Collagen, a primary protein, forms the foundation of various structural supportive connective tissues in our body, including skin, bones, ligaments, tendons, and muscles. It is composed of protein fibrils arranged in a robust triple helical structure, making up over 70% of the dry weight of human skin.
There are numerous identified collagen types. In the dermis, Type I collagen is predominant, lending skin its tensile strength. Fetal skin primarily contains Type III collagen. Types IV and VII are crucial in the skin’s basement membrane zone.
Collagen production occurs in the skin’s dermal fibroblasts. These fibroblasts assemble amino acids into sequences of either glycine-proline-X or glycine-X-hydroxyproline. In collagen, every third amino acid is glycine, and 20% are either proline or hydroxyproline, with X representing any other amino acid. The small size of glycine allows the alpha chains of the protein to form a tight helical configuration. Hydroxylase enzymes, using vitamin C as a cofactor, add hydroxyl groups to proline and lysine. Collagen uniquely contains hydroxyproline. The process of glycosylation attaches glucose and galactose moieties to selected lysine hydroxyl groups. Outside fibroblasts, collagen propeptides are trimmed into tropocollagen molecules, which further undergo a crosslinking process facilitated by the enzyme lysyl oxidase, enhancing the tensile strength of the collagen fibril.
Collagen is subject to continuous turnover, breaking down due to oxidative cell damage and normal metabolic processes involving collagenase. An imbalance between collagen production and degradation leads to reduced tensile strength and wrinkle formation. Factors accelerating collagen degradation include poor nutrition and excessive sun exposure. Conditions like scurvy or genetic mutations in Ehlers-Danlos syndrome and osteogenesis imperfecta can lead to collagen construction errors.
Collagen-rich foods, once ingested, break down into 2–3 amino acid oligopeptides (collagen hydrosylates) in the gastrointestinal tract. These oligopeptides and amino acids are absorbed into the bloodstream, aiding in protein construction. Hydroxyproline, unique to collagen, can be utilized in any connective tissue, not just skin.
Skin aging involves a decrease in collagen synthesis and an increase in its degradation. Young skin’s three-dimensional collagen fibril arrangement progressively flattens, and the collagen bundles thin, fragment, and clump with age. External factors like UV light, pollution, smoking, and poor nutrition exacerbate these changes, leading to skin dryness and wrinkles.
As we age, genetic factors dictate the rate and visible signs of skin aging. Sun exposure and diet are two controllable extrinsic factors affecting visible skin aging. Starting sun protection measures early offers maximum benefits, but starting in adulthood can still slow skin aging. Wearing UPF 50+ clothing and broad-brimmed hats reduces UV-induced collagen breakdown in the skin.
For skin health, a balanced diet is essential, especially as we age and our efficiency in absorbing and utilizing essential nutrients diminishes. A ‘Mediterranean-style diet’, rich in plant-based foods, fresh fruits, vegetables, herbs, nuts, beans, whole grains, moderate seafood, dairy, poultry, eggs, and occasionally red meat, promotes good skin health.
