Collagen is a fibrous, supportive protein that is the main component that makes up bones, skin, muscles, cartilage, tendons, and ligaments. Several types of collagen are found in different organs and tissues. All collagens are protein molecules, composed of chains of amino acids. Types differ by the length of the chains and how the chins are twisted together to form helices. Type I collagen is found in skin, tendons, bones, teeth, and fibrous cartilage; Type II is found in elastic cartilage and joints; Type III is found in skin and blood vessels; and Type IV is found in kidneys, ears, and eyes. One of the important functions of collagen is to provide strength and elasticity to the skin. Types I and III are of greatest interest when it comes to skin care.
Collagen production decreases as we age, giving rise to wrinkled and sagging skin that disturbs many middle-agers as they contemplate their reflection in a mirror. Collagen supplements, reputed to be the 鈥淔ountain of Youth,鈥� promise to reverse skin aging and are often promoted with stories about Chinese women historically relying on eating pig鈥檚 feet, shark fins and donkey skin to smooth wrinkles. Not exactly hard science.
Oral collagen supplements are typically sold in the form of pills and powders and may be sold under various names such as collagen hydrolysate, hydrolyzed collagen, or collagen peptides. They claim to improve the elasticity and appearance of the skin. There is a lack of large, long-term clinical trials but some small studies have shown benefit. However, potential conflicts of interest cloud much of the research on collagen supplements making the drawing of conclusions difficult. There is also the nagging problem of digestion. Proteins are generally broken down into smaller peptides during digestion making it unlikely for collagen to be absorbed intact. But the possibility that the body then reassembles these fragments into functional collagen in the skin cannot be ruled out.
There is no great risk in giving oral collagen supplements a try but there are a few things to keep in mind. While collagen supplements are generally well-tolerated by most people, with few side effects, such as nausea, bloating, heartburn, and feeling of fullness, they are not trouble free. Since they can be made with ingredients derived from fish, shellfish or eggs, supplements can pose a problem for allergy sufferers.
Although collagen is mainly sourced from animals, there is a technique to produce vegan collagen using genetically engineered P. pastoris bacteria.
All in all, oral collagen supplements tend to be expensive and are supported more by anecdotes than solid research. Topical retinoids in the form of creams, lotions or gels have a better scientific record.
鈥淩etinoids鈥� are a group of compounds, either naturally occurring or synthetic, that have vitamin A activity. Vitamin A promotes collagen formation and application to the skin has been shown to reduce wrinkles, fine lines and age spots. The most effective product is 鈥淩etin-A鈥� (also known as tretinoin or all-trans retinoic acid), available only by prescription. Over-the-counter (OTC) retinoids usually contain retinyl palmitate which gets converted in the skin to all-trans retinoic acid. Since this conversion is spotty, OTC products are not as effective as prescription medications but are less likely to cause red or itchy skin, the classic retinoid side effects.
But prevention is always better than treatment. To maintain a healthy complexion, eat a balanced diet, get enough sleep, try to manage stress and don鈥檛 smoke. Above all, use a sunscreen to prevent photoaging. Remember Rudyard Kipling鈥檚 little ditty that 鈥渙nly mad dogs and Englishmen go out in the noon-day sun.鈥�
K. Coco Zhang is a third-year dietetics student at 成人VR视频
