.

Collagen types: I, II, and III

Scientists have identified at least 28 types of collagen, but three account for the vast majority in the human body. Type I is the most common. It provides tensile strength to skin, bones, tendons, and organs, and is stronger than steel on a per-weight basis. Type II is the main structural protein in articular cartilage, providing the cushioning that protects joints during movement. Type III typically occurs alongside Type I in skin, blood vessels, and internal organs, contributing to elasticity. These distinctions matter when choosing supplements: joint protocols typically use Type II (often as undenatured collagen, or UC-II), while skin and anti-aging protocols focus on Types I and III as hydrolyzed peptides ^[2].

Collagen peptide supplements: what the evidence says

Hydrolyzed collagen peptides are collagen broken down enzymatically into small di- and tripeptides of 3-6 kDa. These are absorbed efficiently through the gut and distributed throughout the body. A 2024 meta-analysis of 26 randomized controlled trials with 1,721 participants found that collagen peptide supplementation significantly improved skin hydration, elasticity, and wrinkle depth after 8 weeks of consistent use ^[3]. However, a 2025 meta-analysis of 23 RCTs raised an important caveat: studies funded by supplement companies showed significant skin benefits, while independently funded studies did not ^[4]. This doesn't mean collagen peptides are useless, but it does mean the effect sizes may be smaller than marketing suggests.

The mechanism isn't just about supplying raw materials. Specific peptides like prolyl-hydroxyproline (Pro-Hyp) and hydroxyprolyl-glycine (Hyp-Gly) act as signaling molecules that stimulate fibroblasts to ramp up endogenous collagen production, hyaluronic acid synthesis, and elastin formation ^[5]. A 2025 clinical trial even found that a collagen amino acid supplement reduced biological age by 1.4 years over six months ^[6].

Collagen supplements for joints and bones

Joint health is where collagen supplementation may have its strongest evidence base. A 2024 meta-analysis of 11 RCTs with 870 participants found significant improvements in both pain and function scores for osteoarthritis patients taking collagen ^[7]. A separate trial sequential meta-analysis of 35 RCTs (3,165 patients) confirmed small-to-moderate effects on pain relief ^[5]. Undenatured type II collagen (UC-II) works differently from hydrolyzed peptides. Rather than providing building blocks, it modulates the immune system through oral tolerance, reducing inflammatory attacks on joint cartilage.

For bones, collagen peptide supplementation combined with calcium and vitamin D has shown improvements in bone mineral density at the femoral neck and spine, along with favorable changes in bone turnover markers ^[8]. A 2024 meta-analysis also found that collagen peptides can increase fat-free mass when combined with resistance training ^[9].

How to support your own collagen production

Vitamin C is non-negotiable for collagen synthesis. It hydroxylates proline and lysine residues in procollagen, a step without which collagen fibers can't cross-link properly. A systematic review confirmed that vitamin C supplementation produces a dose-dependent increase in type I collagen synthesis ^[10]. Glycine and proline are the dominant amino acids in collagen, and supplemental glycine (3-5 grams daily) can help, since modern diets often fall short. Copper is another key cofactor, required by the enzyme lysyl oxidase for collagen cross-linking. Zinc, silicon, and manganese support collagen metabolism as well.

What destroys collagen

• UV radiation is the single biggest external driver of collagen breakdown in skin. Daily broad-spectrum sunscreen is the most effective anti-aging measure you can take
• Smoking accelerates collagen degradation by activating matrix metalloproteinases (MMPs) and restricting blood flow to the skin
• Excess sugar intake creates advanced glycation end products (AGEs) that stiffen collagen fibers and make them brittle
• Poor sleep reduces growth hormone secretion, which the body needs for tissue repair and collagen synthesis overnight

Downsides and safety

Collagen supplements are generally well tolerated. The most common complaints are mild digestive issues like bloating or an unpleasant aftertaste. People with fish or shellfish allergies should avoid marine collagen, and those with beef sensitivities should skip bovine sources. There's also the contamination question: since collagen is derived from animal tissues, quality control matters. Look for products tested by third parties for heavy metals and other contaminants. There are no official dosage guidelines, but most studies use 2.5-15 grams of hydrolyzed peptides daily, with 5-10 grams being the most common range ^[3].